src/lib-compression/istream-lzma.c

	istream-lzma.c revision bcb4e51a409d94ae670de96afb8483a4f7855294
/* Copyright (c) 2010-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"

#ifdef HAVE_LZMA

#include "istream-private.h"
#include "istream-zlib.h"
#include <lzma.h>

#define CHUNK_SIZE (1024*64)

#define LZMA_MEMORY_LIMIT (1024*1024*80)

struct lzma_istream {
    struct istream_private istream;

    lzma_stream strm;
    uoff_t eof_offset, stream_size;
    size_t high_pos;
    struct stat last_parent_statbuf;

    bool log_errors:1;
    bool marked:1;
    bool strm_closed:1;
};

static void i_stream_lzma_close(struct iostream_private *stream,
                 bool close_parent)
{
    struct lzma_istream *zstream = (struct lzma_istream *)stream;

    if (!zstream->strm_closed) {
        lzma_end(&zstream->strm);
        zstream->strm_closed = TRUE;
    }
    if (close_parent)
        i_stream_close(zstream->istream.parent);
}

static void lzma_read_error(struct lzma_istream *zstream, const char *error)
{
    io_stream_set_error(&zstream->istream.iostream,
                "lzma.read(%s): %s at %"PRIuUOFF_T,
                i_stream_get_name(&zstream->istream.istream), error,
                i_stream_get_absolute_offset(&zstream->istream.istream));
    if (zstream->log_errors)
        i_error("%s", zstream->istream.iostream.error);
}

static void lzma_stream_end(struct lzma_istream *zstream)
{
    zstream->eof_offset = zstream->istream.istream.v_offset +
        (zstream->istream.pos - zstream->istream.skip);
    zstream->stream_size = zstream->eof_offset;
}

static ssize_t i_stream_lzma_read(struct istream_private *stream)
{
    struct lzma_istream *zstream = (struct lzma_istream *)stream;
    const unsigned char *data;
    uoff_t high_offset;
    size_t size, out_size;
    lzma_ret ret;

    high_offset = stream->istream.v_offset + (stream->pos - stream->skip);
    if (zstream->eof_offset == high_offset) {
        i_assert(zstream->high_pos == 0 ||
             zstream->high_pos == stream->pos);
        stream->istream.eof = TRUE;
        return -1;
    }

    if (stream->pos < zstream->high_pos) {
        /* we're here because we seeked back within the read buffer. */
        ret = zstream->high_pos - stream->pos;
        stream->pos = zstream->high_pos;
        zstream->high_pos = 0;

        if (zstream->eof_offset != (uoff_t)-1) {
            high_offset = stream->istream.v_offset +
                (stream->pos - stream->skip);
            i_assert(zstream->eof_offset == high_offset);
            stream->istream.eof = TRUE;
        }
        return ret;
    }
    zstream->high_pos = 0;

    if (!zstream->marked) {
        if (!i_stream_try_alloc(stream, CHUNK_SIZE, &out_size))
            return -2; /* buffer full */
    } else {
        /* try to avoid compressing, so we can quickly seek backwards */
        if (!i_stream_try_alloc_avoid_compress(stream, CHUNK_SIZE, &out_size))
            return -2; /* buffer full */
    }

    if (i_stream_read_more(stream->parent, &data, &size) < 0) {
        if (stream->parent->stream_errno != 0) {
            stream->istream.stream_errno =
                stream->parent->stream_errno;
        } else {
            i_assert(stream->parent->eof);
            lzma_stream_end(zstream);
            stream->istream.eof = TRUE;
        }
        return -1;
    }
    if (size == 0) {
        /* no more input */
        i_assert(!stream->istream.blocking);
        return 0;
    }

    zstream->strm.next_in = data;
    zstream->strm.avail_in = size;

    zstream->strm.next_out = stream->w_buffer + stream->pos;
    zstream->strm.avail_out = out_size;
    ret = lzma_code(&zstream->strm, LZMA_RUN);

    out_size -= zstream->strm.avail_out;
    stream->pos += out_size;

    i_stream_skip(stream->parent, size - zstream->strm.avail_in);

    switch (ret) {
    case LZMA_OK:
        break;
    case LZMA_DATA_ERROR:
    case LZMA_BUF_ERROR:
        lzma_read_error(zstream, "corrupted data");
        stream->istream.stream_errno = EINVAL;
        return -1;
    case LZMA_FORMAT_ERROR:
        lzma_read_error(zstream, "wrong magic in header (not xz file?)");
        stream->istream.stream_errno = EINVAL;
        return -1;
    case LZMA_OPTIONS_ERROR:
        lzma_read_error(zstream, "Unsupported xz options");
        stream->istream.stream_errno = EIO;
        return -1;
    case LZMA_MEM_ERROR:
        i_fatal_status(FATAL_OUTOFMEM, "lzma.read(%s): Out of memory",
                   i_stream_get_name(&stream->istream));
    case LZMA_STREAM_END:
        lzma_stream_end(zstream);
        if (out_size == 0) {
            stream->istream.eof = TRUE;
            return -1;
        }
        break;
    default:
        lzma_read_error(zstream, t_strdup_printf(
            "lzma_code() failed with %d", ret));
        stream->istream.stream_errno = EIO;
        return -1;
    }
    if (out_size == 0) {
        /* read more input */
        return i_stream_lzma_read(stream);
    }
    return out_size;
}

static void i_stream_lzma_init(struct lzma_istream *zstream)
{
    lzma_ret ret;

