Jim Ingham
parent
7a8c477f2a
commit
87a593687c
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@ -33,17 +33,18 @@ def ls(debugger, command, result, dict):
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for arg in args:
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if options.verbose:
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print commands.getoutput('/bin/ls "%s"' % arg)
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result.PutCString(commands.getoutput('/bin/ls "%s"' % arg))
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else:
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print commands.getoutput('/bin/ls -lAF "%s"' % arg)
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result.PutCString(commands.getoutput('/bin/ls -lAF "%s"' % arg))
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if __name__ == '__main__':
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# This script is being run from the command line, create a debugger in case we are
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# going to use any debugger functions in our function.
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lldb.debugger = lldb.SBDebugger.Create()
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ls (sys.argv)
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elif lldb.debugger:
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# This script is being run from LLDB in the emabedded command interpreter
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def __lldb_init_module (debugger, dict):
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# This initializer is being run from LLDB in the embedded command interpreter
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# Add any commands contained in this module to LLDB
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lldb.debugger.HandleCommand('command script add -f cmdtemplate.ls ls')
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debugger.HandleCommand('command script add -f cmdtemplate.ls ls')
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print '"ls" command installed, type "ls --help" for detailed help'
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@ -19,8 +19,13 @@
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<h1 class ="postheader">Introduction</h1>
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<div class="postcontent">
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<p>The entire LLDB API is available through a script bridging interface in Python. Python can be used
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as an embedded script interpreter, or it can be used directly from python at the command line.</p>
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<p>The entire LLDB API is available as Python functions through a script bridging interface.
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This means the LLDB API's can be used directly from python either interactively or to build python apps that
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provide debugger features. </p>
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<p>Additionally, Python can be used as a programmatic interface within the
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lldb command interpreter (we refer to this for brevity as the embedded interpreter). Of course,
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in this context it has full access to the LLDB API - with some additional conveniences we will
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call out in the FAQ.</p>
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</div>
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<div class="postfooter"></div>
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@ -29,8 +34,8 @@
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<h1 class ="postheader">Embedded Python Interpreter</h1>
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<div class="postcontent">
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<p>The embedded python interpreter can be accessed in a variety of way from within LLDB. The
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easiest way is to type <b>script</b> command prompt:</p>
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<p>The embedded python interpreter can be accessed in a variety of ways from within LLDB. The
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easiest way is to use the lldb command <b>script</b> with no arguments at the lldb command prompt:</p>
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<code><pre><tt>(lldb) <strong>script</strong>
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Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
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>>> 2+3
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@ -40,9 +45,14 @@ Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
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>>>
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</tt></pre></code>
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<p>This drops you into the embedded python interpreter. There are a some convenience variables
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that are set for you in the <b>lldb</b> python module that refer to the current program
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and debugger state:</p>
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<p>This drops you into the embedded python interpreter. When running under the <b>script</b> command,
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lldb sets some convenience variables that give you quick access to the currently selected entities that characterize
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the program and debugger state. In each case, if there is no currently selected entity of the appropriate
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type, the variable's <b>IsValid</b> method will return false.
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<p>Note also, these variables hold the values
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of the selected objects on entry to the embedded interpreter. They do not update as you use the LLDB
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API's to change, for example, the currently selected stack frame or thread.</p>
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These are all global variables contained in the <b>lldb</b> python namespace :</p>
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<table class="stats" width="620" cellspacing="0">
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<tr>
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<td class="hed" width="20%">Variable</td>
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@ -58,9 +68,10 @@ Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
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<b>lldb.SBDebugger</b>
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</td>
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<td class="content">
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A module global variable containing the current debugger object.
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The type is a <b>lldb.SBDebugger</b> object and it contains a reference to the debegger
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object that owns the command interpreter and all targets in your debug session.
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Contains the debugger object whose <b>script</b> command was invoked.
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The <b>lldb.SBDebugger</b> object owns the command interpreter
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and all the targets in your debug session. There will always be a
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Debugger in the embedded interpreter.
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</td>
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</tr>
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<tr>
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@ -71,10 +82,10 @@ Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
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<b>lldb.SBTarget</b>
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</td>
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<td class="content">
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A module global variable containing the currently selected target.
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The type is a <b>lldb.SBTarget</b> object and the object will only be valid if there is a current target.
