Systemd/src/journal/compress.c

/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright 2011 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <lzma.h>

#include "compress.h"
#include "macro.h"
#include "util.h"

bool compress_blob(const void *src, uint64_t src_size, void *dst, uint64_t *dst_size) {
        lzma_ret ret;
        size_t out_pos = 0;

        assert(src);
        assert(src_size > 0);
        assert(dst);
        assert(dst_size);

        /* Returns false if we couldn't compress the data or the
         * compressed result is longer than the original */

        ret = lzma_easy_buffer_encode(LZMA_PRESET_DEFAULT, LZMA_CHECK_NONE, NULL,
                                      src, src_size, dst, &out_pos, src_size);
        if (ret != LZMA_OK)
                return false;

        /* Is it actually shorter? */
        if (out_pos == src_size)
                return false;

        *dst_size = out_pos;
        return true;
}

bool uncompress_blob(const void *src, uint64_t src_size,
                     void **dst, uint64_t *dst_alloc_size, uint64_t* dst_size, uint64_t dst_max) {

        lzma_stream s = LZMA_STREAM_INIT;
        lzma_ret ret;
        uint64_t space;
        bool b = false;

        assert(src);
        assert(src_size > 0);
        assert(dst);
        assert(dst_alloc_size);
        assert(dst_size);
        assert(*dst_alloc_size == 0 || *dst);

        ret = lzma_stream_decoder(&s, UINT64_MAX, 0);
        if (ret != LZMA_OK)
                return false;

        if (*dst_alloc_size <= src_size) {
                void *p;

                p = realloc(*dst, src_size*2);
                if (!p)
                        return false;

                *dst = p;
                *dst_alloc_size = src_size*2;
        }

        s.next_in = src;
        s.avail_in = src_size;

        s.next_out = *dst;
        space = dst_max > 0 ? MIN(*dst_alloc_size, dst_max) : *dst_alloc_size;
        s.avail_out = space;

        for (;;) {
                void *p;

                ret = lzma_code(&s, LZMA_FINISH);

                if (ret == LZMA_STREAM_END)
                        break;

                if (ret != LZMA_OK)
                        goto fail;

                if (dst_max > 0 && (space - s.avail_out) >= dst_max)
                        break;

                p = realloc(*dst, space*2);
                if (!p)
                        goto fail;

                s.next_out = (uint8_t*) p + ((uint8_t*) s.next_out - (uint8_t*) *dst);
                s.avail_out += space;

                space *= 2;

                *dst = p;
                *dst_alloc_size = space;
        }

        *dst_size = space - s.avail_out;
        b = true;

fail:
        lzma_end(&s);

        return b;
}

bool uncompress_startswith(const void *src, uint64_t src_size,
                           void **buffer, uint64_t *buffer_size,
                           const void *prefix, uint64_t prefix_len,
                           uint8_t extra) {

        lzma_stream s = LZMA_STREAM_INIT;
        lzma_ret ret;
        bool b = false;

        /* Checks whether the uncompressed blob starts with the
         * mentioned prefix. The byte extra needs to follow the
         * prefix */

        assert(src);
        assert(src_size > 0);
        assert(buffer);
        assert(buffer_size);
        assert(prefix);
        assert(*buffer_size == 0 || *buffer);

        ret = lzma_stream_decoder(&s, UINT64_MAX, 0);
        if (ret != LZMA_OK)
                return false;

        if (*buffer_size <= prefix_len) {
                void *p;

                p = realloc(*buffer, prefix_len*2);
                if (!p)
                        return false;

                *buffer = p;
                *buffer_size = prefix_len*2;
        }

        s.next_in = src;
        s.avail_in = src_size;

        s.next_out = *buffer;
        s.avail_out = *buffer_size;

        for (;;) {
                void *p;

                ret = lzma_code(&s, LZMA_FINISH);

                if (ret != LZMA_STREAM_END && ret != LZMA_OK)
                        goto fail;

                if ((*buffer_size - s.avail_out > prefix_len) &&
                    memcmp(*buffer, prefix, prefix_len) == 0 &&
                    ((const uint8_t*) *buffer)[prefix_len] == extra)
                        break;

                if (ret == LZMA_STREAM_END)
                        goto fail;

                p = realloc(*buffer, *buffer_size*2);
                if (!p)
                        goto fail;

                s.next_out = (uint8_t*) p + ((uint8_t*) s.next_out - (uint8_t*) *buffer);
                s.avail_out += *buffer_size;

