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From AppSecEU 2015 in Amsterdam https://2015.appsec.eu/ Frederik Braun Using A JavaScript CDN That Can Not XSS You - With Subresource Integrity You can download all Videos at https://www.its.fh-muenster.de/owasp-appseceu/2015/ ⇩ - Managed by the official OWASP Media Project https://www.owasp.org/index.php/OWASP_Media_Project Source: https://www.youtube.com/watch?v=K8ws8qxBJqg Uploader: OWASP

It is a time-honored fashion to implement a domain-specific language (DSL) by translation to a general-purpose language. Such an implementation is more portable, but an unidiomatic translation jeopardizes performance because, in practice, language implementations favor the common cases. This tension arises especially when the domain calls for complex control structures. We illustrate this tension by revisiting Landin's original correspondence between Algol and Church's lambda-notation. We translate domain-specific programs with lexically scoped jumps to JavaScript. Our translation produces the same block structure and binding structure as in the source program, a la Abdali. The target code uses a control operator in direct style, a la Landin. In fact, the control operator used is almost Landin's J---hence our title. Our translation thus complements a continuation-passing translation a la Steele. These two extreme translations require JavaScript implementations to cater either for first-class continuations, as Rhino does, or for proper tail recursion. Less extreme translations should emit more idiomatic control-flow instructions such as for, break, and throw. The present experiment leads us to conclude that translations should preserve not just the data structures and the block structure of a source program, but also its control structure. We thus identify a new class of use cases for control structures in JavaScript, namely the idiomatic translation of control structures from DSLs. ©2009 Microsoft Corporation. All rights reserved.

It's pretty easy to make use of an add on API using the maps Javascript API - today we'll look at a simple example

Linux Audio Conference 2014 Paper: From Faust to Web Audio: Compiling Faust to JavaScript using Emscripten Myles Borins The Web Audio API is a platform for doing audio synthesis in the browser. Currently it has a number of natively compiled audio nodes capable of doing advanced synthesis. One of the available nodes the "JavaScriptNode" allows individuals to create their own custom unit generators in pure JavaScript. The Faust project, developed at Grame CNCM, consists of both a language and a compiler and allows individuals to deploy a signal processor to various languages and platforms. This paper examines a technology stack that allows for Faust to be compiled to highly optimized JavaScript unit generators that synthesize sound using the Web Audio API. Original URL: http://lac.linuxaudio.org/2014/video.php?id=21

Javascript has become widely popular for developing hybrid mobile technologies by the advent of tools like Phonegap, Kony, Telerik App Builder. In this talk, I will demo how to create a Hybrid Mobile app using Javascript - AngularJS & Ionic Framework.

HTML provides a platform-independent way of creating and making multimedia presentations for classroom instruction and making that content available on the Internet. However, time in class is very valuable, so that any way to automate or otherwise assist the presenter in Web page navigation during class can save valuable seconds. This paper describes the use of frames and JavaScript in conjunction with VGA/TV project systems to automate teacher-side Web page navigation for classroom presentations. The methods used are not visually distracting to the students during class, do not require Web server support or an Internet connection (i.e., they can be used with only local hard drive access), and can be used independently of the student-side Web page access so that students who may or may not have browsers that support the features used on the teacher side can still access the content of those pages. (Author/AEF)

The Chromium Projects Home Chromium ChromiumOS Quick links Report bugs Discuss Other sites Chromium Blog Google Chrome Extensions Except as otherwise  noted , the content of this page is licensed under a  Creative Commons Attribution 2.5 license , and examples are licensed under the  BSD License . Privacy Edit this page For Developers  >  How-Tos  > Debugging Chromium on Windows First see  get the code  for checkout and build instructions. Getting started You can use Visual Studio's built-in debugger or  WinDBG  to debug Chromium. You don't need to use the IDE to build in order to use the debugger: autoninja is used to build Chromium and most developers invoke it from a command prompt, and then open the IDE for debugging as necessary. To start debugging an already-built executable with Visual Studio just launch Visual Studio (2019 or higher) and select File-> Open-> Project/Solution (Ctrl+Shift+O) and select the executable of interest. This will create a solution with that executable as the 'project'. You can then launch the debugger with F5 or F11 or from the Debug menu. If you right-click on the executable in Solution Explorer and select properties then you can edit things such as the executable path, command-line arguments, and working directory. You can add additional executables to the solution by using File-> Add-> Existing Project and selecting another already-built executable. You can select which one to debug by right-clicking on one of them in Solution Explorer and selecting Set as Startup Project. When your solution file is customized to your taste you can save it to a directory such as out\solutions. Saving it there helps ensure that relative paths to source files, printed from build commands, will correctly identify the source files. The Tools menu can be used to add commands to do things like invoke autoninja to build Chrome, compile the selected source file, or other things. Visual Studio 2017 is not recommended for debugging of Chromium - use a newer version for best performance and stability. symbol_level=2  is the default on Windows and gives full debugging information with types, locals, globals, function names, and source/line information.  symbol_level=1  creates smaller PDBs with just function names, and source/line information - source-level debugging is still supported (new from June 2019), but local variables and type information are missing.  symbol_level=0  gives extremely limited debugging abilities, mostly just viewing call stacks when Chromium crashes. Browsing source code If you use a solution file generated by gn ( gn gen --ide=vs ) then Intellisense may help you navigate the code. If this doesn't work or if you use a solution created as above then you may want to install  VsChromium  to help navigate the code, as well as using  https://source.chromium.org . Profiles It's a good idea to use a different Chrome profile for your debugging. If you are debugging Google Chrome branded builds, or use a Chromium build as your primary browser, the profiles can collide so you can't run both at once, and your stable browser might see profile versions from the future (Google Chrome and Chromium use different profile directories by default so won't collide). Use the command-line option: --user-data-dir =C:\tmp\my_debug_profile (replace the path as necessary) Using the IDE, go to the  Debugging  tab of the properties of the chrome project, and set the  Command Arguments. Chrome debug log Enable Chrome debug logging to a file by passing  --enable-logging --v=1  command-line flags at startup. Debug builds place the  chrome_debug.log  file in the  out\Debug  directory. Release builds place the file in the top level of the user data Chromium app directory, which is OS-version-dependent. For more information, see  logging  and  user data directory  details. Symbol server If you are debugging official Google Chrome release builds, use the symbol server: https://chromium-browser-symsrv.commondatastorage.googleapis.com In Visual Studio, this goes in  Tools > Options  under  Debugging > Symbols . You should set up a local cache in a empty directory on your computer. In windbg you can add this to your symbol server search path with the command below, where C:\symbols is a local cache directory: .sympath+ SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Alternately, You can set the _NT_SYMBOL_PATH environment variable to include both the Microsoft and Google symbol servers - VS, windbg, and other tools should both respect this environment variable: _NT_SYMBOL_PATH =SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols ;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Note that symbol servers will let the debuggers download both the PE files (DLLs and EXEs) and the PDB files. Chrome often loads third party libraries and partial symbols for some of these are also public. For example: AMD : https://download.amd.com/dir/bin Nvidia : https://driver-symbols.nvidia.com/ Intel : https://software.intel.com/sites/downloads/symbols/ For example, for completeness, the following symbol server environment variable will resolve all of the above sources - but this is more than is normally needed: _NT_SYMBOL_PATH=SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com;SRV\*C:\symbols\*https://download.amd.com/dir/bin;SRV\*C:\symbols\*https://driver-symbols.nvidia.com/;SRV\*C:\symbols\*https://software.intel.com/sites/downloads/symbols/ Source indexing You should set up source indexing in your debugger ( .srcfix  in windbg, Tools-> Options-> Debugging-> General->  Enable source server support  in Visual Studio) so that the correct source files will automatically be downloaded based on information in the downloaded symbols. Additionally, you must have  python  in your  path  in order for the  command that fetches source files  to succeed; launching the debugger from the same environment as where you build Chromium is an easy way to ensure it's present. This is highly recommended when debugging released Google Chrome builds or looking at crash dumps. Having the correct version of the source files automatically show up saves significant time so you should definitely set this. Multi-process issues Chromium can be challenging to debug because of its  multi-process architecture . When you select  Run  in the debugger, only the main browser process will be debugged. The code that actually renders web pages (the Renderer) and the plugins will be in separate processes that's not (yet!) being debugged. The  ProcessExplorer  tool has a process tree view where you can see how these processes are related. You can also get the process IDs associated with each tab from the Chrome Task Manager (right-click on an empty area of the window title bar to open). Automatically attach to child processes There are two Visual Studio extensions that enable the debugger to automatically attach to all Chrome processes, so you can debug all of Chrome at once. Microsoft's  Child Process Debugging Power Tool  is a standalone extension for this, and  VsChromium  is another option that bundles many other additional features. In addition to installing one of these extensions, you  must  run Visual Studio as Administrator, or it will silently fail to attach to some of Chrome's child processes. Single-process mode One way to debug issues is to run Chromium in single-process mode. This will allow you to see the entire state of the program without extra work (although it will still have many threads). To use single-process mode, add the command-line flag --single-process This approach isn't perfect because some problems won't manifest themselves in this mode and some features don't work and worker threads are still