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1 // Copyright 2012 Google Inc. All Rights Reserved.
2 //
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the COPYING file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS. All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 // -----------------------------------------------------------------------------
9 //
10 // Misc. common utility functions
11 //
12 // Author: Skal (pascal.massimino@gmail.com)
13 
14 #include <stdlib.h>
15 #include "./utils.h"
16 
17 // If PRINT_MEM_INFO is defined, extra info (like total memory used, number of
18 // alloc/free etc) is printed. For debugging/tuning purpose only (it's slow,
19 // and not multi-thread safe!).
20 // An interesting alternative is valgrind's 'massif' tool:
21 //    http://valgrind.org/docs/manual/ms-manual.html
22 // Here is an example command line:
23 /*    valgrind --tool=massif --massif-out-file=massif.out \
24                --stacks=yes --alloc-fn=WebPSafeAlloc --alloc-fn=WebPSafeCalloc
25       ms_print massif.out
26 */
27 // In addition:
28 // * if PRINT_MEM_TRAFFIC is defined, all the details of the malloc/free cycles
29 //   are printed.
30 // * if MALLOC_FAIL_AT is defined, the global environment variable
31 //   $MALLOC_FAIL_AT is used to simulate a memory error when calloc or malloc
32 //   is called for the nth time. Example usage:
33 //   export MALLOC_FAIL_AT=50 && ./examples/cwebp input.png
34 // * if MALLOC_LIMIT is defined, the global environment variable $MALLOC_LIMIT
35 //   sets the maximum amount of memory (in bytes) made available to libwebp.
36 //   This can be used to emulate environment with very limited memory.
37 //   Example: export MALLOC_LIMIT=64000000 && ./examples/dwebp picture.webp
38 
39 // #define PRINT_MEM_INFO
40 // #define PRINT_MEM_TRAFFIC
41 // #define MALLOC_FAIL_AT
42 // #define MALLOC_LIMIT
43 
44 //------------------------------------------------------------------------------
45 // Checked memory allocation
46 
47 #if defined(PRINT_MEM_INFO)
48 
49 #include <stdio.h>
50 #include <stdlib.h>  // for abort()
51 
52 static int num_malloc_calls = 0;
53 static int num_calloc_calls = 0;
54 static int num_free_calls = 0;
55 static int countdown_to_fail = 0;     // 0 = off
56 
57 typedef struct MemBlock MemBlock;
58 struct MemBlock {
59   void* ptr_;
60   size_t size_;
61   MemBlock* next_;
62 };
63 
64 static MemBlock* all_blocks = NULL;
65 static size_t total_mem = 0;
66 static size_t total_mem_allocated = 0;
67 static size_t high_water_mark = 0;
68 static size_t mem_limit = 0;
69 
70 static int exit_registered = 0;
71 
PrintMemInfo(void)72 static void PrintMemInfo(void) {
73   fprintf(stderr, "\nMEMORY INFO:\n");
74   fprintf(stderr, "num calls to: malloc = %4d\n", num_malloc_calls);
75   fprintf(stderr, "              calloc = %4d\n", num_calloc_calls);
76   fprintf(stderr, "              free   = %4d\n", num_free_calls);
77   fprintf(stderr, "total_mem: %u\n", (uint32_t)total_mem);
78   fprintf(stderr, "total_mem allocated: %u\n", (uint32_t)total_mem_allocated);
79   fprintf(stderr, "high-water mark: %u\n", (uint32_t)high_water_mark);
80   while (all_blocks != NULL) {
81     MemBlock* b = all_blocks;
82     all_blocks = b->next_;
83     free(b);
84   }
85 }
86 
Increment(int * const v)87 static void Increment(int* const v) {
88   if (!exit_registered) {
89 #if defined(MALLOC_FAIL_AT)
90     {
91       const char* const malloc_fail_at_str = getenv("MALLOC_FAIL_AT");
92       if (malloc_fail_at_str != NULL) {
93         countdown_to_fail = atoi(malloc_fail_at_str);
94       }
95     }
96 #endif
97 #if defined(MALLOC_LIMIT)
98     {
99       const char* const malloc_limit_str = getenv("MALLOC_LIMIT");
100       if (malloc_limit_str != NULL) {
101         mem_limit = atoi(malloc_limit_str);
102       }
103     }
104 #endif
105     (void)countdown_to_fail;
106     (void)mem_limit;
107     atexit(PrintMemInfo);
108     exit_registered = 1;
109   }
110   ++*v;
111 }
112 
AddMem(void * ptr,size_t size)113 static void AddMem(void* ptr, size_t size) {
114   if (ptr != NULL) {
115     MemBlock* const b = (MemBlock*)malloc(sizeof(*b));
116     if (b == NULL) abort();
117     b->next_ = all_blocks;
118     all_blocks = b;
119     b->ptr_ = ptr;
120     b->size_ = size;
121     total_mem += size;
122     total_mem_allocated += size;
123 #if defined(PRINT_MEM_TRAFFIC)
124 #if defined(MALLOC_FAIL_AT)
125     fprintf(stderr, "fail-count: %5d [mem=%u]\n",
126             num_malloc_calls + num_calloc_calls, (uint32_t)total_mem);
127 #else
128     fprintf(stderr, "Mem: %u (+%u)\n", (uint32_t)total_mem, (uint32_t)size);
129 #endif
130 #endif
131     if (total_mem > high_water_mark) high_water_mark = total_mem;
132   }
133 }
134 
SubMem(void * ptr)135 static void SubMem(void* ptr) {
136   if (ptr != NULL) {
137     MemBlock** b = &all_blocks;
138     // Inefficient search, but that's just for debugging.
