/*
   * uncompress.c
   *
   * (C) Copyright 1999 Linus Torvalds
   *
   * cramfs interfaces to the uncompression library. There's really just
   * three entrypoints:
   *
   *  - cramfs_uncompress_init() - called to initialize the thing.
   *  - cramfs_uncompress_exit() - tell me when you're done
   *  - cramfs_uncompress_block() - uncompress a block.
   *
   * NOTE NOTE NOTE! The uncompression is entirely single-threaded. We
   * only have one stream, and we'll initialize it only once even if it
   * then is used by multiple filesystems.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/kernel.h>
  #include <linux/errno.h>
  #include <linux/vmalloc.h>
  #include <linux/zlib.h>

  #include "internal.h"

  
  static z_stream stream;
  static int initialized;
  
  /* Returns length of decompressed data. */
  int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen)
  {
  	int err;
  
  	stream.next_in = src;
  	stream.avail_in = srclen;
  
  	stream.next_out = dst;
  	stream.avail_out = dstlen;
  
  	err = zlib_inflateReset(&stream);
  	if (err != Z_OK) {

  		pr_err("zlib_inflateReset error %d
  ", err);

  		zlib_inflateEnd(&stream);
  		zlib_inflateInit(&stream);
  	}
  
  	err = zlib_inflate(&stream, Z_FINISH);
  	if (err != Z_STREAM_END)
  		goto err;
  	return stream.total_out;
  
  err:

  	pr_err("Error %d while decompressing!
  ", err);
  	pr_err("%p(%d)->%p(%d)
  ", src, srclen, dst, dstlen);

  	return -EIO;

  }
  
  int cramfs_uncompress_init(void)
  {
  	if (!initialized++) {
  		stream.workspace = vmalloc(zlib_inflate_workspacesize());

  		if (!stream.workspace) {

  			initialized = 0;
  			return -ENOMEM;
  		}
  		stream.next_in = NULL;
  		stream.avail_in = 0;
  		zlib_inflateInit(&stream);
  	}
  	return 0;
  }

  void cramfs_uncompress_exit(void)

  {
  	if (!--initialized) {
  		zlib_inflateEnd(&stream);
  		vfree(stream.workspace);
  	}

  }