Fixed wrong spelling "limitter" to "limiter". This affects

liblzma's API.

1 files changed, 288 insertions, 0 deletions

diff --git a/src/liblzma/common/memory_limiter.c b/src/liblzma/common/memory_limiter.c
new file mode 100644
index 00000000..a2a0cbdc
--- /dev/null
+++ b/src/liblzma/common/memory_limiter.c
@@ -0,0 +1,288 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       memory_limiter.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)))
+
+
+/// Add approximated overhead of malloc() to size and round upwards to the
+/// next multiple of 2 * sizeof(size_t). I suppose that most malloc()
+/// implementations align small allocations this way, but the overhead
+/// varies due to several reasons (free lists, mmap() usage etc.).
+///
+/// This doesn't need to be exact at all. It's enough to take into account
+/// that there is some overhead. That way our memory usage count won't be
+/// horribly wrong if we are used to allocate lots of small memory chunks.
+#define malloc_ceil(size) \
+	my_ceil((size) + 2 * sizeof(void *), 2 * sizeof(size_t))
+
+
+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 {
+	/// List of allocated memory chunks
+	lzma_memlimit_list *list;
+
+	/// Number of bytes currently allocated; this includes the memory
+	/// needed for the helper structures.
+	size_t used;
+
+	/// Memory usage limit
+	size_t limit;
+
+	/// Maximum amount of memory that have been or would have been needed.
+	/// That is, this is updated also if memory allocation fails, letting
+	/// the application check how much memory was tried to be allocated
+	/// in total.
+	size_t max;
+
+	/// True if lzma_memlimit_alloc() has returned NULL due to memory
+	/// usage limit.
+	bool limit_reached;
+};
+
+
+extern LZMA_API lzma_memlimit *
+lzma_memlimit_create(size_t limit)
+{
+	const size_t base_size = malloc_ceil(sizeof(lzma_memlimit));
+
+	if (limit < base_size)
+		return NULL;
+
+	lzma_memlimit *mem = malloc(sizeof(lzma_memlimit));
+
+	if (mem != NULL) {
+		mem->list = NULL;
+		mem->used = base_size;
+		mem->limit = limit;
+		mem->max = base_size;
+		mem->limit_reached = false;
+	}
+
+	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 size_t
+lzma_memlimit_max(lzma_memlimit *mem, lzma_bool clear)
+{
+	const size_t ret = mem->max;
+
+	if (clear)
+		mem->max = mem->used;
+
+	return ret;
+}
+
+
+extern LZMA_API lzma_bool
+lzma_memlimit_reached(lzma_memlimit *mem, lzma_bool clear)
+{
+	const bool ret = mem->limit_reached;
+
+	if (clear)
+		mem->limit_reached = false;
+
+	return ret;
+}
+
+
+extern LZMA_API size_t
+lzma_memlimit_count(const lzma_memlimit *mem)
+{
+	// This is slow; we could have a counter in lzma_memlimit
+	// for fast version. I expect the primary use of this
+	// function to be limited to easy checking of memory leaks,
+	// in which this implementation is just fine.
+	size_t count = 0;
+	const lzma_memlimit_list *record = mem->list;
+
+	while (record != NULL) {
+		++count;
+		record = record->next;
+	}
+
+	return count;
+}
+
+
+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.
+	const size_t total_size = malloc_ceil(size)
+			+ malloc_ceil(sizeof(lzma_memlimit_list));
+
+	// Integer overflow protection for total_size and mem->used.
+	if (total_size <= size || SIZE_MAX - total_size < mem->used) {
+		mem->max = SIZE_MAX;
+		mem->limit_reached = true;
+		return NULL;
+	}
+
+	// Update the maximum memory requirement counter if needed. This
+	// is updated even if memory allocation would fail or limit would
+	// be reached.
+	if (mem->used + total_size > mem->max)
+		mem->max = mem->used + total_size;
+
+	// Check if we would stay in the memory usage limits. We need to
+	// check also that the current usage is in the limits, because
+	// the application could have decreased the limit between calls
+	// to this function.
+	if (mem->limit < mem->used || mem->limit - mem->used < total_size) {
+		mem->limit_reached = true;
+		return NULL;
+	}
+
+	// Allocate separate memory chunks for lzma_memlimit_list and the
+	// actual requested memory. Optimizing this to use only one
+	// allocation is not a good idea, because applications may want to
+	// detach lzma_extra structures that have been allocated with
+	// lzma_memlimit_alloc().
+	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;
+}