Fix `lsinfo` and `add` for mounted databases.

If `SimpleDatabase::Visit` is called on a database that contains a mounted directry the URIs of the elements passed to the callbacks are not prefixed by the mountpoint path. This leads to lsinfo and add not working because they use the wrong URI. This pull request is using the `WalkMount` helper function to create prefixed versions of `VisitDirectory`, `VisitSong` and `VisitPlaylist` to add the correct prefix to the parameters of the callback functions.

5 files changed, 18 insertions, 4 deletions

diff --git a/NEWS b/NEWS
index 5b7c83cfb..c9d376f21 100644
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,7 @@ ver 0.20.13 (not yet released)
 * database
   - simple: don't purge mount points on update/rescan
   - simple: fix "mount" bug caused by bad compiler optimization
+  - simple: fix "lsinfo" into mount points
   - upnp: work around libupnp 1.6.24 API breakage
 * queue: fix spuriously misplaced prioritized songs
 * include Windows cross-build script in source tarball
diff --git a/src/db/plugins/simple/Directory.cxx b/src/db/plugins/simple/Directory.cxx
index 30b044b1f..a1beb344f 100644
--- a/src/db/plugins/simple/Directory.cxx
+++ b/src/db/plugins/simple/Directory.cxx
@@ -230,7 +230,7 @@ Directory::Walk(bool recursive, const SongFilter *filter,
 		   call will lock it again */
 		const ScopeDatabaseUnlock unlock;
 		WalkMount(GetPath(), *mounted_database,
-			  recursive, filter,
+			  "", recursive, filter,
 			  visit_directory, visit_song,
 			  visit_playlist);
 		return;
diff --git a/src/db/plugins/simple/Mount.cxx b/src/db/plugins/simple/Mount.cxx
index bf3a4b815..c07b67abc 100644
--- a/src/db/plugins/simple/Mount.cxx
+++ b/src/db/plugins/simple/Mount.cxx
@@ -72,7 +72,7 @@ PrefixVisitPlaylist(const char *base, const VisitPlaylist &visit_playlist,
 
 void
 WalkMount(const char *base, const Database &db,
-	  bool recursive, const SongFilter *filter,
+	  const char* uri, bool recursive, const SongFilter *filter,
 	  const VisitDirectory &visit_directory, const VisitSong &visit_song,
 	  const VisitPlaylist &visit_playlist)
 {
@@ -93,5 +93,5 @@ WalkMount(const char *base, const Database &db,
 		vp = std::bind(PrefixVisitPlaylist,
 			       base, std::ref(visit_playlist), _1, _2);
 
-	db.Visit(DatabaseSelection("", recursive, filter), vd, vs, vp);
+	db.Visit(DatabaseSelection(uri, recursive, filter), vd, vs, vp);
 }
diff --git a/src/db/plugins/simple/Mount.hxx b/src/db/plugins/simple/Mount.hxx
index 0c6abd1d1..c79e52354 100644
--- a/src/db/plugins/simple/Mount.hxx
+++ b/src/db/plugins/simple/Mount.hxx
@@ -27,7 +27,7 @@ class SongFilter;
 
 void
 WalkMount(const char *base, const Database &db,
-	  bool recursive, const SongFilter *filter,
+	  const char* uri, bool recursive, const SongFilter *filter,
 	  const VisitDirectory &visit_directory, const VisitSong &visit_song,
 	  const VisitPlaylist &visit_playlist);
 
diff --git a/src/db/plugins/simple/SimpleDatabasePlugin.cxx b/src/db/plugins/simple/SimpleDatabasePlugin.cxx
index 9f06105f5..a27c070c6 100644
--- a/src/db/plugins/simple/SimpleDatabasePlugin.cxx
+++ b/src/db/plugins/simple/SimpleDatabasePlugin.cxx
@@ -20,6 +20,7 @@
 #include "config.h"
 #include "SimpleDatabasePlugin.hxx"
 #include "PrefixedLightSong.hxx"
+#include "Mount.hxx"
 #include "db/DatabasePlugin.hxx"
 #include "db/Selection.hxx"
 #include "db/Helpers.hxx"
@@ -270,6 +271,18 @@ SimpleDatabase::Visit(const DatabaseSelection &selection,
 	ScopeDatabaseLock protect;
 
 	auto r = root->LookupDirectory(selection.uri.c_str());
+
+	if (r.directory->IsMount()) {
+		/* pass the request and the remaining uri to the mounted database */
+		protect.unlock();
+
+		WalkMount(r.directory->GetPath(), *(r.directory->mounted_database),
+			(r.uri == nullptr)?"":r.uri, selection.recursive, selection.filter,
+			visit_directory, visit_song, visit_playlist);
+
+		return;
+	}
+
 	if (r.uri == nullptr) {
 		/* it's a directory */