apprt/gtk: default working-directory to home if launched from desktop

Fixes #573

src/config/Config.zig

@@ -212,8 +212,10 @@ command: ?[]const u8 = null,
 /// The directory to change to after starting the command.
 ///
 /// The default is "inherit" except in special scenarios listed next.
-/// If ghostty can detect it is launched on macOS from launchd
+/// On macOS, if Ghostty can detect it is launched from launchd
-/// (double-clicked), then it defaults to "home".
+/// (double-clicked) or `open`, then it defaults to "home".
+/// On Linux with GTK, if Ghostty can detect it was launched from
+/// a desktop launcher, then it defaults to "home".
 ///
 /// The value of this must be an absolute value or one of the special
 /// values below:
@@ -922,9 +924,14 @@ pub fn finalize(self: *Config) !void {
     }
 
     // The default for the working directory depends on the system.
-    const wd = self.@"working-directory" orelse switch (builtin.os.tag) {
+    const wd = self.@"working-directory" orelse wd: {
-        .macos => if (c.getppid() == 1) "home" else "inherit",
+        // If we have no working directory set, our default depends on
-        else => "inherit",
+        // whether we were launched from the desktop or CLI.
+        if (internal_os.launchedFromDesktop()) {
+            break :wd "home";
+        }
+
+        break :wd "inherit";
     };
 
     // If we are missing either a command or home directory, we need

src/os/desktop.zig

@@ -0,0 +1,48 @@
+const std = @import("std");
+const builtin = @import("builtin");
+const build_config = @import("../build_config.zig");
+
+const c = @cImport({
+    @cInclude("unistd.h");
+});
+
+/// Returns true if the program was launched from a desktop environment.
+///
+/// On macOS, this returns true if the program was launched from Finder.
+///
+/// On Linux GTK, this returns true if the program was launched using the
+/// desktop file. This also includes when `gtk-launch` is used because I
+/// can't find a way to distinguish the two scenarios.
+///
+/// For other platforms and app runtimes, this returns false.
+pub fn launchedFromDesktop() bool {
+    if (comptime build_config.artifact != .exe) return false;
+
+    return switch (builtin.os.tag) {
+        // macOS apps launched from finder or `open` always have the init
+        // process as their parent.
+        .macos => c.getppid() == 1,
+
+        // On Linux, GTK sets GIO_LAUNCHED_DESKTOP_FILE and
+        // GIO_LAUNCHED_DESKTOP_FILE_PID. We only check the latter to see if
+        // we match the PID and assume that if we do, we were launched from
+        // the desktop file. Pid comparing catches the scenario where
+        // another terminal was launched from a desktop file and then launches
+        // Ghostty and Ghostty inherits the env.
+        .linux => linux: {
+            const gio_pid_str = std.os.getenv("GIO_LAUNCHED_DESKTOP_FILE_PID") orelse
+                break :linux false;
+
+            const pid = c.getpid();
+            const gio_pid = std.fmt.parseInt(
+                @TypeOf(pid),
+                gio_pid_str,
+                10,
+            ) catch break :linux false;
+
+            break :linux gio_pid == pid;
+        },
+
+        else => @compileError("unsupported platform"),
+    };
+}

src/os/main.zig

@@ -2,6 +2,7 @@
 //! system.
 
 pub usingnamespace @import("env.zig");
+pub usingnamespace @import("desktop.zig");
 pub usingnamespace @import("file.zig");
 pub usingnamespace @import("flatpak.zig");
 pub usingnamespace @import("homedir.zig");