FreeBSD-5.3/lib/libarchive/archive_read_support_compression_compress.c
/*-
* Copyright (c) 2003-2004 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
* in this position and unchanged.
* 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.
*/
/*
* This code borrows heavily from "compress" source code, which is
* protected by the following copyright. (Clause 3 dropped by request
* of the Regents.)
*/
/*-
* Copyright (c) 1985, 1986, 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Diomidis Spinellis and James A. Woods, derived from original
* work by Spencer Thomas and Joseph Orost.
*
* 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.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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: src/lib/libarchive/archive_read_support_compression_compress.c,v 1.2 2004/08/14 03:45:45 kientzle Exp $");
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "archive.h"
#include "archive_private.h"
/*
* Because LZW decompression is pretty simple, I've just implemented
* the whole decompressor here (cribbing from "compress" source code,
* of course), rather than relying on an external library. I have
* made an effort to clarify and simplify the algorithm, so the
* names and structure here don't exactly match those used by compress.
*/
struct private_data {
/* Input variables. */
const unsigned char *next_in;
size_t avail_in;
int bit_buffer;
int bits_avail;
size_t bytes_in_section;
/* Output variables. */
size_t uncompressed_buffer_size;
void *uncompressed_buffer;
unsigned char *read_next; /* Data for client. */
unsigned char *next_out; /* Where to write new data. */
size_t avail_out; /* Space at end of buffer. */
/* Decompression status variables. */
int use_reset_code;
int end_of_stream; /* EOF status. */
int maxcode; /* Largest code. */
int maxcode_bits; /* Length of largest code. */
int section_end_code; /* When to increase bits. */
int bits; /* Current code length. */
int oldcode; /* Previous code. */
int finbyte; /* Last byte of prev code. */
/* Dictionary. */
int free_ent; /* Next dictionary entry. */
unsigned char suffix[65536];
uint16_t prefix[65536];
/*
* Scratch area for expanding dictionary entries. Note:
* "worst" case here comes from compressing /dev/zero: the
* last code in the dictionary will code a sequence of
* 65536-256 zero bytes. Thus, we need stack space to expand
* a 65280-byte dictionary entry. (Of course, 32640:1
* compression could also be considered the "best" case. ;-)
*/
unsigned char *stackp;
unsigned char stack[65300];
};
static int bid(const void *, size_t);
static int finish(struct archive *);
static int init(struct archive *, const void *, size_t);
static ssize_t read_ahead(struct archive *, const void **, size_t);
static ssize_t read_consume(struct archive *, size_t);
static int getbits(struct archive *, struct private_data *, int n);
static int next_code(struct archive *a, struct private_data *state);
int
archive_read_support_compression_compress(struct archive *a)
{
return (__archive_read_register_compression(a, bid, init));
}
/*
* Test whether we can handle this data.
*
* This logic returns zero if any part of the signature fails. It
* also tries to Do The Right Thing if a very short buffer prevents us
* from verifying as much as we would like.
*/
static int
bid(const void *buff, size_t len)
{
const unsigned char *buffer;
int bits_checked;
if (len < 1)
return (0);
buffer = buff;
bits_checked = 0;
if (buffer[0] != 037) /* Verify first ID byte. */
return (0);
bits_checked += 8;
if (len < 2)
return (bits_checked);
if (buffer[1] != 0235) /* Verify second ID byte. */
return (0);
bits_checked += 8;
if (len < 3)
return (bits_checked);
/*
* TODO: Verify more.
*/
return (bits_checked);
}
/*
* Setup the callbacks.
*/
static int
init(struct archive *a, const void *buff, size_t n)
{
struct private_data *state;
int code;
a->compression_code = ARCHIVE_COMPRESSION_COMPRESS;
a->compression_name = "compress (.Z)";
a->compression_read_ahead = read_ahead;
a->compression_read_consume = read_consume;
a->compression_finish = finish;
state = malloc(sizeof(*state));
if (state == NULL) {
archive_set_error(a, ENOMEM,
"Can't allocate data for %s decompression",
a->compression_name);
return (ARCHIVE_FATAL);
}
memset(state, 0, sizeof(*state));
state->uncompressed_buffer_size = 64 * 1024;
state->uncompressed_buffer = malloc(state->uncompressed_buffer_size);
if (state->uncompressed_buffer == NULL) {
archive_set_error(a, ENOMEM,
"Can't allocate %s decompression buffers",
a->compression_name);
goto fatal;
}
state->next_in = buff;
state->avail_in = n;
state->read_next = state->next_out = state->uncompressed_buffer;
state->avail_out = state->uncompressed_buffer_size;
code = getbits(a, state, 8);
if (code != 037)
goto fatal;
code = getbits(a, state, 8);
if (code != 0235)
goto fatal;
code = getbits(a, state, 8);
state->maxcode_bits = code & 0x1f;
state->maxcode = (1 << state->maxcode_bits);
state->use_reset_code = code & 0x80;
/* Initialize decompressor. */
state->free_ent = 256;
state->stackp = state->stack;
if (state->use_reset_code)
state->free_ent++;
state->bits = 9;
state->section_end_code = (1<<state->bits) - 1;
state->oldcode = -1;
for (code = 255; code >= 0; code--) {
state->prefix[code] = 0;
state->suffix[code] = code;
}
next_code(a, state);
a->compression_data = state;
return (ARCHIVE_OK);
fatal:
finish(a);
return (ARCHIVE_FATAL);
}
/*
* Return a block of data from the decompression buffer. Decompress more
* as necessary.
