[tracker/wip/carlosg/fix-cursor-string-length: 1/2] libtracker-sparql: Fix out parameter in VAPI/Vala files

[Carlos Garnacho <carlosg src gnome org>]

commit 0b25059e853235dc46ffa17d1261d6e3f4d303c9
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sat Dec 26 12:45:39 2020 +0100

    libtracker-sparql: Fix out parameter in VAPI/Vala files
    
    This argument was made nullable in commit 5ea2e77fa. While this sounds
    what we want (the argument is nullable in C API and the vmethod). This
    makes Vala introduce a double indirection for the out parameter, so
    the argument ends up as "glong**" in the generated C code.
    
    Of course, this breaks the interaction with C code and cursor class
    definition expecting a "glong*" there, extra points for the C compiler
    error being silenced. Undoing these specific changes from that commit
    makes Vala and C code agree again about the levels of indirection.
    
    This broke callers that rely on the string length being meaningful,
    a glaring known broken case is the portal, as it breaks the
    redirection/serialization of cursors to sandboxed apps.
    
    Fixes: https://gitlab.gnome.org/GNOME/tracker/-/issues/282

 src/libtracker-sparql/bus/tracker-bus-fd-cursor.vala  | 2 +-
 src/libtracker-sparql/remote/tracker-json-cursor.vala | 2 +-
 src/libtracker-sparql/remote/tracker-xml-cursor.vala  | 2 +-
 src/libtracker-sparql/tracker-sparql.vapi             | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/src/libtracker-sparql/bus/tracker-bus-fd-cursor.vala 
b/src/libtracker-sparql/bus/tracker-bus-fd-cursor.vala
index b0ea605ab..954ad1ec7 100644
--- a/src/libtracker-sparql/bus/tracker-bus-fd-cursor.vala
+++ b/src/libtracker-sparql/bus/tracker-bus-fd-cursor.vala
@@ -69,7 +69,7 @@ class Tracker.Bus.FDCursor : Tracker.Sparql.Cursor {
                return variable_names[column];
        }
 
-       public override unowned string? get_string (int column, out long? length = null)
+       public override unowned string? get_string (int column, out long length = null)
        requires (cursor_finished == false) {
                unowned string str = null;
 
diff --git a/src/libtracker-sparql/remote/tracker-json-cursor.vala 
b/src/libtracker-sparql/remote/tracker-json-cursor.vala
index e85c6f459..047d47278 100644
--- a/src/libtracker-sparql/remote/tracker-json-cursor.vala
+++ b/src/libtracker-sparql/remote/tracker-json-cursor.vala
@@ -95,7 +95,7 @@ public class Tracker.Remote.JsonCursor : Tracker.Sparql.Cursor {
                return _vars.get_string_element (column);
        }
 
-       public override unowned string? get_string (int column, out long? length = null) requires (_cur_row 
!= null) {
+       public override unowned string? get_string (int column, out long length = null) requires (_cur_row != 
null) {
                var col_node = _cur_row.get_member (get_variable_name (column));
                length = 0;
 
diff --git a/src/libtracker-sparql/remote/tracker-xml-cursor.vala 
b/src/libtracker-sparql/remote/tracker-xml-cursor.vala
index 47314c960..a7a710041 100644
--- a/src/libtracker-sparql/remote/tracker-xml-cursor.vala
+++ b/src/libtracker-sparql/remote/tracker-xml-cursor.vala
@@ -144,7 +144,7 @@ public class Tracker.Remote.XmlCursor : Tracker.Sparql.Cursor {
                return _vars[column];
        }
 
-       public override unowned string? get_string (int column, out long? length = null) requires (_cur_row 
!= null) {
+       public override unowned string? get_string (int column, out long length = null) requires (_cur_row != 
null) {
                length = 0;
 
                var variable = _vars[column];
diff --git a/src/libtracker-sparql/tracker-sparql.vapi b/src/libtracker-sparql/tracker-sparql.vapi
index a7c758d5f..6174ff8c4 100644
--- a/src/libtracker-sparql/tracker-sparql.vapi
+++ b/src/libtracker-sparql/tracker-sparql.vapi
@@ -122,7 +122,7 @@ namespace Tracker {
                public abstract Sparql.ValueType get_value_type (int column);
 
                public abstract unowned string? get_variable_name (int column);
-               public abstract unowned string? get_string (int column, out long? length = null);
+               public abstract unowned string? get_string (int column, out long length = null);
 
                public abstract bool next (GLib.Cancellable? cancellable = null) throws GLib.Error;
                public async abstract bool next_async (GLib.Cancellable? cancellable = null) throws 
GLib.Error;