139     while (*b != NULL && (*b)->ptr_ != ptr) b = &(*b)->next_;
140     if (*b == NULL) {
141       fprintf(stderr, "Invalid pointer free! (%p)\n", ptr);
142       abort();
143     }
144     {
145       MemBlock* const block = *b;
146       *b = block->next_;
147       total_mem -= block->size_;
148 #if defined(PRINT_MEM_TRAFFIC)
149       fprintf(stderr, "Mem: %u (-%u)\n",
150               (uint32_t)total_mem, (uint32_t)block->size_);
151 #endif
152       free(block);
153     }
154   }
155 }
156 
157 #else
158 #define Increment(v) do {} while(0)
159 #define AddMem(p, s) do {} while(0)
160 #define SubMem(p)    do {} while(0)
161 #endif
162 
163 // Returns 0 in case of overflow of nmemb * size.
CheckSizeArgumentsOverflow(uint64_t nmemb,size_t size)164 static int CheckSizeArgumentsOverflow(uint64_t nmemb, size_t size) {
165   const uint64_t total_size = nmemb * size;
166   if (nmemb == 0) return 1;
167   if ((uint64_t)size > WEBP_MAX_ALLOCABLE_MEMORY / nmemb) return 0;
168   if (total_size != (size_t)total_size) return 0;
169 #if defined(PRINT_MEM_INFO) && defined(MALLOC_FAIL_AT)
170   if (countdown_to_fail > 0 && --countdown_to_fail == 0) {
171     return 0;    // fake fail!
172   }
173 #endif
174 #if defined(MALLOC_LIMIT)
175   if (mem_limit > 0 && total_mem + total_size >= mem_limit) {
176     return 0;   // fake fail!
177   }
178 #endif
179 
180   return 1;
181 }
182 
WebPSafeMalloc(uint64_t nmemb,size_t size)183 void* WebPSafeMalloc(uint64_t nmemb, size_t size) {
184   void* ptr;
185   Increment(&num_malloc_calls);
186   if (!CheckSizeArgumentsOverflow(nmemb, size)) return NULL;
187   assert(nmemb * size > 0);
188   ptr = malloc((size_t)(nmemb * size));
189   AddMem(ptr, (size_t)(nmemb * size));
190   return ptr;
191 }
192 
WebPSafeCalloc(uint64_t nmemb,size_t size)193 void* WebPSafeCalloc(uint64_t nmemb, size_t size) {
194   void* ptr;
195   Increment(&num_calloc_calls);
196   if (!CheckSizeArgumentsOverflow(nmemb, size)) return NULL;
197   assert(nmemb * size > 0);
198   ptr = calloc((size_t)nmemb, size);
199   AddMem(ptr, (size_t)(nmemb * size));
200   return ptr;
201 }
202 
WebPSafeFree(void * const ptr)203 void WebPSafeFree(void* const ptr) {
204   if (ptr != NULL) {
205     Increment(&num_free_calls);
206     SubMem(ptr);
207   }
208   free(ptr);
209 }
210 
211 //------------------------------------------------------------------------------
212