ÈçºÎʹÓÃGDBµ÷ÊÔPHP³ÌÐò

Ò»°aÀ´Ëµ£¬GDBÖ÷ÒªÍe³ÉÏÂÃaeËĸo*½ÃaeµÄ¹¦ÄÜ£º

(1)Æo¶¯ÄaµÄ³ÌÐo£¬¿ÉÒÔ°´ÕÕÄaµÄ×Ô¶¨ÒaµÄÒªÇoËaeÐÄËuÓuµÄÔËÐгÌÐo¡£
(2)¿ÉÈñ»µ÷ÊԵijÌÐoÔÚÄaËuÖ¸¶¨µÄµ÷ÖõĶϵa´¦Í£×¡¡££¨¶Ïµa¿ÉÒÔÊÇÌo¼þ±i´iʽ£(C)
(3)µ±³ÌÐo±»Í£×¡Ê±£¬¿ÉÒÔ¼i²e´ËʱÄaµÄ³ÌÐoÖÐËu¢ÉuµÄÊ¡£
(4)¶¯Ì¬µÄ¸Ä±aÄa³ÌÐoµÄÖ´Ðл¾³¡£

1¡¢¼o½e

GDBÊÇGNU¿ªÔ´×eÖ¯¢²¼µÄÒ»¸oÇ¿´oµÄUNIXϵijÌÐoµ÷ÊÔ¹¤¾ß¡£Èç¹uÄaÊÇÔÚ UNIXƽ̨ÏÂ×oÈi¼þ£¬Äa»a¢ÏÖGDBÕa¸oµ÷ÊÔ¹¤¾ßÓбÈVC¡¢BCBµÄͼÐλ¯µ÷ÊÔÆ÷¸uÇ¿´oµÄ¹¦ÄÜ¡£Í¬Ê±GDBÒ²¾ßÓÐÀýÈçdddÕaÑuµÄͼÐλ¯µÄµ÷ÊԶˡ£

2¡¢µ÷ÊÔC/C++³ÌÐo

Ö±½ÓÉÏ´uÂeÁË

    #include<iostream>
    using namespace std;
    long factorial(int n); 
    int main()
    {
    int n(0);
    cin>>n;
    long val=factorial(n);
    cout<<val<<endl;
    cin.get();
    return 0;
    }
    long factorial(int n)
    {
    long result(1);
    while(n--)
    { 
    result*=n;
    } 
    return result;
    } 

±aÒe

1

g++ k.cpp -g -Wall -Werror -o main

¿ªÊ¼µ÷ÊÔ

    [root@localhost code]# gdb ./main
    GNU gdb (GDB) Red Hat Enterprise Linux (7.2-83.el6)
    Copyright (C) 2010 Free Software Foundation, Inc.
    License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
    This is free software: you are free to change and redistribute it.
    There is NO WARRANTY, to the extent permitted by law. Type "show copying"
    and "show warranty" for details.
    This GDB was configured as "i686-redhat-linux-gnu".
    For bug reporting instructions, please see:
    <http://www.gnu.org/software/gdb/bugs/>...
    Reading symbols from /code/main...done.
    (gdb) l 

    warning: Source file is more recent than executable.
    1 #include<iostream>
    2 using namespace std;
    3 long factorial(int n);
    4
    5 int main()
    6 {
    7 int n(0);
    8 cin>>n;
    9 long val=factorial(n);
    10 cout<<val<<endl;
    (gdb) 

ÉeÖöϵa break linenumber

    (gdb) b 9
    Breakpoint 1 at 0x80486f9: file k.cpp, line 9.
    (gdb) r
    Starting program: /code/main 
    4
    Breakpoint 1, main () at k.cpp:9
    9 long val=factorial(n); 

