SNAPPY C APIs - 5.2 English - 68552

Enums

enum snappy_status#

Return values; see the documentation for each function to know what each can return.

Values:

enumerator SNAPPY_OK#

enumerator SNAPPY_INVALID_INPUT#

enumerator SNAPPY_BUFFER_TOO_SMALL#

Functions

snappy_status snappy_compress(const char *input, size_t input_length, char *compressed, size_t *compressed_length)#

Takes the data stored in “input[0..input_length-1]” and stores it in the array pointed to by “compressed”.

Parameters	Direction	Description
input	in	This is the buffer where the data we want to compress is accessible.
input_length	in	Length of the input buffer.
compressed	out	This is a buffer in which compressed data is stored.
compressed_length	in,out	compressed_length signals the space available in “compressed” buffer. After successful compression compressed_length contains the true length of the compressed output.

Note

- 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);

Returns:

Result	Description
Success	Returns SNAPPY_OK if successful.
Failure	While calling this function if compressed_length is not at least equal to “snappy_max_compressed_length(input_length)”, SNAPPY_BUFFER_TOO_SMALL is returned.

size_t snappy_max_compressed_length(size_t source_length)#

This function determines the maximal size of the compressed representation of input data that is “source_length” bytes in length.

Parameters	Direction	Description
source_length	in	The size of source in bytes.

Returns:

Result	Description
Success	Returns the maximal size of the compressed representation of input data that is “source_bytes” bytes in length.

snappy_status snappy_uncompress(const char *compressed, size_t compressed_length, char *uncompressed, size_t *uncompressed_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].

Parameters	Direction	Description
compressed	in	This is a buffer which contains compressed data.
compressed_length	in	This is the length of the compressed buffer.
uncompressed	out	Uncompressed data is stored in this buffer.
uncompressed_length	in,out	uncompressed_length signals the space available in “uncompressed”. After successful decompression, uncompressed_length contains the true length of the decompressed output.

Note

- 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);

Returns:

Result	Description
Success	Returns SNAPPY_OK if successful.
Failure	While calling this function if uncompressed_length is not at least equal to the value returned by snappy_uncompressed_length for this stream, SNAPPY_BUFFER_TOO_SMALL is returned Returns (a value not equal to SNAPPY_OK) if the message is corrupted and could not be decrypted.

snappy_status snappy_uncompressed_length(const char *compressed, size_t compressed_length, size_t *result)#

Get the Uncompressed Length object.

This operation takes O(1) time.

Parameters	Direction	Description
compressed	in	This is a buffer which contains compressed data.
compressed_length	in	This is the length of the compressed buffer.
result	out	This is the pointer to type size_t where the uncompressed length is stored.

Attention

REQUIRES: “compressed[]” was produced by RawCompress() or Compress().

Returns:

Result	Description
Success	Returns true on successful parsing.
Failure	Returns false on parsing error.

snappy_status snappy_validate_compressed_buffer(const char *compressed, size_t compressed_length)#

Returns true iff the contents of “compressed[]” can be uncompressed successfully. Does not return the uncompressed data. Takes time proportional to compressed_length, but is usually at least a factor of four faster than actual decompression.

Parameters	Direction	Description
compressed	in	This is a buffer which contains compressed data.
compressed_length	in	This is the length of the compressed buffer.

Returns:

Result	Description
Success	Returns true iff the contents of “compressed[]” can be uncompressed successfully.
Failure	Returns false if error.