原文出处 http://blog.csdn.net/yetyongjin/article/details/7759144
以下不能windows + mingw下执行. windows下参考 http://code.google.com/p/backtrace-mingw/
我们知道,GDB的backtrace命令可以查看堆栈信息。但很多时候,GDB根本用不上。比如说,在线上环境中可能没有GDB,即使有,也不太可能让我们直接在上面调试。如果能让程序自己输出调用栈,那是最好不过了。本文介绍和调用椎栈相关的几个函数。
NAME
backtrace, backtrace_symbols, backtrace_symbols_fd - support for application self-debugging
SYNOPSIS
#include <execinfo.h>
int backtrace(void **buffer, int size);
char **backtrace_symbols(void *const *buffer, int size);
void backtrace_symbols_fd(void *const *buffer, int size, int fd);
以上内容源自这几个函数的man手册。
先简单介绍一下这几个函数的功能:
l backtrace:获取当前的调用栈信息,结果存储在buffer中,返回值为栈的深度,参数size限制栈的最大深度,即最大取size步的栈信息。
l backtrace_symbols:把backtrace获取的栈信息转化为字符串,以字符指针数组的形式返回,参数size限定转换的深度,一般用backtrace调用的返回值。
l backtrace_symbols_fd:它的功能和backtrace_symbols差不多,只不过它不把转换结果返回给调用方,而是写入fd指定的文件描述符。
Man手册里,给出了一个简单的实例,我们看一下:
1 #include<execinfo.h>
2 #include<stdio.h>
3 #include<stdlib.h>
4 #include<unistd.h>
5 6 void myfunc3(
void) {
7 int j, nptrs;
8 #define SIZE 100
9 void *buffer[100];
10 char **strings;
11 nptrs = backtrace(buffer, SIZE);
12 printf("backtrace() returned %d addresses\n", nptrs);
13 /* The call backtrace_symbols_fd(buffer, nptrs, STDOUT_FILENO)
14 * would produce similar output to the following: */15 16 strings = backtrace_symbols(buffer, nptrs);
17 if (strings == NULL) {
18 perror("backtrace_symbols");
19 exit(EXIT_FAILURE);
20 }
21 22 for (j = 0; j < nptrs; j++)
23 printf("%s\n", strings[j]);
24 free(strings);
25 }
26 27 static void myfunc2(
void) {
/* "static" means don't export the symbol */28 myfunc3();
29 }
30 31 void myfunc(
int ncalls) {
32 if (ncalls > 1)
33 myfunc(ncalls - 1);
34 else35 myfunc2();
36 }
37 38 int main(
int argc,
char *argv[]) {
39 if (argc != 2) {
40 fprintf(stderr,"%s num-calls\n", argv[0]);
41 exit(EXIT_FAILURE);
42 }
43 myfunc(atoi(argv[1]));
44 exit(EXIT_SUCCESS);
45 }
46 编译:
# cc prog.c -o prog
运行:
# ./prog 0
backtrace() returned 6 addresses
./prog() [0x80485a3]
./prog() [0x8048630]
./prog() [0x8048653]
./prog() [0x80486a7]
这样,是输出了调用栈,不过只是以十六进制输出函数地址而已,可读性很差。仔细看下man手册,原来很简单,编译时加上个参数:
重新编译:
# cc -rdynamic prog.c -o prog
通过gcc手册,我们可以也解下参数的说明:
-rdynamic
Pass the flag -export-dynamic to the ELF linker, on targets that support it. This instructs the linker to add all symbols, not only used ones, to the dynamic symbol table. This option is needed for some uses of "dlopen" or to allow obtaining backtraces from within a program.
再执行:
# ./prog 0
backtrace() returned 6 addresses
./prog(myfunc3+0x1f) [0x8048763]
./prog() [0x80487f0]
./prog(myfunc+0x21) [0x8048813]
./prog(main+0x52) [0x8048867]
/lib/libc.so.6(__libc_start_main+0xe6) [0xaf9cc6]
./prog() [0x80486b1]
这回,可以看到函数名了。