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The <b>target select <target-index></b> commmand can be used to change the
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currently selected target.
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Contains the currently selected target - for instance the one made with the
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<b>file</b> or selected by the <b>target select <target-index></b> command.
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The <b>lldb.SBTarget</b> manages one running process, and all the executable
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and debug files for the process.
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</td>
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</tr>
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<tr>
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@ -85,9 +96,9 @@ Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
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<b>lldb.SBProcess</b>
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</td>
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<td class="content">
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A module global variable containing the current process.
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The type is a <b>lldb.SBProcess</b> object and the object will only be
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valid if there is a current target and that target has a process.
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Contains the process of the currently selected target.
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The <b>lldb.SBProcess</b> object manages the threads and allows access to
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memory for the process.
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</td>
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</tr>
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<tr>
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@ -98,12 +109,12 @@ Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
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<b>lldb.SBThread</b>
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</td>
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<td class="content">
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A module global variable containing the current thread.
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The type is a <b>lldb.SBThread</b> object and the object will only be valid if
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the process has threads, and if the process has a thread selected.
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Contains the currently selected thread.
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The <b>lldb.SBThread</b> object manages the stack frames in that thread.
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A thread is always selected in the command interpreter when a target stops.
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The <b>thread select <thread-index></b> commmand can be used to change the
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currently selected thread.
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currently selected thread. So as long as you have a stopped process, there will be
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some selected thread.
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</td>
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</tr>
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<tr>
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@ -114,18 +125,20 @@ Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
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<b>lldb.SBFrame</b>
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</td>
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<td class="content">
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A module global variable containing the current stack frame.
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The type is a <b>lldb.SBFrame</b> object and the object will only be valid if
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the thread is stopped and has a frame selected.
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Contains the currently selected stack frame.
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The <b>lldb.SBFrame</b> object manage the stack locals and the register set for
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that stack.
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A stack frame is always selected in the command interpreter when a target stops.
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The <b>frame select <frame-index></b> commmand can be used to change the
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currently selected thread.
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currently selected frame. So as long as you have a stopped process, there will
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be some selected frame.
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</td>
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</tr>
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</table>
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<p>One in the embedded interpreter, these objects can be used. Almost all of the <b>lldb.SB</b> objects
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are able to briefly describe themselves by printing them:
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<p>Once in the embedded interpreter, these objects can be used. To get started, note that almost
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all of the <b>lldb</b> Python objects are able to briefly describe themselves when you pass them
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to the Python <b>print</b> function:
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<code><pre><tt>(lldb) <b>script</b>
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Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
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>>> <strong>print lldb.debugger</strong>
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@ -148,13 +161,13 @@ frame #0: 0x0000000100000bb6 a.out main + 54 at main.c:16
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<h1 class ="postheader">Running a Python script when a breakpoint gets hit</h1>
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<div class="postcontent">
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<p>A python script can be run when a breakpoint gets hit. Adding python
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<p>One very powerful use of the lldb Python API is to have a python script run when a breakpoint gets hit. Adding python
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scripts to breakpoints provides a way to create complex breakpoint
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conditions and also allows for smart logging and data gathering.</p>
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<p>A python function gets run when a breakpoint, and this function has
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two arguments:</p>
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<p>When your process hits a breakpoint to which you have attached some python code, the code is executed as the
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body of a function which takes two arguments:</p>
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<p>
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<code><pre><tt>def breakpoint_function(<b>frame</b>, <b>bp_loc</b>):
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<code><pre><tt>def breakpoint_function_wrapper(<b>frame</b>, <b>bp_loc</b>):
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<font color=green># Your code goes here</font>
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</tt></pre></code>
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<p><table class="stats" width="620" cellspacing="0">
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@ -173,7 +186,7 @@ frame #0: 0x0000000100000bb6 a.out main + 54 at main.c:16
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</td>
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<td class="content">
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The current stack frame where the breakpoint got hit.
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The type is a <b>lldb.SBFrame</b> object and the object will always be valid.
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The object will always be valid.
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This <b>frame</b> argument might <i>not</i> match the currently selected stack frame found in the <b>lldb</b> module global variable <b>lldb.frame</b>.