spawned into new processes. Manually attaching to a child process You can attach to the running child processes with the debugger. Select  Tools > Attach to Process  and click the  chrome.exe  process you want to attach to. Before attaching, make sure you have selected only Native code when attaching to the process This is done by clicking Select... in the Attach to Process window and only checking Native. If you forget this, it may attempt to attach in "WebKit" mode to debug JavaScript, and you'll get an error message "An operation is not legal in the current state." You can now debug the two processes as if they were one. When you are debugging multiple processes, open the  Debug > Windows > Processes  window to switch between them. Sometimes you are debugging something that only happens on startup, and want to see the child process as soon as it starts. Use: --renderer-startup-dialog --no-sandbox You have to disable the sandbox or the dialog box will be prohibited from showing. When the dialog appears, visit Tools > Attach to Process and attach to the process showing the Renderer startup dialog. Now you're debugging in the renderer and can continue execution by pressing OK in the dialog. Startup dialogs also exist for other child process types:  --gpu-startup-dialog ,  --ppapi-startup-dialog ,  --utility-startup-dialog ,  --plugin-startup-dialog  (for NPAPI). For utilities, you can add a service type  --utility-startup-dialog=data_decoder.mojom.DataDecoderService . You can also try  the vs-chromium plug-in  to attach to the right processes. Semi-automatically attaching the debugger to child processes The following flags cause child processes to wait for 60 seconds in a busy loop for a debugger to attach to the process. Once either condition is true, it continues on; no exception is thrown. --wait-for-debugger-children [=filter] The filter, if provided, will fire only if it matches the  --type  parameter to the process. Values include  renderer ,  plugin  (for NPAPI),  ppapi ,  gpu-process , and  utility . When using this option, it may be helpful to limit the number of renderer processes spawned, using: --renderer-process-limit = 1 Image File Execution Options Using Image File Execution Options (IFEO) will not work because CreateProcess() returns the handle to the debugger process instead of the intended child process. There are also issues with the sandbox. Time travel debugging You can do  time travel debugging using WinDbg Preview  (must be installed from the Microsoft Store). This lets you execute a program forward and backwards. After capturing a trace, you can set breakpoints and step through code as normal, but also provides 'backwards' commands (g-, t-, p-) so that you can go back and forth through the execution. It is especially useful to set data breakpoints ( ba command ) and reverse continuing, so you can see when a certain variable was last changed to its current value. Chromium specifics: The type of injection the time travel tracer needs to perform is incompatible with the Chromium sandbox. In order to record a trace, you'll need to run with  --no-sandbox . Chromium cannot run elevated with Administrator privileges, so the "Launch executable (advance)" option won't work, you'll need to attach after the process has already launched via the checkbox in the bottom right. If you need to record startup-like things, you'll have to use --{browser,gpu,renderer,utility}-startup-dialog, then attach (and hope the relevant code hasn't executed before that point). JsDbg -- data structure visualization You can install  JsDbg as a plugin for WinDbg or Visual Studio . It interactively lets you look at data structures (such as the DOM tree, Accessibility tree, layout object tree, and others) in a web browser as you debug. See the  JsDbg site  for some screen shots and usage examples. This also works when examining memory dumps (though not minidumps), and also works together with time travel debugging. Visual Studio hints Debug visualizers Chrome's custom debug visualizers should be added to the pdb files and automatically picked up by Visual Studio. The definitions are in  //tools/win/DebugVisualizers  if you need to modify them (the BUILD.gn file there has additional instructions). Don't step into trivial functions The debugger can be configured to automatically not step into functions based on regular expression. Edit  default.natstepfilter  in the following directory: For Visual Studio 2015:  C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2015\Visualizers  (for the current user only) For Visual Studio 2017 Pro:  C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2017\Visualizers  (for the current user only) Add regular expressions of functions to not step into. Remember to regex-escape  and  XML-escape them, e.g. < for < and \. for a literal dot. Example: < Function > < Name > operator new </ Name > < Action > NoStepInto </ Action > </ Function > < Function > < Name > operator delete </ Name > < Action > NoStepInto </ Action > </ Function > <!-- Skip everything in std --> < Function > < Name > std::.* </ Name > < Action > NoStepInto </ Action > </ Function > <!-- all methods on WebKit OwnPtr and variants, ... WTF::*Ptr<*>::* --> < Function > < Name > WTF::.*Ptr<.*>::.* </ Name > < Action > NoStepInto </ Action > </ Function > This file is read at start of a debugging session (F5), so you don't need to restart Visual Studio after changing it. More info:  Microsoft email thread V8 and Chromium V8 supports many command-line flags that are useful for debugging. V8 command-line flags can be set via the Chromium command-line flag --js-flags; for instance: chrome.exe --js-flags= "--trace_exception --heap_stats" Note that some V8 command-line flags exist only in the debug build of V8. For a list of all V8 flags try: chrome.exe --js-flags= "--help" Graphics debugging GPU Acceleration of rendering can be more easily debugged with tools. See: Graphics Debugging in Visual Studio 2013 Graphical debugging with NVIDIA NSight Debugging on another machine Sometimes it's useful to debug installation and execution on a machine other than your primary build box. To run the installer on said other machine, first build the mini_installer target on your main build machine (e.g., autoninja -C out\Debug mini_installer). Next, on the debug machine: Make the build machine's build volume available on the debug machine either by mounting it locally (e.g., Z:\) or by crafting a UNC path to it (e.g., \\builder\src) Open up a command prompt and change to a local disk Run src\tools\win\ copy-installer.bat  in the remote checkout by way of the mount (e.g., Z:\PATHTOCHECKOUT\src\...) or UNC path (e.g., \\builder\src\...). This will copy the installer, DLLs, and PDBs into your debug machine's C:\out or C:\build (depending on if you're rocking the component=shared_library build or not) Run  C:\out\Debug\mini_installer.exe  with the flags of your choice to install Chrome. This can take some time, especially on a slow machine. Watch the Task Manager and wait until mini_installer.exe exits before trying to launch Chrome (by way of the shortcut(s) created by the installer) For extra pleasure, add C:\out\Debug to your _NT_SYMBOL_PATH environment variable Consider reading the documentation at the top of copy-installer.bat to see how you can run it. It tries to be smart and copy the right things, but you may need to be explicit (e.g., "copy-installer.bat out Debug"). It is safe to re-run the script to copy only modified files (after a rebuild, for example). You can also use the zip action of the isolate scripts (tools\mb\mb.py) to package all the files for a target into a single zip file, for example: python tools\mb\mb.py zip out/Release base_unittests base_unittests. zip Finding all memory allocations It is possible to use Heap Snapshots to get call stacks on all outstanding allocations that use the OS heap. This works particularly well if heap snapshots are started as soon as the Chrome browser process is created, but before it starts running. Details can be found in  this batch file . However, with  PartitionAlloc Everywhere  most Chromium allocations no longer use the Windows heap so this will only find a subset of allocations, mostly from OS DLLs. Find memory leaks Note: as with Heap Snapshots the utility of UMDH is greatly reduced now because PartitionAlloc Everywhere has mostly replaced the Windows heap. The Windows heap manager has a really useful debug flag, where it can be asked to capture and store a stack trace with every allocation. The tool to scrape these stack traces out of processes is UMDH, which comes with  WinDbg . UMDH is great. It will capture a snapshot of the heap state as many times as you like, and it'll do it fairly quickly. You then run it again against either a single snapshot, or a pair of snapshots, at which time it'll symbolize the stack traces and aggregate usage up to unique stack traces. Turning on the user stack trace database for chrome.exe with gflags.exe makes it run unbearably slowly; however, turning on the user stack trace database on for the browser alone is just fine. While it's possible to turn on the user stack database with the "!gflag" debugging extension, it's too late to do this by the time the initial debugger breakpoint hits. The only reasonable way to do this is to Launch GFlags.exe, Enable the user stack trace database (per image below), Launch Chrome under the debugger. Set a breakpont when chrome.dll loads with "sxe ld chrome.dll". Step up, to allow Chrome.dll to initialize. Disable the stack trace database in GFlags.exe. Continue chrome, optionally detaching the debugger. GFlags.exe settings for user mode stack trace database. If you then ever suffer a browser memory leak, you can snarf a dump of the process with umdh - p :<my browser pid> > chrome-browser-leak-umdh-dump.txt which can then typically be "trivially" analyzed to find the culprit. Miscellaneous Note that by default Application Verifier only works with non-official builds of Chromium. To use Application Verifier on official builds you need to add --disable-features=RendererCodeIntegrity to avoid sandbox crashes in renderer processes. See  crbug.com/1004989  for details. See also  this page . Application Verifier  is a free tool from Microsoft (available as part of the Windows SDK) that can be used to flush out programming errors. Starting with M68 Application Verifier can be enabled for chrome.exe without needing to disable the sandbox. After adding chrome.exe to the list of applications to be stressed you need to expand the list of Basics checks and disable the  Leak  checks. You may also need to disable  Handles  and  Locks  checks depending on your graphics driver and specific Chrome version, but the eventual goal is to have Chrome run with  Handles  and  Locks  checks enabled. When bugs are found Chrome will trigger a breakpoint so running all Chrome processes under a debugger is recommended. Chrome will run much more slowly because Application Verifier puts every heap allocation on a separate page. Note that with PartitionAlloc Everywhere most Chromium allocations don't actually go through the Windows heap and are therefore unaffected by Application Verifier. You can check the undocumented 'Cuzz' checkbox in Application Verifier to get the Windows thread scheduler to add some extra randomness in order to help expose race conditions in your code. To put a breakpoint on CreateFile(), add this break point: {,,kernel32.dll}_CreateFileW@28 {,,kernel32.dll} specifies the DLL (context operator). _ prefix means extern "C". @28 postfix means _stdcall with the stack pop at the end of the function. i.e. the number of arguments in BYTES. You can use  DebugView  from SysInternals or  sawbuck  to view LOG() messages that normally go to stderr on POSIX.

