#include "zutil.h"
#include "zlib.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 */
}
