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/* memory.c
* Minimal mmap-based malloc/free implementation to be used by libsandbox
* internal routines, since we can't trust the current process to have a
* malloc/free implementation that is sane and available at all times.
*
* Copyright 1999-2008 Gentoo Foundation
* Licensed under the GPL-2
*/
#include "headers.h"
#include "libsandbox.h"
#include "sbutil.h"
#define SB_MALLOC_TO_MMAP(ptr) ((void*)(((size_t*)ptr) - 1))
#define SB_MMAP_TO_MALLOC(ptr) ((void*)(((size_t*)ptr) + 1))
#define SB_MALLOC_TO_SIZE(ptr) (*((size_t*)SB_MALLOC_TO_MMAP(ptr)))
void *malloc(size_t size)
{
size_t *ret;
size += sizeof(size_t);
ret = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (ret == MAP_FAILED)
return NULL;
*ret = size;
return SB_MMAP_TO_MALLOC(ret);
}
void free(void *ptr)
{
if (ptr == NULL)
return;
if (munmap(SB_MALLOC_TO_MMAP(ptr), SB_MALLOC_TO_SIZE(ptr))) {
SB_EERROR("sandbox memory corruption", " free(%p): %s\n",
ptr, strerror(errno));
#ifdef HAVE_BACKTRACE
void *funcs[10];
int num_funcs;
num_funcs = backtrace(funcs, sizeof(funcs));
backtrace_symbols_fd(funcs, num_funcs, STDERR_FILENO);
#endif
}
}
void *calloc(size_t nmemb, size_t size)
{
return xzalloc(nmemb * size); /* dont care about overflow */
}
void *realloc(void *ptr, size_t size)
{
void *ret;
size_t old_malloc_size;
if (ptr == NULL)
return xmalloc(size);
if (size == 0) {
free(ptr);
return ptr;
}
old_malloc_size = SB_MALLOC_TO_SIZE(ptr);
ret = xmalloc(size);
memcpy(ret, ptr, MIN(size, old_malloc_size));
free(ptr);
return ret;
}
char *strdup(const char *s)
{
size_t len;
char *ret;
if (s == NULL)
return NULL;
len = strlen(s);
ret = xmalloc(len + 1);
return memcpy(ret, s, len + 1);
}
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