The Chromium Projects Home Chromium ChromiumOS Quick links Report bugs Discuss Other sites Chromium Blog Google Chrome Extensions Except as otherwise  noted , the content of this page is licensed under a  Creative Commons Attribution 2.5 license , and examples are licensed under the  BSD License . Privacy Edit this page For Developers  >  How-Tos  > Debugging Chromium on Windows First see  get the code  for checkout and build instructions. Getting started You can use Visual Studio's built-in debugger or  WinDBG  to debug Chromium. You don't need to use the IDE to build in order to use the debugger: autoninja is used to build Chromium and most developers invoke it from a command prompt, and then open the IDE for debugging as necessary. To start debugging an already-built executable with Visual Studio just launch Visual Studio (2019 or higher) and select File-> Open-> Project/Solution (Ctrl+Shift+O) and select the executable of interest. This will create a solution with that executable as the 'project'. You can then launch the debugger with F5 or F11 or from the Debug menu. If you right-click on the executable in Solution Explorer and select properties then you can edit things such as the executable path, command-line arguments, and working directory. You can add additional executables to the solution by using File-> Add-> Existing Project and selecting another already-built executable. You can select which one to debug by right-clicking on one of them in Solution Explorer and selecting Set as Startup Project. When your solution file is customized to your taste you can save it to a directory such as out\solutions. Saving it there helps ensure that relative paths to source files, printed from build commands, will correctly identify the source files. The Tools menu can be used to add commands to do things like invoke autoninja to build Chrome, compile the selected source file, or other things. Visual Studio 2017 is not recommended for debugging of Chromium - use a newer version for best performance and stability. symbol_level=2  is the default on Windows and gives full debugging information with types, locals, globals, function names, and source/line information.  symbol_level=1  creates smaller PDBs with just function names, and source/line information - source-level debugging is still supported (new from June 2019), but local variables and type information are missing.  symbol_level=0  gives extremely limited debugging abilities, mostly just viewing call stacks when Chromium crashes. Browsing source code If you use a solution file generated by gn ( gn gen --ide=vs ) then Intellisense may help you navigate the code. If this doesn't work or if you use a solution created as above then you may want to install  VsChromium  to help navigate the code, as well as using  https://source.chromium.org . Profiles It's a good idea to use a different Chrome profile for your debugging. If you are debugging Google Chrome branded builds, or use a Chromium build as your primary browser, the profiles can collide so you can't run both at once, and your stable browser might see profile versions from the future (Google Chrome and Chromium use different profile directories by default so won't collide). Use the command-line option: --user-data-dir =C:\tmp\my_debug_profile (replace the path as necessary) Using the IDE, go to the  Debugging  tab of the properties of the chrome project, and set the  Command Arguments. Chrome debug log Enable Chrome debug logging to a file by passing  --enable-logging --v=1  command-line flags at startup. Debug builds place the  chrome_debug.log  file in the  out\Debug  directory. Release builds place the file in the top level of the user data Chromium app directory, which is OS-version-dependent. For more information, see  logging  and  user data directory  details. Symbol server If you are debugging official Google Chrome release builds, use the symbol server: https://chromium-browser-symsrv.commondatastorage.googleapis.com In Visual Studio, this goes in  Tools > Options  under  Debugging > Symbols . You should set up a local cache in a empty directory on your computer. In windbg you can add this to your symbol server search path with the command below, where C:\symbols is a local cache directory: .sympath+ SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Alternately, You can set the _NT_SYMBOL_PATH environment variable to include both the Microsoft and Google symbol servers - VS, windbg, and other tools should both respect this environment variable: _NT_SYMBOL_PATH =SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols ;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Note that symbol servers will let the debuggers download both the PE files (DLLs and EXEs) and the PDB files. Chrome often loads third party libraries and partial symbols for some of these are also public. For example: AMD : https://download.amd.com/dir/bin Nvidia : https://driver-symbols.nvidia.com/ Intel : https://software.intel.com/sites/downloads/symbols/ For example, for completeness, the following symbol server environment variable will resolve all of the above sources - but this is more than is normally needed: _NT_SYMBOL_PATH=SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com;SRV\*C:\symbols\*https://download.amd.com/dir/bin;SRV\*C:\symbols\*https://driver-symbols.nvidia.com/;SRV\*C:\symbols\*https://software.intel.com/sites/downloads/symbols/ Source indexing You should set up source indexing in your debugger ( .srcfix  in windbg, Tools-> Options-> Debugging-> General->  Enable source server support  in Visual Studio) so that the correct source files will automatically be downloaded based on information in the downloaded symbols. Additionally, you must have  python  in your  path  in order for the  command that fetches source files  to succeed; launching the debugger from the same environment as where you build Chromium is an easy way to ensure it's present. This is highly recommended when debugging released Google Chrome builds or looking at crash dumps. Having the correct version of the source files automatically show up saves significant time so you should definitely set this. Multi-process issues Chromium can be challenging to debug because of its  multi-process architecture . When you select  Run  in the debugger, only the main browser process will be debugged. The code that actually renders web pages (the Renderer) and the plugins will be in separate processes that's not (yet!) being debugged. The  ProcessExplorer  tool has a process tree view where you can see how these processes are related. You can also get the process IDs associated with each tab from the Chrome Task Manager (right-click on an empty area of the window title bar to open). Automatically attach to child processes There are two Visual Studio extensions that enable the debugger to automatically attach to all Chrome processes, so you can debug all of Chrome at once. Microsoft's  Child Process Debugging Power Tool  is a standalone extension for this, and  VsChromium  is another option that bundles many other additional features. In addition to installing one of these extensions, you  must  run Visual Studio as Administrator, or it will silently fail to attach to some of Chrome's child processes. Single-process mode One way to debug issues is to run Chromium in single-process mode. This will allow you to see the entire state of the program without extra work (although it will still have many threads). To use single-process mode, add the command-line flag --single-process This approach isn't perfect because some problems won't manifest themselves in this mode and some features don't work and worker threads are still spawned into new processes. Manually attaching to a child process You can attach to the running child processes with the debugger. Select  Tools > Attach to Process  and click the  chrome.exe  process you want to attach to. Before attaching, make sure you have selected only Native code when attaching to the process This is done by clicking Select... in the Attach to Process window and only checking Native. If you forget this, it may attempt to attach in "WebKit" mode to debug JavaScript, and you'll get an error message "An operation is not legal in the current state." You can now debug the two processes as if they were one. When you are debugging multiple processes, open the  Debug > Windows > Processes  window to switch between them. Sometimes you are debugging something that only happens on startup, and want to see the child process as soon as it starts. Use: --renderer-startup-dialog --no-sandbox You have to disable the sandbox or the dialog box will be prohibited from showing. When the dialog appears, visit Tools > Attach to Process and attach to the process showing the Renderer startup dialog. Now you're debugging in the renderer and can continue execution by pressing OK in the dialog. Startup dialogs also exist for other child process types:  --gpu-startup-dialog ,  --ppapi-startup-dialog ,  --utility-startup-dialog ,  --plugin-startup-dialog  (for NPAPI). For utilities, you can add a service type  --utility-startup-dialog=data_decoder.mojom.DataDecoderService . You can also try  the vs-chromium plug-in  to attach to the right processes. Semi-automatically attaching the debugger to child processes The following flags cause child processes to wait for 60 seconds in a busy loop for a debugger to attach to the process. Once either condition is true, it continues on; no exception is thrown. --wait-for-debugger-children [=filter] The filter, if provided, will fire only if it matches the  --type  parameter to the process. Values include  renderer ,  plugin  (for NPAPI),  ppapi ,  gpu-process , and  utility . When using this option, it may be helpful to limit the number of renderer processes spawned, using: --renderer-process-limit = 1 Image File Execution Options Using Image File Execution Options (IFEO) will not work because CreateProcess() returns the handle to the debugger process instead of the intended child process. There are also issues with the sandbox. Time travel debugging You can do  time travel debugging using WinDbg Preview  (must be installed from the Microsoft Store). This lets you execute a program forward and backwards. After capturing a trace, you can set breakpoints and step through code as normal, but also provides 'backwards' commands (g-, t-, p-) so that you can go back and forth through the execution. It is especially useful to set data breakpoints ( ba command ) and reverse continuing, so you can see when a certain variable was last changed to its current value. Chromium specifics: The type of injection the time travel tracer needs to perform is incompatible with the Chromium sandbox. In order to record a trace, you'll need to run with  --no-sandbox . Chromium cannot run elevated with Administrator privileges, so the "Launch executable (advance)" option won't work, you'll need to attach after the process has already launched via the checkbox in the bottom right. If you need to record startup-like things, you'll have to use --{browser,gpu,renderer,utility}-startup-dialog, then attach (and hope the relevant code hasn't executed before that point). JsDbg -- data structure visualization You can install  JsDbg as a plugin for WinDbg or Visual Studio . It interactively lets you look at data structures (such as the DOM tree, Accessibility tree, layout object tree, and others) in a web browser as you debug. See the  JsDbg site  for some screen shots and usage examples. This also works when examining memory dumps (though not minidumps), and also works together with time travel debugging. Visual Studio hints Debug visualizers Chrome's custom debug visualizers should be added to the pdb files and automatically picked up by Visual Studio. The definitions are in  //tools/win/DebugVisualizers  if you need to modify them (the BUILD.gn file there has additional instructions). Don't step into trivial functions The debugger can be configured to automatically not step into functions based on regular expression. Edit  default.natstepfilter  in the following directory: For Visual Studio 2015:  C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2015\Visualizers  (for the current user only) For Visual Studio 2017 Pro:  C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2017\Visualizers  (for the current user only) Add regular expressions of functions to not step into. Remember to regex-escape  and  XML-escape them, e.g. < for < and \. for a literal dot. Example: < Function > < Name > operator new </ Name > < Action > NoStepInto </ Action > </ Function > < Function > < Name > operator delete </ Name > < Action > NoStepInto </ Action > </ Function > <!-- Skip everything in std --> < Function > < Name > std::.* </ Name > < Action > NoStepInto </ Action > </ Function > <!-- all methods on WebKit OwnPtr and variants, ... WTF::*Ptr<*>::* --> < Function > < Name > WTF::.*Ptr<.*>::.* </ Name > < Action > NoStepInto </ Action > </ Function > This file is read at start of a debugging session (F5), so you don't need to restart Visual Studio after changing it. More info:  Microsoft email thread V8 and Chromium V8 supports many command-line flags that are useful for debugging. V8 command-line flags can be set via the Chromium command-line flag --js-flags; for instance: chrome.exe --js-flags= "--trace_exception --heap_stats" Note that some V8 command-line flags exist only in the debug build of V8. For a list of all V8 flags try: chrome.exe --js-flags= "--help" Graphics debugging GPU Acceleration of rendering can be more easily debugged with tools. See: Graphics Debugging in Visual Studio 2013 Graphical debugging with NVIDIA NSight Debugging on another machine Sometimes it's useful to debug installation and execution on a machine other than your primary build box. To run the installer on said other machine, first build the mini_installer target on your main build machine (e.g., autoninja -C out\Debug mini_installer). Next, on the debug machine: Make the build machine's build volume available on the debug machine either by mounting it locally (e.g., Z:\) or by crafting a UNC path to it (e.g., \\builder\src) Open up a command prompt and change to a local disk Run src\tools\win\ copy-installer.bat  in the remote checkout by way of the mount (e.g., Z:\PATHTOCHECKOUT\src\...) or UNC path (e.g., \\builder\src\...). This will copy the installer, DLLs, and PDBs into your debug machine's C:\out or C:\build (depending on if you're rocking the component=shared_library build or not) Run  C:\out\Debug\mini_installer.exe  with the flags of your choice to install Chrome. This can take some time, especially on a slow machine. Watch the Task Manager and wait until mini_installer.exe exits before trying to launch Chrome (by way of the shortcut(s) created by the installer) For extra pleasure, add C:\out\Debug to your _NT_SYMBOL_PATH environment variable Consider reading the documentation at the top of copy-installer.bat to see how you can run it. It tries to be smart and copy the right things, but you may need to be explicit (e.g., "copy-installer.bat out Debug"). It is safe to re-run the script to copy only modified files (after a rebuild, for example). You can also use the zip action of the isolate scripts (tools\mb\mb.py) to package all the files for a target into a single zip file, for example: python tools\mb\mb.py zip out/Release base_unittests base_unittests. zip Finding all memory allocations It is possible to use Heap Snapshots to get call stacks on all outstanding allocations that use the OS heap. This works particularly well if heap snapshots are started as soon as the Chrome browser process is created, but before it starts running. Details can be found in  this batch file . However, with  PartitionAlloc Everywhere  most Chromium allocations no longer use the Windows heap so this will only find a subset of allocations, mostly from OS DLLs. Find memory leaks Note: as with Heap Snapshots the utility of UMDH is greatly reduced now because PartitionAlloc Everywhere has mostly replaced the Windows heap. The Windows heap manager has a really useful debug flag, where it can be asked to capture and store a stack trace with every allocation. The tool to scrape these stack traces out of processes is UMDH, which comes with  WinDbg . UMDH is great. It will capture a snapshot of the heap state as many times as you like, and it'll do it fairly quickly. You then run it again against either a single snapshot, or a pair of snapshots, at which time it'll symbolize the stack traces and aggregate usage up to unique stack traces. Turning on the user stack trace database for chrome.exe with gflags.exe makes it run unbearably slowly; however, turning on the user stack trace database on for the browser alone is just fine. While it's possible to turn on the user stack database with the "!gflag" debugging extension, it's too late to do this by the time the initial debugger breakpoint hits. The only reasonable way to do this is to Launch GFlags.exe, Enable the user stack trace database (per image below), Launch Chrome under the debugger. Set a breakpont when chrome.dll loads with "sxe ld chrome.dll". Step up, to allow Chrome.dll to initialize. Disable the stack trace database in GFlags.exe. Continue chrome, optionally detaching the debugger. GFlags.exe settings for user mode stack trace database. If you then ever suffer a browser memory leak, you can snarf a dump of the process with umdh - p :<my browser pid> > chrome-browser-leak-umdh-dump.txt which can then typically be "trivially" analyzed to find the culprit. Miscellaneous Note that by default Application Verifier only works with non-official builds of Chromium. To use Application Verifier on official builds you need to add --disable-features=RendererCodeIntegrity to avoid sandbox crashes in renderer processes. See  crbug.com/1004989  for details. See also  this page . Application Verifier  is a free tool from Microsoft (available as part of the Windows SDK) that can be used to flush out programming errors. Starting with M68 Application Verifier can be enabled for chrome.exe without needing to disable the sandbox. After adding chrome.exe to the list of applications to be stressed you need to expand the list of Basics checks and disable the  Leak  checks. You may also need to disable  Handles  and  Locks  checks depending on your graphics driver and specific Chrome version, but the eventual goal is to have Chrome run with  Handles  and  Locks  checks enabled. When bugs are found Chrome will trigger a breakpoint so running all Chrome processes under a debugger is recommended. Chrome will run much more slowly because Application Verifier puts every heap allocation on a separate page. Note that with PartitionAlloc Everywhere most Chromium allocations don't actually go through the Windows heap and are therefore unaffected by Application Verifier. You can check the undocumented 'Cuzz' checkbox in Application Verifier to get the Windows thread scheduler to add some extra randomness in order to help expose race conditions in your code. To put a breakpoint on CreateFile(), add this break point: {,,kernel32.dll}_CreateFileW@28 {,,kernel32.dll} specifies the DLL (context operator). _ prefix means extern "C". @28 postfix means _stdcall with the stack pop at the end of the function. i.e. the number of arguments in BYTES. You can use  DebugView  from SysInternals or  sawbuck  to view LOG() messages that normally go to stderr on POSIX.

