如何使用phpdbg来调试php程序

这篇文章主要介绍了如何使用phpdbg 来调试php程序，具有一定借鉴价值，需要的朋友可以参考下。希望大家阅读完这篇文章后大有收获。下面让小编带着大家一起了解一下。

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PHPDBG是一个PHP的SAPI模块，可以在不用修改代码和不影响性能的情况下控制PHP的运行环境

可以在PHP5.4和之上版本中使用。在PHP5.6和之上版本将内部集成

功能

• 单步调试
• 灵活的下断点方式（类方法、函数、文件:行、内存地址、opcode）
• 可直接调用php的eval
• 可以查看当前执行的代码
• 用户空间API（userland/user space）
• 方便集成
• 支持指定php配置文件
• JIT全局变量
• readline支持（可选），终端操作更方便
• 远程debug，使用java GUI
• 操作简便（具体看help）

安装

如果是PHP56一下

cd /usr/src/php-src/sapi
git clone https://github.com/krakjoe/phpdbg
cd ../
./buildconf --force
./config.nice
make -j8
make install-phpdbg

PHP56的话直接启用phpdbg就可以了

注意: php 配置中可以启用 --with-readline for phpdbg to support history, autocompletion, tab-listing etc

phpdbginit

Setting up your debugging session automatically

phpdbg -imy.phpdbginit

the setup of auto completionIn addition, .phpdbginit can contain embedded code, allowing, for example

• the registration of functions
• the acquisition and pre-compilation of code
• bootstrapping a web application

The default .phpdbginit

##########################################################
# .phpdbginit
#
# Lines starting with # are ignored
# Code must start and end with <: and :> respectively
##########################################################
# Place initialization commands one per line
##########################################################
# exec sapi/phpdbg/test.php
 
##########################################################
# Embedding code in .phpdbginit
##########################################################
<:
/*
 If readline is loaded, you might want to setup completion:
*/
if (function_exists('readline_completion_function')) {
    readline_completion_function(function(){
        return array_merge(
            get_defined_functions()['user'],
            array_keys(get_defined_constants())
        );
    });
}
:>
##########################################################
# Now carry on initializing phpdbg ...
##########################################################
# R my_debugging_function
 
##########################################################
# PHP has many functions that might be useful
# ... you choose ...
##########################################################
# R touch
# R unlink
# R scandir
# R glob
 
##########################################################
# Remember: *you have access to the shell*
##########################################################
# The output of registered function calls is not,
# by default, very pretty (unless you implement
# and register a new implementation for phpdbg)
# The output of shell commands will usually be more
# readable on the console
##########################################################
# TLDR; if you have a good shell, use it ...
##########################################################　

查看版本号

[root@localhost ~]# php -v
PHP 5.6.16 (cli) (built: Dec  8 2015 09:10:23) (DEBUG)
Copyright (c) 1997-2015 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2015 Zend Technologies
    with Xdebug v2.3.3, Copyright (c) 2002-2015, by Derick Rethans
[root@localhost ~]# phpdbg -V
phpdbg 0.4.0 (built: Dec  8 2015 09:10:43)
PHP 5.6.16, Copyright (c) 1997-2015 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2015 Zend Technologies
    with Xdebug v2.3.3, Copyright (c) 2002-2015, by Derick Rethans

查看help

[root@localhost ~]# phpdbg
[Welcome to phpdbg, the interactive PHP debugger, v0.4.0]
To get help using phpdbg type "help" and press enter
[Please report bugs to ]
phpdbg> help
 
phpdbg is a lightweight, powerful and easy to use debugging platform for PHP5.4+
It supports the following commands:
 
Information
  list     list PHP source
  info     displays information on the debug session
  print    show opcodes
  frame    select a stack frame and print a stack frame summary
  back     shows the current backtrace
  help     provide help on a topic
 
Starting and Stopping Execution
  exec     set execution context
  run      attempt execution
  step     continue execution until other line is reached
  continue continue execution
  until    continue execution up to the given location
  finish   continue up to end of the current execution frame
  leave    continue up to end of the current execution frame and halt after the calling instruction
  break    set a breakpoint at the specified target
  watch    set a watchpoint on $variable
  clear    clear one or all breakpoints
  clean    clean the execution environment
 
