cli: add pager support for +show-config

src/cli/show_config.zig

@@ -4,6 +4,7 @@ const Allocator = std.mem.Allocator;
 const Action = @import("ghostty.zig").Action;
 const configpkg = @import("../config.zig");
 const Config = configpkg.Config;
+const Pager = @import("Pager.zig");
 
 pub const Options = struct {
     /// If true, do not load the user configuration, only load the defaults.
@@ -17,6 +18,9 @@ pub const Options = struct {
     /// if available.
     docs: bool = false,
 
+    /// Disable automatic paging of output.
+    @"no-pager": bool = false,
+
     pub fn deinit(self: Options) void {
         _ = self;
     }
@@ -55,6 +59,8 @@ pub const Options = struct {
 ///   * `--docs`: Print the documentation above each option as a comment,
 ///     This is very noisy but is very useful to learn about available
 ///     options, especially paired with `--default`.
+///
+///   * `--no-pager`: Disable automatic paging of output.
 pub fn run(alloc: Allocator) !u8 {
     var opts: Options = .{};
     defer opts.deinit();
@@ -75,12 +81,12 @@ pub fn run(alloc: Allocator) !u8 {
         .docs = opts.docs,
     };
 
-    // For some reason `std.fmt.format` isn't working here but it works in
-    // tests so we just do configfmt.format.
-    var stdout: std.fs.File = .stdout();
+    var pager: Pager = if (!opts.@"no-pager") .init(alloc) else .{};
+    defer pager.deinit();
     var buffer: [4096]u8 = undefined;
-    var stdout_writer = stdout.writer(&buffer);
-    try configfmt.format(&stdout_writer.interface);
-    try stdout_writer.end();
+    const writer = pager.writer(&buffer);
+
+    try configfmt.format(writer);
+    try writer.flush();
     return 0;
 }