Follow Type=Link standard desktop entries with drun (#1168)

* [DRun] Introduce data structure changes for Link desktop entries

From the [freedesktop spec][1]:

> This specification defines 3 types of desktop entries:
> Application (type 1), Link (type 2) and Directory (type 3). To allow
> the addition of new types in the future, implementations should
> ignore desktop entries with an unknown type.

This commit adds an enum to capture these types, and adds `type` to
DRunModeEntry.

  [1]: https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html

part of #1166

* [DRun] Sanity check Link entries and capture the URL

Note that we're introducing some logic that will differ depending on
the Desktop entry type (Application or Link). The logic is:

- if entry is Application type,
  - then Exec is required
  - and the value is saved in .exec
  - and drun_mode_result calls exec_cmd_entry
- if entry is Link type,
  - then URL is required (but is not saved in the DRunModeEntry)
  - and drun_mode_result calls new function launch_link_entry

part of #1166

* [DRun] Launch desktop links via xdg-open

Note that this introduces a new dependency on xdg-open, which may not
be installed. In that case, rofi will display an error dialog
with something like:

  "Failed to execute child process xdg-open (No such file or directory)"

which hopefully is explanatory enough for folks.

part of #1166

* Make drun options comments consistent and add a bit of whitespace

* [DRun] new config option drun-url-launcher for opening links

In previous commit, this was a hard-coded string.

part of #1166

4 files changed, 102 insertions, 14 deletions

diff --git a/config/config.c b/config/config.c
index fe8fcc42..6e256e53 100644
--- a/config/config.c
+++ b/config/config.c
@@ -116,14 +116,18 @@ Settings config = {
     .tokenize        = TRUE,
     .matching        = "normal",
     .matching_method = MM_NORMAL,
-    /** Desktop entry fields to match*/
+
+    /** Desktop entries to match in drun */
     .drun_match_fields = "name,generic,exec,categories,keywords",
+    /** Only show entries in this category */
     .drun_categories   = NULL,
-    /**  Desktop format display */
-    .drun_display_format       = "{name} [<span weight='light' size='small'><i>({generic})</i></span>]",
     /** Desktop entry show actions */
     .drun_show_actions         = FALSE,
-    /** Desktop entry show actions */
+    /** Desktop format display */
+    .drun_display_format       = "{name} [<span weight='light' size='small'><i>({generic})</i></span>]",
+    /** Desktop Link launch command */
+    .drun_url_launcher         = "xdg-open",
+
     /** Window fields to match in window mode*/
     .window_match_fields       = "all",
     /** Monitor */
@@ -160,8 +164,11 @@ Settings config = {
 
     .cache_dir                 = NULL,
     .window_thumbnail          = FALSE,
+
+    /** drun cache */
     .drun_use_desktop_cache    = FALSE,
     .drun_reload_desktop_cache = FALSE,
+
     /** Benchmarks */
     .benchmark_ui              = FALSE
 };
diff --git a/include/settings.h b/include/settings.h
index 7c57080d..cecb9c34 100644
--- a/include/settings.h
+++ b/include/settings.h
@@ -119,14 +119,18 @@ typedef struct
     SortingMethod  sorting_method_enum;
     /** Sorting method. */
     char           * sorting_method;
+
     /** Desktop entries to match in drun */
     char           * drun_match_fields;
     /** Only show entries in this category */
     char           * drun_categories;
     /** Desktop entry show actions */
     unsigned int   drun_show_actions;
-    /** Desktop entry show */
+    /** Desktop format display */
     char           * drun_display_format;
+    /** Desktop Link launch command */
+    char           * drun_url_launcher;
+
     /** Search case sensitivity */
     unsigned int   case_sensitive;
     /** Cycle through in the element list */
diff --git a/source/dialogs/drun.c b/source/dialogs/drun.c
index afc19ba6..26fe73a1 100644
--- a/source/dialogs/drun.c
+++ b/source/dialogs/drun.c
@@ -61,6 +61,15 @@
 char *DRUN_GROUP_NAME = "Desktop Entry";
 
 typedef struct _DRunModePrivateData DRunModePrivateData;
+
+typedef enum
+{
+    DRUN_DESKTOP_ENTRY_TYPE_UNDETERMINED = 0,
+    DRUN_DESKTOP_ENTRY_TYPE_APPLICATION,
+    DRUN_DESKTOP_ENTRY_TYPE_LINK,
+    DRUN_DESKTOP_ENTRY_TYPE_DIRECTORY,
+} DRunDesktopEntryType;
+
 /**
  * Store extra information about the entry.
  * Currently the executable and if it should run in terminal.
@@ -86,7 +95,7 @@ typedef struct
     int             icon_size;
     /* Surface holding the icon. */
     cairo_surface_t *icon;
-    /* Executable */
+    /* Executable - for Application entries only */
     char            *exec;
     /* Name of the Entry */
     char            *name;
@@ -104,6 +113,8 @@ typedef struct
     gint            sort_index;
 
