152 lines
4.1 KiB
C
152 lines
4.1 KiB
C
/*
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* Copyright 2009-2010 10gen, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdlib.h>
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#include <string.h>
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#include "bson_buffer.h"
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#define INITIAL_BUFFER_SIZE 256
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#define DEFAULT_MAX_SIZE 4 * 1024 * 1024
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struct bson_buffer {
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char* buffer;
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int size;
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int position;
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int max_size;
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};
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/* Allocate and return a new buffer.
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* Return NULL on allocation failure. */
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bson_buffer_t bson_buffer_new(void) {
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bson_buffer_t buffer;
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buffer = (bson_buffer_t)malloc(sizeof(struct bson_buffer));
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if (buffer == NULL) {
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return NULL;
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}
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buffer->size = INITIAL_BUFFER_SIZE;
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buffer->position = 0;
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buffer->buffer = (char*)malloc(sizeof(char) * INITIAL_BUFFER_SIZE);
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if (buffer->buffer == NULL) {
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free(buffer);
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return NULL;
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}
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buffer->max_size = DEFAULT_MAX_SIZE;
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return buffer;
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}
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void bson_buffer_set_max_size(bson_buffer_t buffer, int max_size) {
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buffer->max_size = max_size;
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}
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int bson_buffer_get_max_size(bson_buffer_t buffer) {
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return buffer->max_size;
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}
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/* Free the memory allocated for `buffer`.
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* Return non-zero on failure. */
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int bson_buffer_free(bson_buffer_t buffer) {
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if (buffer == NULL) {
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return 1;
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}
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free(buffer->buffer);
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free(buffer);
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return 0;
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}
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/* Grow `buffer` to at least `min_length`.
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* Return non-zero on allocation failure. */
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static int buffer_grow(bson_buffer_t buffer, int min_length) {
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int size = buffer->size;
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int old_size;
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char* old_buffer = buffer->buffer;
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if (size >= min_length) {
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return 0;
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}
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while (size < min_length) {
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old_size = size;
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size *= 2;
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/* Prevent potential overflow. */
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if( size < old_size )
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size = min_length;
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}
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buffer->buffer = (char*)realloc(buffer->buffer, sizeof(char) * size);
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if (buffer->buffer == NULL) {
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free(old_buffer);
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free(buffer);
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return 1;
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}
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buffer->size = size;
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return 0;
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}
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/* Assure that `buffer` has at least `size` free bytes (and grow if needed).
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* Return non-zero on allocation failure. */
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static int buffer_assure_space(bson_buffer_t buffer, int size) {
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if (buffer->position + size <= buffer->size) {
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return 0;
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}
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return buffer_grow(buffer, buffer->position + size);
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}
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/* Save `size` bytes from the current position in `buffer` (and grow if needed).
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* Return offset for writing, or -1 on allocation failure. */
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bson_buffer_position bson_buffer_save_space(bson_buffer_t buffer, int size) {
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int position = buffer->position;
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if (buffer_assure_space(buffer, size) != 0) {
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return -1;
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}
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buffer->position += size;
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return position;
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}
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/* Write `size` bytes from `data` to `buffer` (and grow if needed).
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* Return non-zero on allocation failure. */
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int bson_buffer_write(bson_buffer_t buffer, const char* data, int size) {
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if (buffer_assure_space(buffer, size) != 0) {
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return 1;
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}
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memcpy(buffer->buffer + buffer->position, data, size);
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buffer->position += size;
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return 0;
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}
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/* Write `size` bytes from `data` to `buffer` at position `position`.
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* Does not change the internal position of `buffer`.
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* Return non-zero if buffer isn't large enough for write. */
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int bson_buffer_write_at_position(bson_buffer_t buffer, bson_buffer_position position,
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const char* data, int size) {
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if (position + size > buffer->size) {
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bson_buffer_free(buffer);
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return 1;
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}
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memcpy(buffer->buffer + position, data, size);
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return 0;
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}
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int bson_buffer_get_position(bson_buffer_t buffer) {
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return buffer->position;
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}
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char* bson_buffer_get_buffer(bson_buffer_t buffer) {
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return buffer->buffer;
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}
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