Miscellaneous
  set      set the phpdbg configuration
  source   execute a phpdbginit script
  register register a phpdbginit function as a command alias
  sh       shell a command
  ev       evaluate some code
  quit     exit phpdbg
 
Type help  or (help alias) to get detailed help on any of the above commands, for example help list or h l.  Note that help will also match partial commands if unique (and list
out options if not unique), so help clea will give help on the clean command, but help cl will list the summary for clean and clear.
 
Type help aliases to show a full alias list, including any registered phpdginit functions
Type help syntax for a general introduction to the command syntax.
Type help options for a list of phpdbg command line options.
Type help phpdbginit to show how to customise the debugger environment.
phpdbg> help list
Command: list  Alias: l  lists some code
 
The list command displays source code for the given argument.  The target type is specficied by a second subcommand keyword:
 
  Type     Alias  Purpose
  lines    l      List N lines from the current execution point
  func     f      List the complete source for a specified function
  method   m      List the complete source for a specified class::method
  class    c      List the complete source for a specified class
 
Note that the context of lines, func and method can be determined by parsing the argument, so these subcommands are optional.  However, you must specify the class keyword to list off a
class.
 
Examples
 
    phpdbg>  list 2
    phpdbg>  l l 2
    List the next 2 lines from the current file
 
    phpdbg>  list my_function
    phpdbg>  l f my_function
    List the source of the function my_function
 
    phpdbg>  list func .mine
    phpdbg>  l f .mine
    List the source of the method mine from the active class in scope
 
    phpdbg>  list m my::method
    phpdbg>  l my::method
    List the source of my::method
 
    phpdbg>  list c myClass
    phpdbg>  l c myClass
    List the source of myClass
 
Note that functions and classes can only be listed if the corresponding classes and functions table in the Zend executor has a corresponding entry.  You can use the compile command to
populate these tables for a given execution context.
phpdbg> help break
Command: break  Alias: b  set breakpoint
 
Breakpoints can be set at a range of targets within the execution environment.  Execution will be paused if the program flow hits a breakpoint.  The break target can be one of the
following types:
 
  Target   Alias Purpose
  at       A     specify breakpoint by location and condition
  del      d     delete breakpoint by breakpoint identifier number
 
Break at takes two arguments. The first is any valid target. The second is a valid PHP expression which will trigger the break in execution, if evaluated as true in a boolean context at
the specified target.
 
Note that breakpoints can also be disabled and re-enabled by the set break command.
 
Examples
 
    phpdbg>  break test.php:100
    phpdbg>  b test.php:100
    Break execution at line 100 of test.php
 
    phpdbg>  break 200
    phpdbg>  b 200
    Break execution at line 200 of the currently PHP script file
 
    phpdbg>  break \mynamespace\my_function
    phpdbg>  b \mynamespace\my_function
    Break execution on entry to \mynamespace\my_function
 
    phpdbg>  break classX::method
    phpdbg>  b classX::method
    Break execution on entry to classX::method
 
    phpdbg>  break 0x7ff68f570e08
    phpdbg>  b 0x7ff68f570e08
    Break at the opline at the address 0x7ff68f570e08
 
    phpdbg>  break my_function#14
    phpdbg>  b my_function#14
    Break at the opline #14 of the function my_function
 
    phpdbg>  break \my\class::method#2
    phpdbg>  b \my\class::method#2
    Break at the opline #2 of the method \my\class::method
 
    phpdbg>  break test.php:#3
    phpdbg>  b test.php:#3
    Break at opline #3 in test.php
 
    phpdbg>  break if $cnt > 10
    phpdbg>  b if $cnt > 10
    Break when the condition ($cnt > 10) evaluates to true
 
    phpdbg>  break at phpdbg::isGreat if $opt == 'S'
    phpdbg>  break @ phpdbg::isGreat if $opt == 'S'
    Break at any opcode in phpdbg::isGreat when the condition ($opt == 'S') is true
 
