I tried to get inspiration from:
Code: Select all
Here's an example program that installs a SIGSEGV handler and prints a stacktrace to stderr
when it segfaults.
The baz() function here causes the segfault that triggers the handler:
#include <stdio.h>
#include <execinfo.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
void handler(int sig) {
void *array[10];
size_t size;
// get void*'s for all entries on the stack
size = backtrace(array, 10);
// print out all the frames to stderr
fprintf(stderr, "Error: signal %d:\n", sig);
backtrace_symbols_fd(array, size, STDERR_FILENO);
exit(1);
}
void baz() {
int *foo = (int*)-1; // make a bad pointer
printf("%d\n", *foo); // causes segfault
}
void bar() { baz(); }
void foo() { bar(); }
int main(int argc, char **argv) {
signal(SIGSEGV, handler); // install our handler
foo(); // this will call foo, bar, and baz. baz segfaults.
}
Compiling with -g -rdynamic gets you symbol info in your output,
which glibc can use to make a nice stacktrace:
$ gcc -g -rdynamic ./test.c -o test
Executing this gets you this output:
$ ./test
Error: signal 11:
./test(handler+0x19)[0x400911]
/lib64/tls/libc.so.6[0x3a9b92e380]
./test(baz+0x14)[0x400962]
./test(bar+0xe)[0x400983]
./test(foo+0xe)[0x400993]
./test(main+0x28)[0x4009bd]
/lib64/tls/libc.so.6(__libc_start_main+0xdb)[0x3a9b91c4bb]
./test[0x40086a]
This shows the load module, offset, and function that each frame in the stack came from.
Here you can see the signal handler on top of the stack, and the libc functions before main
in addition to main, foo, bar, and baz.There also need to get a stack trace from crash - to debug it