1 | /* Copyright (C) 2002-2024 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either |
7 | version 2.1 of the License, or (at your option) any later version. |
8 | |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public |
15 | License along with the GNU C Library; if not, see |
16 | <https://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <errno.h> |
19 | #include <semaphore.h> |
20 | #include <stdint.h> |
21 | #include <stdio.h> |
22 | #include <stdlib.h> |
23 | #include <string.h> |
24 | #include <unistd.h> |
25 | #include <sys/mman.h> |
26 | #include <sys/wait.h> |
27 | |
28 | |
29 | int |
30 | do_test (void) |
31 | { |
32 | size_t ps = sysconf (_SC_PAGESIZE); |
33 | char tmpfname[] = "/tmp/tst-sem3.XXXXXX" ; |
34 | char data[ps]; |
35 | void *mem; |
36 | int fd; |
37 | sem_t *s; |
38 | pid_t pid; |
39 | char *p; |
40 | |
41 | fd = mkstemp (template: tmpfname); |
42 | if (fd == -1) |
43 | { |
44 | printf (format: "cannot open temporary file: %m\n" ); |
45 | return 1; |
46 | } |
47 | |
48 | /* Make sure it is always removed. */ |
49 | unlink (name: tmpfname); |
50 | |
51 | /* Create one page of data. */ |
52 | memset (data, '\0', ps); |
53 | |
54 | /* Write the data to the file. */ |
55 | if (write (fd, data, ps) != (ssize_t) ps) |
56 | { |
57 | puts (s: "short write" ); |
58 | return 1; |
59 | } |
60 | |
61 | mem = mmap (NULL, len: ps, PROT_READ | PROT_WRITE, MAP_SHARED, fd: fd, offset: 0); |
62 | if (mem == MAP_FAILED) |
63 | { |
64 | printf (format: "mmap failed: %m\n" ); |
65 | return 1; |
66 | } |
67 | |
68 | s = (sem_t *) (((uintptr_t) mem + __alignof (sem_t)) |
69 | & ~(__alignof (sem_t) - 1)); |
70 | p = (char *) (s + 1); |
71 | |
72 | if (sem_init (sem: s, pshared: 1, value: 1) == -1) |
73 | { |
74 | puts (s: "init failed" ); |
75 | return 1; |
76 | } |
77 | |
78 | if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1) |
79 | { |
80 | puts (s: "1st wait failed" ); |
81 | return 1; |
82 | } |
83 | |
84 | errno = 0; |
85 | if (TEMP_FAILURE_RETRY (sem_trywait (s)) != -1) |
86 | { |
87 | puts (s: "trywait succeeded" ); |
88 | return 1; |
89 | } |
90 | else if (errno != EAGAIN) |
91 | { |
92 | puts (s: "trywait didn't return EAGAIN" ); |
93 | return 1; |
94 | } |
95 | |
96 | *p = 0; |
97 | |
98 | puts (s: "going to fork now" ); |
99 | pid = fork (); |
100 | if (pid == -1) |
101 | { |
102 | puts (s: "fork failed" ); |
103 | return 1; |
104 | } |
105 | else if (pid == 0) |
106 | { |
107 | /* Play some lock ping-pong. It's our turn to unlock first. */ |
108 | if ((*p)++ != 0) |
109 | { |
110 | puts (s: "child: *p != 0" ); |
111 | return 1; |
112 | } |
113 | |
114 | if (sem_post (sem: s) == -1) |
115 | { |
116 | puts (s: "child: 1st post failed" ); |
117 | return 1; |
118 | } |
119 | |
120 | puts (s: "child done" ); |
121 | } |
122 | else |
123 | { |
124 | if (TEMP_FAILURE_RETRY (sem_wait (s)) == -1) |
125 | { |
126 | printf (format: "parent: 2nd wait failed: %m\n" ); |
127 | return 1; |
128 | } |
129 | |
130 | if (*p != 1) |
131 | { |
132 | puts (s: "*p != 1" ); |
133 | return 1; |
134 | } |
135 | |
136 | puts (s: "parent done" ); |
137 | } |
138 | |
139 | return 0; |
140 | } |
141 | |
142 | #define TEST_FUNCTION do_test () |
143 | #include "../test-skeleton.c" |
144 | |