                *buffer = p;
                *buffer_size *= 2;
        }

        b = true;

fail:
        lzma_end(&s);

        return b;
}

int compress_stream(int fdf, int fdt, uint32_t preset, off_t max_bytes) {
        _cleanup_(lzma_end) lzma_stream s = LZMA_STREAM_INIT;
        lzma_ret ret;

        uint8_t buf[BUFSIZ], out[BUFSIZ];
        lzma_action action = LZMA_RUN;

        assert(fdf >= 0);
        assert(fdt >= 0);

        ret = lzma_easy_encoder(&s, preset, LZMA_CHECK_CRC64);
        if (ret != LZMA_OK) {
                log_error("Failed to initialize XZ encoder: code %d", ret);
                return -EINVAL;
        }

        for (;;) {
                if (s.avail_in == 0 && action == LZMA_RUN) {
                        size_t m = sizeof(buf);
                        ssize_t n;

                        if (max_bytes != -1 && m > (size_t) max_bytes)
                                m = max_bytes;

                        n = read(fdf, buf, m);
                        if (n < 0)
                                return -errno;
                        if (n == 0)
                                action = LZMA_FINISH;
                        else {
                                s.next_in = buf;
                                s.avail_in = n;

                                if (max_bytes != -1) {
                                        assert(max_bytes >= n);
                                        max_bytes -= n;
                                }
                        }
                }

                if (s.avail_out == 0) {
                        s.next_out = out;
                        s.avail_out = sizeof(out);
                }

                ret = lzma_code(&s, action);
                if (ret != LZMA_OK && ret != LZMA_STREAM_END) {
                        log_error("Compression failed: code %d", ret);
                        return -EBADMSG;
                }

                if (s.avail_out == 0 || ret == LZMA_STREAM_END) {
                        ssize_t n, k;

                        n = sizeof(out) - s.avail_out;

                        errno = 0;
                        k = loop_write(fdt, out, n, false);
                        if (k < 0)
                                return k;
                        if (k != n)
                                return errno ? -errno : -EIO;

                        if (ret == LZMA_STREAM_END) {
                                log_debug("Compression finished (%zu -> %zu bytes, %.1f%%)",
                                          s.total_in, s.total_out,
                                          (double) s.total_out / s.total_in * 100);

                                return 0;
                        }
                }
        }
}

int decompress_stream(int fdf, int fdt, off_t max_bytes) {
        _cleanup_(lzma_end) lzma_stream s = LZMA_STREAM_INIT;
        lzma_ret ret;

        uint8_t buf[BUFSIZ], out[BUFSIZ];
        lzma_action action = LZMA_RUN;

        assert(fdf >= 0);
        assert(fdt >= 0);

        ret = lzma_stream_decoder(&s, UINT64_MAX, 0);
        if (ret != LZMA_OK) {
                log_error("Failed to initialize XZ decoder: code %d", ret);
                return -EINVAL;
        }

        for (;;) {
                if (s.avail_in == 0 && action == LZMA_RUN) {
                        ssize_t n;

                        n = read(fdf, buf, sizeof(buf));
                        if (n < 0)
                                return -errno;
                        if (n == 0)
                                action = LZMA_FINISH;
                        else {
                                s.next_in = buf;
                                s.avail_in = n;
                        }
                }

                if (s.avail_out == 0) {
                        s.next_out = out;
                        s.avail_out = sizeof(out);
                }

                ret = lzma_code(&s, action);
                if (ret != LZMA_OK && ret != LZMA_STREAM_END) {
                        log_error("Decompression failed: code %d", ret);
                        return -EBADMSG;
                }

                if (s.avail_out == 0 || ret == LZMA_STREAM_END) {
                        ssize_t n, k;

                        n = sizeof(out) - s.avail_out;

                        if (max_bytes != -1) {
                                if (max_bytes < n)
                                        return -E2BIG;

                                max_bytes -= n;
                        }

                        errno = 0;
                        k = loop_write(fdt, out, n, false);
                        if (k < 0)
                                return k;
                        if (k != n)
                                return errno ? -errno : -EIO;

                        if (ret == LZMA_STREAM_END) {
                                log_debug("Decompression finished (%zu -> %zu bytes, %.1f%%)",
                                          s.total_in, s.total_out,
                                          (double) s.total_out / s.total_in * 100);

                                return 0;
                        }
                }
        }
}