    phpdbg>  break at test.php:20 if !isset($x)
    Break at every opcode on line 20 of test.php when the condition evaluates to true
 
    phpdbg>  break ZEND_ADD
    phpdbg>  b ZEND_ADD
    Break on any occurence of the opcode ZEND_ADD
 
    phpdbg>  break del 2
    phpdbg>  b ~ 2
    Remove breakpoint 2
 
Note: Conditional breaks are costly in terms of runtime overhead. Use them only when required as they significantly slow execution.
 
Note: An address is only valid for the current compilation.
phpdbg> help watch
Command: watch  Alias: w  set watchpoint
 
Sets watchpoints on variables as long as they are defined
Passing no parameter to watch, lists all actually active watchpoints
 
Format for $variable
 
   $var      Variable $var
   $var[]    All array elements of $var
   $var->    All properties of $var
   $var->a   Property $var->a
   $var[b]   Array element with key b in array $var
 
Subcommands of watch:
 
   Type     Alias      Purpose
   array       a       Sets watchpoint on array/object to observe if an entry is added or removed
   recursive   r       Watches variable recursively and automatically adds watchpoints if some entry is added to an array/object
   delete      d       Removes watchpoint
 
Note when recursive watchpoints are removed, watchpoints on all the children are removed too
 
Examples
 
     phpdbg>  watch
     List currently active watchpoints
 
     phpdbg>  watch $array
     phpdbg>  w $array
     Set watchpoint on $array
 
     phpdbg>  watch recursive $obj->
     phpdbg>  w r $obj->
     Set recursive watchpoint on $obj->
 
     phpdbg>  watch delete $obj->a
     phpdbg>  w d $obj->a
     Remove watchpoint $obj->a
 
Technical note: If using this feature with a debugger, you will get many segmentation faults, each time when a memory page containing a watched address is hit.
                You then you can continue, phpdbg will remove the write protection, so that the program can continue.
                If phpdbg could not handle that segfault, the same segfault is triggered again and this time phpdbg will abort.

这些帮助文档足够了

示例代码 testb 与 testa的输出为什么是这样？

 0){
            $y = $x --;
            if($arr[$x] < $arr[$y]){
                $z = $len;
                while($arr[$x] > $arr[$z]){
                    $z--;
                }
                list($arr[$x],$arr[$z]) = array($arr[$z],$arr[$x]);
 
                for($i=$len;$i>$y;$i--,$y++){
                    list($arr[$i],$arr[$y]) = array($arr[$y],$arr[$i]);
                }
                $x = $len;
                $rs[] = $arr;
            }
 
        }
        return $rs;
    }
}
 
$s = new test();
$resa = $s->testa();
$resb = $s->testb();
$resc = $s->allsort([1,2,3]);
echo $resa,"\n",$resb,"\n";
#print_r($resb);

开始调试

[root@localhost ~]# phpdbg -e kk.php
[Welcome to phpdbg, the interactive PHP debugger, v0.4.0]
To get help using phpdbg type "help" and press enter
[Please report bugs to ]
[Attempting compilation of /root/kk.php]
[Success]

