1 | /* Tests for fork. |
2 | Copyright (C) 2000-2022 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
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. |
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 |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <https://www.gnu.org/licenses/>. */ |
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; |
40 | pid_t ppid; |
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 (size: tmpdirlen + strlen ("/forkXXXXXX" ) + 1); |
49 | if (name == NULL) |
50 | error (EXIT_FAILURE, errno, format: "cannot allocate file name" ); |
51 | |
52 | mempcpy (mempcpy (name, tmpdir, tmpdirlen), |
53 | "/forkXXXXXX" , sizeof ("/forkXXXXXX" )); |
54 | |
55 | /* Open our test file. */ |
56 | fd = mkstemp (template: name); |
57 | if (fd == -1) |
58 | error (EXIT_FAILURE, errno, format: "cannot open test file `%s'" , name); |
59 | |
60 | /* Make sure it gets removed. */ |
61 | unlink (name: name); |
62 | |
63 | /* Write some data. */ |
64 | if (write (fd, testdata, strlen (testdata)) != strlen (testdata)) |
65 | error (EXIT_FAILURE, errno, format: "cannot write test data" ); |
66 | |
67 | /* Get the position in the stream. */ |
68 | off = lseek (fd: fd, offset: 0, SEEK_CUR); |
69 | if (off == (off_t) -1 || off != strlen (testdata)) |
70 | error (EXIT_FAILURE, errno, format: "wrong file position" ); |
71 | |
72 | /* Get the parent PID. */ |
73 | ppid = getpid (); |
74 | |
75 | /* Now fork of the process. */ |
76 | pid = fork (); |
77 | if (pid == 0) |
78 | { |
79 | /* One little test first: the PID must have changed. */ |
80 | if (getpid () == ppid) |
81 | error (EXIT_FAILURE, errnum: 0, format: "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, errnum: 0, |
87 | format: "getppid returned wrong PID (%ld, should be %ld)" , |
88 | (long int) pid, (long int) ppid); |
89 | |
90 | /* This is the child. First get the position of the descriptor. */ |
91 | off = lseek (fd: fd, offset: 0, SEEK_CUR); |
92 | if (off == (off_t) -1 || off != strlen (testdata)) |
93 | error (EXIT_FAILURE, errno, format: "wrong file position in child" ); |
94 | |
95 | /* Reset the position. */ |
96 | if (lseek (fd: fd, offset: 0, SEEK_SET) != 0) |
97 | error (EXIT_FAILURE, errno, format: "cannot reset position in child" ); |
98 | |
99 | /* Read the data. */ |
100 | if (read (fd, buf, sizeof buf) != strlen (testdata)) |
101 | error (EXIT_FAILURE, errno, format: "cannot read data in child" ); |
102 | |
103 | /* Compare the data. */ |
104 | if (memcmp (buf, testdata, strlen (testdata)) != 0) |
105 | error (EXIT_FAILURE, errnum: 0, format: "data comparison failed in child" ); |
106 | |
107 | /* Reset position again. */ |
108 | if (lseek (fd: fd, offset: 0, SEEK_SET) != 0) |
109 | error (EXIT_FAILURE, errno, format: "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, format: "cannot write new data in child" ); |
114 | |
115 | /* Close the file. This must not remove it. */ |
116 | close (fd: fd); |
117 | |
118 | _exit (0); |
119 | } |
120 | else if (pid < 0) |
121 | /* Something went wrong. */ |
122 | error (EXIT_FAILURE, errno, format: "cannot fork" ); |
123 | |
124 | /* Wait for the child. */ |
125 | if (waitpid (pid: pid, stat_loc: &status, options: 0) != pid) |
126 | error (EXIT_FAILURE, errnum: 0, format: "Oops, wrong test program terminated" ); |
127 | |
128 | if (WTERMSIG (status) != 0) |
129 | error (EXIT_FAILURE, errnum: 0, format: "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: fd, offset: 0, SEEK_CUR) != strlen (testdata2)) |
137 | error (EXIT_FAILURE, errnum: 0, format: "file position not changed" ); |
138 | |
139 | if (lseek (fd: fd, offset: 0, SEEK_SET) != 0) |
140 | error (EXIT_FAILURE, errno, format: "cannot reset file position" ); |
141 | |
142 | if (read (fd, buf, sizeof buf) != strlen (testdata2)) |
143 | error (EXIT_FAILURE, errno, format: "cannot read new data" ); |
144 | |
145 | if (memcmp (buf, testdata2, strlen (testdata2)) != 0) |
146 | error (EXIT_FAILURE, errnum: 0, format: "new data not read correctly" ); |
147 | } |
148 | |
149 | return status; |
150 | } |
151 | |