pgp-compress.c

Go to the documentation of this file.

/*
 * pgp-compress.c
 *    ZIP and ZLIB compression via zlib.
 *
 * Copyright (c) 2005 Marko Kreen
 * 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 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 AUTHOR 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.
 *
 * contrib/pgcrypto/pgp-compress.c
 */
 
#include "postgres.h"
 
#include "pgp.h"
#include "px.h"
 
/*
 * Compressed pkt writer
 */
 
#ifdef HAVE_LIBZ
 
#include <zlib.h>
 
#define ZIP_OUT_BUF 8192
#define ZIP_IN_BLOCK 8192
 
struct ZipStat
{
    uint8       type;
    int         buf_len;
    int         hdr_done;
    z_stream    stream;
    uint8       buf[ZIP_OUT_BUF];
};
 
static void *
z_alloc(void *priv, unsigned n_items, unsigned item_len)
{
    return palloc(n_items * item_len);
}
 
static void
z_free(void *priv, void *addr)
{
    pfree(addr);
}
 
static int
compress_init(PushFilter *next, void *init_arg, void **priv_p)
{
    int         res;
    struct ZipStat *st;
    PGP_Context *ctx = init_arg;
    uint8       type = ctx->compress_algo;
 
    if (type != PGP_COMPR_ZLIB && type != PGP_COMPR_ZIP)
        return PXE_PGP_UNSUPPORTED_COMPR;
 
    /*
     * init
     */
    st = palloc0_object(struct ZipStat);
    st->buf_len = ZIP_OUT_BUF;
    st->stream.zalloc = z_alloc;
    st->stream.zfree = z_free;
 
    if (type == PGP_COMPR_ZIP)
        res = deflateInit2(&st->stream, ctx->compress_level,
                           Z_DEFLATED, -15, 8, Z_DEFAULT_STRATEGY);
    else
        res = deflateInit(&st->stream, ctx->compress_level);
    if (res != Z_OK)
    {
        pfree(st);
        return PXE_PGP_COMPRESSION_ERROR;
    }
    *priv_p = st;
 
    return ZIP_IN_BLOCK;
}
 
/* writes compressed data packet */
 
/* can handle zero-len incoming data, but shouldn't */
static int
compress_process(PushFilter *next, void *priv, const uint8 *data, int len)
{
    int         res,
                n_out;
    struct ZipStat *st = priv;
 
    /*
     * process data
     */
    st->stream.next_in = data;
    st->stream.avail_in = len;
    while (st->stream.avail_in > 0)
    {
        st->stream.next_out = st->buf;
        st->stream.avail_out = st->buf_len;
        res = deflate(&st->stream, Z_NO_FLUSH);
        if (res != Z_OK)
            return PXE_PGP_COMPRESSION_ERROR;
 
        n_out = st->buf_len - st->stream.avail_out;
        if (n_out > 0)
        {
            res = pushf_write(next, st->buf, n_out);
            if (res < 0)
                return res;
        }
    }
 
    return 0;
}
 
static int
compress_flush(PushFilter *next, void *priv)
{
    int         res,
                zres,
                n_out;
    struct ZipStat *st = priv;
 
    st->stream.next_in = NULL;
    st->stream.avail_in = 0;
    while (1)
    {
        st->stream.next_out = st->buf;
        st->stream.avail_out = st->buf_len;
        zres = deflate(&st->stream, Z_FINISH);
        if (zres != Z_STREAM_END && zres != Z_OK)
            return PXE_PGP_COMPRESSION_ERROR;
 
        n_out = st->buf_len - st->stream.avail_out;
        if (n_out > 0)
        {
            res = pushf_write(next, st->buf, n_out);
            if (res < 0)
                return res;
        }
        if (zres == Z_STREAM_END)
            break;
    }
    return 0;
}
 
static void
compress_free(void *priv)
{
    struct ZipStat *st = priv;
 
    deflateEnd(&st->stream);
    px_memset(st, 0, sizeof(*st));
    pfree(st);
}
 
static const PushFilterOps
            compress_filter = {
    compress_init, compress_process, compress_flush, compress_free
};
 
int
pgp_compress_filter(PushFilter **res, PGP_Context *ctx, PushFilter *dst)
{
    return pushf_create(res, &compress_filter, ctx, dst);
}
 
