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/*-
* Copyright (c) 2003-2007 Tim Kientzle
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``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 AUTHOR(S) 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.
*/

#include "archive_platform.h"

__FBSDID("$FreeBSD$");


#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_ZLIB_H
#include <zlib.h>
#endif

#include "archive.h"
#include "archive_private.h"
#include "archive_read_private.h"

#ifdef HAVE_ZLIB_H
struct private_data {
z_stream stream;
char in_stream;
unsigned char *out_block;
size_t out_block_size;
int64_t total_out;
unsigned long crc;
char eof; /* True = found end of compressed data. */
};

/* Gzip Filter. */
static ssize_t gzip_filter_read(struct archive_read_filter *, const void **);
static int gzip_filter_close(struct archive_read_filter *);
#endif

/*
* Note that we can detect gzip archives even if we can't decompress
* them. (In fact, we like detecting them because we can give better
* error messages.) So the bid framework here gets compiled even
* if zlib is unavailable.
*
* TODO: If zlib is unavailable, gzip_bidder_init() should
* use the compress_program framework to try to fire up an external
* gzip program.
*/
static int gzip_bidder_bid(struct archive_read_filter_bidder *,
struct archive_read_filter *);
static int gzip_bidder_init(struct archive_read_filter *);

#if ARCHIVE_VERSION_NUMBER < 4000000
/* Deprecated; remove in libarchive 4.0 */
int
archive_read_support_compression_gzip(struct archive *a)
{
return archive_read_support_filter_gzip(a);
}
#endif

int
archive_read_support_filter_gzip(struct archive *_a)
{
struct archive_read *a = (struct archive_read *)_a;
struct archive_read_filter_bidder *bidder;

archive_check_magic(_a, ARCHIVE_READ_MAGIC,
ARCHIVE_STATE_NEW, "archive_read_support_filter_gzip");

if (__archive_read_get_bidder(a, &bidder) != ARCHIVE_OK)
return (ARCHIVE_FATAL);

bidder->data = NULL;
bidder->name = "gzip";
bidder->bid = gzip_bidder_bid;
bidder->init = gzip_bidder_init;
bidder->options = NULL;
bidder->free = NULL; /* No data, so no cleanup necessary. */
/* Signal the extent of gzip support with the return value here. */
#if HAVE_ZLIB_H
return (ARCHIVE_OK);
#else
archive_set_error(_a, ARCHIVE_ERRNO_MISC,
"Using external gzip program");
return (ARCHIVE_WARN);
#endif
}

/*
* Read and verify the header.
*
* Returns zero if the header couldn't be validated, else returns
* number of bytes in header. If pbits is non-NULL, it receives a
* count of bits verified, suitable for use by bidder.
*/
static ssize_t
peek_at_header(struct archive_read_filter *filter, int *pbits)
{
const unsigned char *p;
ssize_t avail, len;
int bits = 0;
int header_flags;

/* Start by looking at the first ten bytes of the header, which
* is all fixed layout. */
len = 10;
p = __archive_read_filter_ahead(filter, len, &avail);
if (p == NULL || avail == 0)
return (0);
/* We only support deflation- third byte must be 0x08. */
if (memcmp(p, "\x1F\x8B\x08", 3) != 0)
return (0);
bits += 24;
if ((p[3] & 0xE0)!= 0) /* No reserved flags set. */
return (0);
bits += 3;
header_flags = p[3];
/* Bytes 4-7 are mod time. */
/* Byte 8 is deflate flags. */
/* XXXX TODO: return deflate flags back to consume_header for use
in initializing the decompressor. */
/* Byte 9 is OS. */

/* Optional extra data: 2 byte length plus variable body. */
if (header_flags & 4) {
p = __archive_read_filter_ahead(filter, len + 2, &avail);
if (p == NULL)
return (0);
len += ((int)p[len + 1] << 8) | (int)p[len];
len += 2;
}

/* Null-terminated optional filename. */
if (header_flags & 8) {
do {
++len;
if (avail < len)
p = __archive_read_filter_ahead(filter,
len, &avail);
if (p == NULL)
return (0);
} while (p[len - 1] != 0);
}