The Chromium Projects Home Chromium ChromiumOS Quick links Report bugs Discuss Other sites Chromium Blog Google Chrome Extensions Except as otherwise  noted , the content of this page is licensed under a  Creative Commons Attribution 2.5 license , and examples are licensed under the  BSD License . Privacy Edit this page For Developers  >  How-Tos  > Debugging Chromium on Windows First see  get the code  for checkout and build instructions. Getting started You can use Visual Studio's built-in debugger or  WinDBG  to debug Chromium. You don't need to use the IDE to build in order to use the debugger: autoninja is used to build Chromium and most developers invoke it from a command prompt, and then open the IDE for debugging as necessary. To start debugging an already-built executable with Visual Studio just launch Visual Studio (2019 or higher) and select File-> Open-> Project/Solution (Ctrl+Shift+O) and select the executable of interest. This will create a solution with that executable as the 'project'. You can then launch the debugger with F5 or F11 or from the Debug menu. If you right-click on the executable in Solution Explorer and select properties then you can edit things such as the executable path, command-line arguments, and working directory. You can add additional executables to the solution by using File-> Add-> Existing Project and selecting another already-built executable. You can select which one to debug by right-clicking on one of them in Solution Explorer and selecting Set as Startup Project. When your solution file is customized to your taste you can save it to a directory such as out\solutions. Saving it there helps ensure that relative paths to source files, printed from build commands, will correctly identify the source files. The Tools menu can be used to add commands to do things like invoke autoninja to build Chrome, compile the selected source file, or other things. Visual Studio 2017 is not recommended for debugging of Chromium - use a newer version for best performance and stability. symbol_level=2  is the default on Windows and gives full debugging information with types, locals, globals, function names, and source/line information.  symbol_level=1  creates smaller PDBs with just function names, and source/line information - source-level debugging is still supported (new from June 2019), but local variables and type information are missing.  symbol_level=0  gives extremely limited debugging abilities, mostly just viewing call stacks when Chromium crashes. Browsing source code If you use a solution file generated by gn ( gn gen --ide=vs ) then Intellisense may help you navigate the code. If this doesn't work or if you use a solution created as above then you may want to install  VsChromium  to help navigate the code, as well as using  https://source.chromium.org . Profiles It's a good idea to use a different Chrome profile for your debugging. If you are debugging Google Chrome branded builds, or use a Chromium build as your primary browser, the profiles can collide so you can't run both at once, and your stable browser might see profile versions from the future (Google Chrome and Chromium use different profile directories by default so won't collide). Use the command-line option: --user-data-dir =C:\tmp\my_debug_profile (replace the path as necessary) Using the IDE, go to the  Debugging  tab of the properties of the chrome project, and set the  Command Arguments. Chrome debug log Enable Chrome debug logging to a file by passing  --enable-logging --v=1  command-line flags at startup. Debug builds place the  chrome_debug.log  file in the  out\Debug  directory. Release builds place the file in the top level of the user data Chromium app directory, which is OS-version-dependent. For more information, see  logging  and  user data directory  details. Symbol server If you are debugging official Google Chrome release builds, use the symbol server: https://chromium-browser-symsrv.commondatastorage.googleapis.com In Visual Studio, this goes in  Tools > Options  under  Debugging > Symbols . You should set up a local cache in a empty directory on your computer. In windbg you can add this to your symbol server search path with the command below, where C:\symbols is a local cache directory: .sympath+ SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Alternately, You can set the _NT_SYMBOL_PATH environment variable to include both the Microsoft and Google symbol servers - VS, windbg, and other tools should both respect this environment variable: _NT_SYMBOL_PATH =SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols ;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Note that symbol servers will let the debuggers download both the PE files (DLLs and EXEs) and the PDB files. Chrome often loads third party libraries and partial symbols for some of these are also public. For example: AMD : https://download.amd.com/dir/bin Nvidia : https://driver-symbols.nvidia.com/ Intel : https://software.intel.com/sites/downloads/symbols/ For example, for completeness, the following symbol server environment variable will resolve all of the above sources - but this is more than is normally needed: _NT_SYMBOL_PATH=SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com;SRV\*C:\symbols\*https://download.amd.com/dir/bin;SRV\*C:\symbols\*https://driver-symbols.nvidia.com/;SRV\*C:\symbols\*https://software.intel.com/sites/downloads/symbols/ Source indexing You should set up source indexing in your debugger ( .srcfix  in windbg, Tools-> Options-> Debugging-> General->  Enable source server support  in Visual Studio) so that the correct source files will automatically be downloaded based on information in the downloaded symbols. Additionally, you must have  python  in your  path  in order for the  command that fetches source files  to succeed; launching the debugger from the same environment as where you build Chromium is an easy way to ensure it's present. This is highly recommended when debugging released Google Chrome builds or looking at crash dumps. Having the correct version of the source files automatically show up saves significant time so you should definitely set this. Multi-process issues Chromium can be challenging to debug because of its  multi-process architecture . When you select  Run  in the debugger, only the main browser process will be debugged. The code that actually renders web pages (the Renderer) and the plugins will be in separate processes that's not (yet!) being debugged. The  ProcessExplorer  tool has a process tree view where you can see how these processes are related. You can also get the process IDs associated with each tab from the Chrome Task Manager (right-click on an empty area of the window title bar to open). Automatically attach to child processes There are two Visual Studio extensions that enable the debugger to automatically attach to all Chrome processes, so you can debug all of Chrome at once. Microsoft's  Child Process Debugging Power Tool  is a standalone extension for this, and  VsChromium  is another option that bundles many other additional features. In addition to installing one of these extensions, you  must  run Visual Studio as Administrator, or it will silently fail to attach to some of Chrome's child processes. Single-process mode One way to debug issues is to run Chromium in single-process mode. This will allow you to see the entire state of the program without extra work (although it will still have many threads). To use single-process mode, add the command-line flag --single-process This approach isn't perfect because some problems won't manifest themselves in this mode and some features don't work and worker threads are still spawned into new processes. Manually attaching to a child process You can attach to the running child processes with the debugger. Select  Tools > Attach to Process  and click the  chrome.exe  process you want to attach to. Before attaching, make sure you have selected only Native code when attaching to the process This is done by clicking Select... in the Attach to Process window and only checking Native. If you forget this, it may attempt to attach in "WebKit" mode to debug JavaScript, and you'll get an error message "An operation is not legal in the current state." You can now debug the two processes as if they were one. When you are debugging multiple processes, open the  Debug > Windows > Processes  window to switch between them. Sometimes you are debugging something that only happens on startup, and want to see the child process as soon as it starts. Use: --renderer-startup-dialog --no-sandbox You have to disable the sandbox or the dialog box will be prohibited from showing. When the dialog appears, visit Tools > Attach to Process and attach to the process showing the Renderer startup dialog. Now you're debugging in the renderer and can continue execution by pressing OK in the dialog. Startup dialogs also exist for other child process types:  --gpu-startup-dialog ,  --ppapi-startup-dialog ,  --utility-startup-dialog ,  --plugin-startup-dialog  (for NPAPI). For utilities, you can add a service type  --utility-startup-dialog=data_decoder.mojom.DataDecoderService . You can also try  the vs-chromium plug-in  to attach to the right processes. Semi-automatically attaching the debugger to child processes The following flags cause child processes to wait for 60 seconds in a busy loop for a debugger to attach to the process. Once either condition is true, it continues on; no exception is thrown. --wait-for-debugger-children [=filter] The filter, if provided, will fire only if it matches the  --type  parameter to the process. Values include  renderer ,  plugin  (for NPAPI),  ppapi ,  gpu-process , and  utility . When using this option, it may be helpful to limit the number of renderer processes spawned, using: --renderer-process-limit = 1 Image File Execution Options Using Image File Execution Options (IFEO) will not work because CreateProcess() returns the handle to the debugger process instead of the intended child process. There are also issues with the sandbox. Time travel debugging You can do  time travel debugging using WinDbg Preview  (must be installed from the Microsoft Store). This lets you execute a program forward and backwards. After capturing a trace, you can set breakpoints and step through code as normal, but also provides 'backwards' commands (g-, t-, p-) so that you can go back and forth through the execution. It is especially useful to set data breakpoints ( ba command ) and reverse continuing, so you can see when a certain variable was last changed to its current value. Chromium specifics: The type of injection the time travel tracer needs to perform is incompatible with the Chromium sandbox. In order to record a trace, you'll need to run with  --no-sandbox . Chromium cannot run elevated with Administrator privileges, so the "Launch executable (advance)" option won't work, you'll need to attach after the process has already launched via the checkbox in the bottom right. If you need to record startup-like things, you'll have to use --{browser,gpu,renderer,utility}-startup-dialog, then attach (and hope the relevant code hasn't executed before that point). JsDbg -- data structure visualization You can install  JsDbg as a plugin for WinDbg or Visual Studio . It interactively lets you look at data structures (such as the DOM tree, Accessibility tree, layout object tree, and others) in a web browser as you debug. See the  JsDbg site  for some screen shots and usage examples. This also works when examining memory dumps (though not minidumps), and also works together with time travel debugging. Visual Studio hints Debug visualizers Chrome's custom debug visualizers should be added to the pdb files and automatically picked up by Visual Studio. The definitions are in  //tools/win/DebugVisualizers  if you need to modify them (the BUILD.gn file there has additional instructions). Don't step into trivial functions The debugger can be configured to automatically not step into functions based on regular expression. Edit  default.natstepfilter  in the following directory: For Visual Studio 2015:  C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2015\Visualizers  (for the current user only) For Visual Studio 2017 Pro:  C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2017\Visualizers  (for the current user only) Add regular expressions of functions to not step into. Remember to regex-escape  and  XML-escape them, e.g. < for < and \. for a literal dot. Example: < Function > < Name > operator new </ Name > < Action > NoStepInto </ Action > </ Function > < Function > < Name > operator delete </ Name > < Action > NoStepInto </ Action > </ Function > <!-- Skip everything in std --> < Function > < Name > std::.* </ Name > < Action > NoStepInto </ Action > </ Function > <!-- all methods on WebKit OwnPtr and variants, ... WTF::*Ptr<*>::* --> < Function > < Name > WTF::.*Ptr<.*>::.* </ Name > < Action > NoStepInto </ Action > </ Function > This file is read at start of a debugging session (F5), so you don't need to restart Visual Studio after changing it. More info:  Microsoft email thread V8 and Chromium V8 supports many command-line flags that are useful for debugging. V8 command-line flags can be set via the Chromium command-line flag --js-flags; for instance: chrome.exe --js-flags= "--trace_exception --heap_stats" Note that some V8 command-line flags exist only in the debug build of V8. For a list of all V8 flags try: chrome.exe --js-flags= "--help" Graphics debugging GPU Acceleration of rendering can be more easily debugged with tools. See: Graphics Debugging in Visual Studio 2013 Graphical debugging with NVIDIA NSight Debugging on another machine Sometimes it's useful to debug installation and execution on a machine other than your primary build box. To run the installer on said other machine, first build the mini_installer target on your main build machine (e.g., autoninja -C out\Debug mini_installer). Next, on the debug machine: Make the build machine's build volume available on the debug machine either by mounting it locally (e.g., Z:\) or by crafting a UNC path to it (e.g., \\builder\src) Open up a command prompt and change to a local disk Run src\tools\win\ copy-installer.bat  in the remote checkout by way of the mount (e.g., Z:\PATHTOCHECKOUT\src\...) or UNC path (e.g., \\builder\src\...). This will copy the installer, DLLs, and PDBs into your debug machine's C:\out or C:\build (depending on if you're rocking the component=shared_library build or not) Run  C:\out\Debug\mini_installer.exe  with the flags of your choice to install Chrome. This can take some time, especially on a slow machine. Watch the Task Manager and wait until mini_installer.exe exits before trying to launch Chrome (by way of the shortcut(s) created by the installer) For extra pleasure, add C:\out\Debug to your _NT_SYMBOL_PATH environment variable Consider reading the documentation at the top of copy-installer.bat to see how you can run it. It tries to be smart and copy the right things, but you may need to be explicit (e.g., "copy-installer.bat out Debug"). It is safe to re-run the script to copy only modified files (after a rebuild, for example). You can also use the zip action of the isolate scripts (tools\mb\mb.py) to package all the files for a target into a single zip file, for example: python tools\mb\mb.py zip out/Release base_unittests base_unittests. zip Finding all memory allocations It is possible to use Heap Snapshots to get call stacks on all outstanding allocations that use the OS heap. This works particularly well if heap snapshots are started as soon as the Chrome browser process is created, but before it starts running. Details can be found in  this batch file . However, with  PartitionAlloc Everywhere  most Chromium allocations no longer use the Windows heap so this will only find a subset of allocations, mostly from OS DLLs. Find memory leaks Note: as with Heap Snapshots the utility of UMDH is greatly reduced now because PartitionAlloc Everywhere has mostly replaced the Windows heap. The Windows heap manager has a really useful debug flag, where it can be asked to capture and store a stack trace with every allocation. The tool to scrape these stack traces out of processes is UMDH, which comes with  WinDbg . UMDH is great. It will capture a snapshot of the heap state as many times as you like, and it'll do it fairly quickly. You then run it again against either a single snapshot, or a pair of snapshots, at which time it'll symbolize the stack traces and aggregate usage up to unique stack traces. Turning on the user stack trace database for chrome.exe with gflags.exe makes it run unbearably slowly; however, turning on the user stack trace database on for the browser alone is just fine. While it's possible to turn on the user stack database with the "!gflag" debugging extension, it's too late to do this by the time the initial debugger breakpoint hits. The only reasonable way to do this is to Launch GFlags.exe, Enable the user stack trace database (per image below), Launch Chrome under the debugger. Set a breakpont when chrome.dll loads with "sxe ld chrome.dll". Step up, to allow Chrome.dll to initialize. Disable the stack trace database in GFlags.exe. Continue chrome, optionally detaching the debugger. GFlags.exe settings for user mode stack trace database. If you then ever suffer a browser memory leak, you can snarf a dump of the process with umdh - p :<my browser pid> > chrome-browser-leak-umdh-dump.txt which can then typically be "trivially" analyzed to find the culprit. Miscellaneous Note that by default Application Verifier only works with non-official builds of Chromium. To use Application Verifier on official builds you need to add --disable-features=RendererCodeIntegrity to avoid sandbox crashes in renderer processes. See  crbug.com/1004989  for details. See also  this page . Application Verifier  is a free tool from Microsoft (available as part of the Windows SDK) that can be used to flush out programming errors. Starting with M68 Application Verifier can be enabled for chrome.exe without needing to disable the sandbox. After adding chrome.exe to the list of applications to be stressed you need to expand the list of Basics checks and disable the  Leak  checks. You may also need to disable  Handles  and  Locks  checks depending on your graphics driver and specific Chrome version, but the eventual goal is to have Chrome run with  Handles  and  Locks  checks enabled. When bugs are found Chrome will trigger a breakpoint so running all Chrome processes under a debugger is recommended. Chrome will run much more slowly because Application Verifier puts every heap allocation on a separate page. Note that with PartitionAlloc Everywhere most Chromium allocations don't actually go through the Windows heap and are therefore unaffected by Application Verifier. You can check the undocumented 'Cuzz' checkbox in Application Verifier to get the Windows thread scheduler to add some extra randomness in order to help expose race conditions in your code. To put a breakpoint on CreateFile(), add this break point: {,,kernel32.dll}_CreateFileW@28 {,,kernel32.dll} specifies the DLL (context operator). _ prefix means extern "C". @28 postfix means _stdcall with the stack pop at the end of the function. i.e. the number of arguments in BYTES. You can use  DebugView  from SysInternals or  sawbuck  to view LOG() messages that normally go to stderr on POSIX.

