From: tb <tb@openbsd.org>
Date: Sat, 12 Aug 2023 13:49:29 +0000 (+0000)
Subject: Fix bug when gzungetc() is used immediately after gzopen().
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=caf6bd1d575af699bee0a8879806121769df6981;p=openbsd

Fix bug when gzungetc() is used immediately after gzopen().

from upstream
---

diff --git a/lib/libz/gzread.c b/lib/libz/gzread.c
index 6034a282371..4168cbc8875 100644
--- a/lib/libz/gzread.c
+++ b/lib/libz/gzread.c
@@ -443,6 +443,10 @@ int ZEXPORT gzungetc(int c, gzFile file) {
         return -1;
     state = (gz_statep)file;
 
+    /* in case this was just opened, set up the input buffer */
+    if (state->mode == GZ_READ && state->how == LOOK && state->x.have == 0)
+        (void)gz_look(state);
+
     /* check that we're reading and that there's no (serious) error */
     if (state->mode != GZ_READ ||
         (state->err != Z_OK && state->err != Z_BUF_ERROR))