LocateUri: new library to classify URIs in a standard way

10 files changed, 474 insertions, 186 deletions

diff --git a/Makefile.am b/Makefile.am
index 28707446b..8a82d708b 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -168,6 +168,7 @@ libmpd_a_SOURCES = \
 	src/ReplayGainConfig.cxx src/ReplayGainConfig.hxx \
 	src/ReplayGainInfo.cxx src/ReplayGainInfo.hxx \
 	src/DetachedSong.cxx src/DetachedSong.hxx \
+	src/LocateUri.cxx src/LocateUri.hxx \
 	src/SongUpdate.cxx \
 	src/SongLoader.cxx src/SongLoader.hxx \
 	src/SongPrint.cxx src/SongPrint.hxx \
@@ -2141,6 +2142,7 @@ test_test_translate_song_SOURCES = \
 	src/PlaylistError.cxx \
 	src/DetachedSong.cxx \
 	src/SongLoader.cxx \
+	src/LocateUri.cxx \
 	src/Log.cxx \
 	test/test_translate_song.cxx
 test_test_translate_song_CPPFLAGS = $(AM_CPPFLAGS) $(CPPUNIT_CFLAGS) -DCPPUNIT_HAVE_RTTI=0
diff --git a/src/LocateUri.cxx b/src/LocateUri.cxx
new file mode 100644
index 000000000..71c8d9093
--- /dev/null
+++ b/src/LocateUri.cxx
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2003-2015 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "LocateUri.hxx"
+#include "client/Client.hxx"
+#include "fs/AllocatedPath.hxx"
+#include "ls.hxx"
+#include "util/UriUtil.hxx"
+#include "util/StringUtil.hxx"
+#include "util/Error.hxx"
+#include "util/Domain.hxx"
+
+#ifdef ENABLE_DATABASE
+#include "storage/StorageInterface.hxx"
+#endif
+
+const Domain locate_uri_domain("locate_uri");
+
+static LocatedUri
+LocateFileUri(const char *uri, const Client *client,
+#ifdef ENABLE_DATABASE
+	      const Storage *storage,
+#endif
+	      Error &error)
+{
+	auto path = AllocatedPath::FromUTF8(uri, error);
+	if (path.IsNull())
+		return LocatedUri::Unknown();
+
+#ifdef ENABLE_DATABASE
+	if (storage != nullptr) {
+		const char *suffix = storage->MapToRelativeUTF8(uri);
+		if (suffix != nullptr)
+			/* this path was relative to the music
+			   directory */
+			return LocatedUri(LocatedUri::Type::RELATIVE, suffix);
+	}
+#endif
+
+	if (client != nullptr && !client->AllowFile(path, error))
+		return LocatedUri::Unknown();
+
+	return LocatedUri(LocatedUri::Type::PATH, uri, std::move(path));
+}
+
+static LocatedUri
+LocateAbsoluteUri(const char *uri,
+#ifdef ENABLE_DATABASE
+		  const Storage *storage,
+#endif
+		  Error &error)
+{
+	if (!uri_supported_scheme(uri)) {
+		error.Set(locate_uri_domain, "Unsupported URI scheme");
+		return LocatedUri::Unknown();
+	}
+
+#ifdef ENABLE_DATABASE
+	if (storage != nullptr) {
+		const char *suffix = storage->MapToRelativeUTF8(uri);
+		if (suffix != nullptr)
+			return LocatedUri(LocatedUri::Type::RELATIVE, suffix);
+	}
+#endif
+
+	return LocatedUri(LocatedUri::Type::ABSOLUTE, uri);
+}
+
+LocatedUri
+LocateUri(const char *uri, const Client *client,
+#ifdef ENABLE_DATABASE
+	  const Storage *storage,
+#endif
+	  Error &error)
+{