The Chromium Projects Home Chromium ChromiumOS Quick links Report bugs Discuss Other sites Chromium Blog Google Chrome Extensions Except as otherwise  noted , the content of this page is licensed under a  Creative Commons Attribution 2.5 license , and examples are licensed under the  BSD License . Privacy Edit this page For Developers  >  How-Tos  > Debugging Chromium on Windows First see  get the code  for checkout and build instructions. Getting started You can use Visual Studio's built-in debugger or  WinDBG  to debug Chromium. You don't need to use the IDE to build in order to use the debugger: autoninja is used to build Chromium and most developers invoke it from a command prompt, and then open the IDE for debugging as necessary. To start debugging an already-built executable with Visual Studio just launch Visual Studio (2019 or higher) and select File-> Open-> Project/Solution (Ctrl+Shift+O) and select the executable of interest. This will create a solution with that executable as the 'project'. You can then launch the debugger with F5 or F11 or from the Debug menu. If you right-click on the executable in Solution Explorer and select properties then you can edit things such as the executable path, command-line arguments, and working directory. You can add additional executables to the solution by using File-> Add-> Existing Project and selecting another already-built executable. You can select which one to debug by right-clicking on one of them in Solution Explorer and selecting Set as Startup Project. When your solution file is customized to your taste you can save it to a directory such as out\solutions. Saving it there helps ensure that relative paths to source files, printed from build commands, will correctly identify the source files. The Tools menu can be used to add commands to do things like invoke autoninja to build Chrome, compile the selected source file, or other things. Visual Studio 2017 is not recommended for debugging of Chromium - use a newer version for best performance and stability. symbol_level=2  is the default on Windows and gives full debugging information with types, locals, globals, function names, and source/line information.  symbol_level=1  creates smaller PDBs with just function names, and source/line information - source-level debugging is still supported (new from June 2019), but local variables and type information are missing.  symbol_level=0  gives extremely limited debugging abilities, mostly just viewing call stacks when Chromium crashes. Browsing source code If you use a solution file generated by gn ( gn gen --ide=vs ) then Intellisense may help you navigate the code. If this doesn't work or if you use a solution created as above then you may want to install  VsChromium  to help navigate the code, as well as using  https://source.chromium.org . Profiles It's a good idea to use a different Chrome profile for your debugging. If you are debugging Google Chrome branded builds, or use a Chromium build as your primary browser, the profiles can collide so you can't run both at once, and your stable browser might see profile versions from the future (Google Chrome and Chromium use different profile directories by default so won't collide). Use the command-line option: --user-data-dir =C:\tmp\my_debug_profile (replace the path as necessary) Using the IDE, go to the  Debugging  tab of the properties of the chrome project, and set the  Command Arguments. Chrome debug log Enable Chrome debug logging to a file by passing  --enable-logging --v=1  command-line flags at startup. Debug builds place the  chrome_debug.log  file in the  out\Debug  directory. Release builds place the file in the top level of the user data Chromium app directory, which is OS-version-dependent. For more information, see  logging  and  user data directory  details. Symbol server If you are debugging official Google Chrome release builds, use the symbol server: https://chromium-browser-symsrv.commondatastorage.googleapis.com In Visual Studio, this goes in  Tools > Options  under  Debugging > Symbols . You should set up a local cache in a empty directory on your computer. In windbg you can add this to your symbol server search path with the command below, where C:\symbols is a local cache directory: .sympath+ SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Alternately, You can set the _NT_SYMBOL_PATH environment variable to include both the Microsoft and Google symbol servers - VS, windbg, and other tools should both respect this environment variable: _NT_SYMBOL_PATH =SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols ;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Note that symbol servers will let the debuggers download both the PE files (DLLs and EXEs) and the PDB files. Chrome often loads third party libraries and partial symbols for some of these are also public. For example: AMD : https://download.amd.com/dir/bin Nvidia : https://driver-symbols.nvidia.com/ Intel : https://software.intel.com/sites/downloads/symbols/ For example, for completeness, the following symbol server environment variable will resolve all of the above sources - but this is more than is normally needed: _NT_SYMBOL_PATH=SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com;SRV\*C:\symbols\*https://download.amd.com/dir/bin;SRV\*C:\symbols\*https://driver-symbols.nvidia.com/;SRV\*C:\symbols\*https://software.intel.com/sites/downloads/symbols/ Source indexing You should set up source indexing in your debugger ( .srcfix  in windbg, Tools-> Options-> Debugging-> General->  Enable source server support  in Visual Studio) so that the correct source files will automatically be downloaded based on information in the downloaded symbols. Additionally, you must have  python  in your  path  in order for the  command that fetches source files  to succeed; launching the debugger from the same environment as where you build Chromium is an easy way to ensure it's present. This is highly recommended when debugging released Google Chrome builds or looking at crash dumps. Having the correct version of the source files automatically show up saves significant time so you should definitely set this. Multi-process issues Chromium can be challenging to debug because of its  multi-process architecture . When you select  Run  in the debugger, only the main browser process will be debugged. The code that actually renders web pages (the Renderer) and the plugins will be in separate processes that's not (yet!) being debugged. The  ProcessExplorer  tool has a process tree view where you can see how these processes are related. You can also get the process IDs associated with each tab from the Chrome Task Manager (right-click on an empty area of the window title bar to open). Automatically attach to child processes There are two Visual Studio extensions that enable the debugger to automatically attach to all Chrome processes, so you can debug all of Chrome at once. Microsoft's  Child Process Debugging Power Tool  is a standalone extension for this, and  VsChromium  is another option that bundles many other additional features. In addition to installing one of these extensions, you  must  run Visual Studio as Administrator, or it will silently fail to attach to some of Chrome's child processes. Single-process mode One way to debug issues is to run Chromium in single-process mode. This will allow you to see the entire state of the program without extra work (although it will still have many threads). To use single-process mode, add the command-line flag --single-process This approach isn't perfect because some problems won't manifest themselves in this mode and some features don't work and worker threads are still spawned into new processes. Manually attaching to a child process You can attach to the running child processes with the debugger. Select  Tools > Attach to Process  and click the  chrome.exe  process you want to attach to. Before attaching, make sure you have selected only Native code when attaching to the process This is done by clicking Select... in the Attach to Process window and only checking Native. If you forget this, it may attempt to attach in "WebKit" mode to debug JavaScript, and you'll get an error message "An operation is not legal in the current state." You can now debug the two processes as if they were one. When you are debugging multiple processes, open the  Debug > Windows > Processes  window to switch between them. Sometimes you are debugging something that only happens on startup, and want to see the child process as soon as it starts. Use: --renderer-startup-dialog --no-sandbox You have to disable the sandbox or the dialog box will be prohibited from showing. When the dialog appears, visit Tools > Attach to Process and attach to the process showing the Renderer startup dialog. Now you're debugging in the renderer and can continue execution by pressing OK in the dialog. Startup dialogs also exist for other child process types:  --gpu-startup-dialog ,  --ppapi-startup-dialog ,  --utility-startup-dialog ,  --plugin-startup-dialog  (for NPAPI). For utilities, you can add a service type  --utility-startup-dialog=data_decoder.mojom.DataDecoderService . You can also try  the vs-chromium plug-in  to attach to the right processes. Semi-automatically attaching the debugger to child processes The following flags cause child processes to wait for 60 seconds in a busy loop for a debugger to attach to the process. Once either condition is true, it continues on; no exception is thrown. --wait-for-debugger-children [=filter] The filter, if provided, will fire only if it matches the  --type  parameter to the process. Values include  renderer ,  plugin  (for NPAPI),  ppapi ,  gpu-process , and  utility . When using this option, it may be helpful to limit the number of renderer processes spawned, using: --renderer-process-limit = 1 Image File Execution Options Using Image File Execution Options (IFEO) will not work because CreateProcess() returns the handle to the debugger process instead of the intended child process. There are also issues with the sandbox. Time travel debugging You can do  time travel debugging using WinDbg Preview  (must be installed from the Microsoft Store). This lets you execute a program forward and backwards. After capturing a trace, you can set breakpoints and step through code as normal, but also provides 'backwards' commands (g-, t-, p-) so that you can go back and forth through the execution. It is especially useful to set data breakpoints ( ba command ) and reverse continuing, so you can see when a certain variable was last changed to its current value. Chromium specifics: The type of injection the time travel tracer needs to perform is incompatible with the Chromium sandbox. In order to record a trace, you'll need to run with  --no-sandbox . Chromium cannot run elevated with Administrator privileges, so the "Launch executable (advance)" option won't work, you'll need to attach after the process has already launched via the checkbox in the bottom right. If you need to record startup-like things, you'll have to use --{browser,gpu,renderer,utility}-startup-dialog, then attach (and hope the relevant code hasn't executed before that point). JsDbg -- data structure visualization You can install  JsDbg as a plugin for WinDbg or Visual Studio . It interactively lets you look at data structures (such as the DOM tree, Accessibility tree, layout object tree, and others) in a web browser as you debug. See the  JsDbg site  for some screen shots and usage examples. This also works when examining memory dumps (though not minidumps), and also works together with time travel debugging. Visual Studio hints Debug visualizers Chrome's custom debug visualizers should be added to the pdb files and automatically picked up by Visual Studio. The definitions are in  //tools/win/DebugVisualizers  if you need to modify them (the BUILD.gn file there has additional instructions). Don't step into trivial functions The debugger can be configured to automatically not step into functions based on regular expression. Edit  default.natstepfilter  in the following directory: For Visual Studio 2015:  C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2015\Visualizers  (for the current user only) For Visual Studio 2017 Pro:  C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2017\Visualizers  (for the current user only) Add regular expressions of functions to not step into. Remember to regex-escape  and  XML-escape them, e.g. < for < and \. for a literal dot. Example: < Function > < Name > operator new </ Name > < Action > NoStepInto </ Action > </ Function > < Function > < Name > operator delete </ Name > < Action > NoStepInto </ Action > </ Function > <!-- Skip everything in std --> < Function > < Name > std::.* </ Name > < Action > NoStepInto </ Action > </ Function > <!-- all methods on WebKit OwnPtr and variants, ... WTF::*Ptr<*>::* --> < Function > < Name > WTF::.*Ptr<.*>::.* </ Name > < Action > NoStepInto </ Action > </ Function > This file is read at start of a debugging session (F5), so you don't need to restart Visual Studio after changing it. More info:  Microsoft email thread V8 and Chromium V8 supports many command-line flags that are useful for debugging. V8 command-line flags can be set via the Chromium command-line flag --js-flags; for instance: chrome.exe --js-flags= "--trace_exception --heap_stats" Note that some V8 command-line flags exist only in the debug build of V8. For a list of all V8 flags try: chrome.exe --js-flags= "--help" Graphics debugging GPU Acceleration of rendering can be more easily debugged with tools. See: Graphics Debugging in Visual Studio 2013 Graphical debugging with NVIDIA NSight Debugging on another machine Sometimes it's useful to debug installation and execution on a machine other than your primary build box. To run the installer on said other machine, first build the mini_installer target on your main build machine (e.g., autoninja -C out\Debug mini_installer). Next, on the debug machine: Make the build machine's build volume available on the debug machine either by mounting it locally (e.g., Z:\) or by crafting a UNC path to it (e.g., \\builder\src) Open up a command prompt and change to a local disk Run src\tools\win\ copy-installer.bat  in the remote checkout by way of the mount (e.g., Z:\PATHTOCHECKOUT\src\...) or UNC path (e.g., \\builder\src\...). This will copy the installer, DLLs, and PDBs into your debug machine's C:\out or C:\build (depending on if you're rocking the component=shared_library build or not) Run  C:\out\Debug\mini_installer.exe  with the flags of your choice to install Chrome. This can take some time, especially on a slow machine. Watch the Task Manager and wait until mini_installer.exe exits before trying to launch Chrome (by way of the shortcut(s) created by the installer) For extra pleasure, add C:\out\Debug to your _NT_SYMBOL_PATH environment variable Consider reading the documentation at the top of copy-installer.bat to see how you can run it. It tries to be smart and copy the right things, but you may need to be explicit (e.g., "copy-installer.bat out Debug"). It is safe to re-run the script to copy only modified files (after a rebuild, for example). You can also use the zip action of the isolate scripts (tools\mb\mb.py) to package all the files for a target into a single zip file, for example: python tools\mb\mb.py zip out/Release base_unittests base_unittests. zip Finding all memory allocations It is possible to use Heap Snapshots to get call stacks on all outstanding allocations that use the OS heap. This works particularly well if heap snapshots are started as soon as the Chrome browser process is created, but before it starts running. Details can be found in  this batch file . However, with  PartitionAlloc Everywhere  most Chromium allocations no longer use the Windows heap so this will only find a subset of allocations, mostly from OS DLLs. Find memory leaks Note: as with Heap Snapshots the utility of UMDH is greatly reduced now because PartitionAlloc Everywhere has mostly replaced the Windows heap. The Windows heap manager has a really useful debug flag, where it can be asked to capture and store a stack trace with every allocation. The tool to scrape these stack traces out of processes is UMDH, which comes with  WinDbg . UMDH is great. It will capture a snapshot of the heap state as many times as you like, and it'll do it fairly quickly. You then run it again against either a single snapshot, or a pair of snapshots, at which time it'll symbolize the stack traces and aggregate usage up to unique stack traces. Turning on the user stack trace database for chrome.exe with gflags.exe makes it run unbearably slowly; however, turning on the user stack trace database on for the browser alone is just fine. While it's possible to turn on the user stack database with the "!gflag" debugging extension, it's too late to do this by the time the initial debugger breakpoint hits. The only reasonable way to do this is to Launch GFlags.exe, Enable the user stack trace database (per image below), Launch Chrome under the debugger. Set a breakpont when chrome.dll loads with "sxe ld chrome.dll". Step up, to allow Chrome.dll to initialize. Disable the stack trace database in GFlags.exe. Continue chrome, optionally detaching the debugger. GFlags.exe settings for user mode stack trace database. If you then ever suffer a browser memory leak, you can snarf a dump of the process with umdh - p :<my browser pid> > chrome-browser-leak-umdh-dump.txt which can then typically be "trivially" analyzed to find the culprit. Miscellaneous Note that by default Application Verifier only works with non-official builds of Chromium. To use Application Verifier on official builds you need to add --disable-features=RendererCodeIntegrity to avoid sandbox crashes in renderer processes. See  crbug.com/1004989  for details. See also  this page . Application Verifier  is a free tool from Microsoft (available as part of the Windows SDK) that can be used to flush out programming errors. Starting with M68 Application Verifier can be enabled for chrome.exe without needing to disable the sandbox. After adding chrome.exe to the list of applications to be stressed you need to expand the list of Basics checks and disable the  Leak  checks. You may also need to disable  Handles  and  Locks  checks depending on your graphics driver and specific Chrome version, but the eventual goal is to have Chrome run with  Handles  and  Locks  checks enabled. When bugs are found Chrome will trigger a breakpoint so running all Chrome processes under a debugger is recommended. Chrome will run much more slowly because Application Verifier puts every heap allocation on a separate page. Note that with PartitionAlloc Everywhere most Chromium allocations don't actually go through the Windows heap and are therefore unaffected by Application Verifier. You can check the undocumented 'Cuzz' checkbox in Application Verifier to get the Windows thread scheduler to add some extra randomness in order to help expose race conditions in your code. To put a breakpoint on CreateFile(), add this break point: {,,kernel32.dll}_CreateFileW@28 {,,kernel32.dll} specifies the DLL (context operator). _ prefix means extern "C". @28 postfix means _stdcall with the stack pop at the end of the function. i.e. the number of arguments in BYTES. You can use  DebugView  from SysInternals or  sawbuck  to view LOG() messages that normally go to stderr on POSIX.

