Accessing frame info in gdb
- by Maelstrom
In gdb, is there a way to access the contents of info frame in a script?
I'm debugging a problem somewhere between Apache, PHP, APC and my own code, and I have about a hundred cores to choose from. Following the instructions here
http://bugs.php.net/bugs-generating-backtrace.php
I end up with a stacktrace like:
#0 0x0121a31a in do_bind_function (opline=0xa94dd750, function_table=0x9b9cf98, compile_time=0 '\0') at /usr/src/debug/php-5.2.7/Zend/zend_compile.c:2407
#1 0x0124bb2e in ZEND_DECLARE_FUNCTION_SPEC_HANDLER (execute_data=0xbfef7990) at /usr/src/debug/php-5.2.7/Zend/zend_vm_execute.h:498
#2 0x01249dfa in execute (op_array=0xb79d5d3c) at /usr/src/debug/php-5.2.7/Zend/zend_vm_execute.h:92
#3 0x01261e31 in ZEND_INCLUDE_OR_EVAL_SPEC_VAR_HANDLER (execute_data=0xbfef80d0) at /usr/src/debug/php-5.2.7/Zend/zend_vm_execute.h:7809
#4 0x01249dfa in execute (op_array=0xb79d55ec) at /usr/src/debug/php-5.2.7/Zend/zend_vm_execute.h:92
...
#26 0x09caa894 in ?? ()
#27 0x00000000 in ?? ()
The stack will always look similar, with function execute and ZEND_something interleaved several times. I need to go up to the last instance of execute (up 2 in this case) and print myVar.
Obviously gdb knows the function names, but does it surface them in any user variables I could access?
Typing frame 2 shows a one-line version, and info frame shows a single stackframe in detail. I want to do something like
while ($current_frame.function_name != "execute") {up;} print myVar but I don't see how to do it strictly within gdb.
Is there a variable / structure / special memory location / something that allows access to gdb's information on either the whole stack (like bt) or to the current stack frame (like info frame)?