+	/* skip the obsolete "file://" prefix */
+	const char *path_utf8 = StringAfterPrefix(uri, "file://");
+	if (path_utf8 != nullptr) {
+		if (!PathTraitsUTF8::IsAbsolute(path_utf8)) {
+			error.Set(locate_uri_domain, "Malformed file:// URI");
+			return LocatedUri::Unknown();
+		}
+
+		return LocateFileUri(path_utf8, client,
+#ifdef ENABLE_DATABASE
+				     storage,
+#endif
+				     error);
+	} else if (PathTraitsUTF8::IsAbsolute(uri))
+		return LocateFileUri(uri, client,
+#ifdef ENABLE_DATABASE
+				     storage,
+#endif
+				     error);
+	else if (uri_has_scheme(uri))
+		return LocateAbsoluteUri(uri,
+#ifdef ENABLE_DATABASE
+					 storage,
+#endif
+					 error);
+	else
+		return LocatedUri(LocatedUri::Type::RELATIVE, uri);
+}
diff --git a/src/LocateUri.hxx b/src/LocateUri.hxx
new file mode 100644
index 000000000..1cb57ace4
--- /dev/null
+++ b/src/LocateUri.hxx
@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2003-2015 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_LOCATE_URI_HXX
+#define MPD_LOCATE_URI_HXX
+
+#include "check.h"
+#include "Compiler.h"
+#include "fs/AllocatedPath.hxx"
+
+#ifdef WIN32
+#include <windows.h>
+/* damn you, windows.h! */
+#ifdef ABSOLUTE
+#undef ABSOLUTE
+#endif
+#ifdef RELATIVE
+#undef RELATIVE
+#endif
+#endif
+
+class Domain;
+class Error;
+class Client;
+
+#ifdef ENABLE_DATABASE
+class Storage;
+#endif
+
+struct LocatedUri {
+	enum class Type {
+		/**
+		 * Failed to parse the URI.
+		 */
+		UNKNOWN,
+
+		/**
+		 * An absolute URI with a supported scheme.
+		 */
+		ABSOLUTE,
+
+		/**
+		 * A relative URI path.
+		 */
+		RELATIVE,
+
+		/**
+		 * A local file.  The #path attribute is valid.
+		 */
+		PATH,
+	} type;
+
+	const char *canonical_uri;
+
+	/**
+	 * Contains the local file path if type==FILE.
+	 */
+	AllocatedPath path;
+
+	LocatedUri(Type _type, const char *_uri,
+		   AllocatedPath &&_path=AllocatedPath::Null())
+		:type(_type), canonical_uri(_uri), path(std::move(_path)) {}
+
+	gcc_const
+	static LocatedUri Unknown() {
+		return LocatedUri(Type::UNKNOWN, nullptr);
+	}
+
+	bool IsUnknown() const {
+		return type == Type::UNKNOWN;
+	}
+};
+
+extern const Domain locate_uri_domain;
+
+/**
+ * Classify a URI.
+ *
+ * @param client the #Client that is used to determine whether a local
+ * file is allowed; nullptr disables the check and allows all local
+ * files
+ * @param storage a #Storage instance which may be used to convert
+ * absolute URIs to relative ones, using Storage::MapToRelativeUTF8();
+ * that feature is disabled if this parameter is nullptr
+ */
+LocatedUri
+LocateUri(const char *uri, const Client *client,
+#ifdef ENABLE_DATABASE
+	  const Storage *storage,
+#endif
+	  Error &error);
+
+#endif
diff --git a/src/SongLoader.cxx b/src/SongLoader.cxx
index 9f7359a31..14f9f4dd6 100644
--- a/src/SongLoader.cxx
+++ b/src/SongLoader.cxx
@@ -19,19 +19,15 @@
 