The Chromium Projects Home Chromium ChromiumOS Quick links Report bugs Discuss Other sites Chromium Blog Google Chrome Extensions Except as otherwise  noted , the content of this page is licensed under a  Creative Commons Attribution 2.5 license , and examples are licensed under the  BSD License . Privacy Edit this page For Developers  >  How-Tos  > Debugging Chromium on Windows First see  get the code  for checkout and build instructions. Getting started You can use Visual Studio's built-in debugger or  WinDBG  to debug Chromium. You don't need to use the IDE to build in order to use the debugger: autoninja is used to build Chromium and most developers invoke it from a command prompt, and then open the IDE for debugging as necessary. To start debugging an already-built executable with Visual Studio just launch Visual Studio (2019 or higher) and select File-> Open-> Project/Solution (Ctrl+Shift+O) and select the executable of interest. This will create a solution with that executable as the 'project'. You can then launch the debugger with F5 or F11 or from the Debug menu. If you right-click on the executable in Solution Explorer and select properties then you can edit things such as the executable path, command-line arguments, and working directory. You can add additional executables to the solution by using File-> Add-> Existing Project and selecting another already-built executable. You can select which one to debug by right-clicking on one of them in Solution Explorer and selecting Set as Startup Project. When your solution file is customized to your taste you can save it to a directory such as out\solutions. Saving it there helps ensure that relative paths to source files, printed from build commands, will correctly identify the source files. The Tools menu can be used to add commands to do things like invoke autoninja to build Chrome, compile the selected source file, or other things. Visual Studio 2017 is not recommended for debugging of Chromium - use a newer version for best performance and stability. symbol_level=2  is the default on Windows and gives full debugging information with types, locals, globals, function names, and source/line information.  symbol_level=1  creates smaller PDBs with just function names, and source/line information - source-level debugging is still supported (new from June 2019), but local variables and type information are missing.  symbol_level=0  gives extremely limited debugging abilities, mostly just viewing call stacks when Chromium crashes. Browsing source code If you use a solution file generated by gn ( gn gen --ide=vs ) then Intellisense may help you navigate the code. If this doesn't work or if you use a solution created as above then you may want to install  VsChromium  to help navigate the code, as well as using  https://source.chromium.org . Profiles It's a good idea to use a different Chrome profile for your debugging. If you are debugging Google Chrome branded builds, or use a Chromium build as your primary browser, the profiles can collide so you can't run both at once, and your stable browser might see profile versions from the future (Google Chrome and Chromium use different profile directories by default so won't collide). Use the command-line option: --user-data-dir =C:\tmp\my_debug_profile (replace the path as necessary) Using the IDE, go to the  Debugging  tab of the properties of the chrome project, and set the  Command Arguments. Chrome debug log Enable Chrome debug logging to a file by passing  --enable-logging --v=1  command-line flags at startup. Debug builds place the  chrome_debug.log  file in the  out\Debug  directory. Release builds place the file in the top level of the user data Chromium app directory, which is OS-version-dependent. For more information, see  logging  and  user data directory  details. Symbol server If you are debugging official Google Chrome release builds, use the symbol server: https://chromium-browser-symsrv.commondatastorage.googleapis.com In Visual Studio, this goes in  Tools > Options  under  Debugging > Symbols . You should set up a local cache in a empty directory on your computer. In windbg you can add this to your symbol server search path with the command below, where C:\symbols is a local cache directory: .sympath+ SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Alternately, You can set the _NT_SYMBOL_PATH environment variable to include both the Microsoft and Google symbol servers - VS, windbg, and other tools should both respect this environment variable: _NT_SYMBOL_PATH =SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols ;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Note that symbol servers will let the debuggers download both the PE files (DLLs and EXEs) and the PDB files. Chrome often loads third party libraries and partial symbols for some of these are also public. For example: AMD : https://download.amd.com/dir/bin Nvidia : https://driver-symbols.nvidia.com/ Intel : https://software.intel.com/sites/downloads/symbols/ For example, for completeness, the following symbol server environment variable will resolve all of the above sources - but this is more than is normally needed: _NT_SYMBOL_PATH=SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com;SRV\*C:\symbols\*https://download.amd.com/dir/bin;SRV\*C:\symbols\*https://driver-symbols.nvidia.com/;SRV\*C:\symbols\*https://software.intel.com/sites/downloads/symbols/ Source indexing You should set up source indexing in your debugger ( .srcfix  in windbg, Tools-> Options-> Debugging-> General->  Enable source server support  in Visual Studio) so that the correct source files will automatically be downloaded based on information in the downloaded symbols. Additionally, you must have  python  in your  path  in order for the  command that fetches source files  to succeed; launching the debugger from the same environment as where you build Chromium is an easy way to ensure it's present. This is highly recommended when debugging released Google Chrome builds or looking at crash dumps. Having the correct version of the source files automatically show up saves significant time so you should definitely set this. Multi-process issues Chromium can be challenging to debug because of its  multi-process architecture . When you select  Run  in the debugger, only the main browser process will be debugged. The code that actually renders web pages (the Renderer) and the plugins will be in separate processes that's not (yet!) being debugged. The  ProcessExplorer  tool has a process tree view where you can see how these processes are related. You can also get the process IDs associated with each tab from the Chrome Task Manager (right-click on an empty area of the window title bar to open). Automatically attach to child processes There are two Visual Studio extensions that enable the debugger to automatically attach to all Chrome processes, so you can debug all of Chrome at once. Microsoft's  Child Process Debugging Power Tool  is a standalone extension for this, and  VsChromium  is another option that bundles many other additional features. In addition to installing one of these extensions, you  must  run Visual Studio as Administrator, or it will silently fail to attach to some of Chrome's child processes. Single-process mode One way to debug issues is to run Chromium in single-process mode. This will allow you to see the entire state of the program without extra work (although it will still have many threads). To use single-process mode, add the command-line flag --single-process This approach isn't perfect because some problems won't manifest themselves in this mode and some features don't work and worker threads are still spawned into new processes. Manually attaching to a child process You can attach to the running child processes with the debugger. Select  Tools > Attach to Process  and click the  chrome.exe  process you want to attach to. Before attaching, make sure you have selected only Native code when attaching to the process This is done by clicking Select... in the Attach to Process window and only checking Native. If you forget this, it may attempt to attach in "WebKit" mode to debug JavaScript, and you'll get an error message "An operation is not legal in the current state." You can now debug the two processes as if they were one. When you are debugging multiple processes, open the  Debug > Windows > Processes  window to switch between them. Sometimes you are debugging something that only happens on startup, and want to see the child process as soon as it starts. Use: --renderer-startup-dialog --no-sandbox You have to disable the sandbox or the dialog box will be prohibited from showing. When the dialog appears, visit Tools > Attach to Process and attach to the process showing the Renderer startup dialog. Now you're debugging in the renderer and can continue execution by pressing OK in the dialog. Startup dialogs also exist for other child process types:  --gpu-startup-dialog ,  --ppapi-startup-dialog ,  --utility-startup-dialog ,  --plugin-startup-dialog  (for NPAPI). For utilities, you can add a service type  --utility-startup-dialog=data_decoder.mojom.DataDecoderService . You can also try  the vs-chromium plug-in  to attach to the right processes. Semi-automatically attaching the debugger to child processes The following flags cause child processes to wait for 60 seconds in a busy loop for a debugger to attach to the process. Once either condition is true, it continues on; no exception is thrown. --wait-for-debugger-children [=filter] The filter, if provided, will fire only if it matches the  --type  parameter to the process. Values include  renderer ,  plugin  (for NPAPI),  ppapi ,  gpu-process , and  utility . When using this option, it may be helpful to limit the number of renderer processes spawned, using: --renderer-process-limit = 1 Image File Execution Options Using Image File Execution Options (IFEO) will not work because CreateProcess() returns the handle to the debugger process instead of the intended child process. There are also issues with the sandbox. Time travel debugging You can do  time travel debugging using WinDbg Preview  (must be installed from the Microsoft Store). This lets you execute a program forward and backwards. After capturing a trace, you can set breakpoints and step through code as normal, but also provides 'backwards' commands (g-, t-, p-) so that you can go back and forth through the execution. It is especially useful to set data breakpoints ( ba command ) and reverse continuing, so you can see when a certain variable was last changed to its current value. Chromium specifics: The type of injection the time travel tracer needs to perform is incompatible with the Chromium sandbox. In order to record a trace, you'll need to run with  --no-sandbox . Chromium cannot run elevated with Administrator privileges, so the "Launch executable (advance)" option won't work, you'll need to attach after the process has already launched via the checkbox in the bottom right. If you need to record startup-like things, you'll have to use --{browser,gpu,renderer,utility}-startup-dialog, then attach (and hope the relevant code hasn't executed before that point). JsDbg -- data structure visualization You can install  JsDbg as a plugin for WinDbg or Visual Studio . It interactively lets you look at data structures (such as the DOM tree, Accessibility tree, layout object tree, and others) in a web browser as you debug. See the  JsDbg site  for some screen shots and usage examples. This also works when examining memory dumps (though not minidumps), and also works together with time travel debugging. Visual Studio hints Debug visualizers Chrome's custom debug visualizers should be added to the pdb files and automatically picked up by Visual Studio. The definitions are in  //tools/win/DebugVisualizers  if you need to modify them (the BUILD.gn file there has additional instructions). Don't step into trivial functions The debugger can be configured to automatically not step into functions based on regular expression. Edit  default.natstepfilter  in the following directory: For Visual Studio 2015:  C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2015\Visualizers  (for the current user only) For Visual Studio 2017 Pro:  C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2017\Visualizers  (for the current user only) Add regular expressions of functions to not step into. Remember to regex-escape  and  XML-escape them, e.g. < for < and \. for a literal dot. Example: < Function > < Name > operator new </ Name > < Action > NoStepInto </ Action > </ Function > < Function > < Name > operator delete </ Name > < Action > NoStepInto </ Action > </ Function > <!-- Skip everything in std --> < Function > < Name > std::.* </ Name > < Action > NoStepInto </ Action > </ Function > <!-- all methods on WebKit OwnPtr and variants, ... WTF::*Ptr<*>::* --> < Function > < Name > WTF::.*Ptr<.*>::.* </ Name > < Action > NoStepInto </ Action > </ Function > This file is read at start of a debugging session (F5), so you don't need to restart Visual Studio after changing it. More info:  Microsoft email thread V8 and Chromium V8 supports many command-line flags that are useful for debugging. V8 command-line flags can be set via the Chromium command-line flag --js-flags; for instance: chrome.exe --js-flags= "--trace_exception --heap_stats" Note that some V8 command-line flags exist only in the debug build of V8. For a list of all V8 flags try: chrome.exe --js-flags= "--help" Graphics debugging GPU Acceleration of rendering can be more easily debugged with tools. See: Graphics Debugging in Visual Studio 2013 Graphical debugging with NVIDIA NSight Debugging on another machine Sometimes it's useful to debug installation and execution on a machine other than your primary build box. To run the installer on said other machine, first build the mini_installer target on your main build machine (e.g., autoninja -C out\Debug mini_installer). Next, on the debug machine: Make the build machine's build volume available on the debug machine either by mounting it locally (e.g., Z:\) or by crafting a UNC path to it (e.g., \\builder\src) Open up a command prompt and change to a local disk Run src\tools\win\ copy-installer.bat  in the remote checkout by way of the mount (e.g., Z:\PATHTOCHECKOUT\src\...) or UNC path (e.g., \\builder\src\...). This will copy the installer, DLLs, and PDBs into your debug machine's C:\out or C:\build (depending on if you're rocking the component=shared_library build or not) Run  C:\out\Debug\mini_installer.exe  with the flags of your choice to install Chrome. This can take some time, especially on a slow machine. Watch the Task Manager and wait until mini_installer.exe exits before trying to launch Chrome (by way of the shortcut(s) created by the installer) For extra pleasure, add C:\out\Debug to your _NT_SYMBOL_PATH environment variable Consider reading the documentation at the top of copy-installer.bat to see how you can run it. It tries to be smart and copy the right things, but you may need to be explicit (e.g., "copy-installer.bat out Debug"). It is safe to re-run the script to copy only modified files (after a rebuild, for example). You can also use the zip action of the isolate scripts (tools\mb\mb.py) to package all the files for a target into a single zip file, for example: python tools\mb\mb.py zip out/Release base_unittests base_unittests. zip Finding all memory allocations It is possible to use Heap Snapshots to get call stacks on all outstanding allocations that use the OS heap. This works particularly well if heap snapshots are started as soon as the Chrome browser process is created, but before it starts running. Details can be found in  this batch file . However, with  PartitionAlloc Everywhere  most Chromium allocations no longer use the Windows heap so this will only find a subset of allocations, mostly from OS DLLs. Find memory leaks Note: as with Heap Snapshots the utility of UMDH is greatly reduced now because PartitionAlloc Everywhere has mostly replaced the Windows heap. The Windows heap manager has a really useful debug flag, where it can be asked to capture and store a stack trace with every allocation. The tool to scrape these stack traces out of processes is UMDH, which comes with  WinDbg . UMDH is great. It will capture a snapshot of the heap state as many times as you like, and it'll do it fairly quickly. You then run it again against either a single snapshot, or a pair of snapshots, at which time it'll symbolize the stack traces and aggregate usage up to unique stack traces. Turning on the user stack trace database for chrome.exe with gflags.exe makes it run unbearably slowly; however, turning on the user stack trace database on for the browser alone is just fine. While it's possible to turn on the user stack database with the "!gflag" debugging extension, it's too late to do this by the time the initial debugger breakpoint hits. The only reasonable way to do this is to Launch GFlags.exe, Enable the user stack trace database (per image below), Launch Chrome under the debugger. Set a breakpont when chrome.dll loads with "sxe ld chrome.dll". Step up, to allow Chrome.dll to initialize. Disable the stack trace database in GFlags.exe. Continue chrome, optionally detaching the debugger. GFlags.exe settings for user mode stack trace database. If you then ever suffer a browser memory leak, you can snarf a dump of the process with umdh - p :<my browser pid> > chrome-browser-leak-umdh-dump.txt which can then typically be "trivially" analyzed to find the culprit. Miscellaneous Note that by default Application Verifier only works with non-official builds of Chromium. To use Application Verifier on official builds you need to add --disable-features=RendererCodeIntegrity to avoid sandbox crashes in renderer processes. See  crbug.com/1004989  for details. See also  this page . Application Verifier  is a free tool from Microsoft (available as part of the Windows SDK) that can be used to flush out programming errors. Starting with M68 Application Verifier can be enabled for chrome.exe without needing to disable the sandbox. After adding chrome.exe to the list of applications to be stressed you need to expand the list of Basics checks and disable the  Leak  checks. You may also need to disable  Handles  and  Locks  checks depending on your graphics driver and specific Chrome version, but the eventual goal is to have Chrome run with  Handles  and  Locks  checks enabled. When bugs are found Chrome will trigger a breakpoint so running all Chrome processes under a debugger is recommended. Chrome will run much more slowly because Application Verifier puts every heap allocation on a separate page. Note that with PartitionAlloc Everywhere most Chromium allocations don't actually go through the Windows heap and are therefore unaffected by Application Verifier. You can check the undocumented 'Cuzz' checkbox in Application Verifier to get the Windows thread scheduler to add some extra randomness in order to help expose race conditions in your code. To put a breakpoint on CreateFile(), add this break point: {,,kernel32.dll}_CreateFileW@28 {,,kernel32.dll} specifies the DLL (context operator). _ prefix means extern "C". @28 postfix means _stdcall with the stack pop at the end of the function. i.e. the number of arguments in BYTES. You can use  DebugView  from SysInternals or  sawbuck  to view LOG() messages that normally go to stderr on POSIX.

