fix some cases in the `dirname` function. (#3785)

Close: #3782

2 files changed, 169 insertions, 21 deletions

diff --git a/src/bun.js/node/types.zig b/src/bun.js/node/types.zig
index d1c92e970..bc2144095 100644
--- a/src/bun.js/node/types.zig
+++ b/src/bun.js/node/types.zig
@@ -1682,6 +1682,87 @@ pub const Path = struct {
 
         return JSC.ZigString.init(out).withEncoding().toValueGC(globalThis);
     }
+
+    fn dirnameWindows(path: []const u8) []const u8 {
+        if (path.len == 0)
+            return ".";
+
+        const root_slice = std.fs.path.diskDesignatorWindows(path);
+        if (path.len == root_slice.len)
+            return root_slice;
+
+        const have_root_slash = path.len > root_slice.len and (path[root_slice.len] == '/' or path[root_slice.len] == '\\');
+
+        var end_index: usize = path.len - 1;
+
+        while (path[end_index] == '/' or path[end_index] == '\\') {
+            // e.g. '\\' => "\\"
+            if (end_index == 0) {
+                return path[0..1];
+            }
+            end_index -= 1;
+        }
+
+        while (path[end_index] != '/' and path[end_index] != '\\') {
+            if (end_index == 0) {
+                if (root_slice.len == 0) {
+                    return ".";
+                }
+                if (have_root_slash) {
+                    // e.g. "c:\\" => "c:\\"
+                    return path[0 .. root_slice.len + 1];
+                } else {
+                    // e.g. "c:foo" => "c:"
+                    return root_slice;
+                }
+            }
+            end_index -= 1;
+        }
+
+        if (have_root_slash and end_index == root_slice.len) {
+            end_index += 1;
+        }
+
+        return path[0..end_index];
+    }
+
+    fn dirnamePosix(path: []const u8) []const u8 {
+        if (path.len == 0)
+            return ".";
+
+        var end_index: usize = path.len - 1;
+
+        while (path[end_index] == '/') {
+            // e.g. "////" => "/"
+            if (end_index == 0) {
+                return "/";
+            }
+            end_index -= 1;
+        }
+
+        while (path[end_index] != '/') {
+            if (end_index == 0) {
+                // e.g. "a/", "a"
+                return ".";
+            }
+            end_index -= 1;
+        }
+
+        // e.g. "/a/" => "/"
+        if (end_index == 0 and path[0] == '/') {
+            return "/";
+        }
+
+        // "a/b" => "a" or "//b" => "//"
+        if (end_index <= 1) {
+            if (path[0] == '/' and path[1] == '/') {
+                end_index += 1;
+            }
+        }
+
+        return path[0..end_index];
+    }
+
     pub fn dirname(globalThis: *JSC.JSGlobalObject, isWindows: bool, args_ptr: [*]JSC.JSValue, args_len: u16) callconv(.C) JSC.JSValue {
         if (comptime is_bindgen) return JSC.JSValue.jsUndefined();
         if (args_len == 0) {
@@ -1697,9 +1778,9 @@ pub const Path = struct {
         const base_slice = path.slice();
 
         const out = if (isWindows)
-            std.fs.path.dirnameWindows(base_slice) orelse "."
+            @This().dirnameWindows(base_slice)
         else
-            std.fs.path.dirnamePosix(base_slice) orelse ".";
+            @This().dirnamePosix(base_slice);
 
         return JSC.ZigString.init(out).toValueGC(globalThis);
     }
diff --git a/test/js/node/path/path.test.js b/test/js/node/path/path.test.js
index 03037c2e9..deab41796 100644
--- a/test/js/node/path/path.test.js
+++ b/test/js/node/path/path.test.js
@@ -19,26 +19,93 @@ it("should not inherit Object.prototype", () => {
   expect(path).not.toHaveProperty("toString");
 });
 
