From 71388f94c694a36b0ac360b34f09d7c16a51f803 Mon Sep 17 00:00:00 2001
From: Juhani Krekelä
Date: Sat, 23 Oct 2021 00:33:17 +0300
Subject: Add procfs fallback for figuring out the cwd

Opening a terminal or file manager window requires weltschmerz to know
the current working directory. At the moment weltschmerz relies on the
application being run in the terminal to generate OSC 7 codes that
specify the path. However, OSC 7 is not yet widely supported by default,
and the VTE terminal emulation layer, which manages the OSC 7 path state
for weltschmerz, will overwrite local paths with ones that point to a
remote computer if an OSC 7 enabled application is run under ssh.

This change adds a fallback that uses the symlink to current working
directory located at /proc/<child pid>/cwd. On Linux this method should
always work and was how these features were implemented before adoption
of OSC 7. The procfs method is used as a fallback instead of the primary
method since it can only see the working directory changes of the direct
child process.
---
 terminal.vala | 21 +++++++++++++++------
 weltschmerz.1 | 20 ++++++++------------
 2 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/terminal.vala b/terminal.vala
index 47c33bc..1005996 100644
--- a/terminal.vala
+++ b/terminal.vala
@@ -40,6 +40,8 @@ class Terminal : Gtk.Overlay {
 
 	Gtk.MenuItem[] open_with_items = {};
 
+	Pid child_pid;
+
 	bool has_search;
 	bool overlay_scrolling_env_override;
 	string url_match;
@@ -83,7 +85,7 @@ class Terminal : Gtk.Overlay {
 				argv = { Utils.get_shell() };
 			}
 
-			vte.spawn_sync(DEFAULT, null, argv, null, SEARCH_PATH, null, null, null);
+			vte.spawn_sync(DEFAULT, null, argv, null, SEARCH_PATH, null, out child_pid, null);
 		} catch (Error e) {
 			error(e.message);
 		}
@@ -368,7 +370,7 @@ class Terminal : Gtk.Overlay {
 		adjust_font_scale(vte.get_font_scale() / FONT_SCALE_FACTOR);
 	}
 
-	string? get_local_directory_path() {
+	string? get_osc7_path() {
 		var uri = vte.get_current_directory_uri();
 		if (uri == null)
 			return null;
@@ -392,6 +394,13 @@ class Terminal : Gtk.Overlay {
 		return path;
 	}
 
+	string? get_cwd() {
+		string? osc7_path = get_osc7_path();
+		if (osc7_path != null)
+			return osc7_path;
+		return Posix.realpath("/proc/%i/cwd".printf(child_pid));
+	}
+
 	void spawn_process(string? cwd, string[] argv) {
 		Pid child;
 
@@ -407,7 +416,7 @@ class Terminal : Gtk.Overlay {
 
 	[GtkCallback]
 	void open_terminal() {
-		var cwd = get_local_directory_path();
+		var cwd = get_cwd();
 		if (cwd == null)
 			return;
 		spawn_process(cwd, {PROGRAM_NAME});
@@ -415,7 +424,7 @@ class Terminal : Gtk.Overlay {
 
 	[GtkCallback]
 	void open_directory() {
-		var cwd = get_local_directory_path();
+		var cwd = get_cwd();
 		if (cwd == null)
 			return;
 
@@ -449,8 +458,8 @@ class Terminal : Gtk.Overlay {
 			} else {
 				copy_item_text.set_sensitive(vte.get_has_selection());
 				copy_item_html.set_sensitive(vte.get_has_selection());
-				open_terminal_item.set_sensitive(get_local_directory_path() != null);
-				open_directory_item.set_sensitive(get_local_directory_path() != null);
+				open_terminal_item.set_sensitive(get_cwd() != null);
+				open_directory_item.set_sensitive(get_cwd() != null);
 				standard_context_menu.popup_at_pointer(event);
 			}
 			return true;
diff --git a/weltschmerz.1 b/weltschmerz.1
index 6b64184..2e0a2fb 100644
--- a/weltschmerz.1
+++ b/weltschmerz.1
@@ -45,19 +45,15 @@ and
 It can be reset to its default value with
 .Sy CTRL + 0 .
 .Pp
-The program's current directory can be opened in the default file manager with
-.Sy CTRL + Shift + O .
-Note that
-.Nm
-relies on proper support of OSC 7 to do this.
-If the child program (such as the shell or an editor) does not send OSC 7,
-this feature will not work.
-.Pp
-A new terminal window can likewise be opened in the program's current directory with
-.Sy CTRL + Shift + T .
-The limitations of
+The default file manager can be opened in the current directory with
 .Sy CTRL + Shift + O
-also apply here.
+and a new terminal window with
+.Sy CTRL + Shift + T .
+By default OSC 7 path is used as the current directory, but if OSC 7 path is not
+set to a valid local path and the platform provides a Linux-style procfs at
+.Pa /proc ,
+.Nm
+will use the child process's working directory instead.
 .Sh SEARCH OVERLAY
 The search overlay can be opened by pressing
 .Sy CTRL + Shift + F .
-- 
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