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diff --git a/www/symbols.html b/www/symbols.html new file mode 100755 index 000000000000..af98e7d24dde --- /dev/null +++ b/www/symbols.html @@ -0,0 +1,345 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml"> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> +<link href="style.css" rel="stylesheet" type="text/css" /> +<title>Debug Symbols on Mac OS X</title> +</head> + +<body> + <div class="www_title"> + The <strong>LLDB</strong> Debugger + </div> + +<div id="container"> + <div id="content"> + + <!--#include virtual="sidebar.incl"--> + + <div id="middle"> + <div class="post"> + <h1 class="postheader">Debug Symbols on MacOSX</h1> + <div class="postcontent"> + <p>On MacOSX, debug symbols are often in stand alone bundles called <b>dSYM</b> files. + These are bundles that contain DWARF debug information and other resources related to + builds and debug info.</p> + <p>The DebugSymbols.framework framework helps locate dSYM files when given a UUID. It can + locate the symbols using a variety of methods:</p> + <ul> + <li>Spotlight</li> + <li>Explicit search paths</li> + <li>Implicit search paths</li> + <li>File mapped UUID paths</li> + <li>Running one or more shell scripts</li> + </ul> + <p>DebugSymbols.framework also has global defaults that can be modified to allow + all of the debug tools (lldb, gdb, sample, CoreSymbolication.framework) to easily + find important debug symbols. The domain for the DebugSymbols.framework defaults + is <b>com.apple.DebugSymbols</b>, and the defaults can be read, written or modified + using the <b>defaults</b> shell command: +<code><pre><tt><b>% defaults read com.apple.DebugSymbols +% defaults write com.apple.DebugSymbols KEY ... +% defaults delete com.apple.DebugSymbols KEY</b> +</tt></pre></code> + + <p>The following is a list of the defaults key value + setting pairs that can be used to enhance symbol location:</p> + <table class="stats" width="620" cellspacing="0"> + <tr> + <td class="hed" width="20%">Defaults Key</td> + <td class="hed" width="70%">Description</td> + </tr> + + <tr> + <td class="content"> + <b>DBGFileMappedPaths</b> + </td> + <td class="content"> + This default can be specified as a single string, or an array of strings. + Each string represents a directory that contains file mapped UUID values + that point to dSYM files. See the "File Mapped UUID Directories" section + below for more details. Whenever DebugSymbols.framework is asked to lookup + a dSYM file, it will first look in any file mapped UUID directories + for a quick match. + </td> + </tr> + <td class="content" colspan="2"> +<code><pre><tt><b>% defaults write com.apple.DebugSymbols DBGFileMappedPaths -string /path/to/uuidmap1</b> +<b>% defaults write com.apple.DebugSymbols DBGFileMappedPaths -array /path/to/uuidmap1 + /path/to/uuidmap2</b> +</tt></pre></code> + </tr> + <tr> + <td class="content"> + <b>DBGShellCommands</b> + </td> + <td class="content"> + This default can be specified as a single string, or an array of strings. + Specifies a shell script that will get run in order to find the dSYM. + The shell script will be run given a single UUID value as the shell + command arguments and the shell command is expected to return a property + list. See the property list format defined below. + </td> + </tr> + <td class="content" colspan="2"> +<code><pre><tt><b>% defaults write com.apple.DebugSymbols DBGShellCommands -string /path/to/script1</b> +<b>% defaults write com.apple.DebugSymbols DBGShellCommands -array /path/to/script1 + /path/to/script2</b> +</tt></pre></code> + </td> + </tr> + <tr> + <td class="content"> + <b>DBGSpotlightPaths</b> + </td> + <td class="content"> + Specifies the directories to limit spotlight searches to as a string or array of strings. When any + other defaults are supplied to <b>com.apple.DebugSymbols</b>, spotlight + searches will be disabled unless this default is set to an empty array: + </td> + </tr> + <td class="content" colspan="2"> +<code><pre><tt><font color="green"># Specify an empty array to keep Spotlight searches enabled in all locations</font> +<b>% defaults write com.apple.DebugSymbols DBGSpotlightPaths -array</b> + +<font color="green"># Specify an array of paths to limit spotlight searches to certain directories</font> +<b>% defaults write com.apple.DebugSymbols DBGSpotlightPaths -array /path/dir1 /path/dir2</b> +</tt></pre></code> + </td> + </tr> + </table> + </div> + <div class="postfooter"></div> + </div> + <div class="post"> + <h1 class="postheader">Shell Script Property List Format</h1> + <div class="postcontent"> +<p>Shell scripts that are specified with the <b>DBGShellCommands</b> defaults key +will be run in the order in which they are specified until a match is found. +The