-it("path.dirname", () => {
-  const fixtures = [
-    ["yo", "."],
-    ["/yo", "/"],
-    ["/yo/", "/"],
-    ["/yo/123", "/yo"],
-    [".", "."],
-    ["../", "."],
-    ["../../", ".."],
-    ["../../foo", "../.."],
-    ["../../foo/../", "../../foo"],
-    ["/foo/../", "/foo"],
-    ["../../foo/../bar", "../../foo/.."],
-  ];
-  for (const [input, expected] of fixtures) {
-    expect(path.posix.dirname(input)).toBe(expected);
-    if (process.platform !== "win32") {
-      expect(path.dirname(input)).toBe(expected);
+describe("dirname", () => {
+  it("path.dirname", () => {
+    const fixtures = [
+      ["yo", "."],
+      ["/yo", "/"],
+      ["/yo/", "/"],
+      ["/yo/123", "/yo"],
+      [".", "."],
+      ["../", "."],
+      ["../../", ".."],
+      ["../../foo", "../.."],
+      ["../../foo/../", "../../foo"],
+      ["/foo/../", "/foo"],
+      ["../../foo/../bar", "../../foo/.."],
+    ];
+    for (const [input, expected] of fixtures) {
+      expect(path.posix.dirname(input)).toBe(expected);
+      if (process.platform !== "win32") {
+        expect(path.dirname(input)).toBe(expected);
+      }
     }
-  }
+  });
+  it("path.posix.dirname", () => {
+    expect(path.posix.dirname("/a/b/")).toBe("/a");
+    expect(path.posix.dirname("/a/b")).toBe("/a");
+    expect(path.posix.dirname("/a")).toBe("/");
+    expect(path.posix.dirname("/a/")).toBe("/");
+    expect(path.posix.dirname("")).toBe(".");
+    expect(path.posix.dirname("/")).toBe("/");
+    expect(path.posix.dirname("//")).toBe("/");
+    expect(path.posix.dirname("///")).toBe("/");
+    expect(path.posix.dirname("////")).toBe("/");
+    expect(path.posix.dirname("//a")).toBe("//");
+    expect(path.posix.dirname("//ab")).toBe("//");
+    expect(path.posix.dirname("///a")).toBe("//");
+    expect(path.posix.dirname("////a")).toBe("///");
+    expect(path.posix.dirname("/////a")).toBe("////");
+    expect(path.posix.dirname("foo")).toBe(".");
+    expect(path.posix.dirname("foo/")).toBe(".");
+    expect(path.posix.dirname("a/b")).toBe("a");
+    expect(path.posix.dirname("a/")).toBe(".");
+    expect(path.posix.dirname("a///b")).toBe("a//");
+    expect(path.posix.dirname("a//b")).toBe("a/");
+    expect(path.posix.dirname("\\")).toBe(".");
+    expect(path.posix.dirname("\\a")).toBe(".");
+    expect(path.posix.dirname("a")).toBe(".");
+    expect(path.posix.dirname("/a/b//c")).toBe("/a/b/");
+  });
+  it("path.win32.dirname", () => {
+    expect(path.win32.dirname("c:\\")).toBe("c:\\");
+    expect(path.win32.dirname("c:\\foo")).toBe("c:\\");
+    expect(path.win32.dirname("c:\\foo\\")).toBe("c:\\");
+    expect(path.win32.dirname("c:\\foo\\bar")).toBe("c:\\foo");
+    expect(path.win32.dirname("c:\\foo\\bar\\")).toBe("c:\\foo");
+    expect(path.win32.dirname("c:\\foo\\bar\\baz")).toBe("c:\\foo\\bar");
+    expect(path.win32.dirname("c:\\foo bar\\baz")).toBe("c:\\foo bar");
+    expect(path.win32.dirname("c:\\\\foo")).toBe("c:\\");
+    expect(path.win32.dirname("\\")).toBe("\\");
+    expect(path.win32.dirname("\\foo")).toBe("\\");
+    expect(path.win32.dirname("\\foo\\")).toBe("\\");
+    expect(path.win32.dirname("\\foo\\bar")).toBe("\\foo");
+    expect(path.win32.dirname("\\foo\\bar\\")).toBe("\\foo");
+    expect(path.win32.dirname("\\foo\\bar\\baz")).toBe("\\foo\\bar");
+    expect(path.win32.dirname("\\foo bar\\baz")).toBe("\\foo bar");
+    expect(path.win32.dirname("c:")).toBe("c:");
+    expect(path.win32.dirname("c:foo")).toBe("c:");
+    expect(path.win32.dirname("c:foo\\")).toBe("c:");
+    expect(path.win32.dirname("c:foo\\bar")).toBe("c:foo");
+    expect(path.win32.dirname("c:foo\\bar\\")).toBe("c:foo");
+    expect(path.win32.dirname("c:foo\\bar\\baz")).toBe("c:foo\\bar");
+    expect(path.win32.dirname("c:foo bar\\baz")).toBe("c:foo bar");
+    expect(path.win32.dirname("file:stream")).toBe(".");
+    expect(path.win32.dirname("dir\\file:stream")).toBe("dir");
+    expect(path.win32.dirname("\\\\unc\\share")).toBe("\\\\unc\\share");
+    expect(path.win32.dirname("\\\\unc\\share\\foo")).toBe("\\\\unc\\share\\");
+    expect(path.win32.dirname("\\\\unc\\share\\foo\\")).toBe("\\\\unc\\share\\");
+    expect(path.win32.dirname("\\\\unc\\share\\foo\\bar")).toBe("\\\\unc\\share\\foo");
+    expect(path.win32.dirname("\\\\unc\\share\\foo\\bar\\")).toBe("\\\\unc\\share\\foo");
+    expect(path.win32.dirname("\\\\unc\\share\\foo\\bar\\baz")).toBe("\\\\unc\\share\\foo\\bar");
+    expect(path.win32.dirname("/a/b/")).toBe("/a");
+    expect(path.win32.dirname("/a/b")).toBe("/a");
+    expect(path.win32.dirname("/a")).toBe("/");
+    expect(path.win32.dirname("")).toBe(".");
+    expect(path.win32.dirname("/")).toBe("/");
+    expect(path.win32.dirname("////")).toBe("/");
+    expect(path.win32.dirname("foo")).toBe(".");
+  });
 });
 
 it("path.parse().name", () => {