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

1 files changed, 11 insertions, 4 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
 };