/* Null-terminated optional comment. */
if (header_flags & 16) {
do {
++len;
if (avail < len)
p = __archive_read_filter_ahead(filter,
len, &avail);
if (p == NULL)
return (0);
} while (p[len - 1] != 0);
}

/* Optional header CRC */
if ((header_flags & 2)) {
p = __archive_read_filter_ahead(filter, len + 2, &avail);
if (p == NULL)
return (0);
#if 0
int hcrc = ((int)p[len + 1] << 8) | (int)p[len];
int crc = /* XXX TODO: Compute header CRC. */;
if (crc != hcrc)
return (0);
bits += 16;
#endif
len += 2;
}

if (pbits != NULL)
*pbits = bits;
return (len);
}

/*
* Bidder just verifies the header and returns the number of verified bits.
*/
static int
gzip_bidder_bid(struct archive_read_filter_bidder *self,
    struct archive_read_filter *filter)
{
int bits_checked;

(void)self; /* UNUSED */

if (peek_at_header(filter, &bits_checked))
return (bits_checked);
return (0);
}


#ifndef HAVE_ZLIB_H

/*
* If we don't have the library on this system, we can't do the
* decompression directly. We can, however, try to run "gzip -d"
* in case that's available.
*/
static int
gzip_bidder_init(struct archive_read_filter *self)
{
int r;

r = __archive_read_program(self, "gzip -d");
/* Note: We set the format here even if __archive_read_program()
* above fails. We do, after all, know what the format is
* even if we weren't able to read it. */
self->code = ARCHIVE_FILTER_GZIP;
self->name = "gzip";
return (r);
}

#else

/*
* Initialize the filter object.
*/
static int
gzip_bidder_init(struct archive_read_filter *self)
{
struct private_data *state;
static const size_t out_block_size = 64 * 1024;
void *out_block;

self->code = ARCHIVE_FILTER_GZIP;
self->name = "gzip";

state = (struct private_data *)calloc(sizeof(*state), 1);
out_block = (unsigned char *)malloc(out_block_size);
if (state == NULL || out_block == NULL) {
free(out_block);
free(state);
archive_set_error(&self->archive->archive, ENOMEM,
"Can't allocate data for gzip decompression");
return (ARCHIVE_FATAL);
}

self->data = state;
state->out_block_size = out_block_size;
state->out_block = out_block;
self->read = gzip_filter_read;
self->skip = NULL; /* not supported */
self->close = gzip_filter_close;

state->in_stream = 0; /* We're not actually within a stream yet. */

return (ARCHIVE_OK);
}

static int
consume_header(struct archive_read_filter *self)
{
struct private_data *state;
ssize_t avail;
size_t len;
int ret;

state = (struct private_data *)self->data;

/* If this is a real header, consume it. */
len = peek_at_header(self->upstream, NULL);
if (len == 0)
return (ARCHIVE_EOF);
__archive_read_filter_consume(self->upstream, len);

/* Initialize CRC accumulator. */
state->crc = crc32(0L, NULL, 0);

/* Initialize compression library. */
state->stream.next_in = (unsigned char *)(uintptr_t)
__archive_read_filter_ahead(self->upstream, 1, &avail);
state->stream.avail_in = (uInt)avail;
ret = inflateInit2(&(state->stream),
-15 /* Don't check for zlib header */);

