From 5b51d421daf5d22261e18343ac7b5222abcdfba3 Mon Sep 17 00:00:00 2001
From: Dylan Conway <dylan.conway567@gmail.com>
Date: Mon, 6 Oct 2025 19:47:05 -0700
Subject: [PATCH] fix(node:path): reverse iterate `path.resolve` arguments, and
 stop on absolute (#23293)

### What does this PR do?
Matches node behavior.

Fixes #20975
### How did you verify your code works?
Manually and added a test

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
---
 src/bun.js/node/path.zig          | 46 ++++++++++++++++++++++---------
 test/js/node/path/resolve.test.js | 11 +++++++-
 test/no-validate-exceptions.txt   |  2 ++
 3 files changed, 45 insertions(+), 14 deletions(-)

diff --git a/src/bun.js/node/path.zig b/src/bun.js/node/path.zig
index 94a90dcb1e..c6011c3bb4 100644
--- a/src/bun.js/node/path.zig
+++ b/src/bun.js/node/path.zig
@@ -2767,35 +2767,55 @@ pub fn resolve(globalObject: *jsc.JSGlobalObject, isWindows: bool, args_ptr: [*]
     var stack_fallback = std.heap.stackFallback(stack_fallback_size_large, arena.allocator());
     const allocator = stack_fallback.get();
 
-    var paths = try allocator.alloc(string, args_len);
-    defer allocator.free(paths);
-    var path_count: usize = 0;
+    var paths_buf = try allocator.alloc(string, args_len);
+    defer allocator.free(paths_buf);
+    var paths_offset: usize = args_len;
+    var resolved_root = false;
 
-    for (0..args_len, args_ptr) |i, path_ptr| {
-        // Supress exeption in zig. It does globalThis.vm().throwError() in JS land.
-        try validateString(globalObject, path_ptr, "paths[{d}]", .{i});
-        const pathZStr = try path_ptr.getZigString(globalObject);
-        if (pathZStr.len > 0) {
-            paths[path_count] = pathZStr.toSlice(allocator).slice();
-            path_count += 1;
+    var i = args_len;
+    while (i > 0) {
+        i -= 1;
+
+        if (resolved_root) {
+            break;
+        }
+
+        const path = args_ptr[i];
+        try validateString(globalObject, path, "paths[{d}]", .{i});
+        const path_str = try path.toBunString(globalObject);
+        defer path_str.deref();
+
+        if (path_str.length() == 0) {
+            continue;
+        }
+
+        paths_offset -= 1;
+        paths_buf[paths_offset] = path_str.toSlice(allocator).slice();
+
+        if (!isWindows) {
+            if (path_str.charAt(0) == CHAR_FORWARD_SLASH) {
+                resolved_root = true;
+            }
         }
     }
 
+    const paths = paths_buf[paths_offset..];
+
     if (comptime Environment.isPosix) {
         if (!isWindows) {
             // Micro-optimization #1: avoid creating a new string when passing no arguments or only empty strings.
-            if (path_count == 0) {
+            if (paths.len == 0) {
                 return Process__getCachedCwd(globalObject);
             }
 
             // Micro-optimization #2: path.resolve(".") and path.resolve("./") === process.cwd()
-            else if (path_count == 1 and (strings.eqlComptime(paths[0], ".") or strings.eqlComptime(paths[0], "./"))) {
+            else if (paths.len == 1 and (strings.eqlComptime(paths[0], ".") or strings.eqlComptime(paths[0], "./"))) {
                 return Process__getCachedCwd(globalObject);
             }
         }
     }
 
-    return resolveJS_T(u8, globalObject, allocator, isWindows, paths[0..path_count]);
+    return resolveJS_T(u8, globalObject, allocator, isWindows, paths);
 }
 
 /// Based on Node v21.6.1 path.win32.toNamespacedPath:
diff --git a/test/js/node/path/resolve.test.js b/test/js/node/path/resolve.test.js
index 7204751052..e620a7f60e 100644
--- a/test/js/node/path/resolve.test.js
+++ b/test/js/node/path/resolve.test.js
@@ -1,4 +1,4 @@
-import { describe, test } from "bun:test";
+import { describe, expect, test } from "bun:test";
 import { isWindows } from "harness";
 import assert from "node:assert";
 // import child from "node:child_process";
@@ -93,4 +93,13 @@ describe("path.resolve", () => {
     //   }
     // }
   });
+
+  test("undefined argument are ignored if absolute path comes first (reverse loop through args)", () => {
+    expect(() => {
+      return path.posix.resolve(undefined, "hi");
+    }).toThrow('The "paths[0]" property must be of type string, got undefined');
+    expect(() => {
+      return path.posix.resolve(undefined, "/hi");
+    }).not.toThrow();
+  });
 });
diff --git a/test/no-validate-exceptions.txt b/test/no-validate-exceptions.txt
index 9ca358c41c..4c4aa54228 100644
--- a/test/no-validate-exceptions.txt
+++ b/test/no-validate-exceptions.txt
@@ -144,3 +144,5 @@ vendor/elysia/test/core/dynamic.test.ts
 vendor/elysia/test/lifecycle/error.test.ts
 vendor/elysia/test/validator/body.test.ts
 vendor/elysia/test/ws/message.test.ts
+
+test/js/node/test/parallel/test-worker-abort-on-uncaught-exception.js