 #include "config.h"
 #include "SongLoader.hxx"
+#include "LocateUri.hxx"
 #include "client/Client.hxx"
 #include "db/DatabaseSong.hxx"
 #include "storage/StorageInterface.hxx"
-#include "ls.hxx"
-#include "fs/AllocatedPath.hxx"
-#include "fs/Traits.hxx"
-#include "util/UriUtil.hxx"
 #include "util/Error.hxx"
 #include "DetachedSong.hxx"
 #include "PlaylistError.hxx"
 
 #include <assert.h>
-#include <string.h>
 
 #ifdef ENABLE_DATABASE
 
@@ -57,7 +53,7 @@ SongLoader::LoadFromDatabase(const char *uri, Error &error) const
 }
 
 DetachedSong *
-SongLoader::LoadFile(const char *path_utf8, Error &error) const
+SongLoader::LoadFile(const char *path_utf8, Path path_fs, Error &error) const
 {
 #ifdef ENABLE_DATABASE
 	if (storage != nullptr) {
@@ -69,13 +65,6 @@ SongLoader::LoadFile(const char *path_utf8, Error &error) const
 	}
 #endif
 
-	const auto path_fs = AllocatedPath::FromUTF8(path_utf8, error);
-	if (path_fs.IsNull())
-		return nullptr;
-
-	if (client != nullptr && !client->AllowFile(path_fs, error))
-		return nullptr;
-
 	DetachedSong *song = new DetachedSong(path_utf8);
 	if (!song->LoadFile(path_fs)) {
 		error.Set(playlist_domain, int(PlaylistResult::NO_SUCH_SONG),
@@ -88,6 +77,27 @@ SongLoader::LoadFile(const char *path_utf8, Error &error) const
 }
 
 DetachedSong *
+SongLoader::LoadSong(const LocatedUri &located_uri, Error &error) const
+{
+	switch (located_uri.type) {
+	case LocatedUri::Type::UNKNOWN:
+		gcc_unreachable();
+
+	case LocatedUri::Type::ABSOLUTE:
+		return new DetachedSong(located_uri.canonical_uri);
+
+	case LocatedUri::Type::RELATIVE:
+		return LoadFromDatabase(located_uri.canonical_uri, error);
+
+	case LocatedUri::Type::PATH:
+		return LoadFile(located_uri.canonical_uri, located_uri.path,
+				error);
+	}
+
+	gcc_unreachable();
+}
+
+DetachedSong *
 SongLoader::LoadSong(const char *uri_utf8, Error &error) const
 {
 #if !CLANG_CHECK_VERSION(3,6)
@@ -95,25 +105,13 @@ SongLoader::LoadSong(const char *uri_utf8, Error &error) const
 	assert(uri_utf8 != nullptr);
 #endif
 
-	if (memcmp(uri_utf8, "file:///", 8) == 0)
-		/* absolute path */
-		return LoadFile(uri_utf8 + 7, error);
-	else if (PathTraitsUTF8::IsAbsolute(uri_utf8))
-		/* absolute path */
-		return LoadFile(uri_utf8, error);
-	else if (uri_has_scheme(uri_utf8)) {
-		/* remove URI */
-		if (!uri_supported_scheme(uri_utf8)) {
-			error.Set(playlist_domain,
-				  int(PlaylistResult::NO_SUCH_SONG),
-				  "Unsupported URI scheme");
-			return nullptr;
-		}
-
-		return new DetachedSong(uri_utf8);
-	} else {
-		/* URI relative to the music directory */
-
-		return LoadFromDatabase(uri_utf8, error);
-	}
+	const auto located_uri = LocateUri(uri_utf8, client,
+#ifdef ENABLE_DATABASE
+					   storage,
+#endif
+					   error);
+	if (located_uri.IsUnknown())
+		return nullptr;
+
+	return LoadSong(located_uri, error);
 }
diff --git a/src/SongLoader.hxx b/src/SongLoader.hxx
index 33baa6953..1c1300f11 100644
--- a/src/SongLoader.hxx
+++ b/src/SongLoader.hxx
@@ -29,7 +29,9 @@ class Client;
 class Database;
 class Storage;
 class DetachedSong;
+class Path;
 class Error;
+struct LocatedUri;
 
