src/lib-compression/ostream-bzlib.c

/* Copyright (c) 2010-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"

#ifdef HAVE_BZLIB

#include "ostream-private.h"
#include "ostream-zlib.h"
#include <bzlib.h>

#define CHUNK_SIZE (1024*64)

struct bzlib_ostream {
    struct ostream_private ostream;
    bz_stream zs;

    char outbuf[CHUNK_SIZE];
    unsigned int outbuf_offset, outbuf_used;

    bool flushed:1;
};

static void o_stream_bzlib_close(struct iostream_private *stream,
                 bool close_parent)
{
    struct bzlib_ostream *zstream = (struct bzlib_ostream *)stream;

    (void)BZ2_bzCompressEnd(&zstream->zs);
    if (close_parent)
        o_stream_close(zstream->ostream.parent);
}

static int o_stream_zlib_send_outbuf(struct bzlib_ostream *zstream)
{
    ssize_t ret;
    size_t size;

    if (zstream->outbuf_used == 0)
        return 1;

    size = zstream->outbuf_used - zstream->outbuf_offset;
    i_assert(size > 0);
    ret = o_stream_send(zstream->ostream.parent,
                zstream->outbuf + zstream->outbuf_offset, size);
    if (ret < 0) {
        o_stream_copy_error_from_parent(&zstream->ostream);
        return -1;
    }
    if ((size_t)ret != size) {
        zstream->outbuf_offset += ret;
        return 0;
    }
    zstream->outbuf_offset = 0;
    zstream->outbuf_used = 0;
    return 1;
}

static ssize_t
o_stream_bzlib_send_chunk(struct bzlib_ostream *zstream,
              const void *data, size_t size)
{
    bz_stream *zs = &zstream->zs;
    int ret;

    i_assert(zstream->outbuf_used == 0);

    zs->next_in = (void *)data;
    zs->avail_in = size;
    while (zs->avail_in > 0) {
        if (zs->avail_out == 0) {
            /* previous block was compressed. send it and start
               compression for a new block. */
            zs->next_out = zstream->outbuf;
            zs->avail_out = sizeof(zstream->outbuf);

            zstream->outbuf_used = sizeof(zstream->outbuf);
            if ((ret = o_stream_zlib_send_outbuf(zstream)) < 0)
                return -1;
            if (ret == 0) {
                /* parent stream's buffer full */
                break;
            }
        }

        switch (BZ2_bzCompress(zs, BZ_RUN)) {
        case BZ_RUN_OK:
            break;
        default:
            i_unreached();
        }
    }
    size -= zs->avail_in;

    zstream->flushed = FALSE;
    return size;
}

static int o_stream_bzlib_send_flush(struct bzlib_ostream *zstream)
{
    bz_stream *zs = &zstream->zs;
    size_t len;
    bool done = FALSE;
    int ret;

    i_assert(zs->avail_in == 0);

    if (zstream->flushed)
        return 0;

    if ((ret = o_stream_flush_parent_if_needed(&zstream->ostream)) <= 0)
        return ret;
    if ((ret = o_stream_zlib_send_outbuf(zstream)) <= 0)
        return ret;

    i_assert(zstream->outbuf_used == 0);
    do {
        len = sizeof(zstream->outbuf) - zs->avail_out;
        if (len != 0) {
            zs->next_out = zstream->outbuf;
            zs->avail_out = sizeof(zstream->outbuf);

            zstream->outbuf_used = len;
            if ((ret = o_stream_zlib_send_outbuf(zstream)) <= 0)
                return ret;
            if (done)
                break;
        }

        ret = BZ2_bzCompress(zs, BZ_FINISH);
        switch (ret) {
        case BZ_STREAM_END:
            done = TRUE;
            break;
        case BZ_FINISH_OK:
            break;
        default:
            i_unreached();
        }
    } while (zs->avail_out != sizeof(zstream->outbuf));

    zstream->flushed = TRUE;
    return 0;
}

static int o_stream_bzlib_flush(struct ostream_private *stream)
{
    struct bzlib_ostream *zstream = (struct bzlib_ostream *)stream;

    if (o_stream_bzlib_send_flush(zstream) < 0)
        return -1;

    return o_stream_flush_parent(stream);
}

static ssize_t
o_stream_bzlib_sendv(struct ostream_private *stream,
            const struct const_iovec *iov, unsigned int iov_count)
{
    struct bzlib_ostream *zstream = (struct bzlib_ostream *)stream;
    ssize_t ret, bytes = 0;
    unsigned int i;

    if ((ret = o_stream_zlib_send_outbuf(zstream)) <= 0) {
        /* error / we still couldn't flush existing data to
           parent stream. */
        return ret;
    }

    for (i = 0; i < iov_count; i++) {
        ret = o_stream_bzlib_send_chunk(zstream, iov[i].iov_base,
                        iov[i].iov_len);
        if (ret < 0)
            return -1;
        bytes += ret;
        if ((size_t)ret != iov[i].iov_len)
            break;
    }
    stream->ostream.offset += bytes;

    /* avail_in!=0 check is used to detect errors. if it's non-zero here
       it simply means we didn't send all the data */
    zstream->zs.avail_in = 0;
    return bytes;
}

struct ostream *o_stream_create_bz2(struct ostream *output, int level)
{
    struct bzlib_ostream *zstream;
    int ret;

    i_assert(level >= 1 && level <= 9);

    zstream = i_new(struct bzlib_ostream, 1);
    zstream->ostream.sendv = o_stream_bzlib_sendv;
    zstream->ostream.flush = o_stream_bzlib_flush;
    zstream->ostream.iostream.close = o_stream_bzlib_close;

    ret = BZ2_bzCompressInit(&zstream->zs, level, 0, 0);
    switch (ret) {
    case BZ_OK:
        break;
    case BZ_MEM_ERROR:
        i_fatal_status(FATAL_OUTOFMEM,
                   "bzlib: Out of memory");
    case BZ_CONFIG_ERROR:
        i_fatal("Wrong bzlib library version (broken compilation)");
    case BZ_PARAM_ERROR:
        i_fatal("bzlib: Invalid parameters");
    default:
        i_fatal("BZ2_bzCompressInit() failed with %d", ret);
    }

    zstream->zs.next_out = zstream->outbuf;
    zstream->zs.avail_out = sizeof(zstream->outbuf);
    return o_stream_create(&zstream->ostream, output,
                   o_stream_get_fd(output));
}
#endif