本文给大家介绍关于如何使用gdb调试php(gdb 是c语言的代码调试工具，可以用来调试php、python、mysql等)，希望对需要的朋友有所帮助!
使用gdb调试php
简介
gdb 是c语言的代码调试工具
可以用来调试php、python、mysql等
调试主要有4种形式
gdb：启动之后用attach pid 追踪程序
gdb [options] [executable-file [core-file or process-id]]
gdb [options] --args executable-file [inferior-arguments ...]
gdb [options] [--python|-P] script-file [script-arguments ...]
常用调试命令
attach pid
例：如果向跟踪调试mysql代码
1.先找到mysql进行ID：10111
2.再attach 10111追踪mysql
layout
显示源码/汇编指令
Layout names are:
src : Displays source and command windows. 显示源码
asm : Displays disassembly and command windows. 显示汇编指令
split : Displays source, disassembly and command windows. 显示源码和汇编指令
regs : Displays register window. If existing layout
is source/command or assembly/command, the
register window is displayed. If the
source/assembly/command (split) is displayed,
the register window is displayed with
the window that has current logical focus
break
b 增加断点
info b 显示断点信息
delete num 删除指定断点
continue [num]
c num 执行到num个断点，num可以不填默认=1
next [num]
n num 执行到下num行，num可以不填默认=1,不进入函数内部
step [num]
s num 执行到下num行，num可以不填默认=1,不进入函数内部
backtrace
bt 查看当前调用栈
print [value]
p value 打印变量信息
help
help layout 查看命令如何使用
调试php代码
1. 新增一个php文件
echo date('Y-m-d', strtotime("last day of +2month", strtotime('2020-05-31')));
2.查看php-fpm work进程PID
我这里通过修改php-fpm配置只启动一个work进程方便追踪
pm = static
pm.max_children = 1
[root@test ~]# ps aux|grep php-fpm
www 1127 0.0 0.1 279352 2816 ? S 5月12 0:00 php-fpm: pool www
root 12224 0.0 0.0 112736 976 pts/0 S+ 17:37 0:00 grep --color=auto php-fpm
3.追踪PID
[root@test ~]# gdb
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-115.el7
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
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 "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
.
(gdb) attach 1127
Attaching to process 1127
Reading symbols from /usr/local/php/sbin/php-fpm...done.
Reading symbols from /usr/lib64/libcrypt.so.1...Reading symbols
from /usr/lib/debug/usr/lib64/libcrypt-2.17.so.debug...done.
done.
4.打断点，这里在timelib_update_ts和do_years方法打了一个断点，这里需要你看下php源码，看你需要在哪里调试代码
1
2
(gdb) b timelib_update_ts
Breakpoint 1 at 0x48ba90: file /opt/lnmp1.6/src/php-7.3.11/ext/date/lib/tm2unixtime.c, line 499.
1
2
(gdb) b do_years
`Breakpoint 3 at 0x48bb95: file /opt/lnmp1.6/src/php-7.3.11/ext/date/lib/tm2unixtime.c, line 381.`
5.请求测试文件
请求之后发现没有立刻看到返回结果，被阻塞在了这里，说明执行到了断点的地方
1
[root@test ~]# curl localhost/3.php
6.查看调试信息
通过p *time可以看到变量time里面的内容
(gdb) c
Continuing.
Breakpoint 1, timelib_update_ts (time=time@entry=0x7fc63ec02000, tzi=tzi@entry=0x7fc63ec75000)
at /opt/lnmp1.6/src/php-7.3.11/ext/date/lib/tm2unixtime.c:499
499 {
(gdb) c
Continuing.
Breakpoint 3, timelib_update_ts (time=time@entry=0x7fc63ec02000, tzi=tzi@entry=0x7fc63ec75000)
at /opt/lnmp1.6/src/php-7.3.11/ext/date/lib/tm2unixtime.c:505
505 res += do_years(time->y);
(gdb) s
do_years (year=2020) at /opt/lnmp1.6/src/php-7.3.11/ext/date/lib/tm2unixtime.c:381
381 eras = (year - 1970) / 40000;
(gdb) s
timelib_update_ts (time=time@entry=0x7fc63ec02000, tzi=tzi@entry=0x7fc63ec75000)
at /opt/lnmp1.6/src/php-7.3.11/ext/date/lib/tm2unixtime.c:504
504 do_adjust_special(time);
(gdb) p *time
$1 = {y = 2020, m = 7, d = 31, h = 0, i = 0, s = 0, us = 0, z = 28800, tz_abbr = 0x7fc63ec71018 "CST",
tz_info = 0x7fc63ec75000, dst = 0, relative = {y = 0, m = 2,
d = 0, h = 0, i = 0, s = 0, us = 0, weekday = 0, weekday_behavior = 0, first_last_day_of = 2, invert = 0,
days = -99999, special = {type = 0, amount = 0},
have_weekday_relative = 0, have_special_relative = 0}, sse = 0, have_time = 0, have_date = 0, have_zone = 0,
have_relative = 1, have_weeknr_day = 0,
sse_uptodate = 0, tim_uptodate = 0, is_localtime = 1, zone_type = 3}
(gdb)
下面是do_years方法的代码
static timelib_sll do_years(timelib_sll year)
{
timelib_sll i;
timelib_sll res = 0;
timelib_sll eras;
eras = (year - 1970) / 40000;
if (eras != 0) {
year = year - (eras * 40000);
res += (SECS_PER_ERA * eras * 100);
}
if (year >= 1970) {
for (i = year - 1; i >= 1970; i--) {
//判断是否是闰年，闰年366天，平年365天
if (timelib_is_leap(i)) {
res += (DAYS_PER_LYEAR * SECS_PER_DAY);
} else {
res += (DAYS_PER_YEAR * SECS_PER_DAY);
}
}
} else {
for (i = 1969; i >= year; i--) {
if (timelib_is_leap(i)) {
res -= (DAYS_PER_LYEAR * SECS_PER_DAY);
} else {
res -= (DAYS_PER_YEAR * SECS_PER_DAY);
}
}
}
return res;
}
