Respect XDG_CACHE_HOME and useNSFileManager for cache paths

src/os/macos.zig

@@ -25,43 +25,23 @@ pub fn appSupportDir(
     alloc: Allocator,
     sub_path: []const u8,
 ) AppSupportDirError![]u8 {
-    comptime assert(builtin.target.isDarwin());
-
-    const NSFileManager = objc.getClass("NSFileManager").?;
-    const manager = NSFileManager.msgSend(
-        objc.Object,
-        objc.sel("defaultManager"),
-        .{},
-    );
-
-    const url = manager.msgSend(
-        objc.Object,
-        objc.sel("URLForDirectory:inDomain:appropriateForURL:create:error:"),
-        .{
-            NSSearchPathDirectory.NSApplicationSupportDirectory,
-            NSSearchPathDomainMask.NSUserDomainMask,
-            @as(?*anyopaque, null),
-            true,
-            @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") orelse
-        return error.AppleAPIFailed;
-    const app_support_dir = std.mem.sliceTo(c_str, 0);
-
-    return try std.fs.path.join(alloc, &.{
-        app_support_dir,
+    return try makeCommonPath(alloc, .NSApplicationSupportDirectory, &.{
         build_config.bundle_id,
         sub_path,
     });
 }
 
+pub const CacheDirError = Allocator.Error || error{AppleAPIFailed};
+
+/// Return the path to the system cache directory with the given sub path joined.
+/// This allocates the result using the given allocator.
+pub fn cacheDir(
+    alloc: Allocator,
+    sub_path: []const u8,
+) CacheDirError![]u8 {
+    return try makeCommonPath(alloc, .NSCachesDirectory, &.{sub_path});
+}
+
 pub const SetQosClassError = error{
     // The thread can't have its QoS class changed usually because
     // a different pthread API was called that makes it an invalid
@@ -110,9 +90,52 @@ pub const NSOperatingSystemVersion = extern struct {
 };
 
 pub const NSSearchPathDirectory = enum(c_ulong) {
+    NSCachesDirectory = 13,
     NSApplicationSupportDirectory = 14,
 };
 
 pub const NSSearchPathDomainMask = enum(c_ulong) {
     NSUserDomainMask = 1,
 };
+
+fn makeCommonPath(
+    alloc: Allocator,
+    directory: NSSearchPathDirectory,
+    sub_paths: []const []const u8,
+) (error{AppleAPIFailed} || Allocator.Error)![]u8 {
+    comptime assert(builtin.target.isDarwin());
+
+    const NSFileManager = objc.getClass("NSFileManager").?;
+    const manager = NSFileManager.msgSend(
+        objc.Object,
+        objc.sel("defaultManager"),
+        .{},
+    );
+
+    const url = manager.msgSend(
+        objc.Object,
+        objc.sel("URLForDirectory:inDomain:appropriateForURL:create:error:"),
+        .{
+            directory,
+            NSSearchPathDomainMask.NSUserDomainMask,
+            @as(?*anyopaque, null),
+            true,
+            @as(?*anyopaque, null),
+        },
+    );
+
+    if (url.value == null) return error.AppleAPIFailed;
+
+    const path = url.getProperty(objc.Object, "path");
+    const c_str = path.getProperty(?[*:0]const u8, "UTF8String") orelse
+        return error.AppleAPIFailed;
+    const base_dir = std.mem.sliceTo(c_str, 0);
+
+    // Create a new array with base_dir as the first element
+    var paths = try alloc.alloc([]const u8, sub_paths.len + 1);
+    paths[0] = base_dir;
+    @memcpy(paths[1..], sub_paths);
+    defer alloc.free(paths);
+
+    return try std.fs.path.join(alloc, paths);
+}

src/os/xdg.zig

@@ -7,6 +7,7 @@ const assert = std.debug.assert;
 const Allocator = std.mem.Allocator;
 const posix = std.posix;
 const homedir = @import("homedir.zig");
+const macos = @import("macos.zig");
 
 pub const Options = struct {
     /// Subdirectories to join to the base. This avoids extra allocations
@@ -30,22 +31,17 @@ pub fn config(alloc: Allocator, opts: Options) ![]u8 {
 
 /// Get the XDG cache directory. The returned value is allocated.
 pub fn cache(alloc: Allocator, opts: Options) ![]u8 {
-    // On macOS we should use ~/Library/Caches instead of ~/.cache
-    if (builtin.os.tag == .macos) {
-        // Get our home dir if not provided
-        const home = if (opts.home) |h| h else blk: {
-            var buf: [1024]u8 = undefined;
-            break :blk try homedir.home(&buf) orelse return error.NoHomeDir;
-        };
-
+    if (posix.getenv("XDG_CACHE_HOME")) |env| {
         return try std.fs.path.join(alloc, &[_][]const u8{
-            home,
-            "Library",
-            "Caches",
+            env,
             opts.subdir orelse "",
         });
     }
 
+    if (builtin.os.tag == .macos) {
+        return try macos.cacheDir(alloc, opts.subdir orelse "");
+    }
+
     return try dir(alloc, opts, .{
         .env = "XDG_CACHE_HOME",
         .windows_env = "LOCALAPPDATA",
@@ -170,7 +166,8 @@ test "cache directory paths" {
         {
             const cache_path = try cache(alloc, .{ .home = mock_home });
             defer alloc.free(cache_path);
-            try testing.expectEqualStrings("/Users/test/Library/Caches", cache_path);
+            // We don't test the exact path since it comes from NSFileManager
+            try testing.expect(std.mem.indexOf(u8, cache_path, "Caches") != null);
         }
 
         // Test with subdir
@@ -180,7 +177,7 @@ test "cache directory paths" {
                 .subdir = "ghostty",
             });
             defer alloc.free(cache_path);
-            try testing.expectEqualStrings("/Users/test/Library/Caches/ghostty", cache_path);
+            try testing.expect(std.mem.indexOf(u8, cache_path, "Caches/ghostty") != null);
         }
     }