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</td>
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</tr>
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@ -191,25 +204,34 @@ frame #0: 0x0000000100000bb6 a.out main + 54 at main.c:16
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</td>
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</tr>
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</table>
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<p>Now we are ready to create a python function and attach it to a breakpoint. The following example will wllow you to
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create an order file for a shared library. We do this by setting a regular exprsssion breakpoint
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at every function in a shared library. The regular expression we will use is '.' which will match
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any function that has at least any character in the function name.
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<p>An example will show how simple it is to write some python code and attach it to a breakpoint.
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The following example will allow you to track the order in which the functions in a given shared library
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are first executed during one run of your program. This is a simple method to gather an order file which
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can be used to optimize function placement within a binary for execution locality.</p>
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<p>We do this by setting a regular expression breakpoint
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that will match every function in the shared library. The regular expression '.' will match
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any string that has at least one character in it, so we will use that.
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This will result in one <b>lldb.SBBreakpoint</b> object
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that contains many <b>lldb.SBBreakpointLocation</b> objects. As the breakpoint continually gets
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hit, we use the hit count on the main <b>lldb.SBBreakpoint</b> to tell us the breakpoint hit
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number, and we disable the location (not the main breakpoint) on the <b>lldb.SBBreakpointLocation</b>
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object. Then we log some info and continue the process.
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that contains an <b>lldb.SBBreakpointLocation</b> object for each function. As the breakpoint gets
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hit, we use a counter to track the order in which the function at this particular breakpoint location got hit.
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Since our code is passed the location that was hit, we can get the name of the function from the location,
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disable the location so we won't count this function again; then log some info and continue the process.</p>
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<p>Note we also have to initialize our counter, which we do with the simple one-line version of the <b>script</b>
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command.
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<p>Here is the code:
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<code><pre><tt>(lldb) <strong>breakpoint set --func-regex=. --shlib=libfoo.dylib</strong>
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Breakpoint created: 1: regex = '.', module = libfoo.dylib, locations = 223
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(lldb) <strong>script counter = 0</strong>
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(lldb) <strong>breakpoint command add --script-type python 1</strong>
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Enter your Python command(s). Type 'DONE' to end.
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> <font color=green># Get the hit count of the main breakpoint</font>
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> <strong>hit_count = bp_loc.GetBreakpoint().GetHitCount()</strong>
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> <font color=green># Increment our counter. Since we are in a function, this must be a global python variable</font>
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> <strong>global counter</strong>
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> <strong>counter += 1</strong>
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> <font color=green># Get the name of the function</font>
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> <strong>name = frame.GetFunctionName()</strong>
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> <font color=green># Print the order and the function name</font>
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> <strong>print '[%i] %s' % (hit_count, name)</strong>
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> <strong>print '[%i] %s' % (counter, name)</strong>
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> <font color=green># Disable the current breakpoint location so it doesn't get hit again</font>
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> <strong>bp_loc.SetEnabled(False)</strong>
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> <font color=green># How continue the process</font>
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@ -225,13 +247,10 @@ Enter your Python command(s). Type 'DONE' to end.
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<h1 class ="postheader">Create a new LLDB command using a python function</h1>
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<div class="postcontent">
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<p>Python functions can be used to create new commands that the LLDB command interpreter
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doesn't have. This provides a very flexible and easy way to extend LLDB to meet your
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<p>Python functions can be used to create new LLDB command interpreter commands, which will work
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like all the natively defined lldb commands. This provides a very flexible and easy way to extend LLDB to meet your
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debugging requirements. </p>
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<p>A python function that implements a new LDB command has four arguments:</p>
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<p>
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def Symbolicate(debugger, command, result, dict):
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SymbolicateCrashLog (command.split())
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<p>To write a python function that implements a new LDB command define the function to take four arguments as follows:</p>
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<code><pre><tt>def command_function(<b>debugger</b>, <b>command</b>, <b>result</b>, <b>dict</b>):
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<font color=green># Your code goes here</font>
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@ -277,7 +296,8 @@ Enter your Python command(s). Type 'DONE' to end.
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<td class="content">
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A return object where you can indicate the success or failure of your command. You can also
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provide information for the command result by printing data into it. You can also just print
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data as you normally would in a python script and the outout will show up.
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data as you normally would in a python script and the output will show up; this is useful for
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logging, but the real output for your command should go in the result object.