    ret = lzma_stream_decoder(&zstream->strm, LZMA_MEMORY_LIMIT,
                  LZMA_CONCATENATED);
    switch (ret) {
    case LZMA_OK:
        break;
    case LZMA_MEM_ERROR:
        i_fatal_status(FATAL_OUTOFMEM, "lzma: Out of memory");
    default:
        i_fatal("lzma_stream_decoder() failed with ret=%d", ret);
    }
}

static void i_stream_lzma_reset(struct lzma_istream *zstream)
{
    struct istream_private *stream = &zstream->istream;

    i_stream_seek(stream->parent, stream->parent_start_offset);
    zstream->eof_offset = (uoff_t)-1;
    zstream->strm.next_in = NULL;
    zstream->strm.avail_in = 0;

    stream->parent_expected_offset = stream->parent_start_offset;
    stream->skip = stream->pos = 0;
    stream->istream.v_offset = 0;
    zstream->high_pos = 0;

    lzma_end(&zstream->strm);
    i_stream_lzma_init(zstream);
}

static void
i_stream_lzma_seek(struct istream_private *stream, uoff_t v_offset, bool mark)
{
    struct lzma_istream *zstream = (struct lzma_istream *) stream;
    uoff_t start_offset = stream->istream.v_offset - stream->skip;

    if (v_offset < start_offset) {
        /* have to seek backwards */
        i_stream_lzma_reset(zstream);
        start_offset = 0;
    } else if (zstream->high_pos != 0) {
        stream->pos = zstream->high_pos;
        zstream->high_pos = 0;
    }

    if (v_offset <= start_offset + stream->pos) {
        /* seeking backwards within what's already cached */
        stream->skip = v_offset - start_offset;
        stream->istream.v_offset = v_offset;
        zstream->high_pos = stream->pos;
        stream->pos = stream->skip;
    } else {
        /* read and cache forward */
        ssize_t ret;

        do {
            size_t avail = stream->pos - stream->skip;

            if (stream->istream.v_offset + avail >= v_offset) {
                i_stream_skip(&stream->istream,
                          v_offset -
                          stream->istream.v_offset);
                ret = -1;
                break;
            }

            i_stream_skip(&stream->istream, avail);
        } while ((ret = i_stream_read(&stream->istream)) > 0);
        i_assert(ret == -1);

        if (stream->istream.v_offset != v_offset) {
            /* some failure, we've broken it */
            if (stream->istream.stream_errno != 0) {
                i_error("lzma_istream.seek(%s) failed: %s",
                    i_stream_get_name(&stream->istream),
                    strerror(stream->istream.stream_errno));
                i_stream_close(&stream->istream);
            } else {
                /* unexpected EOF. allow it since we may just
                   want to check if there's anything.. */
                i_assert(stream->istream.eof);
            }
        }
    }

    if (mark)
        zstream->marked = TRUE;
}

static int
i_stream_lzma_stat(struct istream_private *stream, bool exact)
{
    struct lzma_istream *zstream = (struct lzma_istream *) stream;
    const struct stat *st;
    size_t size;

    if (i_stream_stat(stream->parent, exact, &st) < 0) {
        stream->istream.stream_errno = stream->parent->stream_errno;
        return -1;
    }
    stream->statbuf = *st;

    /* when exact=FALSE always return the parent stat's size, even if we
       know the exact value. this is necessary because otherwise e.g. mbox
       code can see two different values and think that a compressed mbox
       file keeps changing. */
    if (!exact)
        return 0;

    if (zstream->stream_size == (uoff_t)-1) {
        uoff_t old_offset = stream->istream.v_offset;
        ssize_t ret;

        do {
            size = i_stream_get_data_size(&stream->istream);
            i_stream_skip(&stream->istream, size);
        } while ((ret = i_stream_read(&stream->istream)) > 0);
        i_assert(ret == -1);

        i_stream_seek(&stream->istream, old_offset);
        if (zstream->stream_size == (uoff_t)-1)
            return -1;
    }
    stream->statbuf.st_size = zstream->stream_size;
    return 0;
}

static void i_stream_lzma_sync(struct istream_private *stream)
{
    struct lzma_istream *zstream = (struct lzma_istream *) stream;
    const struct stat *st;

    if (i_stream_stat(stream->parent, FALSE, &st) < 0) {
        if (memcmp(&zstream->last_parent_statbuf,
               st, sizeof(*st)) == 0) {
            /* a compressed file doesn't change unexpectedly,
               don't clear our caches unnecessarily */
            return;
        }
        zstream->last_parent_statbuf = *st;
    }
    i_stream_lzma_reset(zstream);
}

struct istream *i_stream_create_lzma(struct istream *input, bool log_errors)
{
    struct lzma_istream *zstream;

    zstream = i_new(struct lzma_istream, 1);
    zstream->eof_offset = (uoff_t)-1;
    zstream->stream_size = (uoff_t)-1;
    zstream->log_errors = log_errors;

    i_stream_lzma_init(zstream);

    zstream->istream.iostream.close = i_stream_lzma_close;
    zstream->istream.max_buffer_size = input->real_stream->max_buffer_size;
    zstream->istream.read = i_stream_lzma_read;
    zstream->istream.seek = i_stream_lzma_seek;
    zstream->istream.stat = i_stream_lzma_stat;
    zstream->istream.sync = i_stream_lzma_sync;

    zstream->istream.istream.readable_fd = FALSE;
    zstream->istream.istream.blocking = input->blocking;
    zstream->istream.istream.seekable = input->seekable;

    return i_stream_create(&zstream->istream, input,
                   i_stream_get_fd(input), 0);
}
#endif