查看一些当前类的opcode

phpdbg> p c test
[User Class: test]
Methods (4):
        L7-13 test::testa() /root/kk.php
                L7      0xb77b553c ZEND_EXT_NOP                                                        
                L9      0xb77b5558 ZEND_EXT_STMT                                                       
                L9      0xb77b5574 ZEND_ASSIGN                    $a                   C0                   @0                 
                L10     0xb77b5590 ZEND_EXT_STMT                                                       
                L10     0xb77b55ac ZEND_ASSIGN_REF                $b                   $a                   @1                 
                L11     0xb77b55c8 ZEND_EXT_STMT                                                       
                L11     0xb77b55e4 ZEND_PRE_INC                   $a                                @2                 
                L11     0xb77b5600 ZEND_ADD                       C1                   @2                   @3                 
                L11     0xb77b561c ZEND_PRE_INC                   $a                                @4                 
                L11     0xb77b5638 ZEND_ADD                       @3                   @4                   @5                 
                L11     0xb77b5654 ZEND_RETURN                    @5                                           
                L13     0xb77b5670 ZEND_EXT_STMT                                                       
                L13     0xb77b568c ZEND_RETURN                    C2                                           
        L15-21 test::testb() /root/kk.php
                L15     0xb77b656c ZEND_EXT_NOP                                                        
                L17     0xb77b6588 ZEND_EXT_STMT                                                       
                L17     0xb77b65a4 ZEND_ASSIGN                    $a                   C0                   @0                 
                L18     0xb77b65c0 ZEND_EXT_STMT                                                       
                L18     0xb77b65dc ZEND_ASSIGN_REF                $b                   $a                   @1                 
                L19     0xb77b65f8 ZEND_EXT_STMT                                                       
                L19     0xb77b6614 ZEND_PRE_INC                   $a                                @2                 
                L19     0xb77b6630 ZEND_PRE_INC                   $a                                @3                 
                L19     0xb77b664c ZEND_ADD                       @2                   @3                   @4                 
                L19     0xb77b6668 ZEND_RETURN                    @4                                           
                L21     0xb77b6684 ZEND_EXT_STMT                                                       
                L21     0xb77b66a0 ZEND_RETURN                    C1                                           
        L23-27 test::convert() /root/kk.php
                L23     0xb77b66ec ZEND_EXT_NOP                                                        
                L23     0xb77b6708 ZEND_RECV                                                $size              
                L25     0xb77b6724 ZEND_EXT_STMT                                                       
                L25     0xb77b6740 ZEND_INIT_ARRAY                C0                                @0                 
                L25     0xb77b675c ZEND_ADD_ARRAY_ELEMENT         C1                                @0                 
                L25     0xb77b6778 ZEND_ADD_ARRAY_ELEMENT         C2                                @0                 
                L25     0xb77b6794 ZEND_ADD_ARRAY_ELEMENT         C3                                @0                 
                L25     0xb77b67b0 ZEND_ADD_ARRAY_ELEMENT         C4                                @0                 
                L25     0xb77b67cc ZEND_ADD_ARRAY_ELEMENT         C5                                @0                 
                L25     0xb77b67e8 ZEND_ASSIGN                    $unit                @0                   @1                 
                L26     0xb77b6804 ZEND_EXT_STMT                                                       
                L26     0xb77b6820 ZEND_BEGIN_SILENCE                                       @2                 
                L26     0xb77b683c ZEND_EXT_FCALL_BEGIN                                                
                L26     0xb77b6858 ZEND_EXT_FCALL_BEGIN                                                
                L26     0xb77b6874 ZEND_SEND_VAL                  C6                                           
                L26     0xb77b6890 ZEND_EXT_FCALL_BEGIN                                                
                L26     0xb77b68ac ZEND_EXT_FCALL_BEGIN                                                
                L26     0xb77b68c8 ZEND_SEND_VAR                  $size                                        
                L26     0xb77b68e4 ZEND_SEND_VAL                  C7                                           
                L26     0xb77b6900 ZEND_DO_FCALL                  C8                                @3                 
                L26     0xb77b691c ZEND_EXT_FCALL_END                                                  
                L26     0xb77b6938 ZEND_SEND_VAR_NO_REF           @3                                           
                L26     0xb77b6954 ZEND_DO_FCALL                  C9                                @4                 
                L26     0xb77b6970 ZEND_EXT_FCALL_END                                                  
                L26     0xb77b698c ZEND_ASSIGN                    $i                   @4                   @5                 
                L26     0xb77b69a8 ZEND_SEND_VAR_NO_REF           @5                                           
                L26     0xb77b69c4 ZEND_DO_FCALL                  C10                               @6                 