     uint32_t        icon_fetch_uid;
+
+    DRunDesktopEntryType type;
 } DRunModeEntry;
 
 typedef struct
@@ -209,6 +220,43 @@ static gboolean drun_helper_eval_cb ( const GMatchInfo *info, GString *res, gpoi
     // Continue replacement.
     return FALSE;
 }
+static void launch_link_entry ( DRunModeEntry *e )
+{
+    if ( e->key_file == NULL ) {
+        GKeyFile *kf    = g_key_file_new ();
+        GError   *error = NULL;
+        gboolean res    = g_key_file_load_from_file ( kf, e->path, 0, &error );
+        if ( res ) {
+            e->key_file = kf;
+        }
+        else {
+            g_warning ( "[%s] [%s] Failed to parse desktop file because: %s.", e->app_id, e->path, error->message );
+            g_error_free ( error );
+            g_key_file_free ( kf );
+            return;
+        }
+    }
+
+    gchar *url = g_key_file_get_string ( e->key_file, e->action, "URL", NULL );
+    if ( url == NULL || strlen ( url ) == 0 ) {
+        g_warning ( "[%s] [%s] No URL found.", e->app_id, e->path );
+        g_free ( url );
+        return ;
+    }
+
+    gsize command_len = strlen( config.drun_url_launcher ) + strlen( url ) + 2; // space + terminator = 2
+    gchar *command = g_newa ( gchar, command_len );
+    g_snprintf( command, command_len, "%s %s", config.drun_url_launcher, url );
+    g_free ( url );
+
+    g_debug ( "Link launch command: |%s|", command );
+    if ( helper_execute_command ( NULL, command, FALSE, NULL ) ) {
+        char *path = g_build_filename ( cache_dir, DRUN_CACHE_FILE, NULL );
+        // Store it based on the unique identifiers (desktop_id).
+        history_set ( path, e->desktop_id );
+        g_free ( path );
+    }
+}
 static void exec_cmd_entry ( DRunModeEntry *e )
 {
     GError *error = NULL;
@@ -300,6 +348,7 @@ static gboolean rofi_strv_contains ( const char * const *categories, const char
  */
 static void read_desktop_file ( DRunModePrivateData *pd, const char *root, const char *path, const gchar *basename, const char *action )
 {
+    DRunDesktopEntryType desktop_entry_type = DRUN_DESKTOP_ENTRY_TYPE_UNDETERMINED;
     int parse_action = ( config.drun_show_actions && action != DRUN_GROUP_NAME );
     // Create ID on stack.
     // We know strlen (path ) > strlen(root)+1
@@ -342,8 +391,12 @@ static void read_desktop_file ( DRunModePrivateData *pd, const char *root, const
         g_key_file_free ( kf );
         return;
     }
-    if ( g_strcmp0 ( key, "Application" ) ) {
-        g_debug ( "[%s] [%s] Skipping desktop file: Not of type application (%s)", id, path, key );
+    if ( !g_strcmp0 ( key, "Application" ) ) {
+        desktop_entry_type = DRUN_DESKTOP_ENTRY_TYPE_APPLICATION;
+    } else if ( !g_strcmp0 ( key, "Link" ) ) {
+        desktop_entry_type = DRUN_DESKTOP_ENTRY_TYPE_LINK;
+    } else {
+        g_debug ( "[%s] [%s] Skipping desktop file: Not of type Application or Link (%s)", id, path, key );
         g_free ( key );
         g_key_file_free ( kf );
         return;
@@ -407,9 +460,17 @@ static void read_desktop_file ( DRunModePrivateData *pd, const char *root, const
         g_hash_table_add ( pd->disabled_entries, g_strdup ( id ) );
         return;
     }
+
     // We need Exec, don't support DBusActivatable
-    if ( !g_key_file_has_key ( kf, DRUN_GROUP_NAME, "Exec", NULL ) ) {
-        g_debug ( "[%s] [%s] Unsupported desktop file: no 'Exec' key present.", id, path );
+    if ( desktop_entry_type == DRUN_DESKTOP_ENTRY_TYPE_APPLICATION
+         && !g_key_file_has_key ( kf, DRUN_GROUP_NAME, "Exec", NULL ) ) {
+        g_debug ( "[%s] [%s] Unsupported desktop file: no 'Exec' key present for type Application.", id, path );
+        g_key_file_free ( kf );
+        return;
+    }
+    if ( desktop_entry_type == DRUN_DESKTOP_ENTRY_TYPE_LINK
+         && !g_key_file_has_key ( kf, DRUN_GROUP_NAME, "URL", NULL ) ) {
+        g_debug ( "[%s] [%s] Unsupported desktop file: no 'URL' key present for type Link.", id, path );
         g_key_file_free ( kf );
         return;
     }
@@ -499,7 +560,12 @@ static void read_desktop_file ( DRunModePrivateData *pd, const char *root, const
     }
     g_strfreev ( categories );
 
