1 #include <assert.h>
2 #include <stdlib.h>
3 #include <sys/mman.h>
4 #include <unistd.h>
5 
6 static void test_anonymous(void)
7 {
8     int pagesize = getpagesize();
9     char *page;
10     int ret;
11 
12     page = mmap(NULL, pagesize, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
13     assert(page != MAP_FAILED);
14 
15     /* Check that mprotect() does not interfere with MADV_DONTNEED. */
16     ret = mprotect(page, pagesize, PROT_READ | PROT_WRITE);
17     assert(ret == 0);
18 
19     /* Check that MADV_DONTNEED clears the page. */
20     *page = 42;
21     ret = madvise(page, pagesize, MADV_DONTNEED);
22     assert(ret == 0);
23     assert(*page == 0);
24 
25     ret = munmap(page, pagesize);
26     assert(ret == 0);
27 }
28 
29 static void test_file(void)
30 {
31     char tempname[] = "/tmp/.cmadviseXXXXXX";
32     int pagesize = getpagesize();
33     ssize_t written;
34     char c = 42;
35     char *page;
36     int ret;
37     int fd;
38 
39     fd = mkstemp(tempname);
40     assert(fd != -1);
41     ret = unlink(tempname);
42     assert(ret == 0);
43     written = write(fd, &c, sizeof(c));
44     assert(written == sizeof(c));
45     ret = ftruncate(fd, pagesize);
46     assert(ret == 0);
47     page = mmap(NULL, pagesize, PROT_READ, MAP_PRIVATE, fd, 0);
48     assert(page != MAP_FAILED);
49 
50     /* Check that mprotect() does not interfere with MADV_DONTNEED. */
51     ret = mprotect(page, pagesize, PROT_READ | PROT_WRITE);
52     assert(ret == 0);
53 
54     /* Check that MADV_DONTNEED resets the page. */
55     *page = 0;
56     ret = madvise(page, pagesize, MADV_DONTNEED);
57     assert(ret == 0);
58     assert(*page == c);
59 
60     ret = munmap(page, pagesize);
61     assert(ret == 0);
62     ret = close(fd);
63     assert(ret == 0);
64 }
65 
66 int main(void)
67 {
68     test_anonymous();
69     test_file();
70 
71     return EXIT_SUCCESS;
72 }
73