From 7e8afbb6d605006d7cb867362b225d21c4f5ae57 Mon Sep 17 00:00:00 2001 From: "Pedro F. Giffuni" Date: Sun, 3 Dec 2023 12:33:03 -0500 Subject: [PATCH] patch: fix locate_hunk in empty files if `first_guess' is zero then main() assumes that locate_hunk has failed and aborts the patch operation. Instead, make sure to return 1 (the line number) so that the patch operation can continue. Issue originally found by Neels Hofmeyr in the regress suite of the diff implementation for got, where the tests assume that applying a diff with `patch' and then again with `patch -R' yields back the original file. Obtained from: OpenBSD (CVS patch.c,v 1.71) --- usr.bin/patch/patch.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/usr.bin/patch/patch.c b/usr.bin/patch/patch.c index ecaf799fe9b..403189bc92b 100644 --- a/usr.bin/patch/patch.c +++ b/usr.bin/patch/patch.c @@ -717,6 +717,8 @@ locate_hunk(LINENUM fuzz) || diff_type == UNI_DIFF)) { say("Empty context always matches.\n"); } + if (first_guess == 0) /* empty file */ + return 1; return (first_guess); } if (max_neg_offset >= first_guess) /* do not try lines < 0 */