From bbdd237fca6fd219e47c460ca2e5f9c71bf382e3 Mon Sep 17 00:00:00 2001
From: Anna Henningsen <anna@addaleax.net>
Date: Mon, 25 Jun 2018 18:13:37 +0200
Subject: [PATCH] src: include cwd in chdir error message

Include the current working directory in the error
message for a failing `process.chdir()` since that is
usually information relevant for debugging.

This is semver-major because it moves properties
of the error message object.

Inspired by https://github.com/nodejs/help/issues/1355.
---
 src/node_process.cc                           | 25 ++++++++++++-------
 .../test-process-chdir-errormessage.js        |  5 +++-
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/src/node_process.cc b/src/node_process.cc
index af19ef2d14653f..020f132f825e00 100644
--- a/src/node_process.cc
+++ b/src/node_process.cc
@@ -47,6 +47,13 @@ using v8::Value;
 // used in Hrtime() below
 #define NANOS_PER_SEC 1000000000
 
+#ifdef _WIN32
+/* MAX_PATH is in characters, not bytes. Make sure we have enough headroom. */
+#define CHDIR_BUFSIZE (MAX_PATH * 4)
+#else
+#define CHDIR_BUFSIZE (PATH_MAX)
+#endif
+
 void Abort(const FunctionCallbackInfo<Value>& args) {
   Abort();
 }
@@ -59,8 +66,14 @@ void Chdir(const FunctionCallbackInfo<Value>& args) {
   CHECK(args[0]->IsString());
   Utf8Value path(env->isolate(), args[0]);
   int err = uv_chdir(*path);
-  if (err)
-    return env->ThrowUVException(err, "chdir", nullptr, *path, nullptr);
+  if (err) {
+    // Also include the original working directory, since that will usually
+    // be helpful information when debugging a `chdir()` failure.
+    char buf[CHDIR_BUFSIZE];
+    size_t cwd_len = sizeof(buf);
+    uv_cwd(buf, &cwd_len);
+    return env->ThrowUVException(err, "chdir", nullptr, buf, *path);
+  }
 }
 
 // CPUUsage use libuv's uv_getrusage() this-process resource usage accessor,
@@ -93,13 +106,7 @@ void CPUUsage(const FunctionCallbackInfo<Value>& args) {
 
 void Cwd(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
-#ifdef _WIN32
-  /* MAX_PATH is in characters, not bytes. Make sure we have enough headroom. */
-  char buf[MAX_PATH * 4];
-#else
-  char buf[PATH_MAX];
-#endif
-
+  char buf[CHDIR_BUFSIZE];
   size_t cwd_len = sizeof(buf);
   int err = uv_cwd(buf, &cwd_len);
   if (err)
diff --git a/test/parallel/test-process-chdir-errormessage.js b/test/parallel/test-process-chdir-errormessage.js
index 0475d7940ce16a..3dca040a2f716c 100644
--- a/test/parallel/test-process-chdir-errormessage.js
+++ b/test/parallel/test-process-chdir-errormessage.js
@@ -11,6 +11,9 @@ common.expectsError(
   {
     type: Error,
     code: 'ENOENT',
-    message: "ENOENT: no such file or directory, chdir 'does-not-exist'",
+    message: /ENOENT: no such file or directory, chdir .+ -> 'does-not-exist'/,
+    path: process.cwd(),
+    syscall: 'chdir',
+    dest: 'does-not-exist'
   }
 );