                L26     0xb77b69e0 ZEND_EXT_FCALL_END                                                  
                L26     0xb77b69fc ZEND_DIV                       $size                @6                   @7                 
                L26     0xb77b6a18 ZEND_SEND_VAL                  @7                                           
                L26     0xb77b6a34 ZEND_SEND_VAL                  C11                                          
                L26     0xb77b6a50 ZEND_DO_FCALL                  C12                               @8                 
                L26     0xb77b6a6c ZEND_EXT_FCALL_END                                                  
                L26     0xb77b6a88 ZEND_END_SILENCE               @2                                           
                L26     0xb77b6aa4 ZEND_CONCAT                    @8                   C13                  @9                 
                L26     0xb77b6ac0 ZEND_FETCH_DIM_R               $unit                $i                   @10                
                L26     0xb77b6adc ZEND_CONCAT                    @9                   @10                  @11                
                L26     0xb77b6af8 ZEND_RETURN                    @11                                          
                L27     0xb77b6b14 ZEND_EXT_STMT                                                       
                L27     0xb77b6b30 ZEND_RETURN                    C14                                          
        L29-54 test::allsort() /root/kk.php
                L29     0xb77b818c ZEND_EXT_NOP                                                        
                L29     0xb77b81a8 ZEND_RECV                                                $arr               
                L30     0xb77b81c4 ZEND_EXT_STMT                                                       
                L30     0xb77b81e0 ZEND_EXT_FCALL_BEGIN                                                
                L30     0xb77b81fc ZEND_SEND_REF                  $arr                                         
                L30     0xb77b8218 ZEND_DO_FCALL                  C0                                @0                 
                L30     0xb77b8234 ZEND_EXT_FCALL_END                                                  
                L31     0xb77b8250 ZEND_EXT_STMT                                                       
                L31     0xb77b826c ZEND_EXT_FCALL_BEGIN                                                
                L31     0xb77b8288 ZEND_SEND_VAR                  $arr                                         
                L31     0xb77b82a4 ZEND_DO_FCALL                  C1                                @1                 
                L31     0xb77b82c0 ZEND_EXT_FCALL_END                                                  
                L31     0xb77b82dc ZEND_SUB                       @1                   C2                   @2                 
                L31     0xb77b82f8 ZEND_ASSIGN                    $len                 @2                   @3                 
                L32     0xb77b8314 ZEND_EXT_STMT                                                       
                L32     0xb77b8330 ZEND_INIT_ARRAY                                          @4                 
                L32     0xb77b834c ZEND_ASSIGN                    $rs                  @4                   @5                 
                L33     0xb77b8368 ZEND_EXT_STMT                                                       
                L33     0xb77b8384 ZEND_ASSIGN_DIM                $rs                               @6                 
                L33     0xb77b83a0 UNKNOWN                        $arr                 @7                              
                L34     0xb77b83bc ZEND_EXT_STMT                                                       
                L34     0xb77b83d8 ZEND_ASSIGN                    $x                   $len                 @8                 
                L36     0xb77b83f4 ZEND_EXT_STMT                                                       
                L36     0xb77b8410 ZEND_IS_SMALLER                C3                   $x                   @9                 
                L36     0xb77b842c ZEND_JMPZ                      @9                   J86                             
                L37     0xb77b8448 ZEND_EXT_STMT                                                       
                L37     0xb77b8464 ZEND_POST_DEC                  $x                                @10                
                L37     0xb77b8480 ZEND_ASSIGN                    $y                   @10                  @11                
                L38     0xb77b849c ZEND_EXT_STMT                                                       
                L38     0xb77b84b8 ZEND_FETCH_DIM_R               $arr                 $x                   @12                
                L38     0xb77b84d4 ZEND_FETCH_DIM_R               $arr                 $y                   @13                
                L38     0xb77b84f0 ZEND_IS_SMALLER                @12                  @13                  @14                
                L38     0xb77b850c ZEND_JMPZ                      @14                  J85                             
                L39     0xb77b8528 ZEND_EXT_STMT                                                       
                L39     0xb77b8544 ZEND_ASSIGN                    $z                   $len                 @15                
                L40     0xb77b8560 ZEND_EXT_STMT                                                       
                L40     0xb77b857c ZEND_FETCH_DIM_R               $arr                 $x                   @16                
                L40     0xb77b8598 ZEND_FETCH_DIM_R               $arr                 $z                   @17                
                L40     0xb77b85b4 ZEND_IS_SMALLER                @17                  @16                  @18                