 /**
  * A utility class that loads a #DetachedSong object by its URI.  If
@@ -66,6 +68,8 @@ public:
 	}
 #endif
 
+	DetachedSong *LoadSong(const LocatedUri &uri, Error &error) const;
+
 	gcc_nonnull_all
 	DetachedSong *LoadSong(const char *uri_utf8, Error &error) const;
 
@@ -74,7 +78,8 @@ private:
 	DetachedSong *LoadFromDatabase(const char *uri, Error &error) const;
 
 	gcc_nonnull_all
-	DetachedSong *LoadFile(const char *path_utf8, Error &error) const;
+	DetachedSong *LoadFile(const char *path_utf8, Path path_fs,
+			       Error &error) const;
 };
 
 #endif
diff --git a/src/command/CommandError.cxx b/src/command/CommandError.cxx
index d95722c3b..9f06431b4 100644
--- a/src/command/CommandError.cxx
+++ b/src/command/CommandError.cxx
@@ -20,6 +20,7 @@
 #include "config.h"
 #include "CommandError.hxx"
 #include "db/DatabaseError.hxx"
+#include "LocateUri.hxx"
 #include "client/Response.hxx"
 #include "util/Error.hxx"
 #include "Log.hxx"
@@ -114,6 +115,9 @@ print_error(Response &r, const Error &error)
 			return CommandResult::ERROR;
 		}
 #endif
+	} else if (error.IsDomain(locate_uri_domain)) {
+		r.Error(ACK_ERROR_ARG, error.GetMessage());
+		return CommandResult::ERROR;
 	} else if (error.IsDomain(errno_domain)) {
 		r.Error(ACK_ERROR_SYSTEM, strerror(error.GetCode()));
 		return CommandResult::ERROR;
diff --git a/src/command/FileCommands.cxx b/src/command/FileCommands.cxx
index f7e16a0d2..486c00d89 100644
--- a/src/command/FileCommands.cxx
+++ b/src/command/FileCommands.cxx
@@ -39,8 +39,8 @@
 #include "fs/AllocatedPath.hxx"
 #include "fs/FileInfo.hxx"
 #include "fs/DirectoryReader.hxx"
+#include "LocateUri.hxx"
 #include "TimePrint.hxx"
-#include "ls.hxx"
 
 #include <assert.h>
 #include <sys/stat.h>
@@ -70,21 +70,12 @@ skip_path(Path name_fs)
 #endif
 
 CommandResult
-handle_listfiles_local(Client &client, Response &r,
-		       const char *path_utf8)
+handle_listfiles_local(Response &r,
+		       const char *path_utf8, Path path_fs)
 {
-	const auto path_fs = AllocatedPath::FromUTF8(path_utf8);
-	if (path_fs.IsNull()) {
-		r.Error(ACK_ERROR_NO_EXIST, "unsupported file name");
-		return CommandResult::ERROR;
-	}
-
-	Error error;
-	if (!client.AllowFile(path_fs, error))
-		return print_error(r, error);
-
 	DirectoryReader reader(path_fs);
 	if (reader.HasFailed()) {
+		Error error;
 		error.FormatErrno("Failed to open '%s'", path_utf8);
 		return print_error(r, error);
 	}
@@ -172,11 +163,6 @@ static constexpr tag_handler print_comment_handler = {
 static CommandResult
 read_stream_comments(Response &r, const char *uri)
 {
-	if (!uri_supported_scheme(uri)) {
-		r.Error(ACK_ERROR_NO_EXIST, "unsupported URI scheme");
-		return CommandResult::ERROR;
-	}
-
 	if (!tag_stream_scan(uri, print_comment_handler, &r)) {
 		r.Error(ACK_ERROR_NO_EXIST, "Failed to load file");
 		return CommandResult::ERROR;
@@ -201,63 +187,64 @@ read_file_comments(Response &r, const Path path_fs)
 