Generative Music Box Project Using JavaScript

xxi, 356 pages ; 24 cm

xxi, 356 pages ; 24 cm

xxi, 356 pages ; 24 cm

xxi, 356 pages ; 24 cm

xxi, 356 pages ; 24 cm

Liz Abinante! http://lanyrd.com/2016/nodepdx/sfchfq/ The talk will show taking something real-world and math-based, like knitting, and turning into a program is actually super easy (no one is surprised here). But! What happens when you combine that with best practices and expected conventions, along with industry-wide standards for design and presentation? Things get a lot more complicated than just crunching numbers, especially when your output will result in lots of manual hours for people creating a real object. This is the story of how Liz built a customizable knitting pattern generator in JavaScript (after she'd built it in Ruby first, of course), and the lessons learned when you try and do math for more than just math's sake.

Andrzej Mazur is a HTML5 Game Developer. He joins the show alongside AJ and Chuck to talk about creating games in JavaScript. He begins by outlining his past and current experiences as a game developer. He offers some of his techniques to individuals who want to start developing web games. Sponsors  Chuck's Resume Template   Developer Book Club Become a Top 1% Dev with a Top End Devs Membership Links ENCLAVE GAMES js13kGames Gamedev.js Gamedev.js weekly Gamedev.js Warszawa FOREST CUTIES EnclaveGames/Enclave-Phaser-Template OpenGameArt Unity Asset Store Kenney Game Assets Global Game Jam webinstall.dev/aliasman GitHub: end3r LinkedIn: Andrzej Mazur Twitter: @end3r Picks AJ -  OC Remix AJ -  Ballarini (Granitium Non-Stick Cookware) set AJ -  Utility Series Keychain Knife AJ -  EDC Fans Keychain Knife Andrzej -  NeuroshimaHex.pl Andrzej -  Gamedev.js Jam 2022 Andrzej -  Phaser Chuck -  Mysterium  Chuck - Hold on to people you care about!  Support this podcast at - https://redcircle.com/javascript-jabber/donations Advertising Inquiries: https://redcircle.com/brands Privacy & Opt-Out: https://redcircle.com/privacy

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Javascript has become widely popular for developing hybrid mobile technologies by the advent of tools like Phonegap, Kony, Telerik App Builder. In this talk, I will demo how to create a Hybrid Mobile app using Javascript - AngularJS & Ionic Framework.

