The phpdbg of the powerful tool of PHP debugging

The phpdbg of the powerful tool of PHP debugging

Phpdbg is a PHP SAPI module that allows you to control the operating environment of PHP without modifying the code and without compromising performance.

Phpdbg's goal is to be a lightweight, powerful and easy-to-use PHP debugging platform. Can be used in PHP5.4 and above versions. The php5.6 and above versions will be internally integrated.

Main functions:



– Single Step Commissioning

– Flexible down-Breakpoint mode (class method, function, file: line, memory address, opcode)

– The eval of PHP can be called directly

– You can view the code that is currently executing

– User space API (userland/user spaces)

– Easy Integration

– Support for specifying PHP configuration files

–jit Global Variables

–readline Support (optional), terminal operation more convenient

– Remote debug, using the Java GUI

– Easy to operate (see Help for details)

Installation

In order to use PHPDGB, you first need to download a PHP source package. Then download the PHPDGB source package, and put it in the PHP source package SAPI directory. Finally, you can execute the command to install it. The compile and install examples are as follows:

Suppose we have downloaded the PHP source package and placed it in the/home/php directory.

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

Note:

1, if your PHP version is php5.6 or higher version, PHPDBG has been integrated in the PHP code package, no need to download separately.

2, compile the parameters to remember to add –enable-phpdbg.

3, compile-time parameters, –with-readline can be added selectively. If not added, phpdbg's history and other functions cannot be used.

Basic Use

1. Parameter Introduction

Phpdbg is a PHP sapi that can debug PHP as a command-line method. Common parameters are as follows:

The following switches is implemented (just like CLI SAPI):

-N Ignore php ini

-C Search for PHP ini in path

-Z Load Zend Extension

-D define PHP INI entry

The following switches change the default behaviour of phpdbg:

-V Disables quietness

-S enabled stepping

-E Sets Execution context

-B boring–disables use of colour on the console

-I ignore. Phpdbginit (default init file)

-I override. Phpgdbinit Location (implies-i)

-o set oplog output file

-Q Don't print banner on startup

-R Jump straight to run

-e Enable step through eval ()

NOTE:PASSING-RR would cause phpdbg to quit after execution, rather than returning to the console

2. Common functions

We have previously introduced the GDB tool. In fact, phpdbg and gdb function in some places very similar. For example, you can set breakpoints, you can step through, and so on. Just the language they are debugging is different, GDB focuses on debugging the C or C + + language, while phpdbg focuses on debugging the PHP language. Below we will introduce some common debugging functions of phpdbg. The code to debug is as follows:

The file test_phpdbg_inc.php source code is as follows:

The source code for file test_phpdgb.php is as follows:

 
  Func (1); Func (); Phpdbg_inc_func ();? >

3. Start phpdbg

Phpdbg after the installation is successful, it will be in the bin directory of the installation directory. Go to the Bin directory and enter phpdbg directly. As follows:

#phpdeg [Welcome to Phpdbg, the interactive PHP debugger, v0.4.0]to get help using phpdbg type ' help ' and press Enter[pleas E report bugs to 
 
  
   
  ]prompt>
 
  

To load the PHP script you want to debug, just execute the EXEC command. As follows:

#phpdbg ......prompt> exec./test_phpdbg.php

Of course, we can also specify the e parameter when starting phpdbg. As follows:

#phpdbg-E./test_phpdbg.php

4. View Help information

If you've used other debugging tools before, you'll find phpdbg similar to them. However, you will often need to get help information when you use it early. The help command allows us to obtain assistance information.

......prompt> helpphpdbg is a lightweight, powerful and easy to use debugging platform for Php5.4+it supports the Follo Wing commands:information list   list PHP source ...

5. Set Breakpoints

The command to set breakpoints is the same as GDB. All are break, abbreviated in Form B. However, the specific command parameters are still different. In the same way as GDB's breakpoint commands, they can set breakpoints "by file name: line number" or line number. In addition to this, phpdbg also provides some ways to set breakpoints specific to PHP. For example, set breakpoints according to Opline, set breakpoints according to OpCode, and so on.

It is well known that the PHP code is eventually parsed into opcode and then executed by the PHP kernel. A PHP statement that may parse into multiple opcode. If you can set breakpoints by pressing opcode, we can more precisely track the program execution process. Let's take a look at the specific example of phapdbg setting breakpoints.

Press Opline to set breakpoints:

The opline here is the line number of the current code with the method entry as the starting point. As in the test_phpdgb.php file, line 18th of the code "$param = $param +" Baba ";" The Opline is 2.

......prompt> b func#2prompt> rdemo::__construct:5method func 2[breakpoint #0 resolved at func#2 (Opline 0x7f5b230a 2E38)][breakpoint #0 resolved at func#2 (opline 0x7f5b230a2e38)][breakpoint #0 resolved at func#2 (Opline 0x7f5b230a2e38)] [Breakpoint #0 in Func () #2 at./test_phpdbg.php:18, hits:1]>00018:   $param = $param + "Baba"; 00019:   echo "func tion func $param \ n "; 00020:} ...

6. View Breakpoints

Like GDB, PHPDBG also uses the info Break command to view breakpoints. Examples are as follows:

....prompt> info Break------------------------------------------------File breakpoints: #1   /home/ Hailong.xhl/test_phpdbg.php:10------------------------------------------------opline Breakpoints: #0   7ff3219e1df0    (function Breakpoint)------------------------------------------------function Opline breakpoints : #0   func opline 2 ....

Through the above display, we can know. The type of breakpoint is also displayed in the display result of info break. #后面的数字是断点号. We can delete breakpoints based on the breakpoint number.

7. Delete Breakpoints

Not the same as the GDB command. The phpdbg delete Breakpoint is not the delete command, but the Break del command. Examples are as follows:

......prompt> break del 1[deleted breakpoint #1]prompt>

The number 1 after Break del is the breakpoint number.

8. View Code

phpdbg the command to view the code is also list. But compared to GDB, the way you use it is a bit more.

Displays the code for the specified function:

......prompt> L F func 00017:   $param = "Ali"; 00018:   $param = $param + "Baba"; 00019:   echo "function Func $ Param\n ";; 00020:} 00021:prompt>

Single Step execution

phpdbg single step execution with only one command step. Similar to GDB's step command. is a line of execution code. Note that the phpdbg does not have a next command.

....prompt> S[breakpoint #0 resolved at func#2 (opline 0x152ba40)][l19      0x152ba70 zend_add_string     C2   @0< c3/>./test_phpdbg.php]>00019:   echo "function func $param \ n";; 00020:} 00021: ....

Continue execution

Like GDB, phpdbg's continuation command is also continue, abbreviated as C.

Execute PHP code

This is a feature of phpdbg. You can use the EV command to execute arbitrary PHP code during debugging. Such as:

......prompt> ev $var = "val";valprompt> ev var_dump ($var); string (3) "Val" ...

In this way, variable values are dynamically modified during debugging to see the effect of the execution.

The above is the whole content of this article, easy to play debugging tool phpdbg, I hope you like.

Extended Reading

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