/*-
 * 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: src/lib/libarchive/archive_write_set_compression_gzip.c,v 1.16 2008/02/21 03:21:50 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 <time.h>
#ifdef HAVE_ZLIB_H
#include <cm_zlib.h>
#endif

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

#ifndef HAVE_ZLIB_H
int
archive_write_set_compression_gzip(struct archive *a)
{
    archive_set_error(a, ARCHIVE_ERRNO_MISC,
        "gzip compression not supported on this platform");
    return (ARCHIVE_FATAL);
}
#else
/* Don't compile this if we don't have zlib. */

struct private_data {
    z_stream     stream;
    int64_t      total_in;
    unsigned char   *compressed;
    size_t       compressed_buffer_size;
    unsigned long    crc;
};

struct private_config {
    int      compression_level;
};


/*
 * Yuck.  zlib.h is not const-correct, so I need this one bit
 * of ugly hackery to convert a const * pointer to a non-const pointer.
 */
#define SET_NEXT_IN(st,src)                 \
    (st)->stream.next_in = (Bytef *)(uintptr_t)(const void *)(src)

static int  archive_compressor_gzip_finish(struct archive_write *);
static int  archive_compressor_gzip_init(struct archive_write *);
static int  archive_compressor_gzip_options(struct archive_write *,
            const char *, const char *);
static int  archive_compressor_gzip_write(struct archive_write *,
            const void *, size_t);
static int  drive_compressor(struct archive_write *, struct private_data *,
            int finishing);


/*
 * Allocate, initialize and return a archive object.
 */
int
archive_write_set_compression_gzip(struct archive *_a)
{
    struct archive_write *a = (struct archive_write *)_a;
    struct private_config *config;
    __archive_check_magic(&a->archive, ARCHIVE_WRITE_MAGIC,
        ARCHIVE_STATE_NEW, "archive_write_set_compression_gzip");
    config = malloc(sizeof(*config));
    if (config == NULL) {
        archive_set_error(&a->archive, ENOMEM, "Out of memory");
        return (ARCHIVE_FATAL);
    }
    a->compressor.config = config;
    a->compressor.finish = &archive_compressor_gzip_finish;
    config->compression_level = Z_DEFAULT_COMPRESSION;
    a->compressor.init = &archive_compressor_gzip_init;
    a->compressor.options = &archive_compressor_gzip_options;
    a->archive.compression_code = ARCHIVE_COMPRESSION_GZIP;
    a->archive.compression_name = "gzip";
    return (ARCHIVE_OK);
}

/*
 * Setup callback.
 */
static int
archive_compressor_gzip_init(struct archive_write *a)
{
    int ret;
    struct private_data *state;
    struct private_config *config;
    time_t t;

    config = (struct private_config *)a->compressor.config;

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

    /*
     * The next check is a temporary workaround until the gzip
     * code can be overhauled some.  The code should not require
     * that compressed_buffer_size == bytes_per_block.  Removing
     * this assumption will allow us to compress larger chunks at
     * a time, which should improve overall performance
     * marginally.  As a minor side-effect, such a cleanup would
     * allow us to support truly arbitrary block sizes.
     */
    if (a->bytes_per_block < 10) {
        archive_set_error(&a->archive, EINVAL,
            "GZip compressor requires a minimum 10 byte block size");
        return (ARCHIVE_FATAL);
    }

    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));

    /*
     * See comment above.  We should set compressed_buffer_size to
     * max(bytes_per_block, 65536), but the code can't handle that yet.
     */
    state->compressed_buffer_size = a->bytes_per_block;
    state->compressed = (unsigned char *)malloc(state->compressed_buffer_size);
    state->crc = crc32(0L, NULL, 0);

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

    state->stream.next_out = state->compressed;
    state->stream.avail_out = state->compressed_buffer_size;

