LXR linux/fs/cramfs/uncompress.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * uncompress.c
   4 *
   5 * (C) Copyright 1999 Linus Torvalds
   6 *
   7 * cramfs interfaces to the uncompression library. There's really just
   8 * three entrypoints:
   9 *
  10 *  - cramfs_uncompress_init() - called to initialize the thing.
  11 *  - cramfs_uncompress_exit() - tell me when you're done
  12 *  - cramfs_uncompress_block() - uncompress a block.
  13 *
  14 * NOTE NOTE NOTE! The uncompression is entirely single-threaded. We
  15 * only have one stream, and we'll initialize it only once even if it
  16 * then is used by multiple filesystems.
  17 */
  18
  19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21#include <linux/kernel.h>
  22#include <linux/errno.h>
  23#include <linux/vmalloc.h>
  24#include <linux/zlib.h>
  25#include "internal.h"
  26
  27static z_stream stream;
  28static int initialized;
  29
  30/* Returns length of decompressed data. */
  31int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen)
  32{
  33        int err;
  34
  35        stream.next_in = src;
  36        stream.avail_in = srclen;
  37
  38        stream.next_out = dst;
  39        stream.avail_out = dstlen;
  40
  41        err = zlib_inflateReset(&stream);
  42        if (err != Z_OK) {
  43                pr_err("zlib_inflateReset error %d\n", err);
  44                zlib_inflateEnd(&stream);
  45                zlib_inflateInit(&stream);
  46        }
  47
  48        err = zlib_inflate(&stream, Z_FINISH);
  49        if (err != Z_STREAM_END)
  50                goto err;
  51        return stream.total_out;
  52
  53err:
  54        pr_err("Error %d while decompressing!\n", err);
  55        pr_err("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
  56        return -EIO;
  57}
  58
  59int cramfs_uncompress_init(void)
  60{
  61        if (!initialized++) {
  62                stream.workspace = vmalloc(zlib_inflate_workspacesize());
  63                if (!stream.workspace) {
  64                        initialized = 0;
  65                        return -ENOMEM;
  66                }
  67                stream.next_in = NULL;
  68                stream.avail_in = 0;
  69                zlib_inflateInit(&stream);
  70        }
  71        return 0;
  72}
  73
  74void cramfs_uncompress_exit(void)
  75{
  76        if (!--initialized) {
  77                zlib_inflateEnd(&stream);
  78                vfree(stream.workspace);
  79        }
  80}
  81