ÉeÖù۲iµa watch var

    (gdb) s
    factorial (n=4) at k.cpp:17
    17 long result(1);
    (gdb) l
    12 return 0;
    13 }
    14
    15 long factorial(int n)
    16 {
    17 long result(1);
    18 while(n--)
    19 {
    20 result*=n;
    21 }
    (gdb) watch n
    Hardware watchpoint 2: n
    (gdb) watch result
    Hardware watchpoint 3: result
    (gdb) c
    Continuing.
    Hardware watchpoint 3: result
    Old value = 0
    New value = 1
    factorial (n=4) at k.cpp:18
    18 while(n--)
    (gdb) 
    Continuing.
    Hardware watchpoint 2: n
    Old value = 4
    New value = 3
    0x08048764 in factorial (n=3) at k.cpp:18
    18 while(n--)
    (gdb) 
    Continuing.
    Hardware watchpoint 3: result
    Old value = 1
    New value = 3
    factorial (n=3) at k.cpp:18
    18 while(n--)
    (gdb) 
    Continuing.
    Hardware watchpoint 2: n
    Old value = 3
    New value = 2
    0x08048764 in factorial (n=2) at k.cpp:18
    18 while(n--)
    (gdb) 
    Continuing.
    Hardware watchpoint 3: result
    Old value = 3
    New value = 6
    factorial (n=2) at k.cpp:18
    18 while(n--)
    (gdb) 
    Continuing.
    Hardware watchpoint 2: n
    Old value = 2
    New value = 1
    0x08048764 in factorial (n=1) at k.cpp:18
    18 while(n--)
    (gdb) 
    Continuing.
    Hardware watchpoint 2: n
    Old value = 1
    New value = 0
    0x08048764 in factorial (n=0) at k.cpp:18
    18 while(n--)
    (gdb) 
    Continuing.
    Watchpoint 2 deleted because the program has left the block in
    which its expression is valid.
    Watchpoint 3 deleted because the program has left the block in
    which its expression is valid.
    0x08048705 in main () at k.cpp:9
    9 long val=factorial(n);
    (gdb) p val
    $1 = 11476980
    (gdb) 

¿ÉÒÔ¿´µ½ÊÇwhileÄÇÀi£¬µ¼ÖÂnÔ½½çÁË£¬fix

    while(n>0) //doesn't let n reach 0
    {
    result*=n;
    n--; //decrements only after the evaluation
    } 

Ò»Ð(C)¿i½ÝÃuÁi

l ¨C list
p ¨C print print {variable}
c ¨C continue
s ¨C step
b - break break line_number/break [file_name]:line_number/break [file_name]:func_name
r - run
set =
watch

ENTER: pressing enter key would execute the previously executed command again.

c/n/sµÄÇø±ð

•c or continue: Debugger will continue executing until the next break point.
•n or next: Debugger will execute the next line as single instruction.
•s or step: Same as next, but does not treats function as a single instruction, instead goes into the function and executes it line by line

3¡¢µ÷ÊÔPHP³ÌÐo

PHP´uÂe

    <?php. 
    for($i = 0; $i < 10; $i++){
    echo $i."\n";
    sleep(3);
    if(in_array($i,[1,9,20])){
    print_r($i*$i);
    var_dump($i*$i); 
    print $i*$i;
    } 
    } 