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</td>
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</tr>
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<tr>
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@ -293,8 +313,19 @@ Enter your Python command(s). Type 'DONE' to end.
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</td>
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</tr>
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</table>
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<p>One other handy convenience when defining lldb command-line commands is the command
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<b>command script import</b> which will import a module specified by file path - so you
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don't have to change your PYTHONPATH for temporary scripts. It also has another convenience
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that if your new script module has a function of the form:</p>
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<code><pre><tt>def __lldb_module_init(<b>debugger</b>, <b>dict</b>):
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<font color=green># Command Initialization code goes here</font>
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</tt></pre></code>
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<p>where <b>debugger</b> and <b>dict</b> are as above, that function will get run when the module is loaded
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allowing you to add whatever commands you want into the current debugger.</p>
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<p>Now we can create a module called <b>ls.py</b> that will implement a function that
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can be used by LLDB's python command code:</p>
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can be used by LLDB's python command code:</p>
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<code><pre><tt><font color=green>#!/usr/bin/python</font>
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@ -304,18 +335,16 @@ import optparse
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import shlex
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def ls(debugger, command, result, dict):
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print commands.getoutput('/bin/ls %s' % command)
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result.PutCString(commands.getoutput('/bin/ls %s' % command))
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<font color=green># Any code that isn't in a function in python gets run when the module is loaded</font>
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if lldb.debugger:
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<font color=green># This script is being run from LLDB in the emabedded command interpreter
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# lets register the 'ls' command with the command interpreter automatically!</font>
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lldb.debugger.HandleCommand('command script add -f ls.ls ls')
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<font color=green># And the initialization code to add your commands </font>
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def __lldb_module_init(debugger, dict):
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debugger.HandleCommand('command script add -f ls.ls ls')
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print 'The "ls" python command has been installed and is ready for use.'
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</tt></pre></code>
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<p>Now we can load the module into LLDB and use it</p>
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<code><pre><tt>% lldb
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(lldb) <strong>script import ls</strong>
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(lldb) <strong>command script import ls</strong>
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The "ls" python command has been installed and is ready for use.
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(lldb) <strong>ls -l /tmp/</strong>
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total 365848
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@ -333,17 +362,23 @@ total 365848
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<p>LLDB has all of its core code build into a shared library which gets
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used by the <b>lldb</b> command line application. On Mac OS X this
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shared library is a framework: <b>LLDB.framework</b> and on other
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unix variants the program is a shared library <b>lldb.so</b>. The
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<b>LLDB.framework</b> contains the <b>lldb.py</b> module and you will
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unix variants the program is a shared library: <b>lldb.so</b>. LLDB also
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provides an lldb.py module that contains the bindings from LLDB into Python.
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To use the
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<b>LLDB.framework</b> to create your own stand-alone python programs, you will
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need to tell python where to look in order to find this module. This
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is done by setting the <b>PYTHONPATH</b> environment variable contain
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a path to the directory that contains the <b>lldb.py</b> python module:
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is done by setting the <b>PYTHONPATH</b> environment variable, adding
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a path to the directory that contains the <b>lldb.py</b> python module. On
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Mac OS X, this is contained inside the LLDB.framework, so you would do:
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<p>For csh and tcsh:</p>
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<p><code>% <b>setenv PYTHONPATH /Developer/Library/PrivateFrameworks/LLDB.framework/Resources/Python</b></code></p>
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<p>For sh and bash:
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<p><code>% <b>export PYTHONPATH=/Developer/Library/PrivateFrameworks/LLDB.framework/Resources/Python</b></code></p>
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<p> Alternately, you can append the LLDB Python directory to the <b>sys.path</b> list directly in
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your Python code before importing the lldb module.</p>
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<p>
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Now your python scripts are ready to import the lldb module. Below is a
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python script that will launch a program from the current working directory
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@ -362,7 +397,8 @@ exe = "./a.out"
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debugger = lldb.SBDebugger.Create()
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<font color=green># When we step or continue, don't return from the function until the process
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# stops. We do this by setting the async mode to false.</font>
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# stops. Otherwise we would have to handle the process events ourselves which, while doable is
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#a little tricky. We do this by setting the async mode to false.</font>
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debugger.SetAsync (False)
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<font color=green># Create a target from a file and arch</font>
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Loading…
Reference in New Issue