From e59b2f7fca460a75d12cb639514d86f25c1d4dfa Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Wed, 31 May 2023 18:54:24 -0700
Subject: [PATCH] terminal: track pwd reported via OSC 7

---
 src/terminal/Terminal.zig | 19 ++++++++++++++++++
 src/terminal/osc.zig      | 13 +++++++++++-
 src/terminal/stream.zig   |  6 ++++++
 src/termio/Exec.zig       | 42 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 79 insertions(+), 1 deletion(-)

diff --git a/src/terminal/Terminal.zig b/src/terminal/Terminal.zig
index 9fa814e3e..420d622c5 100644
--- a/src/terminal/Terminal.zig
+++ b/src/terminal/Terminal.zig
@@ -64,6 +64,9 @@ cols: usize,
 /// The current scrolling region.
 scrolling_region: ScrollingRegion,
 
+/// The last reported pwd, if any.
+pwd: std.ArrayList(u8),
+
 /// The charset state
 charset: CharsetState = .{},
 
@@ -169,6 +172,7 @@ pub fn init(alloc: Allocator, cols: usize, rows: usize) !Terminal {
             .top = 0,
             .bottom = rows - 1,
         },
+        .pwd = std.ArrayList(u8).init(alloc),
     };
 }
 
@@ -176,6 +180,7 @@ pub fn deinit(self: *Terminal, alloc: Allocator) void {
     self.tabstops.deinit(alloc);
     self.screen.deinit();
     self.secondary_screen.deinit();
+    self.pwd.deinit();
     self.* = undefined;
 }
 
@@ -1501,6 +1506,19 @@ pub fn cursorIsAtPrompt(self: *Terminal) bool {
     return false;
 }
 
+/// Set the pwd for the terminal.
+pub fn setPwd(self: *Terminal, pwd: []const u8) !void {
+    self.pwd.clearRetainingCapacity();
+    try self.pwd.appendSlice(pwd);
+}
+
+/// Returns the pwd for the terminal, if any. The memory is owned by the
+/// Terminal and is not copied. It is safe until a reset or setPwd.
+pub fn getPwd(self: *Terminal) ?[]const u8 {
+    if (self.pwd.items.len == 0) return null;
+    return self.pwd.items;
+}
+
 /// Full reset
 pub fn fullReset(self: *Terminal) void {
     self.primaryScreen(.{ .clear_on_exit = true, .cursor_save = true });
@@ -1514,6 +1532,7 @@ pub fn fullReset(self: *Terminal) void {
     self.screen.selection = null;
     self.scrolling_region = .{ .top = 0, .bottom = self.rows - 1 };
     self.previous_char = null;
+    self.pwd.clearRetainingCapacity();
 }
 
 test "Terminal: input with no control characters" {
diff --git a/src/terminal/osc.zig b/src/terminal/osc.zig
index 917de83be..ccbdd044e 100644
--- a/src/terminal/osc.zig
+++ b/src/terminal/osc.zig
@@ -242,7 +242,7 @@ pub const Parser = struct {
 
             .@"7" => switch (c) {
                 ';' => {
-                    self.command = .{ .report_pwd = .{ .value = undefined } };
+                    self.command = .{ .report_pwd = .{ .value = "" } };
 
                     self.state = .string;
                     self.temp_state = .{ .str = &self.command.report_pwd.value };
@@ -593,6 +593,17 @@ test "OSC: report pwd" {
     try testing.expect(std.mem.eql(u8, "file:///tmp/example", cmd.report_pwd.value));
 }
 
+test "OSC: report pwd empty" {
+    const testing = std.testing;
+
+    var p: Parser = .{};
+
+    const input = "7;";
+    for (input) |ch| p.next(ch);
+
+    try testing.expect(p.end() == null);
+}
+
 test "OSC: longer than buffer" {
     const testing = std.testing;
 
diff --git a/src/terminal/stream.zig b/src/terminal/stream.zig
index 2f8766c56..f36fa6315 100644
--- a/src/terminal/stream.zig
+++ b/src/terminal/stream.zig
@@ -495,6 +495,12 @@ pub fn Stream(comptime Handler: type) type {
                     } else log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
 
+                .report_pwd => |v| {
+                    if (@hasDecl(T, "reportPwd")) {
+                        try self.handler.reportPwd(v.value);
+                    } else log.warn("unimplemented OSC callback: {}", .{cmd});
+                },
+
                 else => if (@hasDecl(T, "oscUnimplemented"))
                     try self.handler.oscUnimplemented(cmd)
                 else
diff --git a/src/termio/Exec.zig b/src/termio/Exec.zig
index 294019b83..d09963419 100644
--- a/src/termio/Exec.zig
+++ b/src/termio/Exec.zig
@@ -1249,4 +1249,46 @@ const StreamHandler = struct {
     pub fn endOfInput(self: *StreamHandler) !void {
         self.terminal.markSemanticPrompt(.command);
     }
+
+    pub fn reportPwd(self: *StreamHandler, url: []const u8) !void {
+        const uri = std.Uri.parse(url) catch |e| {
+            log.warn("invalid url in OSC 7: {}", .{e});
+            return;
+        };
+
+        if (!std.mem.eql(u8, "file", uri.scheme) and
+            !std.mem.eql(u8, "kitty-shell-cwd", uri.scheme))
+        {
+            log.warn("OSC 7 scheme must be file, got: {s}", .{uri.scheme});
+            return;
+        }
+
+        // OSC 7 is a little sketchy because anyone can send any value from
+        // any host (such an SSH session). The best practice terminals follow
+        // is to valid the hostname to be local.
+        const host_valid = host_valid: {
+            const host = uri.host orelse break :host_valid false;
+
+            // Empty or localhost is always good
+            if (host.len == 0 or std.mem.eql(u8, "localhost", host)) {
+                break :host_valid true;
+            }
+
+            // Otherwise, it must match our hostname.
+            var buf: [std.os.HOST_NAME_MAX]u8 = undefined;
+            const hostname = std.os.gethostname(&buf) catch |err| {
+                log.warn("failed to get hostname for OSC 7 validation: {}", .{err});
+                break :host_valid false;
+            };
+
+            break :host_valid std.mem.eql(u8, host, hostname);
+        };
+        if (!host_valid) {
+            log.warn("OSC 7 host must be local", .{});
+            return;
+        }
+
+        log.debug("terminal pwd: {s}", .{uri.path});
+        try self.terminal.setPwd(uri.path);
+    }
 };