编译点滴

(gdb) r
Starting program: /home/xiaosuo/test/a.out

Program received signal SIGSEGV, Segmentation fault.
0×08048524 in dummy_function () at d.c:4
4               *ptr = 0×00;
(gdb)                      

warning: Can’t read pathname for load map: 输入/输出错误.
Reading symbols from /lib/libc.so.6…done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/ld-linux.so.2…done.
Loaded symbols for /lib/ld-linux.so.2
Core was generated by `./a.out’.
Program terminated with signal 11, Segmentation fault.
#0 0×08048524 in dummy_function () at d.c:4
4               *ptr = 0×00;

void dump(int signo)
{
        char buf[1024];
        char cmd[1024];
        FILE *fh;

        snprintf(buf, sizeof(buf), "/proc/%d/cmdline", getpid());
        if(!(fh = fopen(buf, "r")))
                exit(0);
        if(!fgets(buf, sizeof(buf), fh))
                exit(0);
        fclose(fh);
        if(buf[strlen(buf) - 1] == ‘\n’)
                buf[strlen(buf) - 1] = ‘\0′;
        snprintf(cmd, sizeof(cmd), "gdb %s %d", buf, getpid());
        system(cmd);

        exit(0);
}

        void
dummy_function (void)
{
        unsigned char *ptr = 0×00;
        *ptr = 0×00;
}

        int
main (void)
{
        signal(SIGSEGV, &dump);
        dummy_function ();

        return 0;
}

Attaching to program: /home/xiaosuo/test/a.out, process 9563
Reading symbols from /lib/libc.so.6…done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/ld-linux.so.2…done.
Loaded symbols for /lib/ld-linux.so.2
0xffffe410 in __kernel_vsyscall ()
(gdb) bt
#0 0xffffe410 in __kernel_vsyscall ()
#1 0xb7ee4b53 in waitpid () from /lib/libc.so.6
#2 0xb7e925c9 in strtold_l () from /lib/libc.so.6
#3 0×08048830 in dump (signo=11) at f.c:22
#4 <signal handler called>
#5 0x0804884c in dummy_function () at f.c:31
#6 0×08048886 in main () at f.c:38

/* A dummy function to make the backtrace more interesting. */
        void
dummy_function (void)
{
        unsigned char *ptr = 0×00;
        *ptr = 0×00;
}

void dump(int signo)
{
        void *array[10];
        size_t size;
        char **strings;
        size_t i;

        size = backtrace (array, 10);
        strings = backtrace_symbols (array, size);

        printf ("Obtained %zd stack frames.\n", size);

        for (i = 0; i < size; i++)
                printf ("%s\n", strings[i]);

        free (strings);

        exit(0);
}

        int
main (void)
{
        signal(SIGSEGV, &dump);
        dummy_function ();

        return 0;
}