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284 lines
6.6 KiB
C
284 lines
6.6 KiB
C
/*-
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* Copyright (c) 2011 Pawel Jakub Dawidek <pawel@dawidek.net>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/endian.h>
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#include <errno.h>
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#include <string.h>
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#include <strings.h>
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#include <hast.h>
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#include <lzf.h>
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#include <nv.h>
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#include <pjdlog.h>
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#include "hast_compression.h"
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static bool
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allzeros(const void *data, size_t size)
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{
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const uint64_t *p = data;
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unsigned int i;
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uint64_t v;
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PJDLOG_ASSERT((size % sizeof(*p)) == 0);
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/*
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* This is the fastest method I found for checking if the given
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* buffer contain all zeros.
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* Because inside the loop we don't check at every step, we would
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* get an answer only after walking through entire buffer.
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* To return early if the buffer doesn't contain all zeros, we probe
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* 8 bytes at the beginning, in the middle and at the end of the buffer
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* first.
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*/
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size >>= 3; /* divide by 8 */
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if ((p[0] | p[size >> 1] | p[size - 1]) != 0)
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return (false);
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v = 0;
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for (i = 0; i < size; i++)
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v |= *p++;
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return (v == 0);
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}
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static void *
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hast_hole_compress(const unsigned char *data, size_t *sizep)
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{
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uint32_t size;
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void *newbuf;
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if (!allzeros(data, *sizep))
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return (NULL);
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newbuf = malloc(sizeof(size));
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if (newbuf == NULL) {
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pjdlog_warning("Unable to compress (no memory: %zu).",
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(size_t)*sizep);
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return (NULL);
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}
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size = htole32((uint32_t)*sizep);
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bcopy(&size, newbuf, sizeof(size));
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*sizep = sizeof(size);
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return (newbuf);
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}
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static void *
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hast_hole_decompress(const unsigned char *data, size_t *sizep)
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{
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uint32_t size;
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void *newbuf;
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if (*sizep != sizeof(size)) {
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pjdlog_error("Unable to decompress (invalid size: %zu).",
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*sizep);
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return (NULL);
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}
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bcopy(data, &size, sizeof(size));
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size = le32toh(size);
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newbuf = malloc(size);
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if (newbuf == NULL) {
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pjdlog_error("Unable to decompress (no memory: %zu).",
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(size_t)size);
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return (NULL);
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}
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bzero(newbuf, size);
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*sizep = size;
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return (newbuf);
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}
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/* Minimum block size to try to compress. */
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#define HAST_LZF_COMPRESS_MIN 1024
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static void *
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hast_lzf_compress(const unsigned char *data, size_t *sizep)
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{
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unsigned char *newbuf;
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uint32_t origsize;
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size_t newsize;
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origsize = *sizep;
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if (origsize <= HAST_LZF_COMPRESS_MIN)
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return (NULL);
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newsize = sizeof(origsize) + origsize - HAST_LZF_COMPRESS_MIN;
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newbuf = malloc(newsize);
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if (newbuf == NULL) {
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pjdlog_warning("Unable to compress (no memory: %zu).",
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newsize);
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return (NULL);
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}
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newsize = lzf_compress(data, *sizep, newbuf + sizeof(origsize),
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newsize - sizeof(origsize));
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if (newsize == 0) {
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free(newbuf);
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return (NULL);
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}
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origsize = htole32(origsize);
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bcopy(&origsize, newbuf, sizeof(origsize));
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*sizep = sizeof(origsize) + newsize;
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return (newbuf);
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}
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static void *
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hast_lzf_decompress(const unsigned char *data, size_t *sizep)
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{
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unsigned char *newbuf;
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uint32_t origsize;
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size_t newsize;
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PJDLOG_ASSERT(*sizep > sizeof(origsize));
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bcopy(data, &origsize, sizeof(origsize));
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origsize = le32toh(origsize);
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PJDLOG_ASSERT(origsize > HAST_LZF_COMPRESS_MIN);
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newbuf = malloc(origsize);
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if (newbuf == NULL) {
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pjdlog_error("Unable to decompress (no memory: %zu).",
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(size_t)origsize);
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return (NULL);
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}
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newsize = lzf_decompress(data + sizeof(origsize),
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*sizep - sizeof(origsize), newbuf, origsize);
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if (newsize == 0) {
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free(newbuf);
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pjdlog_error("Unable to decompress.");
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return (NULL);
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}
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PJDLOG_ASSERT(newsize == origsize);
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*sizep = newsize;
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return (newbuf);
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}
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const char *
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compression_name(int num)
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{
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switch (num) {
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case HAST_COMPRESSION_NONE:
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return ("none");
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case HAST_COMPRESSION_HOLE:
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return ("hole");
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case HAST_COMPRESSION_LZF:
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return ("lzf");
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}
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return ("unknown");
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}
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int
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compression_send(const struct hast_resource *res, struct nv *nv, void **datap,
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size_t *sizep, bool *freedatap)
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{
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unsigned char *newbuf;
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int compression;
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size_t size;
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size = *sizep;
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compression = res->hr_compression;
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switch (compression) {
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case HAST_COMPRESSION_NONE:
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return (0);
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case HAST_COMPRESSION_HOLE:
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newbuf = hast_hole_compress(*datap, &size);
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break;
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case HAST_COMPRESSION_LZF:
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/* Try 'hole' compression first. */
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newbuf = hast_hole_compress(*datap, &size);
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if (newbuf != NULL)
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compression = HAST_COMPRESSION_HOLE;
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else
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newbuf = hast_lzf_compress(*datap, &size);
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break;
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default:
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PJDLOG_ABORT("Invalid compression: %d.", res->hr_compression);
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}
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if (newbuf == NULL) {
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/* Unable to compress the data. */
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return (0);
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}
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nv_add_string(nv, compression_name(compression), "compression");
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if (nv_error(nv) != 0) {
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free(newbuf);
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errno = nv_error(nv);
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return (-1);
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}
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if (*freedatap)
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free(*datap);
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*freedatap = true;
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*datap = newbuf;
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*sizep = size;
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return (0);
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}
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int
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compression_recv(const struct hast_resource *res __unused, struct nv *nv,
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void **datap, size_t *sizep, bool *freedatap)
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{
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unsigned char *newbuf;
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const char *algo;
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size_t size;
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algo = nv_get_string(nv, "compression");
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if (algo == NULL)
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return (0); /* No compression. */
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newbuf = NULL;
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size = *sizep;
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if (strcmp(algo, "hole") == 0)
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newbuf = hast_hole_decompress(*datap, &size);
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else if (strcmp(algo, "lzf") == 0)
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newbuf = hast_lzf_decompress(*datap, &size);
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else {
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pjdlog_error("Unknown compression algorithm '%s'.", algo);
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return (-1); /* Unknown compression algorithm. */
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}
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if (newbuf == NULL)
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return (-1);
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if (*freedatap)
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free(*datap);
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*freedatap = true;
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*datap = newbuf;
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*sizep = size;
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return (0);
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}
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