在kernel里可以用dump_stack()打出内核函数调用关系,在应用程序里可以用backtrace+backtrace_symbols打出调用栈。一般来说应用程序里手动跟踪可能更方便,或者crash后用gdb打出调用关系也很简单,但某些特殊需求里还是得请backtrace出来。
这两个函数需要加 <execinfo.h> 头文件,两个函数描述如下:
int backtrace(void **buffer,int size)
---该函数用与获取当前线程的调用堆栈,获取的信息将会被存放在buffer中,它是一个指针数组
char ** backtrace_symbols (void *const *buffer, int size)
--- 从backtrace函数获取的信息转化为一个字符串数组.它包括函数名,函数的偏移地址,和实际的返回地址
从https://www.cnblogs.com/mickole/p/3246702.html 里copy了一个测试程序:
#include <execinfo.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
void myfunc3(void)
{
int j, nptrs;
void *buffer[100];
char **strings;
nptrs = backtrace(buffer, 100);
printf("backtrace() returned %d addresses\n", nptrs);
/* The call backtrace_symbols_fd(buffer, nptrs, STDOUT_FILENO)
would produce similar output to the following: */
strings = backtrace_symbols(buffer, nptrs);
if (strings == NULL) {
perror("backtrace_symbols");
exit(EXIT_FAILURE);
}
for (j = 0; j < nptrs; j++)
printf("%s\n", strings[j]);
free(strings);
}
/* "static" means don't export the symbol... */
static void myfunc2(void)
{
myfunc3();
}
void myfunc(int ncalls)
{
if (ncalls > 1)
myfunc(ncalls - 1);
else
myfunc2();
}
int main(int argc, char *argv[])
{
if (argc != 2) {
fprintf(stderr, "%s num-calls\n", argv[0]);
exit(EXIT_FAILURE);
}
myfunc(atoi(argv[1]));
exit(EXIT_SUCCESS);
}
用GCC 编译:
gcc -rdynamic back_trace.c -o backtrace
-rdynamic 用来通知链接器将所有符号添加到动态符号表中
运行结果如下:
$ ./backtrace 3
backtrace() returned 8 addresses
./backtrace(myfunc3+0x2e) [0x400af4]
./backtrace() [0x400bc2]
./backtrace(myfunc+0x25) [0x400bea]
./backtrace(myfunc+0x1e) [0x400be3]
./backtrace(myfunc+0x1e) [0x400be3]
./backtrace(main+0x59) [0x400c46]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0) [0x7f4f131b9830]
./backtrace(_start+0x29) [0x4009f9]