1 files changed, 10 insertions, 4 deletions

diff --git a/gzio.c b/gzio.c
index e29198a..f7c336a 100644
--- a/gzio.c
+++ b/gzio.c
@@ -414,10 +414,14 @@ int ZEXPORT gzread (file, buf, len)
             s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
             start = s->stream.next_out;
 
-            if (getLong(s) != s->crc || getLong(s) != s->stream.total_out) {
+            if (getLong(s) != s->crc) {
                 s->z_err = Z_DATA_ERROR;
             } else {
-                /* Check for concatenated .gz files: */
+                (void)getLong(s);
+                /* The uncompressed length returned by above getlong() may
+                 * be different from s->stream.total_out) in case of
+                 * concatenated .gz files. Check for such files:
+                 */
                 check_header(s);
                 if (s->z_err == Z_OK) {
                     uLong total_in = s->stream.total_in;
@@ -670,7 +674,7 @@ z_off_t ZEXPORT gzseek (file, offset, whence)
         return -1L;
 #else
         if (whence == SEEK_SET) {
-            offset -= s->stream.total_out;
+            offset -= s->stream.total_in;
         }
         if (offset < 0) return -1L;
 
@@ -745,6 +749,7 @@ int ZEXPORT gzrewind (file)
     s->z_eof = 0;
     s->stream.avail_in = 0;
     s->stream.next_in = s->inbuf;
+    s->crc = crc32(0L, Z_NULL, 0);
         
     if (s->startpos == 0) { /* not a compressed file */
         rewind(s->file);
@@ -793,7 +798,8 @@ local void putLong (file, x)
 }
 
 /* ===========================================================================
-   Reads a long in LSB order from the given gz_stream. Sets 
+   Reads a long in LSB order from the given gz_stream. Sets z_err in case
+   of error.
 */
 local uLong getLong (s)
     gz_stream *s;