/*-
 * Copyright (c) 2008 Joerg Sonnenberger
 * 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.
 */

/*-
 * 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.
 * 3. 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_write_set_compression_compress.c,v 1.1 2008/03/14 20:35:37 kientzle Exp $");

#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif

#include "archive.h"
#include "archive_private.h"
#include "archive_write_private.h"

#define HSIZE       69001   /* 95% occupancy */
#define HSHIFT      8   /* 8 - trunc(log2(HSIZE / 65536)) */
#define CHECK_GAP 10000     /* Ratio check interval. */

#define MAXCODE(bits)   ((1 << (bits)) - 1)

/*
 * the next two codes should not be changed lightly, as they must not
 * lie within the contiguous general code space.
 */
#define FIRST   257     /* First free entry. */
#define CLEAR   256     /* Table clear output code. */

struct private_data {
    off_t in_count, out_count, checkpoint;

    int code_len;           /* Number of bits/code. */
    int cur_maxcode;        /* Maximum code, given n_bits. */
    int max_maxcode;        /* Should NEVER generate this code. */
    int hashtab [HSIZE];
    unsigned short codetab [HSIZE];
    int first_free;     /* First unused entry. */
    int compress_ratio;

    int cur_code, cur_fcode;

    int bit_offset;
    unsigned char bit_buf;

    unsigned char   *compressed;
    size_t       compressed_buffer_size;
    size_t       compressed_offset;
};

static int  archive_compressor_compress_finish(struct archive_write *);
static int  archive_compressor_compress_init(struct archive_write *);
static int  archive_compressor_compress_write(struct archive_write *,
            const void *, size_t);

/*
 * Allocate, initialize and return a archive object.
 */
int
archive_write_set_compression_compress(struct archive *_a)
{
    struct archive_write *a = (struct archive_write *)_a;
    __archive_check_magic(&a->archive, ARCHIVE_WRITE_MAGIC,
        ARCHIVE_STATE_NEW, "archive_write_set_compression_compress");
    a->compressor.init = &archive_compressor_compress_init;
    a->archive.compression_code = ARCHIVE_COMPRESSION_COMPRESS;
    a->archive.compression_name = "compress";
    return (ARCHIVE_OK);
}

/*
 * Setup callback.
 */
static int
archive_compressor_compress_init(struct archive_write *a)
{
    int ret;
    struct private_data *state;

    a->archive.compression_code = ARCHIVE_COMPRESSION_COMPRESS;
    a->archive.compression_name = "compress";

    if (a->bytes_per_block < 4) {
        archive_set_error(&a->archive, EINVAL,
            "Can't write Compress header as single block");
        return (ARCHIVE_FATAL);
    }

    if (a->client_opener != NULL) {
        ret = (a->client_opener)(&a->archive, a->client_data);
        if (ret != ARCHIVE_OK)
            return (ret);
    }

    state = (struct private_data *)malloc(sizeof(*state));
    if (state == NULL) {
        archive_set_error(&a->archive, ENOMEM,
            "Can't allocate data for compression");
        return (ARCHIVE_FATAL);
    }
    memset(state, 0, sizeof(*state));

    state->compressed_buffer_size = a->bytes_per_block;
    state->compressed = malloc(state->compressed_buffer_size);

    if (state->compressed == NULL) {
        archive_set_error(&a->archive, ENOMEM,
            "Can't allocate data for compression buffer");
        free(state);
        return (ARCHIVE_FATAL);
    }

    a->compressor.write = archive_compressor_compress_write;
    a->compressor.finish = archive_compressor_compress_finish;

    state->max_maxcode = 0x10000;   /* Should NEVER generate this code. */
    state->in_count = 0;        /* Length of input. */
    state->bit_buf = 0;
    state->bit_offset = 0;
    state->out_count = 3;       /* Includes 3-byte header mojo. */
    state->compress_ratio = 0;
    state->checkpoint = CHECK_GAP;
    state->code_len = 9;
    state->cur_maxcode = MAXCODE(state->code_len);
    state->first_free = FIRST;

    memset(state->hashtab, 0xff, sizeof(state->hashtab));