¿ªÊ¼µ÷ÊÔ£¬¼ÓÉ϶ϵa

    [root@localhost code]# gdb php 
    GNU gdb (GDB) Red Hat Enterprise Linux (7.2-83.el6)
    Copyright (C) 2010 Free Software Foundation, Inc.
    License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
    This is free software: you are free to change and redistribute it.
    There is NO WARRANTY, to the extent permitted by law. Type "show copying"
    and "show warranty" for details.
    This GDB was configured as "i686-redhat-linux-gnu".
    For bug reporting instructions, please see:
    <http://www.gnu.org/software/gdb/bugs/>...
    Reading symbols from /usr/bin/php...done.
    (gdb) b zif_sleep
    Breakpoint 1 at 0x8435180: file /usr/local/src/php-5.5.23/ext/standard/basic_functions.c, line 4449.
    (gdb) b zif_in_array
    Breakpoint 2 at 0x8426923: file /usr/local/src/php-5.5.23/ext/standard/array.c, line 1215.
    (gdb) b zif_print_r
    Breakpoint 3 at 0x8438273: file /usr/local/src/php-5.5.23/ext/standard/basic_functions.c, line 5553.
    (gdb) b zif_var_dump
    Breakpoint 4 at 0x847d296: file /usr/local/src/php-5.5.23/ext/standard/var.c, line 178.
    (gdb) b zif_printf
    Function "zif_printf" not defined.
    Make breakpoint pending on future shared library load? (y or [n]) n
    (gdb) b zif_sprintf
    Function "zif_sprintf" not defined.
    Make breakpoint pending on future shared library load? (y or [n]) n
    (gdb) b printf
    Breakpoint 5 at 0x806a390
    (gdb) b memcpy
    Breakpoint 6 at 0x8069390
    (gdb) b zif_print
    Function "zif_print" not defined.
    Make breakpoint pending on future shared library load? (y or [n]) n
    (gdb) b zif_echo 
    Function "zif_echo" not defined.
    Make breakpoint pending on future shared library load? (y or [n]) n
    (gdb) info b
    Num Type Disp Enb Address What
    1 breakpoint keep y 0x08435180 in zif_sleep at /usr/local/src/php-5.5.23/ext/standard/basic_functions.c:4449
    2 breakpoint keep y 0x08426923 in zif_in_array at /usr/local/src/php-5.5.23/ext/standard/array.c:1215
    3 breakpoint keep y 0x08438273 in zif_print_r at /usr/local/src/php-5.5.23/ext/standard/basic_functions.c:5553
    4 breakpoint keep y 0x0847d296 in zif_var_dump at /usr/local/src/php-5.5.23/ext/standard/var.c:178
    5 breakpoint keep y 0x0806a390 <printf@plt>
    6 breakpoint keep y 0x08069390 <memcpy@plt>
    (gdb) 

¼Ó¼¸¸o¶Ïµa²aÊÔһϠsyntax£ºbreak [file_name]:func_name£¬ÕaÀi´oÖ¿ÉÒÔ¿´Ò»Ï echo printµÈ²»ÊǺ¯ÊýÁË

È»ºo¿ªÊ¼µ÷ÊÔ

    (gdb) p *return_value
    $1 = {value = {lval = 1515870810, dval = 1.7838867517321418e+127, str = {val = 0x5a5a5a5a <Address 0x5a5a5a5a out of bounds>, 
    len = 1515870810}, ht = 0x5a5a5a5a, obj = {handle = 1515870810, handlers = 0x5a5a5a5a}}, refcount__gc = 1, type = 0 '\000', is_ref__gc = 0 '\000'}
    (gdb) p return_value->value
    $2 = {lval = 1515870810, dval = 1.7838867517321418e+127, str = {val = 0x5a5a5a5a <Address 0x5a5a5a5a out of bounds>, 
    len = 1515870810}, ht = 0x5a5a5a5a, obj = {handle = 1515870810, handlers = 0x5a5a5a5a}}
    (gdb) p return_value->value->lval
    $3 = 1515870810 

ÎÒÃÇ»¹¿ÉÒÔʹÓÃÄÚÖõÄgdbinitÀ´µ÷ÊÔ

    (gdb) source /usr/local/src/php-5.5.23/.gdbinit
    (gdb) zbacktrace
    [0xb7fa1144] sleep(3) /code/kk.php:4 

