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/* Minimal mmap-based malloc/free implementation to be used by libsandbox |
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* internal routines, since we can't trust the current process to have a |
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* malloc/free implementation that is sane and available at all times. |
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*/ |
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#include <stdlib.h> /* malloc()/free() prototypes */ |
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#include <string.h> /* mem*(), strdup() prototype */ |
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#include <sys/mman.h> /* mmap() */ |
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#define SB_MALLOC_TO_MMAP(ptr) ((void*)(((size_t*)ptr) - 1)) |
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#define SB_MMAP_TO_MALLOC(ptr) ((void*)(((size_t*)ptr) + 1)) |
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#define SB_MALLOC_TO_SIZE(ptr) (*((size_t*)SB_MALLOC_TO_MMAP(ptr))) |
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|
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void *malloc(size_t size) |
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{ |
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size_t *ret; |
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size += sizeof(size_t); |
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ret = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); |
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if (ret == MAP_FAILED) |
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return NULL; |
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*ret = size; |
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return SB_MMAP_TO_MALLOC(ret); |
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} |
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|
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void free(void *ptr) |
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{ |
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if (ptr == NULL) |
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return; |
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munmap(SB_MALLOC_TO_MMAP(ptr), SB_MALLOC_TO_SIZE(ptr)); |
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} |
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void *calloc(size_t nmemb, size_t size) |
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{ |
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void *ret; |
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size_t malloc_size = nmemb * size; |
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ret = malloc(malloc_size); /* dont care about overflow */ |
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if (ret == NULL) |
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return NULL; |
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memset(ret, 0x00, malloc_size); |
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return ret; |
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} |
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|
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void *realloc(void *ptr, size_t size) |
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{ |
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void *ret; |
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size_t old_malloc_size; |
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|
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if (ptr == NULL) |
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return malloc(size); |
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if (size == 0) { |
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free(ptr); |
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return ptr; |
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} |
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|
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old_malloc_size = SB_MALLOC_TO_SIZE(ptr); |
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ret = malloc(size); |
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if (ret == NULL) |
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return NULL; |
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memcpy(ret, ptr, (size < old_malloc_size ? size : old_malloc_size)); |
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free(ptr); |
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return ret; |
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} |
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|
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#ifdef strdup |
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#undef strdup |
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#endif |
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char *strdup(const char *s) |
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{ |
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size_t len; |
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char *ret; |
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|
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if (s == NULL) |
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return NULL; |
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len = strlen(s); |
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ret = malloc(len + 1); |
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if (ret == NULL) |
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return NULL; |
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memcpy(ret, s, len + 1); |
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} |
