fs/Traits: add IsSpecialFilename()

Merge some duplicate code in a central library.

src/db/update/InotifyUpdate.cxx

@@ -24,6 +24,7 @@
 #include "storage/StorageInterface.hxx"
 #include "fs/AllocatedPath.hxx"
 #include "fs/FileInfo.hxx"
+#include "fs/Traits.hxx"
 #include "Log.hxx"
 
 #include <string>
@@ -146,8 +147,7 @@ WatchDirectory::GetUriFS() const noexcept
 /* we don't look at "." / ".." nor files with newlines in their name */
 static bool skip_path(const char *path)
 {
-	return (path[0] == '.' && path[1] == 0) ||
+	return PathTraitsFS::IsSpecialFilename(path) ||
-		(path[0] == '.' && path[1] == '.' && path[2] == 0) ||
 		strchr(path, '\n') != nullptr;
 }
 

src/db/update/Walk.cxx

@@ -237,7 +237,7 @@ try {
 	LogError(std::current_exception());
 }
 
-/* we don't look at "." / ".." nor files with newlines in their name */
+/* we don't look at files with newlines in their name */
 gcc_pure
 static bool
 skip_path(const char *name_utf8) noexcept

src/fs/Traits.hxx

@@ -108,6 +108,12 @@ struct PathTraitsFS {
 		return IsSeparator(*p);
 	}
 
+	gcc_pure gcc_nonnull_all
+	static bool IsSpecialFilename(const_pointer_type name) noexcept {
+		return (name[0] == '.' && name[1] == 0) ||
+			(name[0] == '.' && name[1] == '.' && name[2] == 0);
+	}
+
 	gcc_pure gcc_nonnull_all
 	static size_t GetLength(const_pointer_type p) noexcept {
 		return StringLength(p);
@@ -216,6 +222,12 @@ struct PathTraitsUTF8 {
 		return IsSeparator(*p);
 	}
 
+	gcc_pure gcc_nonnull_all
+	static bool IsSpecialFilename(const_pointer_type name) noexcept {
+		return (name[0] == '.' && name[1] == 0) ||
+			(name[0] == '.' && name[1] == '.' && name[2] == 0);
+	}
+
 	gcc_pure gcc_nonnull_all
 	static size_t GetLength(const_pointer_type p) noexcept {
 		return StringLength(p);

src/storage/plugins/LocalStorage.cxx

@@ -144,21 +144,12 @@ LocalStorage::OpenDirectory(const char *uri_utf8)
 	return std::make_unique<LocalDirectoryReader>(MapFSOrThrow(uri_utf8));
 }
 
-gcc_pure
-static bool
-SkipNameFS(PathTraitsFS::const_pointer_type name_fs) noexcept
-{
-	return name_fs[0] == '.' &&
-		(name_fs[1] == 0 ||
-		 (name_fs[1] == '.' && name_fs[2] == 0));
-}
-
 const char *
 LocalDirectoryReader::Read() noexcept
 {
 	while (reader.ReadEntry()) {
 		const Path name_fs = reader.GetEntry();
-		if (SkipNameFS(name_fs.c_str()))
+		if (PathTraitsFS::IsSpecialFilename(name_fs.c_str()))
 			continue;
 
 		try {