#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_obj(*strm);
        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 */
}