shell script will be invoked with a single UUID string value like +"23516BE4-29BE-350C-91C9-F36E7999F0F1". The shell script must respond with a +property list being written to STDOUT. +The property list returned must contain UUID string values as the root key values, with +a dictionary for each UUID. The dictionaries can contain one or more of the following keys: + + <table class="stats" width="620" cellspacing="0"> + <tr> + <td class="hed" width="20%">Key</td> + <td class="hed" width="70%">Description</td> + </tr> + <tr> + <td class="content"> + <b>DBGArchitecture</b> + </td> + <td class="content">A textual architecture or target triple like "x86_64", "i386", or "x86_64-apple-macosx". + </td> + </tr> + <tr> + <td class="content"> + <b>DBGBuildSourcePath</b> + </td> + <td class="content">A path prefix that was used when building the dSYM file. The debug information will + contain paths with this prefix. + </td> + </tr> + <tr> + <td class="content"> + <b>DBGSourcePath</b> + </td> + <td class="content">A path prefix for where the sources exist after the build has completed. Often when + building projects, build machines will host the sources in a temporary directory while building, then + move the sources to another location for archiving. If the paths in the debug info don't match where + the sources are currently hosted, then specifying this path along with the <b>DBGBuildSourcePath</b> + will help the developer tools always show you sources when debugging or symbolicating. + </td> + </tr> + <tr> + <td class="content"> + <b>DBGDSYMPath</b> + </td> + <td class="content">A path to the dSYM mach-o file inside the dSYM bundle. + </td> + </tr> + <tr> + <td class="content"> + <b>DBGSymbolRichExecutable</b> + </td> + <td class="content">A path to the symbol rich executable. Binaries are often stripped after + being built and packaged into a release. If your build systems saves an unstripped executable + a path to this executable can be provided. + </td> + </tr> + <tr> + <td class="content"> + <b>DBGError</b> + </td> + <td class="content">If a binary can not be located for the supplied UUID, a user readable error + can be returned. + </td> + </tr> + </table> + +<p>Below is a sample shell script output for a binary that contains two architectures: +<code><pre><tt> +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> +<plist version="1.0"> +<dict> + <key>23516BE4-29BE-350C-91C9-F36E7999F0F1</key> + <dict> + <key>DBGArchitecture</key> + <string>i386</string> + <key>DBGBuildSourcePath</key> + <string>/path/to/build/sources</string> + <key>DBGSourcePath</key> + <string>/path/to/actual/sources</string> + <key>DBGDSYMPath</key> + <string>/path/to/foo.dSYM/Contents/Resources/DWARF/foo</string> + <key>DBGSymbolRichExecutable</key> + <string>/path/to/unstripped/executable</string> + </dict> + <key>A40597AA-5529-3337-8C09-D8A014EB1578</key> + <dict> + <key>DBGArchitecture</key> + <string>x86_64</string> + <key>DBGBuildSourcePath</key> + <string>/path/to/build/sources</string> + <key>DBGSourcePath</key> + <string>/path/to/actual/sources</string> + <key>DBGDSYMPath</key> + <string>/path/to/foo.dSYM/Contents/Resources/DWARF/foo</string> + <key>DBGSymbolRichExecutable</key> + <string>/path/to/unstripped/executable</string> + </dict> +</dict> +</plist> +</tt></pre></code> + +<p>There is no timeout imposed on a shell script when is it asked to locate a dSYM file, so be careful to not make a shell +script that has high latency or takes a long time to download unless this +is really what you want. This can slow down debug sessions in LLDB and GDB, symbolication +with CoreSymbolication or Report Crash, with no visible feedback to the user. You can +quickly return a plist with a single <b>DBGError</b> key that indicates a timeout +has been reached. You might also want to exec new processes to do the downloads so +that if you return an error that indicates a timeout, your download can still proceed +after your shell script has exited so subsequent debug sessions can use the cached files. +It is also important to track when a current download is in progress in case you get multiple requests for the same UUID so +that you don't end up downloading the same file simultaneously. Also you will want +to verify the download was successful and then and only then place the file into the +cache for tools that will cache files locally. + </div> + <div class="postfooter"></div> + </div> + <div class="post"> + <h1 class="postheader">Embedding UUID property lists inside the dSYM bundles</h1> + <div class="postcontent"> +<p>Since dSYM files are bundles, you can also place UUID info plists files inside +your dSYM bundles in the <b>Contents/Resources</b> directory. One of the main +reasons to create the UUID plists inside