basic pty opening

src/App.zig

@@ -7,10 +7,11 @@ const std = @import("std");
 const Allocator = std.mem.Allocator;
 const Window = @import("Window.zig");
 
-const log = std.log;
-
+/// General purpose allocator
 alloc: Allocator,
 
+/// The primary window for the application. We currently support only
+/// single window operations.
 window: *Window,
 
 /// Initialize the main app instance. This creates the main window, sets

src/Pty.zig

@@ -0,0 +1,76 @@
+//! Linux PTY creation and management. This is just a thin layer on top
+//! of Linux syscalls. The caller is responsible for detail-oriented handling
+//! of the returned file handles.
+const Pty = @This();
+
+const std = @import("std");
+const testing = std.testing;
+const linux = std.os.linux;
+const fd_t = std.os.fd_t;
+const winsize = linux.winsize;
+const c = @cImport({
+    @cInclude("pty.h");
+});
+
+/// The file descriptors for the master and slave side of the pty.
+master: fd_t,
+slave: fd_t,
+
+/// Open a new PTY with the given initial size.
+pub fn open(size: winsize) !Pty {
+    var master_fd: fd_t = undefined;
+    var slave_fd: fd_t = undefined;
+    if (c.openpty(
+        &master_fd,
+        &slave_fd,
+        null,
+        null,
+        @ptrCast([*c]const c.struct_winsize, &size),
+    ) < 0)
+        return error.OpenptyFailed;
+
+    return Pty{
+        .master = master_fd,
+        .slave = slave_fd,
+    };
+}
+
+pub fn deinit(self: *Pty) void {
+    std.os.close(self.master);
+    self.* = undefined;
+}
+
+/// Return the size of the pty.
+pub fn getSize(self: Pty) !winsize {
+    var ws: winsize = undefined;
+    if (linux.ioctl(self.master, linux.T.IOCGWINSZ, @ptrToInt(&ws)) < 0)
+        return error.IoctlFailed;
+
+    return ws;
+}
+
+/// Set the size of the pty.
+pub fn setSize(self: Pty, size: winsize) !void {
+    if (linux.ioctl(self.master, linux.T.IOCSWINSZ, @ptrToInt(&size)) < 0)
+        return error.IoctlFailed;
+}
+
+test {
+    var ws: winsize = .{
+        .ws_row = 50,
+        .ws_col = 80,
+        .ws_xpixel = 1,
+        .ws_ypixel = 1,
+    };
+
+    var pty = try open(ws);
+    defer pty.deinit();
+
+    // Initialize size should match what we gave it
+    try testing.expectEqual(ws, try pty.getSize());
+
+    // Can set and read new sizes
+    ws.ws_row *= 2;
+    try pty.setSize(ws);
+    try testing.expectEqual(ws, try pty.getSize());
+}

src/Window.zig

@@ -11,6 +11,7 @@ const Allocator = std.mem.Allocator;
 const Grid = @import("Grid.zig");
 const glfw = @import("glfw");
 const gl = @import("opengl.zig");
+const Pty = @import("Pty.zig");
 
 const log = std.log.scoped(.window);
 
@@ -20,6 +21,9 @@ window: glfw.Window,
 /// The terminal grid attached to this window.
 grid: Grid,
 
+/// The underlying pty for this window.
+pty: Pty,
+
 /// Create a new window. This allocates and returns a pointer because we
 /// need a stable pointer for user data callbacks. Therefore, a stack-only
 /// initialization is not currently possible.
@@ -61,13 +65,24 @@ pub fn create(alloc: Allocator) !*Window {
     gl.c.glEnable(gl.c.GL_BLEND);
     gl.c.glBlendFunc(gl.c.GL_SRC_ALPHA, gl.c.GL_ONE_MINUS_SRC_ALPHA);
 
-    // Create our terminal grid with a bogus initial size.
+    // Create our terminal grid with the initial window size
+    const window_size = try window.getSize();
     var grid = try Grid.init(alloc);
-    try grid.setScreenSize(.{ .width = 640, .height = 480 });
+    try grid.setScreenSize(.{ .width = window_size.width, .height = window_size.height });
+
+    // Create our pty
+    var pty = try Pty.open(.{
+        .ws_row = @intCast(u16, grid.size.rows),
+        .ws_col = @intCast(u16, grid.size.columns),
+        .ws_xpixel = @intCast(u16, window_size.width),
+        .ws_ypixel = @intCast(u16, window_size.height),
+    });
+    errdefer pty.deinit();
 
     self.* = .{
         .window = window,
         .grid = grid,
+        .pty = pty,
     };
 
     // Setup our callbacks and user data
@@ -78,6 +93,7 @@ pub fn create(alloc: Allocator) !*Window {
 }
 
 pub fn destroy(self: *Window, alloc: Allocator) void {
+    self.pty.deinit();
     self.grid.deinit();
     self.window.destroy();
     alloc.destroy(self);
@@ -114,6 +130,14 @@ fn sizeCallback(window: glfw.Window, width: i32, height: i32) void {
     // TODO: temp
     win.grid.demoCells() catch unreachable;
 
+    // Update the size of our pty
+    win.pty.setSize(.{
+        .ws_row = @intCast(u16, win.grid.size.rows),
+        .ws_col = @intCast(u16, win.grid.size.columns),
+        .ws_xpixel = @intCast(u16, width),
+        .ws_ypixel = @intCast(u16, height),
+    }) catch |err| log.err("error updating pty screen size err={}", .{err});
+
     // Update our viewport for this context to be the entire window
     gl.viewport(0, 0, width, height) catch |err|
         log.err("error updating OpenGL viewport err={}", .{err});

src/main.zig

@@ -22,4 +22,5 @@ test {
     _ = @import("Atlas.zig");
     _ = @import("FontAtlas.zig");
     _ = @import("Grid.zig");
+    _ = @import("Pty.zig");
 }