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 #include <linux/cramfs_fs.h>
  23
  24 static z_stream stream;
  25 static int initialized;
  26
  27 /* Returns length of decompressed data. */
  28 int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen)
  29 {
  30         int err;
  31
  32         stream.next_in = src;
  33         stream.avail_in = srclen;
  34
  35         stream.next_out = dst;
  36         stream.avail_out = dstlen;
  37
  38         err = zlib_inflateReset(&stream);
  39         if (err != Z_OK) {
  40                 printk("zlib_inflateReset error %d\n", err);
  41                 zlib_inflateEnd(&stream);
  42                 zlib_inflateInit(&stream);
  43         }
  44
  45         err = zlib_inflate(&stream, Z_FINISH);
  46         if (err != Z_STREAM_END)
  47                 goto err;
  48         return stream.total_out;
  49
  50 err:
  51         printk("Error %d while decompressing!\n", err);
  52         printk("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
  53         return 0;
  54 }
  55
  56 int cramfs_uncompress_init(void)
  57 {
  58         if (!initialized++) {
  59                 stream.workspace = vmalloc(zlib_inflate_workspacesize());
  60                 if ( !stream.workspace ) {
  61                         initialized = 0;
  62                         return -ENOMEM;
  63                 }
  64                 stream.next_in = NULL;
  65                 stream.avail_in = 0;
  66                 zlib_inflateInit(&stream);
  67         }
  68         return 0;
  69 }
  70
  71 void cramfs_uncompress_exit(void)
  72 {
  73         if (!--initialized) {
  74                 zlib_inflateEnd(&stream);
  75                 vfree(stream.workspace);
  76         }
  77 }