command/{Queue,File}Commands: drop "file:///" prefix for absolute paths

Requiring this prefix makes the client's intention very clear, but it
was too hard to understand why this prefix was needed.  Initially, my
intention was to differentiate from broken clients which prefix relate
URIs with a slash; once MPD allowed that.  In the past few years
however, MPD has disallowed that, and there was no significant
breakage (except for the "add /" special case which some clients
apparently still do).  So I figure it's about time to define that an
URI that begins with a slash points to an arbitrary file on the file
system.

4 files changed, 18 insertions, 16 deletions

diff --git a/NEWS b/NEWS
index 553a9d411..08ef096a1 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,7 @@ ver 0.20 (not yet released)
   - "search"/"find" have a "window" parameter
   - report song duration with milliseconds precision
   - "sticker find" can match sticker values
+  - drop the "file:///" prefix for absolute file paths
 * tags
   - ape, ogg: drop support for non-standard tag "album artist"
     affected filetypes: vorbis, flac, opus & all files with ape2 tags
diff --git a/doc/protocol.xml b/doc/protocol.xml
index 49bc20160..f9f8ea346 100644
--- a/doc/protocol.xml
+++ b/doc/protocol.xml
@@ -1772,7 +1772,7 @@ OK
             <para>
               Clients that are connected via UNIX domain socket may
               use this command to read the tags of an arbitrary local
-              file (URI beginning with "file:///").
+              file (URI is an absolute path).
             </para>
           </listitem>
         </varlistentry>
@@ -1787,8 +1787,7 @@ OK
             <para>
               Read "comments" (i.e. key-value pairs) from the file
               specified by "URI".  This "URI" can be a path relative
-              to the music directory or a URL in the form
-              "file:///foo/bar.ogg".
+              to the music directory or an absolute path.
             </para>
             <para>
               This command may be used to list metadata of remote
diff --git a/src/command/FileCommands.cxx b/src/command/FileCommands.cxx
index 789aa1f28..1e0f9c585 100644
--- a/src/command/FileCommands.cxx
+++ b/src/command/FileCommands.cxx
@@ -202,11 +202,22 @@ read_file_comments(Client &client, const Path path_fs)
 
 }
 
+static const char *
+translate_uri(const char *uri)
+{
+	if (memcmp(uri, "file:///", 8) == 0)
+		/* drop the "file://", leave only an absolute path
+		   (starting with a slash) */
+		return uri + 7;
+
+	return uri;
+}
+
 CommandResult
 handle_read_comments(Client &client, ConstBuffer<const char *> args)
 {
 	assert(args.size == 1);
-	const char *const uri = args.front();
+	const char *const uri = translate_uri(args.front());
 
 	if (memcmp(uri, "file:///", 8) == 0) {
 		/* read comments from arbitrary local file */
diff --git a/src/command/QueueCommands.cxx b/src/command/QueueCommands.cxx
index 20634652a..d461170fd 100644
--- a/src/command/QueueCommands.cxx
+++ b/src/command/QueueCommands.cxx
@@ -43,18 +43,13 @@
 #include <string.h>
 
 static const char *
-translate_uri(Client &client, const char *uri)
+translate_uri(const char *uri)
 {
 	if (memcmp(uri, "file:///", 8) == 0)
 		/* drop the "file://", leave only an absolute path
 		   (starting with a slash) */
 		return uri + 7;
 
-	if (PathTraitsUTF8::IsAbsolute(uri)) {
-		command_error(client, ACK_ERROR_NO_EXIST, "Malformed URI");
-		return nullptr;
-	}
-
 	return uri;
 }
 
@@ -70,9 +65,7 @@ handle_add(Client &client, ConstBuffer<const char *> args)
 		   here */
 		uri = "";
 
-	uri = translate_uri(client, uri);
-	if (uri == nullptr)
-		return CommandResult::ERROR;
+	uri = translate_uri(uri);
 
 	if (uri_has_scheme(uri) || PathTraitsUTF8::IsAbsolute(uri)) {
 		const SongLoader loader(client);
@@ -101,9 +94,7 @@ handle_add(Client &client, ConstBuffer<const char *> args)
 CommandResult
 handle_addid(Client &client, ConstBuffer<const char *> args)
 {
-	const char *const uri = translate_uri(client, args.front());
-	if (uri == nullptr)
-		return CommandResult::ERROR;
+	const char *const uri = translate_uri(args.front());
 
 	const SongLoader loader(client);
 	Error error;