    /* Prime output buffer with a gzip header. */
    t = time(NULL);
    state->compressed[0] = 0x1f; /* GZip signature bytes */
    state->compressed[1] = 0x8b;
    state->compressed[2] = 0x08; /* "Deflate" compression */
    state->compressed[3] = 0; /* No options */
    state->compressed[4] = (t)&0xff;  /* Timestamp */
    state->compressed[5] = (t>>8)&0xff;
    state->compressed[6] = (t>>16)&0xff;
    state->compressed[7] = (t>>24)&0xff;
    state->compressed[8] = 0; /* No deflate options */
    state->compressed[9] = 3; /* OS=Unix */
    state->stream.next_out += 10;
    state->stream.avail_out -= 10;

    a->compressor.write = archive_compressor_gzip_write;

    /* Initialize compression library. */
    ret = deflateInit2(&(state->stream),
        config->compression_level,
        Z_DEFLATED,
        -15 /* < 0 to suppress zlib header */,
        8,
        Z_DEFAULT_STRATEGY);

    if (ret == Z_OK) {
        a->compressor.data = state;
        return (0);
    }

    /* Library setup failed: clean up. */
    archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC, "Internal error "
        "initializing compression library");
    free(state->compressed);
    free(state);

    /* Override the error message if we know what really went wrong. */
    switch (ret) {
    case Z_STREAM_ERROR:
        archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
            "Internal error initializing "
            "compression library: invalid setup parameter");
        break;
    case Z_MEM_ERROR:
        archive_set_error(&a->archive, ENOMEM, "Internal error initializing "
            "compression library");
        break;
    case Z_VERSION_ERROR:
        archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
            "Internal error initializing "
            "compression library: invalid library version");
        break;
    }

    return (ARCHIVE_FATAL);
}

/*
 * Set write options.
 */
static int
archive_compressor_gzip_options(struct archive_write *a, const char *key,
    const char *value)
{
    struct private_config *config;

    config = (struct private_config *)a->compressor.config;
    if (strcmp(key, "compression-level") == 0) {
        if (value == NULL || !(value[0] >= '0' && value[0] <= '9') ||
            value[1] != '\0')
            return (ARCHIVE_WARN);
        config->compression_level = value[0] - '0';
        return (ARCHIVE_OK);
    }

    return (ARCHIVE_WARN);
}

/*
 * Write data to the compressed stream.
 */
static int
archive_compressor_gzip_write(struct archive_write *a, const void *buff,
    size_t length)
{
    struct private_data *state;
    int ret;

    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);
    }

    /* Update statistics */
    state->crc = crc32(state->crc, (const Bytef *)buff, length);
    state->total_in += length;

    /* Compress input data to output buffer */
    SET_NEXT_IN(state, buff);
    state->stream.avail_in = length;
    if ((ret = drive_compressor(a, state, 0)) != ARCHIVE_OK)
        return (ret);

    a->archive.file_position += length;
    return (ARCHIVE_OK);
}

/*
 * Finish the compression...
 */
static int
archive_compressor_gzip_finish(struct archive_write *a)
{
    ssize_t block_length, target_block_length, bytes_written;
    int ret;
    struct private_data *state;
    unsigned tocopy;
    unsigned char trailer[8];

    state = (struct private_data *)a->compressor.data;
    ret = 0;
    if (state != NULL) {
        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) {
            tocopy = a->bytes_per_block -
                (state->total_in % a->bytes_per_block);
            while (tocopy > 0 && tocopy < (unsigned)a->bytes_per_block) {
                SET_NEXT_IN(state, a->nulls);
                state->stream.avail_in = tocopy < a->null_length ?
                    tocopy : a->null_length;
                state->crc = crc32(state->crc, a->nulls,
                    state->stream.avail_in);
                state->total_in += state->stream.avail_in;
                tocopy -= state->stream.avail_in;
                ret = drive_compressor(a, state, 0);
                if (ret != ARCHIVE_OK)
                    goto cleanup;
            }
        }

        /* Finish compression cycle */
        if (((ret = drive_compressor(a, state, 1))) != ARCHIVE_OK)
            goto cleanup;

