Hi Katie,
Kate Deplaix <kit-ty-k...@outlook.com> writes:
> With diffutils 3.10, "diff -Naur a b" returns:
>
> diff -Naur a/test b/test
> --- a/test 2025-02-20 14:50:07.870258052 +0000
> +++ b/test 2025-02-20 14:50:18.957287641 +0000
> @@ -0,0 +1 @@
> +content
>
> but with diffutils 3.11, the same command returns:
>
> File a/test is a regular empty file while file b/test is a regular file
Good catch.
CC'ing Paul Eggert since I think that I found the cause and it appears
unintentional to me.
Commit e016d12581ac4ea6be1ded88279527ceface74e1 has the following
ChangeLog:
diff: improve symlink handling, avoiding a race
[...]
(compare_prepped_files): Use filetype and stat macros, not detype.
[...]
Where filetype refers to a constant string returned by Gnulib's
c_file_type function. The relevant lines are here:
if (S_ISREG (st->st_mode))
return st->st_size == 0 ? N_("regular empty file") : N_("regular file");
So empty files will be treated as different file types because of that
change.
I have attached a patch to check for this condition.
Collin
>From 7d4c55202ec4c0366062ff03d27a4883861ff222 Mon Sep 17 00:00:00 2001
From: Collin Funk <collin.fu...@gmail.com>
Date: Thu, 20 Feb 2025 21:59:55 -0800
Subject: [PATCH] diff: don't treat empty files as a different file type
Reported by Kate Deplaix <kit-ty-k...@outlook.com> in
<https://lists.gnu.org/r/bug-diffutils/2025-02/msg00005.html>.
* src/diff.c (compare_prepped_files): Check for two regular files where
one has a zero size and the other has a non-zero size.
---
src/diff.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/src/diff.c b/src/diff.c
index fa6100e..0c41fd2 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -1226,7 +1226,10 @@ compare_prepped_files (struct comparison const *parent,
if (toplevel
? (!S_ISLNK (cmp->file[0].stat.st_mode)
!= !S_ISLNK (cmp->file[1].stat.st_mode))
- : (cmp->file[0].filetype != cmp->file[1].filetype
+ : ((cmp->file[0].filetype != cmp->file[1].filetype
+ && !(S_ISREG (cmp->file[0].stat.st_mode)
+ && S_ISREG (cmp->file[1].stat.st_mode)
+ && (!!cmp->file[0].stat.st_size == !!!cmp->file[1].stat.st_size)))
|| ! (S_ISREG (cmp->file[0].stat.st_mode)
|| S_ISLNK (cmp->file[0].stat.st_mode)
|| S_ISCHR (cmp->file[0].stat.st_mode)
--
2.48.1
