#include <linux/zutil.h>
  #include <linux/errno.h>
  #include <linux/slab.h>
  #include <linux/vmalloc.h>
  
  /* Utility function: initialize zlib, unpack binary blob, clean up zlib,
   * return len or negative error code.
   */
  int zlib_inflate_blob(void *gunzip_buf, unsigned int sz,
  		      const void *buf, unsigned int len)
  {
  	const u8 *zbuf = buf;
  	struct z_stream_s *strm;
  	int rc;
  
  	rc = -ENOMEM;
  	strm = kmalloc(sizeof(*strm), GFP_KERNEL);
  	if (strm == NULL)
  		goto gunzip_nomem1;
  	strm->workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
  	if (strm->workspace == NULL)
  		goto gunzip_nomem2;
  
  	/* gzip header (1f,8b,08... 10 bytes total + possible asciz filename)
  	 * expected to be stripped from input
  	 */
  	strm->next_in = zbuf;
  	strm->avail_in = len;
  	strm->next_out = gunzip_buf;
  	strm->avail_out = sz;
  
  	rc = zlib_inflateInit2(strm, -MAX_WBITS);
  	if (rc == Z_OK) {
  		rc = zlib_inflate(strm, Z_FINISH);
  		/* after Z_FINISH, only Z_STREAM_END is "we unpacked it all" */
  		if (rc == Z_STREAM_END)
  			rc = sz - strm->avail_out;
  		else
  			rc = -EINVAL;
  		zlib_inflateEnd(strm);
  	} else
  		rc = -EINVAL;
  
  	kfree(strm->workspace);
  gunzip_nomem2:
  	kfree(strm);
  gunzip_nomem1:
  	return rc; /* returns Z_OK (0) if successful */
  }