fs/cramfs/uncompress.c

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