/* Decipher the error code. */
switch (ret) {
case Z_OK:
state->in_stream = 1;
return (ARCHIVE_OK);
case Z_STREAM_ERROR:
archive_set_error(&self->archive->archive,
ARCHIVE_ERRNO_MISC,
"Internal error initializing compression library: "
"invalid setup parameter");
break;
case Z_MEM_ERROR:
archive_set_error(&self->archive->archive, ENOMEM,
"Internal error initializing compression library: "
"out of memory");
break;
case Z_VERSION_ERROR:
archive_set_error(&self->archive->archive,
ARCHIVE_ERRNO_MISC,
"Internal error initializing compression library: "
"invalid library version");
break;
default:
archive_set_error(&self->archive->archive,
ARCHIVE_ERRNO_MISC,
"Internal error initializing compression library: "
" Zlib error %d", ret);
break;
}
return (ARCHIVE_FATAL);
}

static int
consume_trailer(struct archive_read_filter *self)
{
struct private_data *state;
const unsigned char *p;
ssize_t avail;

state = (struct private_data *)self->data;

state->in_stream = 0;
switch (inflateEnd(&(state->stream))) {
case Z_OK:
break;
default:
archive_set_error(&self->archive->archive,
ARCHIVE_ERRNO_MISC,
"Failed to clean up gzip decompressor");
return (ARCHIVE_FATAL);
}

/* GZip trailer is a fixed 8 byte structure. */
p = __archive_read_filter_ahead(self->upstream, 8, &avail);
if (p == NULL || avail == 0)
return (ARCHIVE_FATAL);

/* XXX TODO: Verify the length and CRC. */

/* We've verified the trailer, so consume it now. */
__archive_read_filter_consume(self->upstream, 8);

return (ARCHIVE_OK);
}

static ssize_t
gzip_filter_read(struct archive_read_filter *self, const void **p)
{
struct private_data *state;
size_t decompressed;
ssize_t avail_in;
int ret;

state = (struct private_data *)self->data;

/* Empty our output buffer. */
state->stream.next_out = state->out_block;
state->stream.avail_out = (uInt)state->out_block_size;

/* Try to fill the output buffer. */
while (state->stream.avail_out > 0 && !state->eof) {
/* If we're not in a stream, read a header
* and initialize the decompression library. */
if (!state->in_stream) {
ret = consume_header(self);
if (ret == ARCHIVE_EOF) {
state->eof = 1;
break;
}
if (ret < ARCHIVE_OK)
return (ret);
}

/* Peek at the next available data. */
/* ZLib treats stream.next_in as const but doesn't declare
* it so, hence this ugly cast. */
state->stream.next_in = (unsigned char *)(uintptr_t)
__archive_read_filter_ahead(self->upstream, 1, &avail_in);
if (state->stream.next_in == NULL) {
archive_set_error(&self->archive->archive,
ARCHIVE_ERRNO_MISC,
"truncated gzip input");
return (ARCHIVE_FATAL);
}
state->stream.avail_in = (uInt)avail_in;

/* Decompress and consume some of that data. */
ret = inflate(&(state->stream), 0);
switch (ret) {
case Z_OK: /* Decompressor made some progress. */
__archive_read_filter_consume(self->upstream,
avail_in - state->stream.avail_in);
break;
case Z_STREAM_END: /* Found end of stream. */
__archive_read_filter_consume(self->upstream,
avail_in - state->stream.avail_in);
/* Consume the stream trailer; release the
* decompression library. */
ret = consume_trailer(self);
if (ret < ARCHIVE_OK)
return (ret);
break;
default:
/* Return an error. */
archive_set_error(&self->archive->archive,
ARCHIVE_ERRNO_MISC,
"gzip decompression failed");
return (ARCHIVE_FATAL);
}
}

/* We've read as much as we can. */
decompressed = state->stream.next_out - state->out_block;
state->total_out += decompressed;
if (decompressed == 0)
*p = NULL;
else
*p = state->out_block;
return (decompressed);
}

/*
* Clean up the decompressor.
*/
static int
gzip_filter_close(struct archive_read_filter *self)
{
struct private_data *state;
int ret;

state = (struct private_data *)self->data;
ret = ARCHIVE_OK;

if (state->in_stream) {
switch (inflateEnd(&(state->stream))) {
case Z_OK:
break;
default:
archive_set_error(&(self->archive->archive),
ARCHIVE_ERRNO_MISC,
"Failed to clean up gzip compressor");
ret = ARCHIVE_FATAL;
}
}

free(state->out_block);
free(state);
return (ret);
}

#endif /* HAVE_ZLIB_H */
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