summaryrefslogtreecommitdiff
path: root/posix/tst-fork.c
blob: 893c024e47373500ebba63bcdb0a361fc63ad47f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
/* Tests for fork.
   Copyright (C) 2000-2016 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 2000.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <errno.h>
#include <error.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <wait.h>


static const char testdata[] = "This is a test";
static const char testdata2[] = "And here we go again";


int
main (void)
{
  const char *tmpdir = getenv ("TMPDIR");
  char buf[100];
  size_t tmpdirlen;
  char *name;
  int fd;
  pid_t pid;
  pid_t ppid;
  off_t off;
  int status;

  if (tmpdir == NULL || *tmpdir == '\0')
    tmpdir = "/tmp";
  tmpdirlen = strlen (tmpdir);

  name = (char *) malloc (tmpdirlen + strlen ("/forkXXXXXX") + 1);
  if (name == NULL)
    error (EXIT_FAILURE, errno, "cannot allocate file name");

  mempcpy (mempcpy (name, tmpdir, tmpdirlen),
	   "/forkXXXXXX", sizeof ("/forkXXXXXX"));

  /* Open our test file.   */
  fd = mkstemp (name);
  if (fd == -1)
     error (EXIT_FAILURE, errno, "cannot open test file `%s'", name);

  /* Make sure it gets removed.  */
  unlink (name);

  /* Write some data.  */
  if (write (fd, testdata, strlen (testdata)) != strlen (testdata))
    error (EXIT_FAILURE, errno, "cannot write test data");

  /* Get the position in the stream.  */
  off = lseek (fd, 0, SEEK_CUR);
  if (off == (off_t) -1 || off != strlen (testdata))
    error (EXIT_FAILURE, errno, "wrong file position");

  /* Get the parent PID.  */
  ppid = getpid ();

  /* Now fork of the process.  */
  pid = fork ();
  if (pid == 0)
    {
      /* One little test first: the PID must have changed.  */
      if (getpid () == ppid)
	error (EXIT_FAILURE, 0, "child and parent have same PID");

      /* Test the `getppid' function.  */
      pid = getppid ();
      if (pid == (pid_t) -1 ? errno != ENOSYS : pid != ppid)
	error (EXIT_FAILURE, 0,
	       "getppid returned wrong PID (%ld, should be %ld)",
	       (long int) pid, (long int) ppid);

      /* This is the child.  First get the position of the descriptor.  */
      off = lseek (fd, 0, SEEK_CUR);
      if (off == (off_t) -1 || off != strlen (testdata))
	error (EXIT_FAILURE, errno, "wrong file position in child");

      /* Reset the position.  */
      if (lseek (fd, 0, SEEK_SET) != 0)
	error (EXIT_FAILURE, errno, "cannot reset position in child");

      /* Read the data.  */
      if (read (fd, buf, sizeof buf) != strlen (testdata))
	error (EXIT_FAILURE, errno, "cannot read data in child");

      /* Compare the data.  */
      if (memcmp (buf, testdata, strlen (testdata)) != 0)
	error (EXIT_FAILURE, 0, "data comparison failed in child");

      /* Reset position again.  */
      if (lseek (fd, 0, SEEK_SET) != 0)
	error (EXIT_FAILURE, errno, "cannot reset position again in child");

      /* Write new data.  */
      if (write (fd, testdata2, strlen (testdata2)) != strlen (testdata2))
	error (EXIT_FAILURE, errno, "cannot write new data in child");

      /* Close the file.  This must not remove it.  */
      close (fd);

      _exit (0);
    }
  else if (pid < 0)
    /* Something went wrong.  */
    error (EXIT_FAILURE, errno, "cannot fork");

  /* Wait for the child.  */
  if (waitpid (pid, &status, 0) != pid)
    error (EXIT_FAILURE, 0, "Oops, wrong test program terminated");

  if (WTERMSIG (status) != 0)
    error (EXIT_FAILURE, 0, "Child terminated incorrectly");
  status = WEXITSTATUS (status);

  if (status == 0)
    {
      /* Test whether the child wrote the right data.  First test the
	 position.  It must be the same as in the child.  */
      if (lseek (fd, 0, SEEK_CUR) != strlen (testdata2))
	error (EXIT_FAILURE, 0, "file position not changed");

      if (lseek (fd, 0, SEEK_SET) != 0)
	error (EXIT_FAILURE, errno, "cannot reset file position");

      if (read (fd, buf, sizeof buf) != strlen (testdata2))
	error (EXIT_FAILURE, errno, "cannot read new data");

      if (memcmp (buf, testdata2, strlen (testdata2)) != 0)
	error (EXIT_FAILURE, 0, "new data not read correctly");
    }

  return status;
}