respond to ESC [ c for primary attributes

src/Window.zig

@@ -67,8 +67,7 @@ pty_stream: libuv.Tty,
 write_req_pool: SegmentedPool(libuv.WriteReq.T, WRITE_REQ_PREALLOC) = .{},
 
 /// The pool of available buffers for writing to the pty.
-/// TODO: [1]u8 is probably not right.
-write_buf_pool: SegmentedPool([1]u8, WRITE_REQ_PREALLOC) = .{},
+write_buf_pool: SegmentedPool([64]u8, WRITE_REQ_PREALLOC) = .{},
 
 /// Set this to true whenver an event occurs that we may want to wake up
 /// the event loop. Only set this from the main thread.
@@ -246,6 +245,26 @@ pub fn shouldClose(self: Window) bool {
     return self.window.shouldClose();
 }
 
+/// Queue a write to the pty.
+fn queueWrite(self: *Window, data: []const u8) !void {
+    // We go through and chunk the data if necessary to fit into
+    // our cached buffers that we can queue to the stream.
+    var i: usize = 0;
+    while (i < data.len) {
+        const req = try self.write_req_pool.get();
+        const buf = try self.write_buf_pool.get();
+        const end = @minimum(data.len, i + buf.len);
+        std.mem.copy(u8, buf, data[i..end]);
+        try self.pty_stream.write(
+            .{ .req = req },
+            &[1][]u8{buf[0..(end - i)]},
+            ttyWrite,
+        );
+
+        i += end;
+    }
+}
+
 fn sizeCallback(window: glfw.Window, width: i32, height: i32) void {
     const tracy = trace(@src());
     defer tracy.end();
@@ -288,14 +307,7 @@ fn charCallback(window: glfw.Window, codepoint: u21) void {
     const win = window.getUserPointer(Window) orelse return;
 
     // Write the character to the pty
-    const req = win.write_req_pool.get() catch unreachable;
-    const buf = win.write_buf_pool.get() catch unreachable;
-    buf[0] = @intCast(u8, codepoint);
-    win.pty_stream.write(
-        .{ .req = req },
-        &[1][]u8{buf[0..1]},
-        ttyWrite,
-    ) catch unreachable;
+    win.queueWrite(&[1]u8{@intCast(u8, codepoint)}) catch unreachable;
 }
 
 fn keyCallback(
@@ -597,3 +609,17 @@ pub fn setAttribute(self: *Window, attr: terminal.Attribute) !void {
             log.warn("error setting attribute {}: {}", .{ attr, err }),
     }
 }
+
+pub fn deviceAttributes(
+    self: *Window,
+    req: terminal.DeviceAttributeReq,
+    params: []const u16,
+) !void {
+    _ = params;
+
+    switch (req) {
+        .primary => self.queueWrite("\x1B[?6c") catch |err|
+            log.warn("error queueing device attr response: {}", .{err}),
+        else => log.warn("unimplemented device attributes req: {}", .{req}),
+    }
+}

src/terminal/ansi.zig

@@ -42,3 +42,10 @@ pub const Mode = enum(u16) {
     // Non-exhaustive so that @intToEnum never fails for unsupported modes.
     _,
 };
+
+/// The device attribute request type (ESC [ c).
+pub const DeviceAttributeReq = enum {
+    primary, // Blank
+    secondary, // >
+    tertiary, // =
+};

src/terminal/main.zig

@@ -6,6 +6,7 @@ const sgr = @import("sgr.zig");
 pub const Terminal = @import("Terminal.zig");
 pub const Parser = @import("Parser.zig");
 pub const Stream = stream.Stream;
+pub const DeviceAttributeReq = ansi.DeviceAttributeReq;
 pub const Mode = ansi.Mode;
 pub const EraseDisplay = csi.EraseDisplay;
 pub const EraseLine = csi.EraseLine;

src/terminal/stream.zig

@@ -235,6 +235,24 @@ pub fn Stream(comptime Handler: type) type {
                     },
                 ) else log.warn("unimplemented CSI callback: {}", .{action}),
 
+                // c - Device Attributes (DA1)
+                'c' => if (@hasDecl(T, "deviceAttributes")) {
+                    const req: ansi.DeviceAttributeReq = switch (action.intermediates.len) {
+                        0 => ansi.DeviceAttributeReq.primary,
+                        1 => switch (action.intermediates[0]) {
+                            '>' => ansi.DeviceAttributeReq.secondary,
+                            '=' => ansi.DeviceAttributeReq.tertiary,
+                            else => null,
+                        },
+                        else => @as(?ansi.DeviceAttributeReq, null),
+                    } orelse {
+                        log.warn("invalid device attributes command: {}", .{action});
+                        return;
+                    };
+
+                    try self.handler.deviceAttributes(req, action.params);
+                } else log.warn("unimplemented CSI callback: {}", .{action}),
+
                 // VPA - Cursor Vertical Position Absolute
                 'd' => if (@hasDecl(T, "setCursorRow")) try self.handler.setCursorRow(
                     switch (action.params.len) {