fs/cramfs/uncompress.c

   1 /*
   2  * uncompress.c
   3  *
   4  * Copyright (C) 1999 Linus Torvalds
   5  * Copyright (C) 2000-2002 Transmeta Corporation
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License (Version 2) as
   9  * published by the Free Software Foundation.
  10  *
  11  * cramfs interfaces to the uncompression library. There's really just
  12  * three entrypoints:
  13  *
  14  *  - cramfs_uncompress_init() - called to initialize the thing.
  15  *  - cramfs_uncompress_exit() - tell me when you're done
  16  *  - cramfs_uncompress_block() - uncompress a block.
  17  *
  18  * NOTE NOTE NOTE! The uncompression is entirely single-threaded. We
  19  * only have one stream, and we'll initialize it only once even if it
  20  * then is used by multiple filesystems.
  21  */
  22
  23 #include <linux/kernel.h>
  24 #include <linux/errno.h>
  25 #include <linux/vmalloc.h>
  26 #include <linux/zlib.h>
  27
  28 static z_stream stream;
  29 static int initialized;
  30
  31 /* Returns length of decompressed data. */
  32 int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen)
  33 {
  34         int err;
  35
  36         stream.next_in = src;
  37         stream.avail_in = srclen;
  38
  39         stream.next_out = dst;
  40         stream.avail_out = dstlen;
  41
  42         err = zlib_inflateReset(&stream);
  43         if (err != Z_OK) {
  44                 printk("zlib_inflateReset error %d\n", err);
  45                 zlib_inflateEnd(&stream);
  46                 zlib_inflateInit(&stream);
  47         }
  48
  49         err = zlib_inflate(&stream, Z_FINISH);
  50         if (err != Z_STREAM_END)
  51                 goto err;
  52         return stream.total_out;
  53
  54 err:
  55         printk("Error %d while decompressing!\n", err);
  56         printk("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
  57         return 0;
  58 }
  59
  60 int cramfs_uncompress_init(void)
  61 {
  62         if (!initialized++) {
  63                 stream.workspace = vmalloc(zlib_inflate_workspacesize());
  64                 if ( !stream.workspace ) {
  65                         initialized = 0;
  66                         return -ENOMEM;
  67                 }
  68                 stream.next_in = NULL;
  69                 stream.avail_in = 0;
  70                 zlib_inflateInit(&stream);
  71         }
  72         return 0;
  73 }
  74
  75 int cramfs_uncompress_exit(void)
  76 {
  77         if (!--initialized) {
  78                 zlib_inflateEnd(&stream);
  79                 vfree(stream.workspace);
  80         }
  81         return 0;
  82 }