*/
static ssize_t
read_ahead(struct archive *a, const void **p, size_t min)
{
struct private_data *state;
int read_avail, was_avail, ret;
state = a->compression_data;
was_avail = -1;
if (!a->client_reader) {
archive_set_error(a, ARCHIVE_ERRNO_PROGRAMMER,
"No read callback is registered? "
"This is probably an internal programming error.");
return (ARCHIVE_FATAL);
}
read_avail = state->next_out - state->read_next;
if (read_avail < (int)min && state->end_of_stream) {
if (state->end_of_stream == ARCHIVE_EOF)
return (0);
else
return (-1);
}
if (read_avail < (int)min) {
memmove(state->uncompressed_buffer, state->read_next,
read_avail);
state->read_next = state->uncompressed_buffer;
state->next_out = state->read_next + read_avail;
state->avail_out
= state->uncompressed_buffer_size - read_avail;
while (read_avail < (int)state->uncompressed_buffer_size
&& !state->end_of_stream) {
if (state->stackp > state->stack) {
*state->next_out++ = *--state->stackp;
state->avail_out--;
read_avail++;
} else {
ret = next_code(a, state);
if (ret)
state->end_of_stream = ret;
}
}
}
*p = state->read_next;
return (read_avail);
}
/*
* Mark a previously-returned block of data as read.
*/
static ssize_t
read_consume(struct archive *a, size_t n)
{
struct private_data *state;
state = a->compression_data;
a->file_position += n;
state->read_next += n;
if (state->read_next > state->next_out)
__archive_errx(1, "Request to consume too many "
"bytes from compress decompressor");
return (n);
}
/*
* Clean up the decompressor.
*/
static int
finish(struct archive *a)
{
struct private_data *state;
int ret;
state = a->compression_data;
ret = ARCHIVE_OK;
free(state->uncompressed_buffer);
free(state);
a->compression_data = NULL;
if (a->client_closer != NULL)
(a->client_closer)(a, a->client_data);
return (ret);
}
/*
* Process the next code and fill the stack with the expansion
* of the code. Returns TRUE if we hit the end of the data.
*/
static int
next_code(struct archive *a, struct private_data *state)
{
int code, newcode;
static int debug_buff[1024];
static unsigned debug_index;
code = newcode = getbits(a, state, state->bits);
if (code < 0)
return (code);
debug_buff[debug_index++] = code;
if (debug_index >= sizeof(debug_buff)/sizeof(debug_buff[0]))
debug_index = 0;
/* If it's a reset code, reset the dictionary. */
if ((code == 256) && state->use_reset_code) {
/*
* The original 'compress' implementation blocked its
* I/O in a manner that resulted in junk bytes being
* inserted after every reset. The next section skips
* this junk. (Yes, the number of *bytes* to skip is
* a function of the current *bit* length.)
*/
int skip_bytes = state->bits -
(state->bytes_in_section % state->bits);
skip_bytes %= state->bits;
state->bits_avail = 0; /* Discard rest of this byte. */
while (skip_bytes-- > 0) {
code = getbits(a, state, 8);
if (code < 0)
return (code);
}
/* Now, actually do the reset. */
state->bytes_in_section = 0;
state->bits = 9;
state->section_end_code = (1 << state->bits) - 1;
state->free_ent = 257;
state->oldcode = -1;
return (next_code(a, state));
}
if (code > state->free_ent)
/* XXX invalid code? This is fatal. XXX */
return (1);
/* Special case for KwKwK string. */
if (code >= state->free_ent) {
*state->stackp++ = state->finbyte;
code = state->oldcode;
}
/* Generate output characters in reverse order. */
while (code >= 256) {
*state->stackp++ = state->suffix[code];
code = state->prefix[code];
}
*state->stackp++ = state->finbyte = code;
/* Generate the new entry. */
code = state->free_ent;
if (code < state->maxcode && state->oldcode >= 0) {
state->prefix[code] = state->oldcode;
state->suffix[code] = state->finbyte;
++state->free_ent;
}
if (state->free_ent > state->section_end_code) {
state->bits++;
state->bytes_in_section = 0;
if (state->bits == state->maxcode_bits)
state->section_end_code = state->maxcode;
else
state->section_end_code = (1 << state->bits) - 1;
}
/* Remember previous code. */
state->oldcode = newcode;
return (0);
}
/*
* Return next 'n' bits from stream.
*
* -1 indicates end of available data.
*/
static int
getbits(struct archive *a, struct private_data *state, int n)
{
int code, ret;
static const int mask[] = {
0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff,
0x1ff, 0x3ff, 0x7ff, 0xfff, 0x1fff, 0x3fff, 0x7fff, 0xffff
};
while (state->bits_avail < n) {
if (state->avail_in <= 0) {
ret = (a->client_reader)(a, a->client_data,
(const void **)&state->next_in);
if (ret < 0)
return (ARCHIVE_FATAL);
if (ret == 0)
return (ARCHIVE_EOF);
a->raw_position += ret;
state->avail_in = ret;
}
state->bit_buffer |= *state->next_in++ << state->bits_avail;
state->avail_in--;
state->bits_avail += 8;
state->bytes_in_section++;
}
code = state->bit_buffer;
state->bit_buffer >>= n;
state->bits_avail -= n;
return (code & mask[n]);
}