 }
 
-static const char *
-translate_uri(const char *uri)
+static CommandResult
+read_db_comments(Client &client, Response &r, const char *uri)
 {
-	if (memcmp(uri, "file:///", 8) == 0)
-		/* drop the "file://", leave only an absolute path
-		   (starting with a slash) */
-		return uri + 7;
+#ifdef ENABLE_DATABASE
+	const Storage *storage = client.GetStorage();
+	if (storage == nullptr) {
+#else
+		(void)client;
+		(void)uri;
+#endif
+		r.Error(ACK_ERROR_NO_EXIST, "No database");
+		return CommandResult::ERROR;
+#ifdef ENABLE_DATABASE
+	}
+
+	{
+		AllocatedPath path_fs = storage->MapFS(uri);
+		if (!path_fs.IsNull())
+			return read_file_comments(r, path_fs);
+	}
 
-	return uri;
+	{
+		const std::string uri2 = storage->MapUTF8(uri);
+		if (uri_has_scheme(uri2.c_str()))
+			return read_stream_comments(r, uri2.c_str());
+	}
+
+	r.Error(ACK_ERROR_NO_EXIST, "No such file");
+	return CommandResult::ERROR;
+#endif
 }
 
 CommandResult
 handle_read_comments(Client &client, Request args, Response &r)
 {
 	assert(args.size == 1);
-	const char *const uri = translate_uri(args.front());
-
-	if (PathTraitsUTF8::IsAbsolute(uri)) {
-		/* read comments from arbitrary local file */
-		const char *path_utf8 = uri;
-		AllocatedPath path_fs = AllocatedPath::FromUTF8(path_utf8);
-		if (path_fs.IsNull()) {
-			r.Error(ACK_ERROR_NO_EXIST, "unsupported file name");
-			return CommandResult::ERROR;
-		}
 
-		Error error;
-		if (!client.AllowFile(path_fs, error))
-			return print_error(r, error);
+	const char *const uri = args.front();
 
-		return read_file_comments(r, path_fs);
-	} else if (uri_has_scheme(uri)) {
-		return read_stream_comments(r, uri);
-	} else {
+	Error error;
+	const auto located_uri = LocateUri(uri, &client,
 #ifdef ENABLE_DATABASE
-		const Storage *storage = client.GetStorage();
-		if (storage == nullptr) {
+					   nullptr,
 #endif
-			r.Error(ACK_ERROR_NO_EXIST, "No database");
-			return CommandResult::ERROR;
-#ifdef ENABLE_DATABASE
-		}
+					   error);
+	switch (located_uri.type) {
+	case LocatedUri::Type::UNKNOWN:
+		return print_error(r, error);
 
-		{
-			AllocatedPath path_fs = storage->MapFS(uri);
-			if (!path_fs.IsNull())
-				return read_file_comments(r, path_fs);
-		}
+	case LocatedUri::Type::ABSOLUTE:
+		return read_stream_comments(r, located_uri.canonical_uri);
 
-		{
-			const std::string uri2 = storage->MapUTF8(uri);
-			if (uri_has_scheme(uri2.c_str()))
-				return read_stream_comments(r, uri2.c_str());
-		}
+	case LocatedUri::Type::RELATIVE:
+		return read_db_comments(client, r, located_uri.canonical_uri);
 
-		r.Error(ACK_ERROR_NO_EXIST, "No such file");
-		return CommandResult::ERROR;
-#endif
+	case LocatedUri::Type::PATH:
+		return read_file_comments(r, located_uri.path);
 	}
+
+	gcc_unreachable();
 }
diff --git a/src/command/FileCommands.hxx b/src/command/FileCommands.hxx
index c072d2028..9c6631df5 100644
--- a/src/command/FileCommands.hxx
+++ b/src/command/FileCommands.hxx
@@ -25,10 +25,11 @@
 class Client;
 class Request;
 class Response;
+class Path;
 
