compr_zlib.c

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/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2001-2007 Red Hat, Inc.
 * Copyright © 2004-2010 David Woodhouse <[email protected]>
 *
 * Created by David Woodhouse <[email protected]>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 */

#if !defined(__KERNEL__) && !defined(__ECOS)
#error "The userspace support got too messy and was removed. Update your mkfs.jffs2"
#endif

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/zlib.h>
#include <linux/zutil.h>
#include "nodelist.h"
#include "compr.h"

    /* Plan: call deflate() with avail_in == *sourcelen,
        avail_out = *dstlen - 12 and flush == Z_FINISH.
        If it doesn't manage to finish, call it again with
        avail_in == 0 and avail_out set to the remaining 12
        bytes for it to clean up.
       Q: Is 12 bytes sufficient?
    */
#define STREAM_END_SPACE 12

static DEFINE_MUTEX(deflate_mutex);
static DEFINE_MUTEX(inflate_mutex);
static z_stream inf_strm, def_strm;

#ifdef __KERNEL__ /* Linux-only */
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/mutex.h>

static int __init alloc_workspaces(void)
{
    def_strm.workspace = vmalloc(zlib_deflate_workspacesize(MAX_WBITS,
                            MAX_MEM_LEVEL));
    if (!def_strm.workspace)
        return -ENOMEM;

    jffs2_dbg(1, "Allocated %d bytes for deflate workspace\n",
          zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL));
    inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
    if (!inf_strm.workspace) {
        vfree(def_strm.workspace);
        return -ENOMEM;
    }
    jffs2_dbg(1, "Allocated %d bytes for inflate workspace\n",
          zlib_inflate_workspacesize());
    return 0;
}

static void free_workspaces(void)
{
    vfree(def_strm.workspace);
    vfree(inf_strm.workspace);
}
#else
#define alloc_workspaces() (0)
#define free_workspaces() do { } while(0)
#endif /* __KERNEL__ */

static int jffs2_zlib_compress(unsigned char *data_in,
                   unsigned char *cpage_out,
                   uint32_t *sourcelen, uint32_t *dstlen)
{
    int ret;

    if (*dstlen <= STREAM_END_SPACE)
        return -1;

    mutex_lock(&deflate_mutex);

    if (Z_OK != zlib_deflateInit(&def_strm, 3)) {
        pr_warn("deflateInit failed\n");
        mutex_unlock(&deflate_mutex);
        return -1;
    }

    def_strm.next_in = data_in;
    def_strm.total_in = 0;

    def_strm.next_out = cpage_out;
    def_strm.total_out = 0;

    while (def_strm.total_out < *dstlen - STREAM_END_SPACE && def_strm.total_in < *sourcelen) {
        def_strm.avail_out = *dstlen - (def_strm.total_out + STREAM_END_SPACE);
        def_strm.avail_in = min((unsigned)(*sourcelen-def_strm.total_in), def_strm.avail_out);
        jffs2_dbg(1, "calling deflate with avail_in %d, avail_out %d\n",
              def_strm.avail_in, def_strm.avail_out);
        ret = zlib_deflate(&def_strm, Z_PARTIAL_FLUSH);
        jffs2_dbg(1, "deflate returned with avail_in %d, avail_out %d, total_in %ld, total_out %ld\n",
              def_strm.avail_in, def_strm.avail_out,
              def_strm.total_in, def_strm.total_out);
        if (ret != Z_OK) {
            jffs2_dbg(1, "deflate in loop returned %d\n", ret);
            zlib_deflateEnd(&def_strm);
            mutex_unlock(&deflate_mutex);
            return -1;
        }
    }
    def_strm.avail_out += STREAM_END_SPACE;
    def_strm.avail_in = 0;
    ret = zlib_deflate(&def_strm, Z_FINISH);
    zlib_deflateEnd(&def_strm);

    if (ret != Z_STREAM_END) {
        jffs2_dbg(1, "final deflate returned %d\n", ret);
        ret = -1;
        goto out;
    }

    if (def_strm.total_out >= def_strm.total_in) {
        jffs2_dbg(1, "zlib compressed %ld bytes into %ld; failing\n",
              def_strm.total_in, def_strm.total_out);
        ret = -1;
        goto out;
    }

    jffs2_dbg(1, "zlib compressed %ld bytes into %ld\n",
          def_strm.total_in, def_strm.total_out);

    *dstlen = def_strm.total_out;
    *sourcelen = def_strm.total_in;
    ret = 0;
 out:
    mutex_unlock(&deflate_mutex);
    return ret;
}

static int jffs2_zlib_decompress(unsigned char *data_in,
                 unsigned char *cpage_out,
                 uint32_t srclen, uint32_t destlen)
{
    int ret;
    int wbits = MAX_WBITS;

    mutex_lock(&inflate_mutex);

    inf_strm.next_in = data_in;
    inf_strm.avail_in = srclen;
    inf_strm.total_in = 0;

    inf_strm.next_out = cpage_out;
    inf_strm.avail_out = destlen;
    inf_strm.total_out = 0;

    /* If it's deflate, and it's got no preset dictionary, then
       we can tell zlib to skip the adler32 check. */
    if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
        ((data_in[0] & 0x0f) == Z_DEFLATED) &&
        !(((data_in[0]<<8) + data_in[1]) % 31)) {

        jffs2_dbg(2, "inflate skipping adler32\n");
        wbits = -((data_in[0] >> 4) + 8);
        inf_strm.next_in += 2;
        inf_strm.avail_in -= 2;
    } else {
        /* Let this remain D1 for now -- it should never happen */
        jffs2_dbg(1, "inflate not skipping adler32\n");
    }


    if (Z_OK != zlib_inflateInit2(&inf_strm, wbits)) {
        pr_warn("inflateInit failed\n");
        mutex_unlock(&inflate_mutex);
        return 1;
    }

    while((ret = zlib_inflate(&inf_strm, Z_FINISH)) == Z_OK)
        ;
    if (ret != Z_STREAM_END) {
        pr_notice("inflate returned %d\n", ret);
    }
    zlib_inflateEnd(&inf_strm);
    mutex_unlock(&inflate_mutex);
    return 0;
}

static struct jffs2_compressor jffs2_zlib_comp = {
    .priority = JFFS2_ZLIB_PRIORITY,
    .name = "zlib",
    .compr = JFFS2_COMPR_ZLIB,
    .compress = &jffs2_zlib_compress,
    .decompress = &jffs2_zlib_decompress,
#ifdef JFFS2_ZLIB_DISABLED
    .disabled = 1,
#else
    .disabled = 0,
#endif
};

int __init jffs2_zlib_init(void)
{
    int ret;

    ret = alloc_workspaces();
    if (ret)
        return ret;

    ret = jffs2_register_compressor(&jffs2_zlib_comp);
    if (ret)
        free_workspaces();

    return ret;
}

void jffs2_zlib_exit(void)
{
    jffs2_unregister_compressor(&jffs2_zlib_comp);
    free_workspaces();
}