Our guest is Daniel Lathrop, a freelance investigative data journalist and educator, and formerly a newspaper reporter and Professor of Journalism and Media informatics at the University of Iowa. On this show, Daniel describes how JavaScript is a great choice for doing data analysis and data science, potentially even more so than other languages which are often used for this purpose, such as Python and R. Daniel also provides information about lots of useful tools and techniques to use in this context. Sponsors ? The Complete Software Developer’s Career Guide  – Grab a Copy Today ? CacheFly Panel ? AJ ONeal ? Aimee Knight ? Dan Shappir Special Guest ? Daniel Lathrop Links ? https://daniel.buzz/ Picks Aimee ? Forecasting at Scale Dan Shappir ? https://www.data-forge-notebook.com AJ ? Propaganda in Nazi Germany Daniel Lathrop ? https://www.data-forge-notebook.com ? https://www.claudiajs.com ? https://js4ds.org/ ? Follow JavaScript Jabber on Twitter >  @JSJabber

This talk occurred at DWeb Camp 2023 at Camp Navarro, CA. It was given by Tracey Jaquith. Link to SCHED The first five minutes of this talk are dedicated to explaining the idea, showing a post, and explaining how the simple markdown becomes a full website. Then the speaker will explain the benefits of this approach, explaining what a sitemap is, and how it's used. After that, we'll take a look at some of the JavaScript code that parses the posts, creates the site theme, and transforms the content. Speaker Tracey Jaquith, TV Architect & DevOps: Tracey was a founding coder and system architect for Internet Archive in 1996, writing multi-threaded servers, crawlers and more.  In 2000, Tracey left for four years to follow her Cornell mentor, Dan Huttenlocher, and was a technical lead and founding engineer at a startup. Recently, she rewrote Archive's TV recording system to an opensource single server system, capable of 75 simultaneous 24x7 channels, made the TV site "full stack" first and second versions, and brought archive.org website to "version 2".  Tracey is now leading the containerization of the Internet Archive, holding a Master's and Bachelor's in computer science from Cornell University where she focused on machine vision and robotics.

I'm a #noob with #JavaScript but I wanted Full screen (any size) and to be able to draw on the #html5 #canvas using #coordinates. #Gotit!-M0AnjFeqVg3.mp4

I'm a #noob with #JavaScript but I wanted Full screen (any size) and to be able to draw on the #html5 #canvas using #coordinates. #Gotit!-M0AnjFeqVg3.mp4

I'm a #noob with #JavaScript but I wanted Full screen (any size) and to be able to draw on the #html5 #canvas using #coordinates. #Gotit!-M0AnjFeqVg3.mp4

I'm a #noob with #JavaScript but I wanted Full screen (any size) and to be able to draw on the #html5 #canvas using #coordinates. #Gotit!-M0AnjFeqVg3.mp4

86 str. : 30 cm

86 str. : 30 cm

Not sure how to announce this other than by uploading a 'thing'. So here is one. Enthousiastic about OpenSCAD but somewhat frustrated by the limitations of its language, I've worked on an alternative using Javascript. It's free, completely open source, still seriously under construction, based on Evan Wallace's CSG.js library and can be used in a web browser, See: http://joostn.github.com/OpenJsCad/ The benefits over openSCAD are mainly in the language itself: you can use dynamic arrays for example, and solids can be stored in variables. UPDATE: I've added a parser for local files as well. Create your own .jscad files, go to http://joostn.github.com/OpenJsCad/processfile.html to parse them into an STL file. UPDATE 2: Here's my first real thing designed with OpenJsCad: http://www.thingiverse.com/thing:16329 UPDATE 3: Now with interactive parameter editing! Check out: http://joostn.github.com/OpenJsCad/gearsdemo.html Syntax has been changed slightly! Solids must now be constructed in, and returned from, the main() function. Previously this was done in global scope of the script.

Our guest is Daniel Lathrop, a freelance investigative data journalist and educator, and formerly a newspaper reporter and Professor of Journalism and Media informatics at the University of Iowa. On this show, Daniel describes how JavaScript is a great choice for doing data analysis and data science, potentially even more so than other languages which are often used for this purpose, such as Python and R. Daniel also provides information about lots of useful tools and techniques to use in this context. Sponsors ? The Complete Software Developer’s Career Guide  – Grab a Copy Today ? CacheFly Panel ? AJ ONeal ? Aimee Knight ? Dan Shappir Special Guest ? Daniel Lathrop Links ? https://daniel.buzz/ Picks Aimee ? Forecasting at Scale Dan Shappir ? https://www.data-forge-notebook.com AJ ? Propaganda in Nazi Germany Daniel Lathrop ? https://www.data-forge-notebook.com ? https://www.claudiajs.com ? https://js4ds.org/ ? Follow JavaScript Jabber on Twitter >  @JSJabber

Our guest is Daniel Lathrop, a freelance investigative data journalist and educator, and formerly a newspaper reporter and Professor of Journalism and Media informatics at the University of Iowa. On this show, Daniel describes how JavaScript is a great choice for doing data analysis and data science, potentially even more so than other languages which are often used for this purpose, such as Python and R. Daniel also provides information about lots of useful tools and techniques to use in this context. Sponsors ? The Complete Software Developer’s Career Guide  – Grab a Copy Today ? CacheFly Panel ? AJ ONeal ? Aimee Knight ? Dan Shappir Special Guest ? Daniel Lathrop Links ? https://daniel.buzz/ Picks Aimee ? Forecasting at Scale Dan Shappir ? https://www.data-forge-notebook.com AJ ? Propaganda in Nazi Germany Daniel Lathrop ? https://www.data-forge-notebook.com ? https://www.claudiajs.com ? https://js4ds.org/ ? Follow JavaScript Jabber on Twitter >  @JSJabber

Portfolio Website using HTML, CSS, and JavaScript with Hosting

Portfolio Website using HTML, CSS, and JavaScript with Hosting

Portfolio Website using HTML, CSS, and JavaScript with Hosting

It is a time-honored fashion to implement a domain-specific language (DSL) by translation to a general-purpose language. Such an implementation is more portable, but an unidiomatic translation jeopardizes performance because, in practice, language implementations favor the common cases. This tension arises especially when the domain calls for complex control structures. We illustrate this tension by revisiting Landin's original correspondence between Algol and Church's lambda-notation. We translate domain-specific programs with lexically scoped jumps to JavaScript. Our translation produces the same block structure and binding structure as in the source program, a la Abdali. The target code uses a control operator in direct style, a la Landin. In fact, the control operator used is almost Landin's J---hence our title. Our translation thus complements a continuation-passing translation a la Steele. These two extreme translations require JavaScript implementations to cater either for first-class continuations, as Rhino does, or for proper tail recursion. Less extreme translations should emit more idiomatic control-flow instructions such as for, break, and throw. The present experiment leads us to conclude that translations should preserve not just the data structures and the block structure of a source program, but also its control structure. We thus identify a new class of use cases for control structures in JavaScript, namely the idiomatic translation of control structures from DSLs. ©2009 Microsoft Corporation. All rights reserved.

Build the Game of Life Using JavaScript

The author of Appcelerator Titanium: Up and Running describes how Titanium can be used to generate native mobile apps from JavaScript code. He distinguishes the Titanium platform from native API programming and from other popular JavaScript platforms for mobile devices. We look at the way Titanium exploits the expressiveness and flexibility of JavaScript, and some of the directions that the Appcelerator company is taking Titanium." Source: https://soundcloud.com/programming-podcast/prog-podcast-andy-john Uploader: O'Reilly Programming

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High end augmented reality using Javascript Using markers with a webcam is cool but what about a HoloLens or MagicLeap straight from the browser? by Fabien Benetou (Utopiah) At: FOSDEM 2019 https://video.fosdem.org/2019/H.1308/machine_learning_javascript.webm VR is so 2018. Now is time for AR... or is it? In this talk we will explore practically what is feasible today and how. We'll rely on Exokit for the new Magic Leap ML1 after briefly exploring what is AR, what it's good for then some guiding principles. No AR expertise required, just basic JavaScript frontend of backend will do. Room: H.1308 (Rolin) Scheduled start: 2019-02-03 10:30:00+01 Source: https://www.youtube.com/watch?v=7Y26m2M8l8M Uploader: FOSDEM

High end augmented reality using Javascript Using markers with a webcam is cool but what about a HoloLens or MagicLeap straight from the browser? by Fabien Benetou (Utopiah) At: FOSDEM 2019 https://video.fosdem.org/2019/H.1308/machine_learning_javascript.webm VR is so 2018. Now is time for AR... or is it? In this talk we will explore practically what is feasible today and how. We'll rely on Exokit for the new Magic Leap ML1 after briefly exploring what is AR, what it's good for then some guiding principles. No AR expertise required, just basic JavaScript frontend of backend will do. Room: H.1308 (Rolin) Scheduled start: 2019-02-03 10:30:00+01 Source: https://www.youtube.com/watch?v=7Y26m2M8l8M Uploader: FOSDEM

Talk given at the Framsia meetup in Oslo about progressive enhancement and using JavaScript

Talk given at the Framsia meetup in Oslo about progressive enhancement and using JavaScript

Talk given at the Framsia meetup in Oslo about progressive enhancement and using JavaScript

This thesis investigated the current infrastructure for web-based simulations using the DIS network protocol. The main technologies studied were WebSockets, WebRTC and WebGL. This thesis sought readily available means to establish networks for interchanging DIS message (PDUs), so the WebSocket gateway server from Open-DIS project was used to construct a Client-Server structure and PeerJS API was used to construct a peer-to-peer structure. WebGL was used to create a scene and render 3D models in browsers. A first-person-shooter tank game was used as a test application with both WebSocket and WebRTC infrastructures. Experiments in this thesis included measuring the rate of sending and receiving DIS packets and analysis of the tank game by profiling tools. All the experiments were run on Chrome and Firefox browsers in a closed network. The experimental results showed that both WebSocket and WebRTC infrastructures were competent enough to support web-based DIS simulation. The results also found the significant differences of performance between Chrome and Firefox. Currently, the best performance is provided by the combination of Firefox using the WebRTC framework. The analysis of the tank game showed that most of the browser s computational resources were spent on the WebGL graphics, with only a small percentage of the resources expended on exchanging DIS packets.

This thesis investigated the current infrastructure for web-based simulations using the DIS network protocol. The main technologies studied were WebSockets, WebRTC and WebGL. This thesis sought readily available means to establish networks for interchanging DIS message (PDUs), so the WebSocket gateway server from Open-DIS project was used to construct a Client-Server structure and PeerJS API was used to construct a peer-to-peer structure. WebGL was used to create a scene and render 3D models in browsers. A first-person-shooter tank game was used as a test application with both WebSocket and WebRTC infrastructures. Experiments in this thesis included measuring the rate of sending and receiving DIS packets and analysis of the tank game by profiling tools. All the experiments were run on Chrome and Firefox browsers in a closed network. The experimental results showed that both WebSocket and WebRTC infrastructures were competent enough to support web-based DIS simulation. The results also found the significant differences of performance between Chrome and Firefox. Currently, the best performance is provided by the combination of Firefox using the WebRTC framework. The analysis of the tank game showed that most of the browser s computational resources were spent on the WebGL graphics, with only a small percentage of the resources expended on exchanging DIS packets.

Dive into combining art and coding. Learn how to code creatively by drawing with HTML and JavaScript. Mattaniah, a UX Engineer at Google, shares how to create visual art using web technologies. She explains creative coding, including how to add a background, fill the color, and draw shapes on an HTML canvas. Resources: Visit our website → https://goo.gle/WTM HTML Canvas → https://goo.gle/3foV34N Processing Foundation → https://goo.gle/3SUD3Na OpenFrameworks → https://goo.gle/3Wu6rwA Watch more Women Techmakers in 60 seconds! → https://goo.gle/2LGAgK1 Subscribe for more Women Techmakers videos → https://goo.gle/WomenTech #Creative #Coding #HTML #JavaScript

HiveMind: Distributed File Storage Using JavaScript Botnets SEAN MALONE PRINCIPAL SECURITY CONSULTANT, FUSIONX Some data is too sensitive or volatile to store on systems you own. What if we could store it somewhere else without compromising the security or availability of the data, while leveraging intended functionality to do so? This presentation will cover the methodology and tools required to create a distributed file store built on top of a JavaScript botnet. This type of data storage offers redundancy, encryption, and plausible deniability, but still allows you to store a virtually unlimited amount of data in any type of file. They can seize your server -- but the data's not there! Sean Malone has been building and breaking networks and applications for the last 12 years, and he has a diverse practical and academic background in information technology and security. As a Principal Consultant and the primary engagement manager for FusionX, Sean provides clients across all verticals with sophisticated adversary simulation assessments and strategic security guidance. Sean is a key member of the FusionX internal research and development team and his custom security assessment utilities are used in a majority of FusionX engagements. SeanTMalone.com LinkedIn: http://www.linkedin.com/in/seantmalone Source: https://www.youtube.com/watch?v=GAq86wfeC9E Uploader: DEFCONConference