Ventoy/SQUASHFS/squashfs-tools-4.4/squashfs-tools/lz4_wrapper.c

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2020-04-04 12:07:50 -04:00
/*
* Copyright (c) 2013, 2019
* Phillip Lougher <phillip@squashfs.org.uk>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2,
* or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* lz4_wrapper.c
*
* Support for LZ4 compression http://fastcompression.blogspot.com/p/lz4.html
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <lz4.h>
#include <lz4hc.h>
#include "squashfs_fs.h"
#include "lz4_wrapper.h"
#include "compressor.h"
/* LZ4 1.7.0 introduced new functions, and since r131,
* the older functions produce deprecated warnings.
*
* There are still too many distros using older versions
* to switch to the newer functions, but, the deprecated
* functions may completely disappear. This is a mess.
*
* Support both by checking the library version and
* using shadow definitions
*/
/* Earlier (but > 1.7.0) versions don't define this */
#ifndef LZ4HC_CLEVEL_MAX
#define LZ4HC_CLEVEL_MAX 12
#endif
#if LZ4_VERSION_NUMBER >= 10700
#define COMPRESS(src, dest, size, max) LZ4_compress_default(src, dest, size, max)
#define COMPRESS_HC(src, dest, size, max) LZ4_compress_HC(src, dest, size, max, LZ4HC_CLEVEL_MAX)
#else
#define COMPRESS(src, dest, size, max) LZ4_compress_limitedOutput(src, dest, size, max)
#define COMPRESS_HC(src, dest, size, max) LZ4_compressHC_limitedOutput(src, dest, size, max)
#endif
static int hc = 0;
/*
* This function is called by the options parsing code in mksquashfs.c
* to parse any -X compressor option.
*
* This function returns:
* >=0 (number of additional args parsed) on success
* -1 if the option was unrecognised, or
* -2 if the option was recognised, but otherwise bad in
* some way (e.g. invalid parameter)
*
* Note: this function sets internal compressor state, but does not
* pass back the results of the parsing other than success/failure.
* The lz4_dump_options() function is called later to get the options in
* a format suitable for writing to the filesystem.
*/
static int lz4_options(char *argv[], int argc)
{
if(strcmp(argv[0], "-Xhc") == 0) {
hc = 1;
return 0;
}
return -1;
}
/*
* This function is called by mksquashfs to dump the parsed
* compressor options in a format suitable for writing to the
* compressor options field in the filesystem (stored immediately
* after the superblock).
*
* This function returns a pointer to the compression options structure
* to be stored (and the size), or NULL if there are no compression
* options
*
* Currently LZ4 always returns a comp_opts structure, with
* the version indicating LZ4_LEGACY stream fomat. This is to
* easily accomodate changes in the kernel code to different
* stream formats
*/
static void *lz4_dump_options(int block_size, int *size)
{
static struct lz4_comp_opts comp_opts;
comp_opts.version = LZ4_LEGACY;
comp_opts.flags = hc ? LZ4_HC : 0;
SQUASHFS_INSWAP_COMP_OPTS(&comp_opts);
*size = sizeof(comp_opts);
return &comp_opts;
}
/*
* This function is a helper specifically for the append mode of
* mksquashfs. Its purpose is to set the internal compressor state
* to the stored compressor options in the passed compressor options
* structure.
*
* In effect this function sets up the compressor options
* to the same state they were when the filesystem was originally
* generated, this is to ensure on appending, the compressor uses
* the same compression options that were used to generate the
* original filesystem.
*
* Note, even if there are no compressor options, this function is still
* called with an empty compressor structure (size == 0), to explicitly
* set the default options, this is to ensure any user supplied
* -X options on the appending mksquashfs command line are over-ridden
*
* This function returns 0 on sucessful extraction of options, and
* -1 on error
*/
static int lz4_extract_options(int block_size, void *buffer, int size)
{
struct lz4_comp_opts *comp_opts = buffer;
/* we expect a comp_opts structure to be present */
if(size < sizeof(*comp_opts))
goto failed;
SQUASHFS_INSWAP_COMP_OPTS(comp_opts);
/* we expect the stream format to be LZ4_LEGACY */
if(comp_opts->version != LZ4_LEGACY) {
fprintf(stderr, "lz4: unknown LZ4 version\n");
goto failed;
}
/*
* Check compression flags, currently only LZ4_HC ("high compression")
* can be set.
*/
if(comp_opts->flags == LZ4_HC)
hc = 1;
else if(comp_opts->flags != 0) {
fprintf(stderr, "lz4: unknown LZ4 flags\n");
goto failed;
}
return 0;
failed:
fprintf(stderr, "lz4: error reading stored compressor options from "
"filesystem!\n");
return -1;
}
/*
* This function is a helper specifically for unsquashfs.
* Its purpose is to check that the compression options are
* understood by this version of LZ4.
*
* This is important for LZ4 because the format understood by the
* Linux kernel may change from the already obsolete legacy format
* currently supported.
*
* If this does happen, then this version of LZ4 will not be able to decode
* the newer format. So we need to check for this.
*
* This function returns 0 on sucessful checking of options, and
* -1 on error
*/
static int lz4_check_options(int block_size, void *buffer, int size)
{
struct lz4_comp_opts *comp_opts = buffer;
/* we expect a comp_opts structure to be present */
if(size < sizeof(*comp_opts))
goto failed;
SQUASHFS_INSWAP_COMP_OPTS(comp_opts);
/* we expect the stream format to be LZ4_LEGACY */
if(comp_opts->version != LZ4_LEGACY) {
fprintf(stderr, "lz4: unknown LZ4 version\n");
goto failed;
}
return 0;
failed:
fprintf(stderr, "lz4: error reading stored compressor options from "
"filesystem!\n");
return -1;
}
static void lz4_display_options(void *buffer, int size)
{
struct lz4_comp_opts *comp_opts = buffer;
/* check passed comp opts struct is of the correct length */
if(size < sizeof(*comp_opts))
goto failed;
SQUASHFS_INSWAP_COMP_OPTS(comp_opts);
/* we expect the stream format to be LZ4_LEGACY */
if(comp_opts->version != LZ4_LEGACY) {
fprintf(stderr, "lz4: unknown LZ4 version\n");
goto failed;
}
/*
* Check compression flags, currently only LZ4_HC ("high compression")
* can be set.
*/
if(comp_opts->flags & ~LZ4_FLAGS_MASK) {
fprintf(stderr, "lz4: unknown LZ4 flags\n");
goto failed;
}
if(comp_opts->flags & LZ4_HC)
printf("\tHigh Compression option specified (-Xhc)\n");
return;
failed:
fprintf(stderr, "lz4: error reading stored compressor options from "
"filesystem!\n");
}
static int lz4_compress(void *strm, void *dest, void *src, int size,
int block_size, int *error)
{
return 0;
}
static int lz4_uncompress(void *dest, void *src, int size, int outsize,
int *error)
{
int res = LZ4_decompress_safe(src, dest, size, outsize);
if(res < 0) {
*error = res;
return -1;
}
return res;
}
static void lz4_usage()
{
fprintf(stderr, "\t -Xhc\n");
fprintf(stderr, "\t\tCompress using LZ4 High Compression\n");
}
struct compressor lz4_comp_ops = {
.compress = lz4_compress,
.uncompress = lz4_uncompress,
.options = lz4_options,
.dump_options = lz4_dump_options,
.extract_options = lz4_extract_options,
.check_options = lz4_check_options,
.display_options = lz4_display_options,
.usage = lz4_usage,
.id = LZ4_COMPRESSION,
.name = "lz4",
.supported = 1
};