fix(runtime): `fs.cp` edge cases (#4439)

* yippee

* enable cpSync tests

* much better

* that doesnt actually do anything

* lose

2 files changed, 44 insertions, 8 deletions

diff --git a/src/bun.js/node/node_fs.zig b/src/bun.js/node/node_fs.zig
index 8f822448b..5407c2d5c 100644
--- a/src/bun.js/node/node_fs.zig
+++ b/src/bun.js/node/node_fs.zig
@@ -564,6 +564,11 @@ pub const AsyncCpTask = struct {
         }
 
         this.result = result;
+
+        if (this.result == .err) {
+            this.result.err.path = bun.default_allocator.dupe(u8, this.result.err.path) catch "";
+        }
+
         this.globalObject.bunVMConcurrently().eventLoop().enqueueTaskConcurrent(JSC.ConcurrentTask.fromCallback(this, runFromJSThread));
     }
 
@@ -3584,7 +3589,7 @@ pub const NodeFS = struct {
 
                     const dest_fd = switch (Syscall.open(dest, flags, JSC.Node.default_permission)) {
                         .result => |result| result,
-                        .err => |err| return Maybe(Return.CopyFile){ .err = err },
+                        .err => |err| return Maybe(Return.CopyFile){ .err = err.withPath(args.dest.slice()) },
                     };
                     defer {
                         _ = std.c.ftruncate(dest_fd, @as(std.c.off_t, @intCast(@as(u63, @truncate(wrote)))));
@@ -5392,11 +5397,10 @@ pub const NodeFS = struct {
                     .ACCES,
                     .NAMETOOLONG,
                     .ROFS,
-                    .NOENT,
                     .PERM,
                     .INVAL,
                     => {
-                        @memcpy(this.sync_error_buf[0..src.len], dest);
+                        @memcpy(this.sync_error_buf[0..src.len], src);
                         return .{ .err = err.err.withPath(this.sync_error_buf[0..src.len]) };
                     },
                     // Other errors may be due to clonefile() not being supported
@@ -5792,11 +5796,10 @@ pub const NodeFS = struct {
                     .ACCES,
                     .NAMETOOLONG,
                     .ROFS,
-                    .NOENT,
                     .PERM,
                     .INVAL,
                     => {
-                        @memcpy(this.sync_error_buf[0..src.len], dest);
+                        @memcpy(this.sync_error_buf[0..src.len], src);
                         task.finishConcurrently(.{ .err = err.err.withPath(this.sync_error_buf[0..src.len]) });
                         return false;
                     },
diff --git a/test/js/node/fs/cp.test.ts b/test/js/node/fs/cp.test.ts
index 37da58843..eae8a0e77 100644
--- a/test/js/node/fs/cp.test.ts
+++ b/test/js/node/fs/cp.test.ts
@@ -3,7 +3,7 @@ import { describe, test, expect, jest } from "bun:test";
 import { tempDirWithFiles } from "harness";
 
 const impls = [
-  // ["cpSync", fs.cpSync],
+  ["cpSync", fs.cpSync],
   ["cp", fs.promises.cp],
 ] as const;
 
@@ -40,7 +40,9 @@ for (const [name, copy] of impls) {
         "from/a.txt": "a",
       });
 
-      await copyShouldThrow(basename + "/from", basename + "/result");
+      const e = await copyShouldThrow(basename + "/from", basename + "/result");
+      expect(e.code).toBe("EISDIR");
+      expect(e.path).toBe(basename + "/from");
     });
 
     test("recursive directory structure - no destination", async () => {
@@ -129,7 +131,12 @@ for (const [name, copy] of impls) {
         "result/a.txt": "win",
       });
 
-      await copyShouldThrow(basename + "/from/a.txt", basename + "/result/a.txt", { force: false, errorOnExist: true });
+      const e = await copyShouldThrow(basename + "/from/a.txt", basename + "/result/a.txt", {
+        force: false,
+        errorOnExist: true,
+      });
+      expect(e.code).toBe("EEXIST");
+      expect(e.path).toBe(basename + "/result/a.txt");
 
       assertContent(basename + "/result/a.txt", "win");
     });
@@ -251,5 +258,31 @@ for (const [name, copy] of impls) {
         [basename + "/from/b.txt", basename + "/result/b.txt"],
       ]);
     });
+
+    test("trailing slash", async () => {
+      const basename = tempDirWithFiles("cp", {
+        "from/a.txt": "a",
+        "from/b.txt": "b",
+      });
+
+      await copy(basename + "/from/", basename + "/result/", { recursive: true });
+
+      assertContent(basename + "/result/a.txt", "a");
+      assertContent(basename + "/result/b.txt", "b");
+    });
+
+    test("copy directory will ensure directory exists", async () => {
+      const basename = tempDirWithFiles("cp", {
+        "from/a.txt": "a",
+        "from/b.txt": "b",
+      });
+
+      fs.mkdirSync(basename + "/result/");
+
+      await copy(basename + "/from/", basename + "/hello/world/", { recursive: true });
+
+      assertContent(basename + "/hello/world/a.txt", "a");
+      assertContent(basename + "/hello/world/b.txt", "b");
+    });
   });
 }