    /* Prime output buffer with a gzip header. */
    state->compressed[0] = 0x1f; /* Compress */
    state->compressed[1] = 0x9d;
    state->compressed[2] = 0x90; /* Block mode, 16bit max */
    state->compressed_offset = 3;

    a->compressor.data = state;
    return (0);
}

/*-
 * Output the given code.
 * Inputs:
 *  code:   A n_bits-bit integer.  If == -1, then EOF.  This assumes
 *      that n_bits =< (long)wordsize - 1.
 * Outputs:
 *  Outputs code to the file.
 * Assumptions:
 *  Chars are 8 bits long.
 * Algorithm:
 *  Maintain a BITS character long buffer (so that 8 codes will
 * fit in it exactly).  Use the VAX insv instruction to insert each
 * code in turn.  When the buffer fills up empty it and start over.
 */

static unsigned char rmask[9] =
    {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};

static int
output_byte(struct archive_write *a, unsigned char c)
{
    struct private_data *state = a->compressor.data;
    ssize_t bytes_written;

    state->compressed[state->compressed_offset++] = c;
    ++state->out_count;

    if (state->compressed_buffer_size == state->compressed_offset) {
        bytes_written = (a->client_writer)(&a->archive,
            a->client_data,
            state->compressed, state->compressed_buffer_size);
        if (bytes_written <= 0)
            return ARCHIVE_FATAL;
        a->archive.raw_position += bytes_written;
        state->compressed_offset = 0;
    }

    return ARCHIVE_OK;
}

static int
output_code(struct archive_write *a, int ocode)
{
    struct private_data *state = a->compressor.data;
    int bits, ret, clear_flg, bit_offset;

    clear_flg = ocode == CLEAR;
    bits = state->code_len;

    /*
     * Since ocode is always >= 8 bits, only need to mask the first
     * hunk on the left.
     */
    bit_offset = state->bit_offset % 8;
    state->bit_buf |= (ocode << bit_offset) & 0xff;
    output_byte(a, state->bit_buf);

    bits = state->code_len - (8 - bit_offset);
    ocode >>= 8 - bit_offset;
    /* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */
    if (bits >= 8) {
        output_byte(a, ocode & 0xff);
        ocode >>= 8;
        bits -= 8;
    }
    /* Last bits. */
    state->bit_offset += state->code_len;
    state->bit_buf = ocode & rmask[bits];
    if (state->bit_offset == state->code_len * 8)
        state->bit_offset = 0;

    /*
     * If the next entry is going to be too big for the ocode size,
     * then increase it, if possible.
     */
    if (clear_flg || state->first_free > state->cur_maxcode) {
           /*
        * Write the whole buffer, because the input side won't
        * discover the size increase until after it has read it.
        */
        if (state->bit_offset > 0) {
            while (state->bit_offset < state->code_len * 8) {
                ret = output_byte(a, state->bit_buf);
                if (ret != ARCHIVE_OK)
                    return ret;
                state->bit_offset += 8;
                state->bit_buf = 0;
            }
        }
        state->bit_buf = 0;
        state->bit_offset = 0;

        if (clear_flg) {
            state->code_len = 9;
            state->cur_maxcode = MAXCODE(state->code_len);
        } else {
            state->code_len++;
            if (state->code_len == 16)
                state->cur_maxcode = state->max_maxcode;
            else
                state->cur_maxcode = MAXCODE(state->code_len);
        }
    }

    return (ARCHIVE_OK);
}

static int
output_flush(struct archive_write *a)
{
    struct private_data *state = a->compressor.data;
    int ret;

    /* At EOF, write the rest of the buffer. */
    if (state->bit_offset % 8) {
        state->code_len = (state->bit_offset % 8 + 7) / 8;
        ret = output_byte(a, state->bit_buf);
        if (ret != ARCHIVE_OK)
            return ret;
    }

    return (ARCHIVE_OK);
}

/*
 * Write data to the compressed stream.
 */
static int
archive_compressor_compress_write(struct archive_write *a, const void *buff,
    size_t length)
{
    struct private_data *state;
    int i;
    int ratio;
    int c, disp, ret;
    const unsigned char *bp;

    state = (struct private_data *)a->compressor.data;
    if (a->client_writer == NULL) {
        archive_set_error(&a->archive, ARCHIVE_ERRNO_PROGRAMMER,
            "No write callback is registered?  "
            "This is probably an internal programming error.");
        return (ARCHIVE_FATAL);
    }

    if (length == 0)
        return ARCHIVE_OK;

    bp = buff;

    if (state->in_count == 0) {
        state->cur_code = *bp++;
        ++state->in_count;
        --length;
    }