 CommandResult
-handle_listfiles_local(Client &client, Response &response,
-		       const char *path_utf8);
+handle_listfiles_local(Response &response,
+		       const char *path_utf8, Path path_fs);
 
 CommandResult
 handle_read_comments(Client &client, Request request, Response &response);
diff --git a/src/command/OtherCommands.cxx b/src/command/OtherCommands.cxx
index 09b951b03..b4a23fe4b 100644
--- a/src/command/OtherCommands.cxx
+++ b/src/command/OtherCommands.cxx
@@ -25,6 +25,7 @@
 #include "CommandError.hxx"
 #include "db/Uri.hxx"
 #include "storage/StorageInterface.hxx"
+#include "LocateUri.hxx"
 #include "DetachedSong.hxx"
 #include "SongPrint.hxx"
 #include "TagPrint.hxx"
@@ -122,31 +123,49 @@ handle_listfiles(Client &client, Request args, Response &r)
 	/* default is root directory */
 	const auto uri = args.GetOptional(0, "");
 
-	if (memcmp(uri, "file:///", 8) == 0)
-		/* list local directory */
-		return handle_listfiles_local(client, r, uri + 7);
-
+	Error error;
+	const auto located_uri = LocateUri(uri, &client,
 #ifdef ENABLE_DATABASE
-	if (uri_has_scheme(uri))
-		/* use storage plugin to list remote directory */
-		return handle_listfiles_storage(r, uri);
+					   nullptr,
+#endif
+					   error);
 
-	/* must be a path relative to the configured
-	   music_directory */
+	switch (located_uri.type) {
+	case LocatedUri::Type::UNKNOWN:
+		return print_error(r, error);
 
-	if (client.partition.instance.storage != nullptr)
-		/* if we have a storage instance, obtain a list of
-		   files from it */
-		return handle_listfiles_storage(r,
-						*client.partition.instance.storage,
-						uri);
+	case LocatedUri::Type::ABSOLUTE:
+#ifdef ENABLE_DATABASE
+		/* use storage plugin to list remote directory */
+		return handle_listfiles_storage(r, located_uri.canonical_uri);
+#else
+		r.Error(ACK_ERROR_NO_EXIST, "No database");
+		return CommandResult::ERROR;
+#endif
 
-	/* fall back to entries from database if we have no storage */
-	return handle_listfiles_db(client, r, uri);
+	case LocatedUri::Type::RELATIVE:
+#ifdef ENABLE_DATABASE
+		if (client.partition.instance.storage != nullptr)
+			/* if we have a storage instance, obtain a list of
+			   files from it */
+			return handle_listfiles_storage(r,
+							*client.partition.instance.storage,
+							uri);
+
+		/* fall back to entries from database if we have no storage */
+		return handle_listfiles_db(client, r, uri);
 #else
-	r.Error(ACK_ERROR_NO_EXIST, "No database");
-	return CommandResult::ERROR;
+		r.Error(ACK_ERROR_NO_EXIST, "No database");
+		return CommandResult::ERROR;
 #endif
+
+	case LocatedUri::Type::PATH:
+		/* list local directory */
+		return handle_listfiles_local(r, located_uri.canonical_uri,
+					      located_uri.path);
+	}
+
+	gcc_unreachable();
 }
 
 static constexpr tag_handler print_tag_handler = {
@@ -155,54 +174,26 @@ static constexpr tag_handler print_tag_handler = {
 	nullptr,
 };
 
