static int
wt_snappy_decompress(WT_COMPRESSOR *compressor, WT_SESSION *session,
uint8_t *src, size_t src_len,
uint8_t *dst, size_t dst_len,
size_t *result_lenp)
{
snappy_status snret;
size_t snaplen;
__UNUSED(compressor);
/* retrieve the saved length */
snaplen = *(size_t *)src;
if (snaplen + sizeof(size_t) > src_len) {
wiredtiger_err_printf(
session,
"wt_snappy_decompress: stored size exceeds buffer size");
return (WT_ERROR);
}
/* dst_len is an input and an output arg. */
snret = snappy_uncompress(
(char *)src + sizeof(size_t), snaplen, (char *)dst, &dst_len);
if (snret == SNAPPY_OK) {
*result_lenp = dst_len;
return (0);
}
return (wt_snappy_error(session, "snappy_decompress", snret));
}
/*
* wt_snappy_decompress --
* WiredTiger snappy decompression.
*/
static int
wt_snappy_decompress(WT_COMPRESSOR *compressor, WT_SESSION *session,
uint8_t *src, size_t src_len,
uint8_t *dst, size_t dst_len,
size_t *result_lenp)
{
WT_EXTENSION_API *wt_api;
snappy_status snret;
size_t snaplen;
wt_api = ((SNAPPY_COMPRESSOR *)compressor)->wt_api;
/* retrieve the saved length */
snaplen = *(size_t *)src;
if (snaplen + sizeof(size_t) > src_len) {
(void)wt_api->err_printf(wt_api,
session,
"wt_snappy_decompress: stored size exceeds buffer size");
return (WT_ERROR);
}
/* dst_len is an input and an output arg. */
snret = snappy_uncompress(
(char *)src + sizeof(size_t), snaplen, (char *)dst, &dst_len);
if (snret == SNAPPY_OK) {
*result_lenp = dst_len;
return (0);
}
return (
wt_snappy_error(compressor, session, "snappy_decompress", snret));
}
static int
wt_snappy_compress(WT_COMPRESSOR *compressor, WT_SESSION *session,
uint8_t *src, size_t src_len,
uint8_t *dst, size_t dst_len,
size_t *result_lenp, int *compression_failed)
{
snappy_status snret;
size_t snaplen;
char *snapbuf;
__UNUSED(compressor);
/*
* dst_len was computed in wt_snappy_pre_size, so we know it's big
* enough. Skip past the space we'll use to store the final count
* of compressed bytes.
*/
snaplen = dst_len - sizeof(size_t);
snapbuf = (char *)dst + sizeof(size_t);
/* snaplen is an input and an output arg. */
snret = snappy_compress((char *)src, src_len, snapbuf, &snaplen);
if (snret == SNAPPY_OK) {
/*
* On decompression, snappy requires the exact compressed byte
* count (the current value of snaplen). WiredTiger does not
* preserve that value, so save snaplen at the beginning of the
* destination buffer.
*/
if (snaplen + sizeof(size_t) < src_len) {
*(size_t *)dst = snaplen;
*result_lenp = snaplen + sizeof(size_t);
*compression_failed = 0;
} else
/* The compressor failed to produce a smaller result. */
*compression_failed = 1;
return (0);
}
return (wt_snappy_error(session, "snappy_compress", snret));
}
