core: add iterator to handle XDG_*_DIRS

src/os/xdg.zig

@@ -193,3 +193,77 @@ test parseTerminalExec {
         try testing.expectEqualSlices([*:0]const u8, actual, &.{ "a", "-e", "b", "c" });
     }
 }
+
+/// https://specifications.freedesktop.org/basedir-spec/latest/
+pub const Dir = enum {
+    config,
+    data,
+
+    pub fn key(self: Dir) [:0]const u8 {
+        return switch (self) {
+            .config => "XDG_CONFIG_DIRS",
+            .data => "XDG_DATA_DIRS",
+        };
+    }
+
+    pub fn default(self: Dir) [:0]const u8 {
+        return switch (self) {
+            .config => "/etc/xdg",
+            .data => "/usr/local/share:/usr/share",
+        };
+    }
+};
+
+pub const DirIterator = struct {
+    data: []const u8,
+    iterator: std.mem.SplitIterator(u8, .scalar),
+
+    /// https://specifications.freedesktop.org/basedir-spec/latest/
+    pub fn init(key: Dir) DirIterator {
+        const data = data: {
+            if (posix.getenv(key.key())) |data| {
+                if (std.mem.trim(u8, data, &std.ascii.whitespace).len > 0) break :data data;
+            }
+
+            break :data key.default();
+        };
+
+        return .{
+            .data = data,
+            .iterator = std.mem.splitScalar(u8, data, ':'),
+        };
+    }
+
+    pub fn next(self: *DirIterator) ?[]const u8 {
+        return self.iterator.next();
+    }
+};
+
+test "xdg dirs" {
+    const c = @cImport({
+        @cInclude("stdlib.h");
+    });
+
+    const testing = std.testing;
+    {
+        _ = c.unsetenv(Dir.config.key());
+        var it = DirIterator.init(.config);
+        try testing.expectEqualStrings("/etc/xdg", it.next().?);
+        try testing.expect(it.next() == null);
+    }
+    {
+        _ = c.unsetenv(Dir.data.key());
+        var it = DirIterator.init(.data);
+        try testing.expectEqualStrings("/usr/local/share", it.next().?);
+        try testing.expectEqualStrings("/usr/share", it.next().?);
+        try testing.expect(it.next() == null);
+    }
+    {
+        _ = c.setenv(Dir.config.key(), "a:b:c", 1);
+        var it = DirIterator.init(.config);
+        try testing.expectEqualStrings("a", it.next().?);
+        try testing.expectEqualStrings("b", it.next().?);
+        try testing.expectEqualStrings("c", it.next().?);
+        try testing.expect(it.next() == null);
+    }
+}

src/termio/Exec.zig

@@ -15,6 +15,7 @@ const configpkg = @import("../config.zig");
 const crash = @import("../crash/main.zig");
 const fastmem = @import("../fastmem.zig");
 const internal_os = @import("../os/main.zig");
+const xdg = internal_os.xdg;
 const renderer = @import("../renderer.zig");
 const shell_integration = @import("shell_integration.zig");
 const terminal = @import("../terminal/main.zig");
@@ -801,18 +802,17 @@ const Subprocess = struct {
 
             var buf: [std.fs.max_path_bytes]u8 = undefined;
 
-            const xdg_data_dir_key = "XDG_DATA_DIRS";
             if (std.fmt.bufPrint(&buf, "{s}/..", .{resources_dir})) |data_dir| {
                 try env.put(
-                    xdg_data_dir_key,
+                    xdg.Dir.data.key(),
                     try internal_os.appendEnv(
                         alloc,
-                        env.get(xdg_data_dir_key) orelse "/usr/local/share:/usr/share",
+                        env.get(xdg.Dir.data.key()) orelse xdg.Dir.data.default(),
                         data_dir,
                     ),
                 );
             } else |err| {
-                log.warn("error building {s}; err={}", .{ xdg_data_dir_key, err });
+                log.warn("error building {s}; err={}", .{ xdg.Dir.data.key(), err });
             }
 
             const manpath_key = "MANPATH";

src/termio/shell_integration.zig

@@ -6,6 +6,7 @@ const EnvMap = std.process.EnvMap;
 const config = @import("../config.zig");
 const homedir = @import("../os/homedir.zig");
 const internal_os = @import("../os/main.zig");
+const xdg = internal_os.xdg;
 
 const log = std.log.scoped(.shell_integration);
 
@@ -471,12 +472,11 @@ fn setupXdgDataDirs(
     // This ensures that the default directories aren't lost by setting
     // our desired integration dir directly. See #2711.
     // <https://specifications.freedesktop.org/basedir-spec/0.6/#variables>
-    const xdg_data_dirs_key = "XDG_DATA_DIRS";
     try env.put(
-        xdg_data_dirs_key,
+        xdg.Dir.data.key(),
         try internal_os.prependEnv(
             stack_alloc,
-            env.get(xdg_data_dirs_key) orelse "/usr/local/share:/usr/share",
+            env.get(xdg.Dir.data.key()) orelse xdg.Dir.data.default(),
             integ_dir,
         ),
     );