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///////////////////////////////////////////////////////////////////////////////
//
/// \file memory_limitter.c
/// \brief Limitting memory usage
//
// Copyright (C) 2007 Lasse Collin
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
///////////////////////////////////////////////////////////////////////////////
#include "common.h"
/// Rounds an unsigned integer upwards to the next multiple.
#define my_ceil(num, multiple) \
((num) + (((multiple) - ((num) % (multiple))) % (multiple)))
/// Rounds upwards to the next multiple of 2 * sizeof(void*).
/// malloc() tends to align allocations this way.
#define malloc_ceil(num) my_ceil(num, 2 * sizeof(void *))
typedef struct lzma_memlimit_list_s lzma_memlimit_list;
struct lzma_memlimit_list_s {
lzma_memlimit_list *next;
void *ptr;
size_t size;
};
struct lzma_memlimit_s {
size_t used;
size_t limit;
lzma_memlimit_list *list;
};
extern LZMA_API lzma_memlimit *
lzma_memlimit_create(size_t limit)
{
if (limit < sizeof(lzma_memlimit))
return NULL;
lzma_memlimit *mem = malloc(sizeof(lzma_memlimit));
if (mem != NULL) {
mem->used = sizeof(lzma_memlimit);
mem->limit = limit;
mem->list = NULL;
}
return mem;
}
extern LZMA_API void
lzma_memlimit_set(lzma_memlimit *mem, size_t limit)
{
mem->limit = limit;
return;
}
extern LZMA_API size_t
lzma_memlimit_get(const lzma_memlimit *mem)
{
return mem->limit;
}
extern LZMA_API size_t
lzma_memlimit_used(const lzma_memlimit *mem)
{
return mem->used;
}
extern LZMA_API void
lzma_memlimit_end(lzma_memlimit *mem, lzma_bool free_allocated)
{
if (mem == NULL)
return;
lzma_memlimit_list *record = mem->list;
while (record != NULL) {
if (free_allocated)
free(record->ptr);
lzma_memlimit_list *tmp = record;
record = record->next;
free(tmp);
}
free(mem);
return;
}
extern LZMA_API void *
lzma_memlimit_alloc(lzma_memlimit *mem, size_t nmemb, size_t size)
{
// While liblzma always sets nmemb to one, do this multiplication
// to make these functions usable e.g. with zlib and libbzip2.
// Making sure that this doesn't overflow is up to the application.
size *= nmemb;
// Some malloc() implementations return NULL on malloc(0). We like
// to get a non-NULL value.
if (size == 0)
size = 1;
// Calculate how much memory we are going to allocate in reality.
// TODO: We should add some rough estimate how much malloc() needs
// for its internal structures.
const size_t total_size = malloc_ceil(size)
+ malloc_ceil(sizeof(lzma_memlimit_list));
// Integer overflow protection
if (SIZE_MAX - size <= total_size)
return NULL;
if (mem->limit < mem->used || mem->limit - mem->used < total_size)
return NULL;
lzma_memlimit_list *record = malloc(sizeof(lzma_memlimit_list));
void *ptr = malloc(size);
if (record == NULL || ptr == NULL) {
free(record);
free(ptr);
return NULL;
}
// Add the new entry to the beginning of the list. This should be
// more efficient when freeing memory, because usually it is
// "last allocated, first freed".
record->next = mem->list;
record->ptr = ptr;
record->size = total_size;
mem->list = record;
mem->used += total_size;
return ptr;
}
extern LZMA_API void
lzma_memlimit_detach(lzma_memlimit *mem, void *ptr)
{
if (ptr == NULL || mem->list == NULL)
return;
lzma_memlimit_list *record = mem->list;
lzma_memlimit_list *prev = NULL;
while (record->ptr != ptr) {
prev = record;
record = record->next;
if (record == NULL)
return;
}
if (prev != NULL)
prev->next = record->next;
else
mem->list = record->next;
assert(mem->used >= record->size);
mem->used -= record->size;
free(record);
return;
}
extern LZMA_API void
lzma_memlimit_free(lzma_memlimit *mem, void *ptr)
{
if (ptr == NULL)
return;
lzma_memlimit_detach(mem, ptr);
free(ptr);
return;
}
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