c - Linux内核中的ptrace在哪里？

Question

我无法在内核源代码中使用 global ptrace 找到它，kernel/ptrace.c 中没有定义，就像手册页中所述......我可以看到 kernel/ptrace.c 和 include/linux/ptrace.h 但什么都没有

Answer 1

你需要在你的libc源代码中寻找它，例如 glibc或者 musl .并注意它在NOTES 部分下的 man ptrace:

Although arguments to ptrace() are interpreted according to the prototype given, glibc currently declares ptrace() as a variadic function with only the request argument fixed. It is recommended to always supply four arguments, even if the requested operation does not use them, setting unused/ignored arguments to 0L or (void *) 0.

例如在 glibc 中定义了 ptrace()sysdeps/unix/sysv/linux/ptrace.c:

long int
ptrace (enum __ptrace_request request, ...)
{
  long int res, ret;
  va_list ap;
  pid_t pid;
  void *addr, *data;

  va_start (ap, request);
  pid = va_arg (ap, pid_t);
  addr = va_arg (ap, void *);
  data = va_arg (ap, void *);
  va_end (ap);

  if (request > 0 && request < 4)
    data = &ret;

  res = INLINE_SYSCALL (ptrace, 4, request, pid, addr, data);
  if (res >= 0 && request > 0 && request < 4)
    {
      __set_errno (0);
      return ret;
    }

  return res;
}