1 /*
2 Make sure that leak-check's pointer tracing avoids traps, i.e. tricky
3 memory areas where it could crash if not careful.
4 */
5
6 #include <stdio.h>
7 #include "memcheck/memcheck.h"
8 #include "tests/sys_mman.h"
9 #include <stdlib.h>
10 #include <fcntl.h>
11 #include <unistd.h>
12
13 #if !defined(MAP_NORESERVE)
14 # define MAP_NORESERVE 0
15 #endif
16
main()17 int main()
18 {
19 char **volatile ptrs;
20 int i;
21 int fd;
22 char *map;
23
24 /* I _think_ the point of this is to fill ptrs with a pointer
25 to every 4th page in the entire address space, hence
26 guaranteeing that at least one of them points into one of
27 the below traps, and so checks that the leak checker
28 doesn't bomb when following them. That's fine on 32-bit
29 platforms, but hopeless for a 64-bit system. So the
30 following settings do achieve that on a 32-bit target but
31 merely make a 64-bit target give the same output without
32 properly testing it. */
33 int ptrbits, stepbits, stepsize, nptrs;
34 if (sizeof(void*) == 8) {
35 /* 64-bit machine */
36 ptrbits = 32; //bogus
37 stepbits = 14+1; //bogus
38 stepsize = (1 << stepbits);
39 nptrs = 1 << (ptrbits - stepbits);
40 } else {
41 /* 32-bit machine */
42 ptrbits = 32;
43 stepbits = 14;
44 stepsize = (1 << stepbits);
45 nptrs = 1 << (ptrbits - stepbits);
46 }
47
48 ptrs = malloc(nptrs * sizeof(char *));
49 for (i = 0; i < nptrs; i++)
50 ptrs[i] = (char *)((long)i << stepbits);
51
52 /* lay some traps */
53 /* non-RWX memory, and MAP_NORESERVE if present */
54 map = mmap(0, stepsize * 2, PROT_NONE, MAP_PRIVATE|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
55 if (map == (char *)-1)
56 perror("trap 1 failed");
57
58 /* write-only memory, and MAP_NORESERVE if supported */
59 map = mmap(0, stepsize * 2, PROT_WRITE, MAP_PRIVATE|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
60 if (map == (char *)-1)
61 perror("trap 2 failed");
62
63 /* non-zero mmap of a zero-length file -> SIGBUS */
64 fd = open("./pointer-trace-test-file", O_RDWR | O_CREAT | O_EXCL, 0600);
65 unlink("./pointer-trace-test-file");
66 map = mmap(0, stepsize * 2, PROT_WRITE|PROT_READ, MAP_PRIVATE, fd, 0);
67 if (map == (char *)-1)
68 perror("trap 3 failed");
69 //printf("trap 3 = %p-%p\n", map, map+stepsize*2);
70
71 /* unmapped memory that's marked as defined */
72 map = mmap(0, 256*1024, PROT_NONE, MAP_PRIVATE|MAP_NORESERVE|MAP_ANONYMOUS, -1, 0);
73 if (map == (char *)-1)
74 perror("trap 4 failed");
75 else {
76 munmap(map, 256*1024);
77 (void)VALGRIND_MAKE_MEM_DEFINED(map, 256*1024); /* great big fat lie */
78 }
79
80 VALGRIND_DO_LEAK_CHECK;
81
82 free(ptrs);
83
84 // We deliberately make a leak, it'll be obvious if something went
85 // wrong because the message won't be printed.
86 ptrs = malloc(1000);
87
88 return 0;
89 }
90