cli: _macos-disclaim

src/cli/ghostty.zig

@@ -19,6 +19,7 @@ const crash_report = @import("crash_report.zig");
 const show_face = @import("show_face.zig");
 const boo = @import("boo.zig");
 const new_window = @import("new_window.zig");
+const macos_disclaim = @import("macos_disclaim.zig");
 
 /// Special commands that can be invoked via CLI flags. These are all
 /// invoked by using `+<action>` as a CLI flag. The only exception is
@@ -69,6 +70,9 @@ pub const Action = enum {
     // Use IPC to tell the running Ghostty to open a new window.
     @"new-window",
 
+    // Internal helper for posix_spawn that performs pre-exec setup
+    @"_macos-disclaim",
+
     pub fn detectSpecialCase(arg: []const u8) ?SpecialCase(Action) {
         // If we see a "-e" and we haven't seen a command yet, then
         // we are done looking for commands. This special case enables
@@ -102,6 +106,9 @@ pub const Action = enum {
             // to find this action in the help strings and output that.
             help_error => err: {
                 inline for (@typeInfo(Action).@"enum".fields) |field| {
+                    // Skip internal commands (prefixed with underscore)
+                    if (field.name[0] == '_') continue;
+
                     // Future note: for now we just output the help text directly
                     // to stdout. In the future we can style this much prettier
                     // for all commands by just changing this one place.
@@ -147,6 +154,7 @@ pub const Action = enum {
             .@"show-face" => try show_face.run(alloc),
             .boo => try boo.run(alloc),
             .@"new-window" => try new_window.run(alloc),
+            .@"_macos-disclaim" => try macos_disclaim.run(alloc),
         };
     }
 
@@ -186,6 +194,7 @@ pub const Action = enum {
                 .@"show-face" => show_face.Options,
                 .boo => boo.Options,
                 .@"new-window" => new_window.Options,
+                .@"_macos-disclaim" => macos_disclaim.Options,
             };
         }
     }

src/cli/help.zig

@@ -63,6 +63,8 @@ pub fn run(alloc: Allocator) !u8 {
     );
 
     inline for (@typeInfo(Action).@"enum".fields) |field| {
+        // Skip internal commands (prefixed with underscore)
+        if (field.name[0] == '_') continue;
         try stdout.print("  +{s}\n", .{field.name});
     }
 

src/cli/macos_disclaim.zig

@@ -0,0 +1,76 @@
+const std = @import("std");
+const builtin = @import("builtin");
+const posix = std.posix;
+const Allocator = std.mem.Allocator;
+const posix_spawn = @import("../os/posix_spawn.zig");
+
+const log = std.log.scoped(.macos_disclaim);
+
+pub const Options = struct {
+    pub fn deinit(self: Options) void {
+        _ = self;
+    }
+};
+
+/// The `_macos-disclaim` command is an internal-only Ghostty command that
+/// is only available on macOS. It uses private posix_spawn APIs to
+/// make the child process the "responssible process" in macOS so it is
+/// in charge of its own TCC (permissions like Downloads folder access or
+/// camera) and resource accounting rather than Ghostty.
+pub fn run(alloc: Allocator) !u8 {
+    // This helper is only for Apple systems. POSIX in general has posix_spawn
+    // but we only use it on Apple platforms because it lets us shed our
+    // responsible process bit.
+    if (comptime builtin.os.tag != .macos) {
+        log.warn("macos-disclaim is only supported on macOS", .{});
+        return 1;
+    }
+
+    // Get the command to exec from the remaining args
+    // Skip arg 0 (our program name) and arg 1 (the action "+_macos-disclaim")
+    var arg_iter = try std.process.argsWithAllocator(alloc);
+    defer arg_iter.deinit();
+    _ = arg_iter.skip();
+    _ = arg_iter.skip();
+
+    // Collect remaining args for exec
+    var args: std.ArrayList(?[*:0]const u8) = .empty;
+    defer args.deinit(alloc);
+    while (arg_iter.next()) |arg| try args.append(alloc, arg);
+    if (args.items.len == 0) {
+        log.err("no command specified to exec", .{});
+        return 1;
+    }
+    try args.append(alloc, null);
+
+    var attrs = try posix_spawn.spawn_attr.create();
+    defer posix_spawn.spawn_attr.destroy(&attrs);
+    {
+        try posix_spawn.spawn_attr.setflags(&attrs, .{
+            // Act like exec(): replace this process.
+            .setexec = true,
+        });
+
+        // This is the magical private API that makes it so that this
+        // child process doesn't get looped into the TCC and resource
+        // accounting of Ghostty.
+        try posix_spawn.spawn_attr.disclaim(&attrs, true);
+    }
+
+    _ = posix_spawn.spawnp(
+        std.mem.span(args.items[0].?),
+        null,
+        &attrs,
+        args.items[0 .. args.items.len - 1 :null].ptr,
+        std.c.environ,
+    ) catch |err| {
+        log.err("failed to posix_spawn command '{s}': {}", .{
+            std.mem.span(args.items[0].?),
+            err,
+        });
+        return 1;
+    };
+
+    // We set the exec flag so we can't reach this point.
+    unreachable;
+}

src/helpgen.zig

@@ -82,6 +82,9 @@ fn genActions(alloc: std.mem.Allocator, writer: *std.Io.Writer) !void {
     );
 
     inline for (@typeInfo(Action).@"enum".fields) |field| {
+        // Skip internal commands (prefixed with underscore)
+        if (field.name[0] == '_') continue;
+
         const action_file = comptime action_file: {
             const action = @field(Action, field.name);
             break :action_file action.file();

src/pty.zig

@@ -83,7 +83,7 @@ const NullPty = struct {
 /// 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 PosixPty = struct {
+pub const PosixPty = struct {
     pub const Error = OpenError || GetModeError || GetSizeError || SetSizeError || ChildPreExecError;
 
     pub const Fd = posix.fd_t;
@@ -249,6 +249,20 @@ const PosixPty = struct {
         posix.close(self.slave);
         posix.close(self.master);
     }
+
+    /// This is the pre-exec that needs to happen for posix_spawn on macOS
+    /// because the API doesn't support all the actions/attrs we need to
+    /// create a proper terminal environment.
+    pub fn posixSpawnPreExec(self: PosixPty) !void {
+        // Set controlling terminal
+        switch (posix.errno(c.ioctl(self.slave, TIOCSCTTY, @as(c_ulong, 0)))) {
+            .SUCCESS => {},
+            else => |err| {
+                log.err("error setting controlling terminal errno={}", .{err});
+                return error.SetControllingTerminalFailed;
+            },
+        }
+    }
 };
 
 /// Windows PTY creation and management.