uncompress.c

Go to the documentation of this file.

/*
 * uncompress.c
 *
 * (C) Copyright 1999 Linus Torvalds
 *
 * cramfs interfaces to the uncompression library. There's really just
 * three entrypoints:
 *
 *  - cramfs_uncompress_init() - called to initialize the thing.
 *  - cramfs_uncompress_exit() - tell me when you're done
 *  - cramfs_uncompress_block() - uncompress a block.
 *
 * NOTE NOTE NOTE! The uncompression is entirely single-threaded. We
 * only have one stream, and we'll initialize it only once even if it
 * then is used by multiple filesystems.
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/vmalloc.h>
#include <linux/zlib.h>
#include <linux/cramfs_fs.h>

static z_stream stream;
static int initialized;

/* Returns length of decompressed data. */
int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen)
{
    int err;

    stream.next_in = src;
    stream.avail_in = srclen;

    stream.next_out = dst;
    stream.avail_out = dstlen;

    err = zlib_inflateReset(&stream);
    if (err != Z_OK) {
        printk("zlib_inflateReset error %d\n", err);
        zlib_inflateEnd(&stream);
        zlib_inflateInit(&stream);
    }

    err = zlib_inflate(&stream, Z_FINISH);
    if (err != Z_STREAM_END)
        goto err;
    return stream.total_out;

err:
    printk("Error %d while decompressing!\n", err);
    printk("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
    return -EIO;
}

int cramfs_uncompress_init(void)
{
    if (!initialized++) {
        stream.workspace = vmalloc(zlib_inflate_workspacesize());
        if ( !stream.workspace ) {
            initialized = 0;
            return -ENOMEM;
        }
        stream.next_in = NULL;
        stream.avail_in = 0;
        zlib_inflateInit(&stream);
    }
    return 0;
}

void cramfs_uncompress_exit(void)
{
    if (!--initialized) {
        zlib_inflateEnd(&stream);
        vfree(stream.workspace);
    }
}