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c0f3519d | 1 | /* Tests for fork. |
2b778ceb | 2 | Copyright (C) 2000-2021 Free Software Foundation, Inc. |
41bdb6e2 | 3 | This file is part of the GNU C Library. |
c0f3519d UD |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or | |
41bdb6e2 AJ |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
c0f3519d UD |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
c0f3519d | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
c0f3519d UD |
18 | |
19 | #include <errno.h> | |
20 | #include <error.h> | |
21 | #include <stdlib.h> | |
22 | #include <string.h> | |
23 | #include <unistd.h> | |
24 | #include <wait.h> | |
25 | ||
26 | ||
27 | static const char testdata[] = "This is a test"; | |
28 | static const char testdata2[] = "And here we go again"; | |
29 | ||
30 | ||
31 | int | |
32 | main (void) | |
33 | { | |
34 | const char *tmpdir = getenv ("TMPDIR"); | |
35 | char buf[100]; | |
36 | size_t tmpdirlen; | |
37 | char *name; | |
38 | int fd; | |
39 | pid_t pid; | |
31eb0a91 | 40 | pid_t ppid; |
c0f3519d UD |
41 | off_t off; |
42 | int status; | |
43 | ||
44 | if (tmpdir == NULL || *tmpdir == '\0') | |
45 | tmpdir = "/tmp"; | |
46 | tmpdirlen = strlen (tmpdir); | |
47 | ||
48 | name = (char *) malloc (tmpdirlen + strlen ("/forkXXXXXX") + 1); | |
49 | if (name == NULL) | |
50 | error (EXIT_FAILURE, errno, "cannot allocate file name"); | |
51 | ||
52 | mempcpy (mempcpy (name, tmpdir, tmpdirlen), | |
53 | "/forkXXXXXX", sizeof ("/forkXXXXXX")); | |
54 | ||
55 | /* Open our test file. */ | |
56 | fd = mkstemp (name); | |
57 | if (fd == -1) | |
58 | error (EXIT_FAILURE, errno, "cannot open test file `%s'", name); | |
59 | ||
60 | /* Make sure it gets removed. */ | |
61 | unlink (name); | |
62 | ||
63 | /* Write some data. */ | |
64 | if (write (fd, testdata, strlen (testdata)) != strlen (testdata)) | |
65 | error (EXIT_FAILURE, errno, "cannot write test data"); | |
66 | ||
67 | /* Get the position in the stream. */ | |
68 | off = lseek (fd, 0, SEEK_CUR); | |
69 | if (off == (off_t) -1 || off != strlen (testdata)) | |
70 | error (EXIT_FAILURE, errno, "wrong file position"); | |
71 | ||
31eb0a91 UD |
72 | /* Get the parent PID. */ |
73 | ppid = getpid (); | |
74 | ||
c0f3519d UD |
75 | /* Now fork of the process. */ |
76 | pid = fork (); | |
77 | if (pid == 0) | |
78 | { | |
31eb0a91 UD |
79 | /* One little test first: the PID must have changed. */ |
80 | if (getpid () == ppid) | |
81 | error (EXIT_FAILURE, 0, "child and parent have same PID"); | |
82 | ||
83 | /* Test the `getppid' function. */ | |
84 | pid = getppid (); | |
85 | if (pid == (pid_t) -1 ? errno != ENOSYS : pid != ppid) | |
86 | error (EXIT_FAILURE, 0, | |
87 | "getppid returned wrong PID (%ld, should be %ld)", | |
88 | (long int) pid, (long int) ppid); | |
89 | ||
c0f3519d UD |
90 | /* This is the child. First get the position of the descriptor. */ |
91 | off = lseek (fd, 0, SEEK_CUR); | |
92 | if (off == (off_t) -1 || off != strlen (testdata)) | |
93 | error (EXIT_FAILURE, errno, "wrong file position in child"); | |
94 | ||
95 | /* Reset the position. */ | |
96 | if (lseek (fd, 0, SEEK_SET) != 0) | |
97 | error (EXIT_FAILURE, errno, "cannot reset position in child"); | |
98 | ||
99 | /* Read the data. */ | |
100 | if (read (fd, buf, sizeof buf) != strlen (testdata)) | |
101 | error (EXIT_FAILURE, errno, "cannot read data in child"); | |
102 | ||
103 | /* Compare the data. */ | |
104 | if (memcmp (buf, testdata, strlen (testdata)) != 0) | |
105 | error (EXIT_FAILURE, 0, "data comparison failed in child"); | |
106 | ||
107 | /* Reset position again. */ | |
108 | if (lseek (fd, 0, SEEK_SET) != 0) | |
109 | error (EXIT_FAILURE, errno, "cannot reset position again in child"); | |
110 | ||
111 | /* Write new data. */ | |
112 | if (write (fd, testdata2, strlen (testdata2)) != strlen (testdata2)) | |
113 | error (EXIT_FAILURE, errno, "cannot write new data in child"); | |
114 | ||
115 | /* Close the file. This must not remove it. */ | |
116 | close (fd); | |
117 | ||
118 | _exit (0); | |
119 | } | |
120 | else if (pid < 0) | |
121 | /* Something went wrong. */ | |
122 | error (EXIT_FAILURE, errno, "cannot fork"); | |
123 | ||
124 | /* Wait for the child. */ | |
125 | if (waitpid (pid, &status, 0) != pid) | |
126 | error (EXIT_FAILURE, 0, "Oops, wrong test program terminated"); | |
127 | ||
128 | if (WTERMSIG (status) != 0) | |
129 | error (EXIT_FAILURE, 0, "Child terminated incorrectly"); | |
130 | status = WEXITSTATUS (status); | |
131 | ||
132 | if (status == 0) | |
133 | { | |
134 | /* Test whether the child wrote the right data. First test the | |
135 | position. It must be the same as in the child. */ | |
136 | if (lseek (fd, 0, SEEK_CUR) != strlen (testdata2)) | |
137 | error (EXIT_FAILURE, 0, "file position not changed"); | |
138 | ||
139 | if (lseek (fd, 0, SEEK_SET) != 0) | |
140 | error (EXIT_FAILURE, errno, "cannot reset file position"); | |
141 | ||
142 | if (read (fd, buf, sizeof buf) != strlen (testdata2)) | |
143 | error (EXIT_FAILURE, errno, "cannot read new data"); | |
144 | ||
145 | if (memcmp (buf, testdata2, strlen (testdata2)) != 0) | |
146 | error (EXIT_FAILURE, 0, "new data not read correctly"); | |
147 | } | |
148 | ||
149 | return status; | |
150 | } |