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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19
  20 #include <linux/kernel.h>
  21 #include <linux/errno.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/zlib.h>
  24 #include "internal.h"
  25
  26 static z_stream stream;
  27 static int initialized;
  28
  29 /* Returns length of decompressed data. */
  30 int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen)
  31 {
  32         int err;
  33
  34         stream.next_in = src;
  35         stream.avail_in = srclen;
  36
  37         stream.next_out = dst;
  38         stream.avail_out = dstlen;
  39
  40         err = zlib_inflateReset(&stream);
  41         if (err != Z_OK) {
  42                 pr_err("zlib_inflateReset error %d\n", err);
  43                 zlib_inflateEnd(&stream);
  44                 zlib_inflateInit(&stream);
  45         }
  46
  47         err = zlib_inflate(&stream, Z_FINISH);
  48         if (err != Z_STREAM_END)
  49                 goto err;
  50         return stream.total_out;
  51
  52 err:
  53         pr_err("Error %d while decompressing!\n", err);
  54         pr_err("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
  55         return -EIO;
  56 }
  57
  58 int cramfs_uncompress_init(void)
  59 {
  60         if (!initialized++) {
  61                 stream.workspace = vmalloc(zlib_inflate_workspacesize());
  62                 if (!stream.workspace) {
  63                         initialized = 0;
  64                         return -ENOMEM;
  65                 }
  66                 stream.next_in = NULL;
  67                 stream.avail_in = 0;
  68                 zlib_inflateInit(&stream);
  69         }
  70         return 0;
  71 }
  72
  73 void cramfs_uncompress_exit(void)
  74 {
  75         if (!--initialized) {
  76                 zlib_inflateEnd(&stream);
  77                 vfree(stream.workspace);
  78         }
  79 }