GDB 調試C++異常

http://www.cnblogs.com/zhenjing/archive/2011/06/01/gdb_fork.html

調試C++異常的兩種辦法：
1) 直接獲取異常的相關調用函數，在相應函數處設置斷點。
2) 利用gdb的catch throw/catch。(程序執行後，方有效)

如何獲取C++調用函數信息？
寫一個簡單C++程序，讓程序因異常而終止，bt查看調用棧，即可知道異常相關函數。

一個簡單程序：

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#include <iostream> #include <string> // #include <exception> #include <stdexcept>   void ter_handler(){     printf("custom handler\n"); }   void test(){     throw std::runtime_error("test function"); }   int main(int argc, char** argv) {     std::set_terminate(__gnu_cxx::__verbose_terminate_handler);     // std::set_terminate(ter_handler);       try{     // throw 5;     throw std::runtime_error("test error");     }     catch(...){         printf("catch exception\n");     }       test();     return 0; }

g++ -o test exception.cc
gdb ./test
Program received signal SIGABRT, Aborted.
0x0000003cf592e2ed in raise () from /lib64/tls/libc.so.6
(gdb) bt
#0 0x0000003cf592e2ed in raise () from /lib64/tls/libc.so.6
#1 0x0000003cf592fa3e in abort () from /lib64/tls/libc.so.6
#2 0x0000003cf86b1138 in __gnu_cxx::__verbose_terminate_handler () from /usr/lib64/libstdc++.so.6
#3 0x0000003cf86af166 in __cxa_call_unexpected () from /usr/lib64/libstdc++.so.6
#4 0x0000003cf86af193 in std::terminate () from /usr/lib64/libstdc++.so.6
#5 0x0000003cf86af293 in __cxa_throw () from /usr/lib64/libstdc++.so.6
#6 0x0000000000400e9f in test ()
#7 0x0000000000400f9d in main ()

從上述調用棧，可以得知異常由__cxa_throw ()拋出，可在該函數處設置斷點，從而得知“異常出自哪裏”。

測試環境：
Linux bclnx64 2.6.9-34.ELsmp #1 SMP
GNU gdb Red Hat Linux (6.3.0.0-1.96rh)
Copyright 2004 Free Software Foundation, Inc.

上述給出的獲取異常調用函數信息的方法，應該和操作系統和調試器無關，其他平臺類似。

1) 直接獲取異常的相關調用函數，在相應函數處設置斷點。
利用前一步驟的信息，直接b __cxa_throw，即可設置有效斷點。

2) 利用gdb的catch throw/catch
該方法也很通用，但有一個需要注意的地方：在程序執行之前，catch throw/catch是無效的，需要在程序執行之後(先在main處設置斷點)，使用catch throw纔有效。

簡單示例：

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nochen@bclnx64 ~/test$ gdb ./test GNU gdb Red Hat Linux (6.3.0.0-1.96rh) Copyright 2004 Free Software Foundation, Inc.   (gdb) b __cxa_throw Function "__cxa_throw" not defined. Make breakpoint pending on future shared library load? (y or [n]) y Breakpoint 1 (__cxa_throw) pending. (gdb) r Starting program: /home/nochen/test/test (no debugging symbols found) Breakpoint 2 at 0x3cf86af230 Pending breakpoint "__cxa_throw" resolved   Breakpoint 2, 0x0000003cf86af230 in __cxa_throw () from /usr/lib64/libstdc++.so.6 (gdb) bt #0  0x0000003cf86af230 in __cxa_throw () from /usr/lib64/libstdc++.so.6 #1  0x0000000000400f5b in main () (gdb) c Continuing. catch exception   Breakpoint 2, 0x0000003cf86af230 in __cxa_throw () from /usr/lib64/libstdc++.so.6 (gdb) bt #0  0x0000003cf86af230 in __cxa_throw () from /usr/lib64/libstdc++.so.6 #1  0x0000000000400e9f in test () #2  0x0000000000400f9d in main () (gdb) c Continuing. terminate called after throwing an instance of 'std::runtime_error'   what():  test function   Program received signal SIGABRT, Aborted. 0x0000003cf592e2ed in raise () from /lib64/tls/libc.so.6 (gdb) q The program is running.  Exit anyway? (y or n) y   ===================================   nochen@bclnx64 ~/test$ gdb ./test (gdb) b main Breakpoint 1 at 0x400ea4 (gdb) r Starting program: /home/nochen/test/test (no debugging symbols found)   Breakpoint 1, 0x0000000000400ea4 in main () (gdb) catch throw Catchpoint 2 (throw) (gdb) c Continuing.   Catchpoint 2 (exception thrown) 0x0000003cf86af230 in __cxa_throw () from /usr/lib64/libstdc++.so.6 (gdb) bt #0  0x0000003cf86af230 in __cxa_throw () from /usr/lib64/libstdc++.so.6 #1  0x0000000000400f5b in main () (gdb) c Continuing. catch exception   Catchpoint 2 (exception thrown) 0x0000003cf86af230 in __cxa_throw () from /usr/lib64/libstdc++.so.6 (gdb) bt #0  0x0000003cf86af230 in __cxa_throw () from /usr/lib64/libstdc++.so.6 #1  0x0000000000400e9f in test () #2  0x0000000000400f9d in main () (gdb) c Continuing. terminate called after throwing an instance of 'std::runtime_error'   what():  test function   Program received signal SIGABRT, Aborted. 0x0000003cf592e2ed in raise () from /lib64/tls/libc.so.6 (gdb)