snappy/snappy-c.h

/*
 * Copyright 2011 Martin Gieseking <martin.gieseking@uos.de>.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Plain C interface (a wrapper around the C++ implementation).
 */

#ifndef UTIL_SNAPPY_OPENSOURCE_SNAPPY_C_H_
#define UTIL_SNAPPY_OPENSOURCE_SNAPPY_C_H_

#ifdef __cplusplus
extern "C" {
#endif

#include <stddef.h>

/*
 * Return values; see the documentation for each function to know
 * what each can return.
 */
typedef enum {
  SNAPPY_OK = 0,
  SNAPPY_INVALID_INPUT = 1,
  SNAPPY_BUFFER_TOO_SMALL = 2,
} snappy_status;

/*
 * Takes the data stored in "input[0..input_length-1]" and stores
 * it in the array pointed to by "compressed".
 *
 * <compressed_length> signals the space available in "compressed".
 * If it is not at least equal to "snappy_max_compressed_length(input_length)",
 * SNAPPY_BUFFER_TOO_SMALL is returned. After successful compression,
 * <compressed_length> contains the true length of the compressed output,
 * and SNAPPY_OK is returned.
 *
 * Example:
 *   size_t output_length = snappy_max_compressed_length(input_length);
 *   char* output = (char*)malloc(output_length);
 *   if (snappy_compress(input, input_length, output, &output_length)
 *       == SNAPPY_OK) {
 *     ... Process(output, output_length) ...
 *   }
 *   free(output);
 */
snappy_status snappy_compress(const char* input,
                              size_t input_length,
                              char* compressed,
                              size_t* compressed_length);

/*
 * Given data in "compressed[0..compressed_length-1]" generated by
 * calling the snappy_compress routine, this routine stores
 * the uncompressed data to
 *   uncompressed[0..uncompressed_length-1].
 * Returns failure (a value not equal to SNAPPY_OK) if the message
 * is corrupted and could not be decrypted.
 *
 * <uncompressed_length> signals the space available in "uncompressed".
 * If it is not at least equal to the value returned by
 * snappy_uncompressed_length for this stream, SNAPPY_BUFFER_TOO_SMALL
 * is returned. After successful decompression, <uncompressed_length>
 * contains the true length of the decompressed output.
 *
 * Example:
 *   size_t output_length;
 *   if (snappy_uncompressed_length(input, input_length, &output_length)
 *       != SNAPPY_OK) {
 *     ... fail ...
 *   }
 *   char* output = (char*)malloc(output_length);
 *   if (snappy_uncompress(input, input_length, output, &output_length)
 *       == SNAPPY_OK) {
 *     ... Process(output, output_length) ...
 *   }
 *   free(output);
 */
snappy_status snappy_uncompress(const char* compressed,
                                size_t compressed_length,
                                char* uncompressed,
                                size_t* uncompressed_length);

/*
 * Returns the maximal size of the compressed representation of
 * input data that is "source_length" bytes in length.
 */
size_t snappy_max_compressed_length(size_t source_length);

/*
 * REQUIRES: "compressed[]" was produced by snappy_compress()
 * Returns SNAPPY_OK and stores the length of the uncompressed data in
 * *result normally. Returns SNAPPY_INVALID_INPUT on parsing error.
 * This operation takes O(1) time.
 */
snappy_status snappy_uncompressed_length(const char* compressed,
                                         size_t compressed_length,
                                         size_t* result);

/*
 * Check if the contents of "compressed[]" can be uncompressed successfully.
 * Does not return the uncompressed data; if so, returns SNAPPY_OK,
 * or if not, returns SNAPPY_INVALID_INPUT.
 * Takes time proportional to compressed_length, but is usually at least a
 * factor of four faster than actual decompression.
 */
snappy_status snappy_validate_compressed_buffer(const char* compressed,
                                                size_t compressed_length);

#ifdef __cplusplus
}  // extern "C"
#endif

#endif  /* UTIL_SNAPPY_OPENSOURCE_SNAPPY_C_H_ */