                L40     0xb77b85d0 ZEND_JMPZ                      @18                  J44                             
                L41     0xb77b85ec ZEND_EXT_STMT                                                       
                L41     0xb77b8608 ZEND_POST_DEC                  $z                                @19                
                L41     0xb77b8624 ZEND_FREE                      @19                                          
                L42     0xb77b8640 ZEND_JMP                       J36                                                          
                L43     0xb77b865c ZEND_EXT_STMT                                                       
                L43     0xb77b8678 ZEND_FETCH_DIM_R               $arr                 $z                   @20                
                L43     0xb77b8694 ZEND_INIT_ARRAY                @20                               @21                
                L43     0xb77b86b0 ZEND_FETCH_DIM_R               $arr                 $x                   @22                
                L43     0xb77b86cc ZEND_ADD_ARRAY_ELEMENT         @22                               @21                
                L43     0xb77b86e8 ZEND_FETCH_DIM_TMP_VAR         @21                  C4                   @23                
                L43     0xb77b8704 ZEND_ASSIGN_DIM                $arr                 $z                   @24                
                L43     0xb77b8720 UNKNOWN                        @23                  @25                             
                L43     0xb77b873c ZEND_FETCH_DIM_TMP_VAR         @21                  C5                   @26                
                L43     0xb77b8758 ZEND_ASSIGN_DIM                $arr                 $x                   @27                
                L43     0xb77b8774 UNKNOWN                        @26                  @28                             
                L43     0xb77b8790 ZEND_FREE                      @21                                          
                L45     0xb77b87ac ZEND_EXT_STMT                                                       
                L45     0xb77b87c8 ZEND_ASSIGN                    $i                   $len                 @29                
                L45     0xb77b87e4 ZEND_IS_SMALLER                $y                   $i                   @30                
                L45     0xb77b8800 ZEND_EXT_STMT                                                       
                L45     0xb77b881c ZEND_JMPZNZ                    @30                  J79 or J66                      
                L45     0xb77b8838 ZEND_POST_DEC                  $i                                @31                
                L45     0xb77b8854 ZEND_FREE                      @31                                          
                L45     0xb77b8870 ZEND_POST_INC                  $y                                @32                
                L45     0xb77b888c ZEND_FREE                      @32                                          
                L45     0xb77b88a8 ZEND_JMP                       J58                                                          
                L46     0xb77b88c4 ZEND_EXT_STMT                                                       
                L46     0xb77b88e0 ZEND_FETCH_DIM_R               $arr                 $y                   @33                
                L46     0xb77b88fc ZEND_INIT_ARRAY                @33                               @34                
                L46     0xb77b8918 ZEND_FETCH_DIM_R               $arr                 $i                   @35                
                L46     0xb77b8934 ZEND_ADD_ARRAY_ELEMENT         @35                               @34                
                L46     0xb77b8950 ZEND_FETCH_DIM_TMP_VAR         @34                  C6                   @36                
                L46     0xb77b896c ZEND_ASSIGN_DIM                $arr                 $y                   @37                
                L46     0xb77b8988 UNKNOWN                        @36                  @38                             
                L46     0xb77b89a4 ZEND_FETCH_DIM_TMP_VAR         @34                  C7                   @39                
                L46     0xb77b89c0 ZEND_ASSIGN_DIM                $arr                 $i                   @40                
                L46     0xb77b89dc UNKNOWN                        @39                  @41                             
                L46     0xb77b89f8 ZEND_FREE                      @34                                          
                L47     0xb77b8a14 ZEND_JMP                       J61                                                          
                L48     0xb77b8a30 ZEND_EXT_STMT                                                       
                L48     0xb77b8a4c ZEND_ASSIGN                    $x                   $len                 @42                
                L49     0xb77b8a68 ZEND_EXT_STMT                                                       
                L49     0xb77b8a84 ZEND_ASSIGN_DIM                $rs                               @43                
                L49     0xb77b8aa0 UNKNOWN                        $arr                 @44                             
                L50     0xb77b8abc ZEND_JMP                       J85                                                          
                L52     0xb77b8ad8 ZEND_JMP                       J23                                                          
                L53     0xb77b8af4 ZEND_EXT_STMT                                                       
                L53     0xb77b8b10 ZEND_RETURN                    $rs                                          
                L54     0xb77b8b2c ZEND_EXT_STMT                                                       
                L54     0xb77b8b48 ZEND_RETURN                    C8                                           
phpdbg>

