修改常量字符串导致的 segmentation fault

昨天一同事遇到的问题, 帮他解决了一下, 备忘 :-)

$ cat foo.c
#include 

int main(int argc, char *argv[])
{
    char *s = "foo;bar;car";

    strtok(s, ";");

    return 0;
}
$ gcc foo.c
$ ./a.out
Segmentation fault
$ gcc -S foo.c
$ cat foo.s
        .file   "foo.c"
        .section        .rodata ; read only data (?)
.LC0:
        .string "foo;bar;car"
.LC1:
        .string ";"
        .text
.globl main
        .type   main, @function
main:
        pushl   %ebp
        movl    %esp, %ebp
        subl    $24, %esp
        andl    $-16, %esp
        movl    $0, %eax
        addl    $15, %eax
        addl    $15, %eax
        shrl    $4, %eax
        sall    $4, %eax
        subl    %eax, %esp
        movl    $.LC0, -4(%ebp)
        movl    $.LC1, 4(%esp)
        movl    -4(%ebp), %eax
        movl    %eax, (%esp)
        call    strtok
        movl    $0, %eax
        leave
        ret
        .size   main, .-main
        .ident  "GCC: (GNU) 4.0.3 (Ubuntu 4.0.3-1ubuntu5)"
        .section        .note.GNU-stack,"",@progbits
$