os: more error handling on reading the app support dir

src/config/Config.zig

@@ -1809,14 +1809,10 @@ pub fn deinit(self: *Config) void {
 /// Load the configuration according to the default rules:
 ///
 ///   1. Defaults
-///   2. Configuration Files
-///   3. CLI flags
-///   4. Recursively defined configuration files
-///
-/// Configuration files are loaded in the follow order:
-///
-///   1. XDG Config File
-///   2. "Application Support" Config File on macOS
+///   2. XDG config dir
+///   3. "Application Support" directory (macOS only)
+///   4. CLI flags
+///   5. Recursively defined configuration files
 ///
 pub fn load(alloc_gpa: Allocator) !Config {
     var result = try default(alloc_gpa);
@@ -2423,8 +2419,8 @@ pub fn loadDefaultFiles(self: *Config, alloc: Allocator) !void {
     defer alloc.free(xdg_path);
     self.loadOptionalFile(alloc, xdg_path);
 
-    if (builtin.os.tag == .macos) {
-        const app_support_path = try internal_os.macos.getAppSupportDir(alloc, "config");
+    if (comptime builtin.os.tag == .macos) {
+        const app_support_path = try internal_os.macos.appSupportDir(alloc, "config");
         defer alloc.free(app_support_path);
         self.loadOptionalFile(alloc, app_support_path);
     }

src/os/macos.zig

@@ -4,15 +4,9 @@ const assert = std.debug.assert;
 const objc = @import("objc");
 const Allocator = std.mem.Allocator;
 
-pub const NSOperatingSystemVersion = extern struct {
-    major: i64,
-    minor: i64,
-    patch: i64,
-};
-
 /// Verifies that the running macOS system version is at least the given version.
 pub fn isAtLeastVersion(major: i64, minor: i64, patch: i64) bool {
-    assert(builtin.target.isDarwin());
+    comptime assert(builtin.target.isDarwin());
 
     const NSProcessInfo = objc.getClass("NSProcessInfo").?;
     const info = NSProcessInfo.msgSend(objc.Object, objc.sel("processInfo"), .{});
@@ -21,20 +15,24 @@ pub fn isAtLeastVersion(major: i64, minor: i64, patch: i64) bool {
     });
 }
 
-pub const NSSearchPathDirectory = enum(c_ulong) {
-    NSApplicationSupportDirectory = 14,
-};
+pub const AppSupportDirError = Allocator.Error || error{AppleAPIFailed};
 
-pub const NSSearchPathDomainMask = enum(c_ulong) {
-    NSUserDomainMask = 1,
-};
+/// Return the path to the application support directory for Ghostty
+/// with the given sub path joined. This allocates the result using the
+/// given allocator.
+pub fn appSupportDir(
+    alloc: Allocator,
+    sub_path: []const u8,
+) AppSupportDirError![]u8 {
+    comptime assert(builtin.target.isDarwin());
 
-pub fn getAppSupportDir(alloc: Allocator, sub_path: []const u8) ![]u8 {
-    assert(builtin.target.isDarwin());
-
-    const err: ?*anyopaque = undefined;
     const NSFileManager = objc.getClass("NSFileManager").?;
-    const manager = NSFileManager.msgSend(objc.Object, objc.sel("defaultManager"), .{});
+    const manager = NSFileManager.msgSend(
+        objc.Object,
+        objc.sel("defaultManager"),
+        .{},
+    );
+
     const url = manager.msgSend(
         objc.Object,
         objc.sel("URLForDirectory:inDomain:appropriateForURL:create:error:"),
@@ -43,12 +41,36 @@ pub fn getAppSupportDir(alloc: Allocator, sub_path: []const u8) ![]u8 {
             NSSearchPathDomainMask.NSUserDomainMask,
             @as(?*anyopaque, null),
             true,
-            &err,
+            @as(?*anyopaque, null),
         },
     );
+
+    // I don't think this is possible but just in case.
+    if (url.value == null) return error.AppleAPIFailed;
+
+    // Get the UTF-8 string from the URL.
     const path = url.getProperty(objc.Object, "path");
-    const c_str = path.getProperty([*:0]const u8, "UTF8String");
+    const c_str = path.getProperty(?[*:0]const u8, "UTF8String") orelse
+        return error.AppleAPIFailed;
     const app_support_dir = std.mem.sliceTo(c_str, 0);
 
-    return try std.fs.path.join(alloc, &.{ app_support_dir, "com.mitchellh.ghostty", sub_path });
+    return try std.fs.path.join(alloc, &.{
+        app_support_dir,
+        "com.mitchellh.ghostty",
+        sub_path,
+    });
 }
+
+pub const NSOperatingSystemVersion = extern struct {
+    major: i64,
+    minor: i64,
+    patch: i64,
+};
+
+pub const NSSearchPathDirectory = enum(c_ulong) {
+    NSApplicationSupportDirectory = 14,
+};
+
+pub const NSSearchPathDomainMask = enum(c_ulong) {
+    NSUserDomainMask = 1,
+};