²e¿´µ±Ç°¶ÑÕ»£¬PHPÄں˵ÄÖ´Ðйý³Ì

    (gdb) bt
    #0 zif_sleep (ht=1, return_value=0xb7fbd6f0, return_value_ptr=0x0, this_ptr=0x0, return_value_used=0)
    at /usr/local/src/php-5.5.23/ext/standard/basic_functions.c:4449
    #1 0x085f6870 in execute_internal (execute_data_ptr=0xb7fa1144, fci=0x0, return_value_used=0)
    at /usr/local/src/php-5.5.23/Zend/zend_execute.c:1484
    #2 0x085aea5f in dtrace_execute_internal (execute_data_ptr=0xb7fa1144, fci=0x0, return_value_used=0)
    at /usr/local/src/php-5.5.23/Zend/zend_dtrace.c:97
    #3 0x00935c33 in pt_execute_core (internal=1, execute_data=0xb7fa1144, fci=0x0, rvu=0)
    at /usr/local/src/trace-0.3.0/extension/trace.c:941
    #4 0x00935e49 in pt_execute_internal (execute_data=0xb7fa1144, fci=0x0, return_value_used=0)
    at /usr/local/src/trace-0.3.0/extension/trace.c:1005
    #5 0x085f7523 in zend_do_fcall_common_helper_SPEC (execute_data=0xb7fa1144) at /usr/local/src/php-5.5.23/Zend/zend_vm_execute.h:552
    #6 0x085fb2a9 in ZEND_DO_FCALL_SPEC_CONST_HANDLER (execute_data=0xb7fa1144) at /usr/local/src/php-5.5.23/Zend/zend_vm_execute.h:2332
    #7 0x085f6deb in execute_ex (execute_data=0xb7fa1144) at /usr/local/src/php-5.5.23/Zend/zend_vm_execute.h:363
    #8 0x085ae9dc in dtrace_execute_ex (execute_data=0xb7fa1144) at /usr/local/src/php-5.5.23/Zend/zend_dtrace.c:73
    #9 0x00935c5e in pt_execute_core (internal=0, execute_data=0xb7fa1144, fci=0x0, rvu=0)
    at /usr/local/src/trace-0.3.0/extension/trace.c:946
    #10 0x00935e10 in pt_execute_ex (execute_data=0xb7fa1144) at /usr/local/src/trace-0.3.0/extension/trace.c:1000
    #11 0x085f6e4a in zend_execute (op_array=0xb7fbc7b4) at /usr/local/src/php-5.5.23/Zend/zend_vm_execute.h:388
    #12 0x085c1cf2 in zend_execute_scripts (type=8, retval=0x0, file_count=3) at /usr/local/src/php-5.5.23/Zend/zend.c:1327
    #13 0x085470f9 in php_execute_script (primary_file=0xbffff4a4) at /usr/local/src/php-5.5.23/main/main.c:2525
    #14 0x0865af46 in do_cli (argc=2, argv=0x8b9b908) at /usr/local/src/php-5.5.23/sapi/cli/php_cli.c:994
    #15 0x0865bff3 in main (argc=2, argv=0x8b9b908) at /usr/local/src/php-5.5.23/sapi/cli/php_cli.c:1378 

²e¿´´uÂe¶Î

    (gdb) l
    4444 Delay for a given number of seconds */
    4445 PHP_FUNCTION(sleep)
    4446 {
    4447 long num;
    4448
    4449 if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "l", #) == FAILURE) {
    4450 RETURN_FALSE;
    4451 }
    4452 if (num < 0) {
    4453 php_error_docref(NULL TSRMLS_CC, E_WARNING, "Number of seconds must be greater than or equal to 0");
    (gdb) l 4450
    4445 PHP_FUNCTION(sleep)
    4446 {
    4447 long num;
    4448
    4449 if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "l", &num;) == FAILURE) {
    4450 RETURN_FALSE;
    4451 }
    4452 if (num < 0) {
    4453 php_error_docref(NULL TSRMLS_CC, E_WARNING, "Number of seconds must be greater than or equal to 0");
    4454 RETURN_FALSE;
    (gdb) l zif_usleep
    4463 /* }}} */
    4464
    4465 /* {{{ proto void usleep(int micro_seconds)
    4466 Delay for a given number of micro seconds */
    4467 PHP_FUNCTION(usleep)
    4468 {
    4469 #if HAVE_USLEEP
    4470 long num;
    4471
    4472 if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "l", &num;) == FAILURE) { 

¼ÌÐøÖ´ÐÐ

    (gdb) n
    4452 if (num < 0) {
    (gdb) p num
    $6 = 3
    (gdb) n
    4457 RETURN_LONG(php_sleep(num));
    (gdb) n
    4462 }
    (gdb) n
    execute_internal (execute_data_ptr=0xb7fa1144, fci=0x0, return_value_used=0) at /usr/local/src/php-5.5.23/Zend/zend_execute.c:1488
    1488 } 