-    pd->entry_list[pd->cmd_list_length].exec = g_key_file_get_string ( kf, action, "Exec", NULL );
+    pd->entry_list[pd->cmd_list_length].type = desktop_entry_type;
+    if ( desktop_entry_type == DRUN_DESKTOP_ENTRY_TYPE_APPLICATION ) {
+        pd->entry_list[pd->cmd_list_length].exec = g_key_file_get_string ( kf, action, "Exec", NULL );
+    } else {
+        pd->entry_list[pd->cmd_list_length].exec = NULL;
+    }
 
     if ( matching_entry_fields[DRUN_MATCH_FIELD_COMMENT].enabled ) {
         pd->entry_list[pd->cmd_list_length].comment = g_key_file_get_locale_string ( kf,
@@ -953,7 +1019,16 @@ static ModeMode drun_mode_result ( Mode *sw, int mretv, char **input, unsigned i
         retv = ( mretv & MENU_LOWER_MASK );
     }
     else if ( ( mretv & MENU_OK )  ) {
-        exec_cmd_entry ( &( rmpd->entry_list[selected_line] ) );
+        switch ( rmpd->entry_list[selected_line].type ) {
+            case DRUN_DESKTOP_ENTRY_TYPE_APPLICATION:
+                exec_cmd_entry ( &( rmpd->entry_list[selected_line] ) );
+                break;
+            case DRUN_DESKTOP_ENTRY_TYPE_LINK:
+                launch_link_entry ( &( rmpd->entry_list[selected_line] ) );
+                break;
+            default:
+                g_assert_not_reached ();
+        }
     }
     else if ( ( mretv & MENU_CUSTOM_INPUT ) && *input != NULL && *input[0] != '\0' ) {
         retv = RELOAD_DIALOG;
@@ -1096,7 +1171,7 @@ static int drun_token_match ( const Mode *data, rofi_int_matcher **tokens, unsig
             }
             if ( matching_entry_fields[DRUN_MATCH_FIELD_EXEC].enabled ) {
                 // Match executable name.
-                if ( test == tokens[j]->invert  ) {
+                if ( test == tokens[j]->invert && rmpd->entry_list[index].exec ) {
                     test = helper_token_match ( ftokens, rmpd->entry_list[index].exec );
                 }
             }
diff --git a/source/xrmoptions.c b/source/xrmoptions.c
index 18b925f4..94322edc 100644
--- a/source/xrmoptions.c
+++ b/source/xrmoptions.c
@@ -135,13 +135,15 @@ static XrmOption xrmOptions[] = {
 
     { xrm_String,  "drun-match-fields",         { .str   = &config.drun_match_fields                    }, NULL,
       "Desktop entry fields to match in drun", CONFIG_DEFAULT },
-
     { xrm_String,  "drun-categories",           { .str   = &config.drun_categories                      }, NULL,
       "Only show Desktop entry from these categories", CONFIG_DEFAULT },
     { xrm_Boolean, "drun-show-actions",         { .num   = &config.drun_show_actions                    }, NULL,
       "Desktop entry show actions.", CONFIG_DEFAULT },
     { xrm_String,  "drun-display-format",       { .str   = &config.drun_display_format                  }, NULL,
       "DRUN format string. (Supports: generic,name,comment,exec,categories)", CONFIG_DEFAULT },
+    { xrm_String,  "drun-url-launcher",         { .str   = &config.drun_url_launcher                    }, NULL,
+      "Command to open an Desktop Entry that is a Link.", CONFIG_DEFAULT },
+
     { xrm_Boolean, "disable-history",           { .num   = &config.disable_history                      }, NULL,
       "Disable history in run/ssh", CONFIG_DEFAULT },
     { xrm_String,  "ignored-prefixes",          { .str   = &config.ignored_prefixes                     }, NULL,