-CommandResult
-handle_lsinfo(Client &client, Request args, Response &r)
+static CommandResult
+handle_lsinfo_absolute(Response &r, const char *uri)
 {
-	/* default is root directory */
-	const auto uri = args.GetOptional(0, "");
-
-	if (memcmp(uri, "file:///", 8) == 0) {
-		/* print information about an arbitrary local file */
-		const char *path_utf8 = uri + 7;
-		const auto path_fs = AllocatedPath::FromUTF8(path_utf8);
-
-		if (path_fs.IsNull()) {
-			r.Error(ACK_ERROR_NO_EXIST, "unsupported file name");
-			return CommandResult::ERROR;
-		}
-
-		Error error;
-		if (!client.AllowFile(path_fs, error))
-			return print_error(r, error);
-
-		DetachedSong song(path_utf8);
-		if (!song.LoadFile(path_fs)) {
-			r.Error(ACK_ERROR_NO_EXIST, "No such file");
-			return CommandResult::ERROR;
-		}
-
-		song_print_info(r, client.partition, song);
-		return CommandResult::OK;
+	if (!tag_stream_scan(uri, print_tag_handler, &r)) {
+		r.Error(ACK_ERROR_NO_EXIST, "No such file");
+		return CommandResult::ERROR;
 	}
 
-	if (uri_has_scheme(uri)) {
-		if (!uri_supported_scheme(uri)) {
-			r.Error(ACK_ERROR_NO_EXIST, "unsupported URI scheme");
-			return CommandResult::ERROR;
-		}
-
-		if (!tag_stream_scan(uri, print_tag_handler, &r)) {
-			r.Error(ACK_ERROR_NO_EXIST, "No such file");
-			return CommandResult::ERROR;
-		}
-
-		return CommandResult::OK;
-	}
+	return CommandResult::OK;
+}
 
+static CommandResult
+handle_lsinfo_relative(Client &client, Response &r, const char *uri)
+{
 #ifdef ENABLE_DATABASE
 	CommandResult result = handle_lsinfo2(client, uri, r);
 	if (result != CommandResult::OK)
 		return result;
+#else
+	(void)client;
 #endif
 
 	if (isRootDirectory(uri)) {
@@ -219,6 +210,53 @@ handle_lsinfo(Client &client, Request args, Response &r)
 	return CommandResult::OK;
 }
 
+static CommandResult
+handle_lsinfo_path(Client &client, Response &r,
+		   const char *path_utf8, Path path_fs)
+{
+	DetachedSong song(path_utf8);
+	if (!song.LoadFile(path_fs)) {
+		r.Error(ACK_ERROR_NO_EXIST, "No such file");
+		return CommandResult::ERROR;
+	}
+
+	song_print_info(r, client.partition, song);
+	return CommandResult::OK;
+}
+
+CommandResult
+handle_lsinfo(Client &client, Request args, Response &r)
+{
+	/* default is root directory */
+	const auto uri = args.GetOptional(0, "");
+
+	Error error;
+	const auto located_uri = LocateUri(uri, &client,
+#ifdef ENABLE_DATABASE
+					   nullptr,
+#endif
+					   error);
+
+	switch (located_uri.type) {
+	case LocatedUri::Type::UNKNOWN:
+		return print_error(r, error);
+
+	case LocatedUri::Type::ABSOLUTE:
+		return handle_lsinfo_absolute(r, located_uri.canonical_uri);
+
+	case LocatedUri::Type::RELATIVE:
+		return handle_lsinfo_relative(client, r,
+					      located_uri.canonical_uri);
+
+	case LocatedUri::Type::PATH:
+		/* print information about an arbitrary local file */
+		return handle_lsinfo_path(client, r, located_uri.canonical_uri,
+					  located_uri.path);
+	}
+
+	gcc_unreachable();
+}
+
 #ifdef ENABLE_DATABASE
 
