给出系统调用的包装函数:
ssize_t my_write(int fd, const void *buf, size_t count)
{
long __res;
__asm__ volatile
("int $0x80"
: "=a" (__res)
: "0" (4),"D" ((long)(fd)),"S" ((long)(buf)), "d" ((long)(count))
: "ebx","memory");
if (-125 <= __res && __res < 0)
{
errno = -__res;
__res = -1;
}
return __res;
}
我已尝试使用代码(来自int main()):
int main() {
my_write(2,"an read error occured\n",26);
return 0;
}
然而它不起作用。知道为什么吗?
谢谢
答案 0 :(得分:3)
您的约束已关闭,文件描述符需要进入EBX,即ECX中的缓冲区(不是像您一样的EDI / ESI)。
尝试:
__asm__ volatile
("int $0x80"
: "=a" (__res)
: "0" (4),"b" ((long)(fd)),"c" ((long)(buf)), "d" ((long)(count))
: "memory");