[PATCH 3/4] exclude: notice and report read failure of .gitignore files

[Junio C Hamano <gitster@pobox.com>]

The code that reads .gitignore files was careless in dealing in
unusual circumstances.

 - It let read errors silently ignored.

 - It tried to read ".gitignore" that is a directory on platforms
   that allow open(2) to open directories.

To make the latter consistent with what we do for fopen() on
directories ("git grep" for FREAD_READS_DIRECTORIES for details),
check if we opened a directory, silently close it and return
success.  Catch all read errors before we close and report as
needed.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 dir.c              |  6 ++++++
 t/t0008-ignores.sh | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/dir.c b/dir.c
index ec875e3878..73f89f4d8c 100644
--- a/dir.c
+++ b/dir.c
@@ -1127,6 +1127,10 @@ static int add_patterns(const char *fname, const char *base, int baselen,
 						       oid_stat);
 		if (r != 1)
 			return r;
+	} else if (S_ISDIR(st.st_mode)) {
+		/* On FREAD_READS_DIRECTORIES platforms */
+		close(fd);
+		return 0;
 	} else {
 		size = xsize_t(st.st_size);
 		if (size == 0) {
@@ -1140,6 +1144,8 @@ static int add_patterns(const char *fname, const char *base, int baselen,
 		}
 		buf = xmallocz(size);
 		if (read_in_full(fd, buf, size) != size) {
+			warning_errno(_("failed while reading gitignore file '%s'"),
+				      fname);
 			free(buf);
 			close(fd);
 			return -1;
diff --git a/t/t0008-ignores.sh b/t/t0008-ignores.sh
index 02a18d4fdb..c367824c66 100755
--- a/t/t0008-ignores.sh
+++ b/t/t0008-ignores.sh
@@ -953,4 +953,22 @@ test_expect_success EXPENSIVE 'large exclude file ignored in tree' '
 	test_cmp expect err
 '
 
+test_expect_success POSIXPERM 'unreadable exclude file reported' '
+	test_when_finished "rm -f .gitignore" &&
+	>.gitignore &&
+	chmod a= .gitignore &&
+	# we do not care if the pattern matches
+	{ git check-ignore xyzzy 2>err || :; } &&
+	test_grep "unable to access ${SQ}\.gitignore${SQ}:" err
+'
+
+test_expect_success '.gitignore directory ignored' '
+	test_when_finished "rm -rf .gitignore" &&
+	rm -f .gitignore &&
+	mkdir .gitignore &&
+	# we do not care if the pattern matches
+	{ git check-ignore xyzzy 2>err || :; } &&
+	test_grep ! "failed while reading gitignore file ${SQ}\.gitignore${SQ}:" err
+'
+
 test_done
-- 
2.45.2-711-gd2c001ca14