/*
 * Decompress
 */
struct DecomprData
{
    int         buf_len;        /* = ZIP_OUT_BUF */
    int         buf_data;       /* available data */
    uint8      *pos;
    z_stream    stream;
    int         eof;
    uint8       buf[ZIP_OUT_BUF];
};
 
static int
decompress_init(void **priv_p, void *arg, PullFilter *src)
{
    PGP_Context *ctx = arg;
    struct DecomprData *dec;
    int         res;
 
    if (ctx->compress_algo != PGP_COMPR_ZLIB
        && ctx->compress_algo != PGP_COMPR_ZIP)
        return PXE_PGP_UNSUPPORTED_COMPR;
 
    dec = palloc0_object(struct DecomprData);
    dec->buf_len = ZIP_OUT_BUF;
    *priv_p = dec;
 
    dec->stream.zalloc = z_alloc;
    dec->stream.zfree = z_free;
 
    if (ctx->compress_algo == PGP_COMPR_ZIP)
        res = inflateInit2(&dec->stream, -15);
    else
        res = inflateInit(&dec->stream);
    if (res != Z_OK)
    {
        pfree(dec);
        px_debug("decompress_init: inflateInit error");
        return PXE_PGP_COMPRESSION_ERROR;
    }
 
    return 0;
}
 
static int
decompress_read(void *priv, PullFilter *src, int len,
                uint8 **data_p, uint8 *buf, int buflen)
{
    int         res;
    int         flush;
    struct DecomprData *dec = priv;
 
restart:
    if (dec->buf_data > 0)
    {
        if (len > dec->buf_data)
            len = dec->buf_data;
        *data_p = dec->pos;
        dec->pos += len;
        dec->buf_data -= len;
        return len;
    }
 
    if (dec->eof)
        return 0;
 
    if (dec->stream.avail_in == 0)
    {
        uint8      *tmp;
 
        res = pullf_read(src, 8192, &tmp);
        if (res < 0)
            return res;
        dec->stream.next_in = tmp;
        dec->stream.avail_in = res;
    }
 
    dec->stream.next_out = dec->buf;
    dec->stream.avail_out = dec->buf_len;
    dec->pos = dec->buf;
 
    /*
     * Z_SYNC_FLUSH is tell zlib to output as much as possible. It should do
     * it anyway (Z_NO_FLUSH), but seems to reserve the right not to.  So lets
     * follow the API.
     */
    flush = dec->stream.avail_in ? Z_SYNC_FLUSH : Z_FINISH;
    res = inflate(&dec->stream, flush);
    if (res != Z_OK && res != Z_STREAM_END)
    {
        px_debug("decompress_read: inflate error: %d", res);
        return PXE_PGP_CORRUPT_DATA;
    }
 
    dec->buf_data = dec->buf_len - dec->stream.avail_out;
    if (res == Z_STREAM_END)
    {
        uint8      *tmp;
 
        /*
         * A stream must be terminated by a normal packet.  If the last stream
         * packet in the source stream is a full packet, a normal empty packet
         * must follow.  Since the underlying packet reader doesn't know that
         * the compressed stream has been ended, we need to consume the
         * terminating packet here.  This read does not harm even if the
         * stream has already ended.
         */
        res = pullf_read(src, 1, &tmp);
 
        if (res < 0)
            return res;
        else if (res > 0)
        {
            px_debug("decompress_read: extra bytes after end of stream");
            return PXE_PGP_CORRUPT_DATA;
        }
        dec->eof = 1;
    }
    goto restart;
}
 
static void
decompress_free(void *priv)
{
    struct DecomprData *dec = priv;
 
    inflateEnd(&dec->stream);
    px_memset(dec, 0, sizeof(*dec));
    pfree(dec);
}
 
static const PullFilterOps
            decompress_filter = {
    decompress_init, decompress_read, decompress_free
};
 
int
pgp_decompress_filter(PullFilter **res, PGP_Context *ctx, PullFilter *src)
{
    return pullf_create(res, &decompress_filter, ctx, src);
}
#else                           /* !HAVE_LIBZ */
 
int
pgp_compress_filter(PushFilter **res, PGP_Context *ctx, PushFilter *dst)
{
    return PXE_PGP_UNSUPPORTED_COMPR;
}
 
int
pgp_decompress_filter(PullFilter **res, PGP_Context *ctx, PullFilter *src)
{
    return PXE_PGP_UNSUPPORTED_COMPR;
}
 
#endif