加断点，开始调试

phpdbg> b test::testa
[Breakpoint #0 added at test::testa]
phpdbg> b test::testb
[Breakpoint #1 added at test::testb]
phpdbg> b 0xb77b6614
[Breakpoint #2 added at 0xb77b6614]
phpdbg> b 0xb77b6630
[Breakpoint #3 added at 0xb77b6630]

运行、查看代码

phpdbg> r
[Breakpoint #0 in test::testa() at /root/kk.php:7, hits: 1]
 00006:
>00007:         public function testa(){
 00008:
 00009:                 $a=1;
phpdbg> l test::testa
00007:  public function testa(){
00008:
00009:          $a=1;
00010:          $b = &$a;
00011:          return 0 + (++$a) + (++$a);
00012:
00013:  }
00014:
phpdbg> p s
[Stack in test::testa()]
        L7-13 test::testa() /root/kk.php
                L7      0xb77b553c ZEND_EXT_NOP                                                        
                L9      0xb77b5558 ZEND_EXT_STMT                                                       
                L9      0xb77b5574 ZEND_ASSIGN                    $a                   C0                   @0                 
                L10     0xb77b5590 ZEND_EXT_STMT                                                       
                L10     0xb77b55ac ZEND_ASSIGN_REF                $b                   $a                   @1                 
                L11     0xb77b55c8 ZEND_EXT_STMT                                                       
                L11     0xb77b55e4 ZEND_PRE_INC                   $a                                @2                 
                L11     0xb77b5600 ZEND_ADD                       C1                   @2                   @3                 
                L11     0xb77b561c ZEND_PRE_INC                   $a                                @4                 
                L11     0xb77b5638 ZEND_ADD                       @3                   @4                   @5                 
                L11     0xb77b5654 ZEND_RETURN                    @5                                           
                L13     0xb77b5670 ZEND_EXT_STMT                                                       
                L13     0xb77b568c ZEND_RETURN                    C2                                

继续执行

和gdb一样，phpdbg的继续执行命令也是continue，简写形式为c

查看断点

phpdbg> info b
------------------------------------------------
Method Breakpoints:
#0              test::testa
#1              test::testb
------------------------------------------------
Opline Breakpoints:
#2              0xb77b6614
#3              0xb77b6630

eval操作

可以执行任意的PHP代码

我们可以看到上面例子 testa 与 testb的区别

L7-13 test::testa() /root/kk.php
        L11     0xb77b55e4 ZEND_PRE_INC                   $a                                @2
        L11     0xb77b5600 ZEND_ADD                       C1                   @2                   @3
        L11     0xb77b561c ZEND_PRE_INC                   $a                                @4
        L11     0xb77b5638 ZEND_ADD                       @3                   @4                   @5
L15-21 test::testb() /root/kk.php
        L19     0xb77b6614 ZEND_PRE_INC                   $a                                @2
        L19     0xb77b6630 ZEND_PRE_INC                   $a                                @3
        L19     0xb77b664c ZEND_ADD                       @2                   @3                   @4

区别在于这里  ZEND_PRE_INC  这一个opcode不同，这个opcode就是  ++$a

testb中当引用存在的时候， $a 先自增了两次，然后再加，所以结果为6，这里应该是PHP本身的问题

这个工具比vld丰富多了，PHP会越来越强大的。

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