1/* -*- mode: C; c-basic-offset: 3; -*- */
2
3#include <assert.h>
4#include <elf.h>
5#include <stdio.h>
6#include <stdlib.h>
7#include <string.h>
8#include <unistd.h>
9
10#include <sys/ptrace.h>
11#include <sys/types.h>
12#include <sys/uio.h>
13#include <sys/user.h>
14#include <sys/wait.h>
15
16static int
17err_out(const char *msg)
18{
19   perror(msg);
20   return 1;
21}
22
23static int
24non_empty(const char *buf, size_t len)
25{
26   size_t i;
27   int c = 0;
28   volatile const char *p = buf;
29
30   for (i = 0; i != len; i++)
31      c |= p[i];
32   return c;
33}
34
35static int
36do_child(void)
37{
38   if (ptrace(PTRACE_TRACEME, 0, NULL, NULL) == -1)
39      return err_out("ptrace traceme");
40   raise(SIGUSR1);
41   return 0;
42}
43
44int
45main(void)
46{
47   char buf[1024];
48   struct iovec iov;
49   pid_t cpid, pid;
50   int status;
51
52   cpid = fork();
53   if (cpid == -1)
54      return err_out("fork");
55   if (cpid == 0)
56      return do_child();
57
58   pid = wait(&status);
59   if (pid == -1)
60      return err_out("wait");
61
62   /* Intentionally provide an uninitialized buffer to ptrace. */
63   iov.iov_len = sizeof(buf);
64   iov.iov_base = buf;
65   if (ptrace(0x4204, cpid, NT_PRSTATUS, &iov) == -1)
66      return err_out("ptrace getregset");
67
68   assert(iov.iov_base == buf);
69   assert(iov.iov_len > 0 && iov.iov_len < sizeof(buf));
70
71   /* We're assuming here that NT_PRSTATUS never contains
72      all-zeros. */
73   assert(non_empty(buf, iov.iov_len));
74   puts("OK");
75   return 0;
76}
77