the dSYM bundles +is that it will help LLDB and other developer tools show you source. LLDB currently +knows how to check for these plist files so it can automatically remap the source +location information in the debug info. + +<p>If we take the two UUID values from the returns plist above, we can split +them out and save then in the dSYM bundle: + +<code><pre><tt><b>% ls /path/to/foo.dSYM/Contents/Resources</b> +23516BE4-29BE-350C-91C9-F36E7999F0F1.plist +A40597AA-5529-3337-8C09-D8A014EB1578.plist + +<b>% cat /path/to/foo.dSYM/Contents/Resources/23516BE4-29BE-350C-91C9-F36E7999F0F1.plist</b> +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> +<plist version="1.0"> +<dict> + <key>DBGArchitecture</key> + <string>i386</string> + <key>DBGBuildSourcePath</key> + <string>/path/to/build/sources</string> + <key>DBGSourcePath</key> + <string>/path/to/actual/sources</string> + <key>DBGDSYMPath</key> + <string>/path/to/foo.dSYM/Contents/Resources/DWARF/foo</string> + <key>DBGSymbolRichExecutable</key> + <string>/path/to/unstripped/executable</string> +</dict> +</plist> +</tt></pre></code> + +<p>Note that the output is very close to what is needed by shell script output, +so making the results of your shell script will be very easy to create by +combining two plists into a single one where you take the UUID and use it a + string key, and the value is the contents of the plist. + + + </div> + <div class="postfooter"></div> + </div> + <div class="post"> + <h1 class="postheader">File Mapped UUID Directories</h1> + <div class="postcontent"> +<p>File Mapped directories can be used for efficient dSYM file lookups for +local or remote dSYM files. The UUID is broken up by splitting the first +20 hex digits into 4 character chunks, and a directory is created for each +chunk, and each subsequent directory is created inside the previous one. +A symlink is then created whose name is the last 12 hex digits in the deepest +directory. The symlinks value is a full path to the mach-o files inside the +dSYM bundle which contains the DWARF. Whenever DebugSymbols.framework is asked +to lookup a dSYM file, it will first look in any file mapped UUID directories +for a quick match if the defaults are appropriately set. + +<p>For example, if we take the sample UUID plist inforamtion from above, we +can create a File Mapped UUID directory cache in <b>~/Library/SymbolCache/dsyms/uuids</b>. +We can easily see how things are laid out: + +<code><pre><tt><b>% find ~/Library/SymbolCache/dsyms/uuids -type l</b> +~/Library/SymbolCache/dsyms/uuids/2351/6BE4/29BE/350C/91C9/F36E7999F0F1 +~/Library/SymbolCache/dsyms/uuids/A405/97AA/5529/3337/8C09/D8A014EB1578 +</tt></pre></code> + +<p>The last entries in these file mapped directories are symlinks to the actual dsym mach file in the dsym bundle: + +<code><pre><tt><b>% ls -lAF ~/Library/SymbolCache/dsyms/uuids/2351/6BE4/29BE/350C/91C9/F36E7999F0F1</b> +~/Library/SymbolCache/dsyms/uuids/2351/6BE4/29BE/350C/91C9/F36E7999F0F1@ -> ../../../../../../dsyms/foo.dSYM/Contents/Resources/DWARF/foo +</tt></pre></code> +<p>Then you can also tell DebugSymbols to check this UUID file map cache using: + +<code><pre><tt><b>% defaults write com.apple.DebugSymbols DBGFileMappedPaths ~/Library/SymbolCache/dsyms/uuids</b> +</tt></pre></code> + + + </div> + <div class="postfooter"></div> + </div> + <div class="post"> + <h1 class="postheader">dSYM Locating Shell Script Tips</h1> + <div class="postcontent"> + +<p>One possible implementation of a dSYM finding shell script is to have the script +download and cache files locally in a known location. Then create a UUID map +for each UUID value that was found in a local UUID File Map cache so the next query for the dSYM +file will be able to use the cached version. So the shell script is used to +initially download and cache the file, and subsequent accesses will use the +cache and avoid calling the shell script. + +<p>Then the defaults for DebugSymbols.framework will entail enabling your shell script, +enabling the file mapped path setting so that already downloaded dSYMS fill quickly +be found without needing to run the shell script every time, and also leaving spotlight enabled +so that other normal dSYM files are still found: + +<code><pre><tt><b>% defaults write com.apple.DebugSymbols DBGShellCommands /path/to/shellscript +% defaults write com.apple.DebugSymbols DBGFileMappedPaths ~/Library/SymbolCache/dsyms/uuids +% defaults write com.apple.DebugSymbols DBGSpotlightPaths -array</b> +</tt></pre></code> + +Hopefully this helps explain how DebugSymbols.framework can help any company +implement a smart symbol finding and caching with minimal overhead. +</p> + </div> + <div class="postfooter"></div> + </div> + </div> + </div> +</div> +</body> +</html> |