    while (length--) {
        c = *bp++;
        state->in_count++;
        state->cur_fcode = (c << 16) + state->cur_code;
        i = ((c << HSHIFT) ^ state->cur_code);  /* Xor hashing. */

        if (state->hashtab[i] == state->cur_fcode) {
            state->cur_code = state->codetab[i];
            continue;
        }
        if (state->hashtab[i] < 0)  /* Empty slot. */
            goto nomatch;
        /* Secondary hash (after G. Knott). */
        if (i == 0)
            disp = 1;
        else
            disp = HSIZE - i;
 probe:     
        if ((i -= disp) < 0)
            i += HSIZE;

        if (state->hashtab[i] == state->cur_fcode) {
            state->cur_code = state->codetab[i];
            continue;
        }
        if (state->hashtab[i] >= 0)
            goto probe;
 nomatch:   
        ret = output_code(a, state->cur_code);
        if (ret != ARCHIVE_OK)
            return ret;
        state->cur_code = c;
        if (state->first_free < state->max_maxcode) {
            state->codetab[i] = state->first_free++;    /* code -> hashtable */
            state->hashtab[i] = state->cur_fcode;
            continue;
        }
        if (state->in_count < state->checkpoint)
            continue;

        state->checkpoint = state->in_count + CHECK_GAP;

        if (state->in_count <= 0x007fffff)
            ratio = state->in_count * 256 / state->out_count;
        else if ((ratio = state->out_count / 256) == 0)
            ratio = 0x7fffffff;
        else
            ratio = state->in_count / ratio;

        if (ratio > state->compress_ratio)
            state->compress_ratio = ratio;
        else {
            state->compress_ratio = 0;
            memset(state->hashtab, 0xff, sizeof(state->hashtab));
            state->first_free = FIRST;
            ret = output_code(a, CLEAR);
            if (ret != ARCHIVE_OK)
                return ret;
        }
    }

    return (ARCHIVE_OK);
}


/*
 * Finish the compression...
 */
static int
archive_compressor_compress_finish(struct archive_write *a)
{
    ssize_t block_length, target_block_length, bytes_written;
    int ret;
    struct private_data *state;
    unsigned tocopy;

    state = (struct private_data *)a->compressor.data;
    ret = 0;
    if (a->client_writer == NULL) {
        archive_set_error(&a->archive, ARCHIVE_ERRNO_PROGRAMMER,
            "No write callback is registered?  "
            "This is probably an internal programming error.");
        ret = ARCHIVE_FATAL;
        goto cleanup;
    }

    /* By default, always pad the uncompressed data. */
    if (a->pad_uncompressed) {
        while (state->in_count % a->bytes_per_block != 0) {
            tocopy = a->bytes_per_block -
                (state->in_count % a->bytes_per_block);
            if (tocopy > a->null_length)
                tocopy = a->null_length;
            ret = archive_compressor_compress_write(a, a->nulls,
                tocopy);
            if (ret != ARCHIVE_OK)
                goto cleanup;
        }
    }

    ret = output_code(a, state->cur_code);
    if (ret != ARCHIVE_OK)
        goto cleanup;
    ret = output_flush(a);
    if (ret != ARCHIVE_OK)
        goto cleanup;

    /* Optionally, pad the final compressed block. */
    block_length = state->compressed_offset;

    /* Tricky calculation to determine size of last block. */
    if (a->bytes_in_last_block <= 0)
        /* Default or Zero: pad to full block */
        target_block_length = a->bytes_per_block;
    else
        /* Round length to next multiple of bytes_in_last_block. */
        target_block_length = a->bytes_in_last_block *
            ( (block_length + a->bytes_in_last_block - 1) /
            a->bytes_in_last_block);
    if (target_block_length > a->bytes_per_block)
        target_block_length = a->bytes_per_block;
    if (block_length < target_block_length) {
        memset(state->compressed + state->compressed_offset, 0,
            target_block_length - block_length);
        block_length = target_block_length;
    }

    /* Write the last block */
    bytes_written = (a->client_writer)(&a->archive, a->client_data,
        state->compressed, block_length);
    if (bytes_written <= 0)
        ret = ARCHIVE_FATAL;
    else
        a->archive.raw_position += bytes_written;

cleanup:
    free(state->compressed);
    free(state);
    return (ret);
}
