Merge branch 'jc/noent-notdir'

Our code often opens a path to an optional file, to work on its
contents when we can successfully open it.  We can ignore a failure
to open if such an optional file does not exist, but we do want to
report a failure in opening for other reasons (e.g. we got an I/O
error, or the file is there, but we lack the permission to open).

The exact errors we need to ignore are ENOENT (obviously) and
ENOTDIR (less obvious).  Instead of repeating comparison of errno
with these two constants, introduce a helper function to do so.

* jc/noent-notdir:
  treewide: use is_missing_file_error() where ENOENT and ENOTDIR are checked
  compat-util: is_missing_file_error()

9 files changed, 25 insertions, 10 deletions

diff --git a/apply.c b/apply.c
index c49cef0637..854faa6779 100644
--- a/apply.c
+++ b/apply.c
@@ -3741,7 +3741,7 @@ static int check_to_create(struct apply_state *state,
 			return 0;
 
 		return EXISTS_IN_WORKTREE;
-	} else if ((errno != ENOENT) && (errno != ENOTDIR)) {
+	} else if (!is_missing_file_error(errno)) {
 		return error_errno("%s", new_name);
 	}
 	return 0;
diff --git a/builtin/rm.c b/builtin/rm.c
index 7c323d0123..b39f10fcb6 100644
--- a/builtin/rm.c
+++ b/builtin/rm.c
@@ -129,7 +129,7 @@ static int check_local_mod(struct object_id *head, int index_only)
 		ce = active_cache[pos];
 
 		if (lstat(ce->name, &st) < 0) {
-			if (errno != ENOENT && errno != ENOTDIR)
+			if (!is_missing_file_error(errno))
 				warning_errno(_("failed to stat '%s'"), ce->name);
 			/* It already vanished from the working tree */
 			continue;
diff --git a/builtin/update-index.c b/builtin/update-index.c
index ebfc09faa0..f99b1e5790 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -257,7 +257,7 @@ static int remove_one_path(const char *path)
  */
 static int process_lstat_error(const char *path, int err)
 {
-	if (err == ENOENT || err == ENOTDIR)
+	if (is_missing_file_error(err))
 		return remove_one_path(path);
 	return error("lstat(\"%s\"): %s", path, strerror(err));
 }
diff --git a/diff-lib.c b/diff-lib.c
index 2982bf055a..76c8f185cd 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -29,7 +29,7 @@
 static int check_removed(const struct cache_entry *ce, struct stat *st)
 {
 	if (lstat(ce->name, st) < 0) {
-		if (errno != ENOENT && errno != ENOTDIR)
+		if (!is_missing_file_error(errno))
 			return -1;
 		return 1;
 	}
diff --git a/dir.c b/dir.c
index 9efcf1eab6..70f2de38f2 100644
--- a/dir.c
+++ b/dir.c
@@ -2337,7 +2337,7 @@ int remove_path(const char *name)
 {
 	char *slash;
 
-	if (unlink(name) && errno != ENOENT && errno != ENOTDIR)
+	if (unlink(name) && !is_missing_file_error(errno))
 		return -1;
 
 	slash = strrchr(name, '/');
diff --git a/git-compat-util.h b/git-compat-util.h
index 4b7dcf21ad..e83fd2eb07 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1134,6 +1134,21 @@ struct tm *git_gmtime_r(const time_t *, struct tm *);
 #define getc_unlocked(fh) getc(fh)
 #endif
 
+/*
+ * Our code often opens a path to an optional file, to work on its
+ * contents when we can successfully open it.  We can ignore a failure
+ * to open if such an optional file does not exist, but we do want to
+ * report a failure in opening for other reasons (e.g. we got an I/O
+ * error, or the file is there, but we lack the permission to open).
+ *
+ * Call this function after seeing an error from open() or fopen() to
+ * see if the errno indicates a missing file that we can safely ignore.
+ */
+static inline int is_missing_file_error(int errno_)
+{
+	return (errno_ == ENOENT || errno_ == ENOTDIR);
+}
+
 extern int cmd_main(int, const char **);
 
 #endif
diff --git a/setup.c b/setup.c
index e3f7699a90..ba6e855178 100644
--- a/setup.c
+++ b/setup.c
@@ -150,7 +150,7 @@ int check_filename(const char *prefix, const char *arg)
 		free(to_free);
 		return 1; /* file exists */
 	}
-	if (errno == ENOENT || errno == ENOTDIR) {
+	if (is_missing_file_error(errno)) {
 		free(to_free);
 		return 0; /* file does not exist */
 	}
diff --git a/sha1_name.c b/sha1_name.c
index e9ffe685d5..5126853bb5 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -1408,7 +1408,7 @@ static void diagnose_invalid_sha1_path(const char *prefix,
 	if (file_exists(filename))
 		die("Path '%s' exists on disk, but not in '%.*s'.",
 		    filename, object_name_len, object_name);
-	if (errno == ENOENT || errno == ENOTDIR) {
+	if (is_missing_file_error(errno)) {
 		char *fullname = xstrfmt("%s%s", prefix, filename);
 
 		if (!get_tree_entry(tree_sha1, fullname,
@@ -1473,7 +1473,7 @@ static void diagnose_invalid_index_path(int stage,
 
 	if (file_exists(filename))
 		die("Path '%s' exists on disk, but not in the index.", filename);
-	if (errno == ENOENT || errno == ENOTDIR)
+	if (is_missing_file_error(errno))
 		die("Path '%s' does not exist (neither on disk nor in the index).",
 		    filename);
 
diff --git a/wrapper.c b/wrapper.c
index d837417709..708e98a965 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -583,8 +583,8 @@ void warn_on_inaccessible(const char *path)
 
 static int access_error_is_ok(int err, unsigned flag)
 {
-	return err == ENOENT || err == ENOTDIR ||
-		((flag & ACCESS_EACCES_OK) && err == EACCES);
+	return (is_missing_file_error(err) ||
+		((flag & ACCESS_EACCES_OK) && err == EACCES));
 }
 
 int access_or_warn(const char *path, int mode, unsigned flag)