Debug PHP extensions using gdb

Debug PHP extensions using gdb

From: http://www.codefrom.com/paper/%E4%BD%BF%E7%94%A8gdb%E8%B0%83%E8%AF%95p...

Php extensions are developed using c/c ++ and can be easily debugged using gdb. The procedure is as follows:
Add the ** -- enable-debug ** parameter when compiling php.

./configure --enable-debugmake && make install

Tested on my ubuntu machine, the extended directory defaults to/usr/local/lib/php/extensions/debug-non-zts-20131226/
In this way, php source code debugging is also very convenient.
Next, create extension, go to the ext Directory of the php source code, and run

./ext_skel --extname=mydebug  

The current directory is automatically generated.MydebugDirectory, enter the directory, and editConfig. m4File, remove 10 ~ 12 rows of dnl, as shown below

PHP_ARG_WITH(mydebug, for mydebug support,Make sure that the comment is aligned:[  --with-mydebug             Include mydebug support])

Add

if test -z "$PHP_DEBUG"; then        AC_ARG_ENABLE(debug,                [--enable-debg  compile with debugging system],                [PHP_DEBUG=$enableval], [PHP_DEBUG=no]        )fi

This indicates that the extension can be debugged, then the extension is compiled, and the command is used.

phpize ./configure --enable-debugmake && make install

The phpize and php-config here need to configure the environment variables in advance and then load the extension. The address above my machine is/usr/local/lib/php/extensions/debug-non-zts-20131226 /. Go to the mydebug extension source code directory. the default generated function is confirm_mydebug_compiled, which is defined in mydebug. c. the automatically generated function is extended.

PHP_FUNCTION(confirm_mydebug_compiled){        char *arg = NULL;        int arg_len, len;        char *strg;        if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &arg, &arg_len) == FAILURE) {                return;        }        len = spprintf(&strg, 0, "Congratulations! You have successfully modified ext/%.78s/config.m4. Module %.78s is now compiled into PHP.", "mydebug", arg);        RETURN_STRINGL(strg, len, 0);}

Obtain the string parameters and combine them into a string to return the result. Run the nm command to view the generated mydebug. so exported symbol.

Run nm mydebug. so and return zif_confirm_mydebug_compiled ......

PHP_FUNCTION is actually adding zif _ before the function name, and then performing gdb debugging

Step 1: run gdb php and then run: break zif_confirm_mydebug_compiled terminal prompt: Function "zif_confirm_mydebug_compiled" not defined. Make breakpoint pending on future shared library load? (Y or [n]) input: y input: run/tmp/test. php will echo: Breakpoint 1, timeout (ht = 1, return_value = 0xb7bf0d44, return_value_ptr = 0xb7bd6104, this_ptr = 0x0, return_value_used = 1) /..... /php-5.6.6/ext/mydebug. c: 56 then input: l Display: 54 PHP_FUNCTION (confirm_mydebug_compiled) 55 {56 char * arg = NULL; 57 int arg_len, len; 58 char * strg; 5960 if (zend_parse_parameters (ZEND_NUM_ARGS () TSRMLS_CC, "s", & arg, & arg_len) = FAILURE ){

The file/tmp/test. php contains the following content:

   
As you can see, the function source code has come out and can be debugged using the commonly used gdb command.
  
 
 
   
  
  
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