有谁能告诉我如何在共享库上进行运行时调试?
我需要对我的共享库中的一个函数进行运行时调试,但它被另一个程序调用。 我该如何做类似于dbx的共享库调试?
我正在AIX上使用dbx。 相比我要做的事情,gdb是否更好?
你只需要使用可执行文件调用 gdb(无论是你自己的还是第三方的都可以)。以下是一个示例,我调试ls命令并在(共享)c库中设置断点。该示例使用支持延迟(挂起)断点的 gdb 6.8,这使得操作变得容易:
gdb /bin/ls
GNU gdb 6.8-debian
Copyright (C) 2008 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 "x86_64-linux-gnu"...
(no debugging symbols found)
(gdb) b write
Function "write" not defined.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (write) pending.
(gdb) r
Starting program: /bin/ls
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
[Thread debugging using libthread_db enabled]
(no debugging symbols found)
(no debugging symbols found)
[New Thread 0x7f98d2d23780 (LWP 7029)]
[Switching to Thread 0x7f98d2d23780 (LWP 7029)]
Breakpoint 1, 0x00007f98d2264bb0 in write () from /lib/libc.so.6
(gdb)
正如你所见,gdb会自动管理可执行文件使用的所有线程。在这里,你不需要为线程做任何特殊处理。断点将在任何线程中起作用。
或者,如果你想要将调试器附加到已经运行的应用程序上(我在这里使用tail -f /tmp/ttt作为示例):
ps ux | grep tail
lothar 8496 0.0 0.0 9352 804 pts/3 S+ 12:38 0:00 tail -f /tmp/ttt
lothar 8510 0.0 0.0 5164 840 pts/4 S+ 12:39 0:00 grep tail
gdb
GNU gdb 6.8-debian
Copyright (C) 2008 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 "x86_64-linux-gnu"...
(no debugging symbols found)
(gdb) attach 8496
Attaching to program: /usr/bin/tail, process 8496
Reading symbols from /lib/librt.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/librt.so.1
Reading symbols from /lib/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/libpthread.so.0...(no debugging symbols found)...done.
[Thread debugging using libthread_db enabled]
[New Thread 0x7f24853f56e0 (LWP 8496)]
Loaded symbols for /lib/libpthread.so.0
Reading symbols from /lib/ld-linux-x86-64.so.2...
(no debugging symbols found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
(no debugging symbols found)
0x00007f2484d2bb50 in nanosleep () from /lib/libc.so.6
(gdb) b write
Breakpoint 1 at 0x7f2484d57bb0
(gdb) c
Continuing.
[Switching to Thread 0x7f24853f56e0 (LWP 8496)]
Breakpoint 1, 0x00007f2484d57bb0 in write () from /lib/libc.so.6
(gdb)
通常,调试共享库的过程与调试可执行文件的过程基本相同 - 主要区别在于,在共享库加载到内存之前,您可能无法设置断点。您需要将调试器附加到主可执行文件上。
如果您正在调试一个不属于您但在插件架构中使用您模块的应用程序,则仍然使用相同的方法。请确保(像往常一样)为您的共享库提供了调试信息。在Windows中,您可以生成.pdb文件。使用gcc,我认为您需要指定特殊的编译器标志(-g?)以确保提供调试信息。您需要将调试器附加到第三方应用程序上。
以下是对 lothar 回答的进一步说明:
我正在使用 python
和 python 的单元测试库 unittest
运行位于 Linux 上的动态库 test.so
(由 test.c
编译而来)上的测试,测试脚本为 tests/test_pwmbasic.py
。(我现在才意识到命名方式有点单调)
~/my/test/path/
tests/
__init__.py
test_pwmbasic.py
test.c
test.so
test_pwmbasic.py
的刺激中调试test.so
中的内容。这是我使它工作的方法...$ cd ~/my/test/path
$ gdb $(which python)
... gdb blah ...
(gdb) b test.c:179
(gdb) run
>>> from tests.test_pwmbasic import *
>>> import unittest
>>> unittest.main()
... unittest blah ...
Breakpoint 1, pwmTest_setDutyCycles (dutyCycles=0x7ffff7ece910) at ./test.c:179
(gdb) print pwm_errorCode
$1 = PWM_ERROR_NONE
现在我想要和gdb结婚
注意:test.c
还包括../pwm.c
,因此我也可以在该库内设置断点
(gdb) b pwm.c:123
我很久没有在AIX上使用dbx了,我也遇到了这个问题。但对我来说,安装gdb并不是一个选项。
dbx /path/to/your/program
(dbx) run [args to your program]
(dbx) set $ignoreonbptrap # I kept hitting a trace/bpt trap
(dbx) set $deferevents # allows setting bp in not loaded shared library
(dbx) set $repeat # useful, repeat commands with <enter> tjust like gdb
(dbx) stop in MySharedLibraryFunc # defers breakpoint
(dbx) cont
我记得通过创建一个使用它的模拟应用程序来测试共享库。如果你愿意做很多工作,你可以创建第二个模拟共享库,只收集有关第三方应用程序如何使用该库的信息,然后让你的模拟应用程序重放这些信息。
当然,不要怀疑printf和fprintf调用的威力。