1 /*
2 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License").
5 * You may not use this file except in compliance with the License.
6 * A copy of the License is located at
7 *
8 * http://aws.amazon.com/apache2.0
9 *
10 * or in the "license" file accompanying this file. This file is distributed
11 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
12 * express or implied. See the License for the specific language governing
13 * permissions and limitations under the License.
14 */
15
16 #include <string.h>
17
18 /* Define _GNU_SOURCE to get RTLD_NEXT definition from dlfcn.h */
19 #define _GNU_SOURCE
20 #include <dlfcn.h>
21
22 /* Overrides will work only if RTLD_NEXT is defined */
23 #ifdef RTLD_NEXT
24
25 /* if we use glibc, include malloc.h for malloc_usable_size */
26 #ifdef __GLIBC__
27 #include <malloc.h>
28 #define HAVE_MALLOC_USABLE_SIZE
29 #endif
30
31 typedef int (*posix_memalign_fn)(void **memptr, size_t alignment, size_t size);
32 typedef void *(*realloc_fn)(void *ptr, size_t size);
33
34 posix_memalign_fn orig_posix_memalign = NULL;
35 realloc_fn orig_realloc = NULL;
36
posix_memalign(void ** memptr,size_t alignment,size_t size)37 int posix_memalign(void **memptr, size_t alignment, size_t size)
38 {
39 /* Override original posix_memalign to fill allocated memory with some data
40 * to catch errors due to missing initialization */
41 int rc;
42
43 if (orig_posix_memalign == NULL) {
44 /* C99 forbids converting void * to function pointers, so direct
45 * assignemnt fails with -pedantic. Yet dlsym is still used to return
46 * function pointers in standard library, despite that it returns
47 * void *. Casting function pointer to void ** and dereferencing it
48 * allows to bypass compiler warnings. */
49 *(void **) &orig_posix_memalign = dlsym(RTLD_NEXT, "posix_memalign");
50 }
51
52 rc = orig_posix_memalign(memptr, alignment, size);
53
54 memset(*memptr, 0xff, size);
55
56 return rc;
57 }
58
realloc(void * ptr,size_t size)59 void *realloc(void *ptr, size_t size)
60 {
61 /* Override original realloc to fill allocated memory with some data to
62 * catch errors due to missing initialization */
63 void *p;
64
65 if (orig_realloc == NULL) {
66 /* C99 forbids converting void * to function pointers, so direct
67 * assignemnt fails with -pedantic. Yet dlsym is still used to return
68 * function pointers in standard library, despite that it returns
69 * void *. Casting function pointer to void ** and dereferencing it
70 * allows to bypass compiler warnings. */
71 *(void **) &orig_realloc = dlsym(RTLD_NEXT, "realloc");
72 }
73
74
75 #ifdef HAVE_MALLOC_USABLE_SIZE
76 /* If malloc_usable_size is available, we can get the size of previously
77 * allocated buffer, to find out how many new bytes we've allocated.
78 * Get the usable size for ptr before we call realloc, because realloc may call
79 * free() on the original pointer. */
80 size_t ptr_alloc_size = malloc_usable_size(ptr);
81 #endif
82
83 p = orig_realloc(ptr, size);
84
85 #ifdef HAVE_MALLOC_USABLE_SIZE
86 size_t p_alloc_size = malloc_usable_size(p);
87
88 /* If call succeeded and we're enlarging memory, fill the extension with
89 * non-zero data */
90 if (p && p_alloc_size > ptr_alloc_size) {
91 memset((char *) p + ptr_alloc_size, 0xff, p_alloc_size - ptr_alloc_size);
92 }
93 #else
94 /* If we're allocating new buffer and the call succeeded, fill the buffer
95 * with non-zero data*/
96 if (p && !ptr) {
97 memset(p, 0xff, size);
98 }
99 #endif
100
101 return p;
102 }
103
104 #endif
105