1 /*
2 * Copyright (c) 2002, Intel Corporation. All rights reserved.
3 * Copyright (c) 2012, Cyril Hrubis <chrubis@suse.cz>
4 *
5 * This file is licensed under the GPL license. For the full content
6 * of this license, see the COPYING file at the top level of this
7 * source tree.
8 *
9 * MAP_SHARED and MAP_PRIVATE describe the disposition of write references
10 * to the memory object. If MAP_SHARED is specified, write references shall
11 * change the underlying object. If MAP_PRIVATE is specified, modifications
12 * to the mapped data by the calling process shall be visible only to the
13 * calling process and shall not change the underlying object.
14 * It is unspecified whether modifications to the underlying object done
15 * after the MAP_PRIVATE mapping is established are visible through
16 * the MAP_PRIVATE mapping.
17 *
18 * Test Steps:
19 *
20 * 1. Create a shared memory object.
21 * 2. mmap the shared memory object into memory, setting MAP_PRIVATE.
22 * 3. Modify the mapped memory.
23 * 4. Fork a child process.
24 * 5. Child process mmap the same shared memory object into memory.
25 * 6. Check whether the change in step 3 is visible to the child.
26 *
27 */
28
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <unistd.h>
32 #include <sys/mman.h>
33 #include <sys/types.h>
34 #include <sys/stat.h>
35 #include <sys/wait.h>
36 #include <fcntl.h>
37 #include <string.h>
38 #include <errno.h>
39 #include "posixtest.h"
40
main(void)41 int main(void)
42 {
43 char tmpfname[256];
44 void *pa;
45 size_t size = 1024;
46 int fd;
47 pid_t child;
48 int exit_stat;
49
50 /* Create shared object */
51 snprintf(tmpfname, sizeof(tmpfname), "pts_mmap_7_3_%d", getpid());
52 shm_unlink(tmpfname);
53 fd = shm_open(tmpfname, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
54 if (fd == -1) {
55 printf("Error at shm_open(): %s\n", strerror(errno));
56 return PTS_UNRESOLVED;
57 }
58 shm_unlink(tmpfname);
59
60 if (ftruncate(fd, size) == -1) {
61 printf("Error at ftruncate(): %s\n", strerror(errno));
62 return PTS_UNRESOLVED;
63 }
64
65 pa = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
66 if (pa == MAP_FAILED) {
67 printf("Error at mmap(): %s\n", strerror(errno));
68 return PTS_FAIL;
69 }
70
71 /* Write the mapped memory */
72 *(char *)pa = 'a';
73
74 child = fork();
75
76 switch (child) {
77 case 0:
78 /* Mmap again the same shared memory to child's memory */
79 pa = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd,
80 0);
81 if (pa == MAP_FAILED) {
82 printf("Error at mmap(): %s\n", strerror(errno));
83 return PTS_FAIL;
84 }
85
86 if (*(char *)pa == 'a') {
87 printf("Set flag as MAP_PRIVATE, write reference will "
88 "change the underlying shared memory object\n");
89 return PTS_FAIL;
90 }
91
92 printf("Set flag as MAP_PRIVATE, write reference will "
93 "not change the underlying shared memory object\n"
94 "Test PASSED\n");
95 return PTS_PASS;
96 break;
97 case -1:
98 printf("Error at fork(): %s\n", strerror(errno));
99 return PTS_UNRESOLVED;
100 break;
101 default:
102 waitpid(child, &exit_stat, WUNTRACED);
103
104 close(fd);
105 munmap(pa, size);
106
107 if (WIFEXITED(exit_stat)) {
108 return WEXITSTATUS(exit_stat);
109 } else {
110 printf("Child has not exit properly\n");
111 return PTS_UNRESOLVED;
112 }
113 }
114 }
115