µ½ÁËexecute_internal £¬¿ÉÒÔ²e¿´Ò»Ïµ±Ç°º¯ÊýµÄÒ»¸o״̬

    (gdb) p execute_data_ptr
    $7 = (zend_execute_data *) 0xb7fa1144
    (gdb) p *execute_data_ptr
    $8 = {opline = 0xb7fbcacc, function_state = {function = 0x8bcf3e8, arguments = 0xb7fa119c}, op_array = 0xb7fbc7b4, object = 0x0, 
    symbol_table = 0x8b99cdc, prev_execute_data = 0x0, old_error_reporting = 0x0, nested = 0 '\000', 
    original_return_value = 0x38b4ac9, current_scope = 0x49, current_called_scope = 0x45, current_this = 0x0, fast_ret = 0x0, 
    call_slots = 0xb7fa1188, call = 0xb7fa1188}
    (gdb) p *execute_data_ptr->function_state.function->common->function_name
    $9 = 115 's'
    (gdb) p execute_data_ptr->function_state.function->common->function_name 
    $10 = 0x8af03c9 "sleep"
    (gdb) p execute_data_ptr->op_array->filename
    $11 = 0xb7fbc8e8 "/code/kk.php" 

²e¿´µ±Ç°hashtable

    (gdb) p *execute_data_ptr->symbol_table
    $ = {nTableSize = , nTableMask = , nNumOfElements = , nNextFreeElement = , pInternalPointer = xbfbc, 
    pListHead = xbfbc, pListTail = xbfbd, arBuckets = xbfb, pDestructor = xbff <_zval_ptr_dtor_wrapper>, 
    persistent = '\', nApplyCount = '\', bApplyProtection = '\', inconsistent = } 

¼ÌÐøÖ´ÐÐÊa³ocÖ®ºo£¬»Ø³µ¼´¿É£¬Í¬Ñu¿ÉÒÔ¿´µ½in_arrayµÄÖ´ÐÐÐÅÏ¢

    (gdb) p *execute_data_ptr->function_state.function
    $24 = {type = 1 '\001', common = {type = 1 '\001', function_name = 0x8af1841 "in_array", scope = 0x0, fn_flags = 256, 
    prototype = 0x0, num_args = 3, required_num_args = 2, arg_info = 0x8ae7554}, op_array = {type = 1 '\001', 
    function_name = 0x8af1841 "in_array", scope = 0x0, fn_flags = 256, prototype = 0x0, num_args = 3, required_num_args = 2, 
    arg_info = 0x8ae7554, refcount = 0x842691d, opcodes = 0x8bcf120, last = 0, vars = 0x0, last_var = 0, T = 1, 
    nested_calls = 3086618796, used_stack = 0, brk_cont_array = 0x0, last_brk_cont = 1, try_catch_array = 0xb7fa10dd, 
    last_try_catch = 96, has_finally_block = 160 '\240', static_variables = 0x0, this_var = 11482064, 
    filename = 0xaf1ff4 "|\035\257", line_start = 11482016, line_end = 146381272, 
    doc_comment = 0xbffff238 "x\362\377\277\244\aY\b\021", doc_comment_len = 10305959, early_binding = 11085989, 
    literals = 0x8b7a0a0, last_literal = 140062666, run_time_cache = 0xb7fa10d4, last_cache_slot = 90, reserved = {0x9, 0x8b5f7ac, 
    0x796, 0x0}}, internal_function = {type = 1 '\001', function_name = 0x8af1841 "in_array", scope = 0x0, fn_flags = 256, 
    prototype = 0x0, num_args = 3, required_num_args = 2, arg_info = 0x8ae7554, handler = 0x842691d <zif_in_array>, 
    module = 0x8bcf120}}
    (gdb) p execute_data_ptr->function_state.function->common->function_name 
    $26 = 0x8af1841 "in_array"
    (gdb) p execute_data_ptr->op_array->filename 
    $27 = 0xb7fbc8e8 "/code/kk.php" 

»¹¿ÉÒÔ¼Óһϼa¿Øwatch¡¢ÉeÖÃÒ»Ð(C)µ÷ÊÔ±aÁ¿set µÈµÈ

ÆaËuµÄµ÷ÊÔ¹¤¾ß»¹ÓÐ strace ²e¿´ÏµÍ³µ÷Óá¢ltrace ²e¿´Àa¿aµÄµ÷Óá¢vld²e¿´opcode¡£

ÒÔÉÏÄÚÈÝÊÇС±a¸ø´o¼Ò*ÖÏiµÄ¹ØÓÚÈçºÎʹÓÃGDBµ÷ÊÔPHP³ÌÐoµÄÈ«²¿ÄÚÈÝ£¬Ï£Íu´o¼Òϲ»¶¡£