 static CommandResult
diff --git a/src/command/QueueCommands.cxx b/src/command/QueueCommands.cxx
index 1698e88df..7751aa26d 100644
--- a/src/command/QueueCommands.cxx
+++ b/src/command/QueueCommands.cxx
@@ -25,13 +25,14 @@
 #include "db/Selection.hxx"
 #include "SongFilter.hxx"
 #include "SongLoader.hxx"
+#include "DetachedSong.hxx"
+#include "LocateUri.hxx"
 #include "queue/Playlist.hxx"
 #include "PlaylistPrint.hxx"
 #include "client/Client.hxx"
 #include "client/Response.hxx"
 #include "Partition.hxx"
 #include "BulkEdit.hxx"
-#include "ls.hxx"
 #include "util/ConstBuffer.hxx"
 #include "util/UriUtil.hxx"
 #include "util/NumberParser.hxx"
@@ -42,15 +43,42 @@
 
 #include <string.h>
 
-static const char *
-translate_uri(const char *uri)
+static CommandResult
+AddUri(Client &client, const LocatedUri &uri, Response &r)
 {
-	if (memcmp(uri, "file:///", 8) == 0)
-		/* drop the "file://", leave only an absolute path
-		   (starting with a slash) */
-		return uri + 7;
+	Error error;
+	DetachedSong *song = SongLoader(client).LoadSong(uri, error);
+	if (song == nullptr)
+		return print_error(r, error);
+
+	auto &partition = client.partition;
+	unsigned id = partition.playlist.AppendSong(partition.pc,
+						    std::move(*song), error);
+	delete song;
+	if (id == 0)
+		return print_error(r, error);
 
-	return uri;
+	return CommandResult::OK;
+}
+
+static CommandResult
+AddDatabaseSelection(Client &client, const char *uri, Response &r)
+{
+#ifdef ENABLE_DATABASE
+	const ScopeBulkEdit bulk_edit(client.partition);
+
+	const DatabaseSelection selection(uri, true);
+	Error error;
+	return AddFromDatabase(client.partition, selection, error)
+		? CommandResult::OK
+		: print_error(r, error);
+#else
+	(void)client;
+	(void)uri;
+
+	r.Error(ACK_ERROR_NO_EXIST, "No database");
+	return CommandResult::ERROR;
+#endif
 }
 
 CommandResult
@@ -65,36 +93,32 @@ handle_add(Client &client, Request args, Response &r)
 		   here */
 		uri = "";
 
-	uri = translate_uri(uri);
+	Error error;
+	const auto located_uri = LocateUri(uri, &client,
+#ifdef ENABLE_DATABASE
+					   nullptr,
+#endif
+					   error);
+	switch (located_uri.type) {
+	case LocatedUri::Type::UNKNOWN:
+		return print_error(r, error);
 
-	if (uri_has_scheme(uri) || PathTraitsUTF8::IsAbsolute(uri)) {
-		const SongLoader loader(client);
-		Error error;
-		unsigned id = client.partition.AppendURI(loader, uri, error);
-		if (id == 0)
-			return print_error(r, error);
+	case LocatedUri::Type::ABSOLUTE:
+	case LocatedUri::Type::PATH:
+		return AddUri(client, located_uri, r);
 
-		return CommandResult::OK;
+	case LocatedUri::Type::RELATIVE:
+		return AddDatabaseSelection(client, located_uri.canonical_uri,
+					    r);
 	}
 
-#ifdef ENABLE_DATABASE
-	const ScopeBulkEdit bulk_edit(client.partition);
-
-	const DatabaseSelection selection(uri, true);
-	Error error;
-	return AddFromDatabase(client.partition, selection, error)
-		? CommandResult::OK
-		: print_error(r, error);
-#else
-	r.Error(ACK_ERROR_NO_EXIST, "No database");
-	return CommandResult::ERROR;
-#endif
+	gcc_unreachable();
 }
 
 CommandResult
 handle_addid(Client &client, Request args, Response &r)
 {
-	const char *const uri = translate_uri(args.front());
+	const char *const uri = args.front();
 
 	const SongLoader loader(client);
 	Error error;