From 135cdad8ca64ec38407fcd3515515574f2015dcf Mon Sep 17 00:00:00 2001 From: Mark Adler Date: Mon, 21 Aug 2023 13:48:56 -0700 Subject: [PATCH] Fix bug when gzungetc() is used immediately after gzopen(). --- gzread.c.in | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/gzread.c.in b/gzread.c.in index 67a21a3e..1fc7b370 100644 --- a/gzread.c.in +++ b/gzread.c.in @@ -445,6 +445,10 @@ int Z_EXPORT PREFIX(gzungetc)(int c, gzFile file) { return -1; state = (gz_state *)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)) return -1;