warn_on_inaccessible(): a helper to warn on inaccessible paths

The previous series introduced warnings to multiple places, but it
could become tiring to see the warning on the same path over and
over again during a single run of Git.  Making just one function
responsible for issuing this warning, we could later choose to keep
track of which paths we issued a warning (it would involve a hash
table of paths after running them through real_path() or something)
in order to reduce noise.

Right now we do not know if the noise reduction is necessary, but it
still would be a good code reduction/sharing anyway.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

attr.c

@@ -354,7 +354,7 @@ static struct attr_stack *read_attr_from_file(const char *path, int macro_ok)
 
 	if (!fp) {
 		if (errno != ENOENT)
-			warning(_("unable to access '%s': %s"), path, strerror(errno));
+			warn_on_inaccessible(path);
 		return NULL;
 	}
 	res = xcalloc(1, sizeof(*res));

dir.c

@@ -398,7 +398,7 @@ int add_excludes_from_file_to_list(const char *fname,
 	fd = open(fname, O_RDONLY);
 	if (fd < 0 || fstat(fd, &st) < 0) {
 		if (errno != ENOENT)
-			warning(_("unable to access '%s': %s"), fname, strerror(errno));
+			warn_on_inaccessible(fname);
 		if (0 <= fd)
 			close(fd);
 		if (!check_index ||

git-compat-util.h

@@ -607,6 +607,9 @@ int remove_or_warn(unsigned int mode, const char *path);
 /* Call access(2), but warn for any error besides ENOENT. */
 int access_or_warn(const char *path, int mode);
 
+/* Warn on an inaccessible file that ought to be accessible */
+void warn_on_inaccessible(const char *path);
+
 /* Get the passwd entry for the UID of the current process. */
 struct passwd *xgetpwuid_self(void);
 

wrapper.c

@@ -403,11 +403,16 @@ int remove_or_warn(unsigned int mode, const char *file)
 	return S_ISGITLINK(mode) ? rmdir_or_warn(file) : unlink_or_warn(file);
 }
 
+void warn_on_inaccessible(const char *path)
+{
+	warning(_("unable to access '%s': %s"), path, strerror(errno));
+}
+
 int access_or_warn(const char *path, int mode)
 {
 	int ret = access(path, mode);
 	if (ret && errno != ENOENT)
-		warning(_("unable to access '%s': %s"), path, strerror(errno));
+		warn_on_inaccessible(path);
 	return ret;
 }