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)
This commit is contained in:
Pedro F. Giffuni 2023-12-03 12:33:03 -05:00
parent 970d73856b
commit 7e8afbb6d6

View file

@ -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 */