        /* Build trailer: 4-byte CRC and 4-byte length. */
        trailer[0] = (state->crc)&0xff;
        trailer[1] = (state->crc >> 8)&0xff;
        trailer[2] = (state->crc >> 16)&0xff;
        trailer[3] = (state->crc >> 24)&0xff;
        trailer[4] = (state->total_in)&0xff;
        trailer[5] = (state->total_in >> 8)&0xff;
        trailer[6] = (state->total_in >> 16)&0xff;
        trailer[7] = (state->total_in >> 24)&0xff;

        /* Add trailer to current block. */
        tocopy = 8;
        if (tocopy > state->stream.avail_out)
            tocopy = state->stream.avail_out;
        memcpy(state->stream.next_out, trailer, tocopy);
        state->stream.next_out += tocopy;
        state->stream.avail_out -= tocopy;

        /* If it overflowed, flush and start a new block. */
        if (tocopy < 8) {
            bytes_written = (a->client_writer)(&a->archive, a->client_data,
                state->compressed, state->compressed_buffer_size);
            if (bytes_written <= 0) {
                ret = ARCHIVE_FATAL;
                goto cleanup;
            }
            a->archive.raw_position += bytes_written;
            state->stream.next_out = state->compressed;
            state->stream.avail_out = state->compressed_buffer_size;
            memcpy(state->stream.next_out, trailer + tocopy, 8-tocopy);
            state->stream.next_out += 8-tocopy;
            state->stream.avail_out -= 8-tocopy;
        }

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

        /* Tricky calculation to determine size of last block. */
        target_block_length = block_length;
        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->stream.next_out, 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;
            goto cleanup;
        }
        a->archive.raw_position += bytes_written;

        /* Cleanup: shut down compressor, release memory, etc. */
    cleanup:
        switch (deflateEnd(&(state->stream))) {
        case Z_OK:
            break;
        default:
            archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
                "Failed to clean up compressor");
            ret = ARCHIVE_FATAL;
        }
        free(state->compressed);
        free(state);
    }
    /* Clean up config area even if we never initialized. */
    free(a->compressor.config);
    a->compressor.config = NULL;
    return (ret);
}

/*
 * Utility function to push input data through compressor,
 * writing full output blocks as necessary.
 *
 * Note that this handles both the regular write case (finishing ==
 * false) and the end-of-archive case (finishing == true).
 */
static int
drive_compressor(struct archive_write *a, struct private_data *state, int finishing)
{
    ssize_t bytes_written;
    int ret;

    for (;;) {
        if (state->stream.avail_out == 0) {
            bytes_written = (a->client_writer)(&a->archive,
                a->client_data, state->compressed,
                state->compressed_buffer_size);
            if (bytes_written <= 0) {
                /* TODO: Handle this write failure */
                return (ARCHIVE_FATAL);
            } else if ((size_t)bytes_written < state->compressed_buffer_size) {
                /* Short write: Move remaining to
                 * front of block and keep filling */
                memmove(state->compressed,
                    state->compressed + bytes_written,
                    state->compressed_buffer_size - bytes_written);
            }
            a->archive.raw_position += bytes_written;
            state->stream.next_out
                = state->compressed +
                state->compressed_buffer_size - bytes_written;
            state->stream.avail_out = bytes_written;
        }

        /* If there's nothing to do, we're done. */
        if (!finishing && state->stream.avail_in == 0)
            return (ARCHIVE_OK);

        ret = deflate(&(state->stream),
            finishing ? Z_FINISH : Z_NO_FLUSH );

        switch (ret) {
        case Z_OK:
            /* In non-finishing case, check if compressor
             * consumed everything */
            if (!finishing && state->stream.avail_in == 0)
                return (ARCHIVE_OK);
            /* In finishing case, this return always means
             * there's more work */
            break;
        case Z_STREAM_END:
            /* This return can only occur in finishing case. */
            return (ARCHIVE_OK);
        default:
            /* Any other return value indicates an error. */
            archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
                "GZip compression failed:"
                " deflate() call returned status %d",
                ret);
            return (ARCHIVE_FATAL);
        }
    }
}

#endif /* HAVE_ZLIB_H */
