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[dragonfly.git] / contrib / 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 1.3 2004/10/17 23:40:10 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 == ARCHIVE_EOF)
                                        state->end_of_stream = ret;
                                else if (ret != ARCHIVE_OK)
                                        return (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 ARCHIVE_FATAL if there is a fatal I/O or
 * format error, ARCHIVE_EOF if we hit end of data, ARCHIVE_OK otherwise.
 */
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) {
                /* An invalid code is a fatal error. */
                archive_set_error(a, -1, "Invalid compressed data");
                return (ARCHIVE_FATAL);
        }

        /* 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 (ARCHIVE_OK);
}

/*
 * 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]);
}