From 83306585ff03dc1325f272922ad9c7737c2ad0b0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?H=C3=BCseyin=20A=C3=A7acak?=
 <110401522+huseyinacacak-janea@users.noreply.github.com>
Date: Tue, 30 Jul 2024 00:50:11 +0300
Subject: [PATCH] win: fix env var in uv_os_homedir and uv_os_tmpdir (#4464)

If the corresponding environment variables are empty, the
uv_us_homedir() and uv_os_tmpdir() return garbage values. The reason
for this situation is the Windows API which doesn't return an error
even if the path is empty.

This PR fixes this problem by checking the return value of the API
call. If it is not an error and the length of the value is less than 3,
uv_us_homedir() and uv_os_tmpdir() will return UV_ENOENT.

Fixes: https://github.com/libuv/libuv/issues/2328
---
 src/win/util.c      | 13 ++++++++++++-
 test/test-homedir.c |  9 +++++++++
 test/test-tmpdir.c  |  7 +++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/win/util.c b/src/win/util.c
index c4dd8bf7..628136c4 100644
--- a/src/win/util.c
+++ b/src/win/util.c
@@ -942,8 +942,13 @@ int uv_os_homedir(char* buffer, size_t* size) {
   r = uv_os_getenv("USERPROFILE", buffer, size);
 
   /* Don't return an error if USERPROFILE was not found. */
-  if (r != UV_ENOENT)
+  if (r != UV_ENOENT) {
+    /* USERPROFILE is empty or invalid */
+    if (r == 0 && *size < 3) {
+      return UV_ENOENT;
+    }
     return r;
+  }
 
   /* USERPROFILE is not set, so call uv_os_get_passwd() */
   r = uv_os_get_passwd(&pwd);
@@ -980,6 +985,12 @@ int uv_os_tmpdir(char* buffer, size_t* size) {
   if (len == 0) {
     return uv_translate_sys_error(GetLastError());
   }
+
+  /* tmp path is empty or invalid */
+  if (len < 3) {
+    return UV_ENOENT;
+  }
+
   /* Include space for terminating null char. */
   len += 1;
   path = uv__malloc(len * sizeof(wchar_t));
diff --git a/test/test-homedir.c b/test/test-homedir.c
index 769d5c81..e335540d 100644
--- a/test/test-homedir.c
+++ b/test/test-homedir.c
@@ -68,5 +68,14 @@ TEST_IMPL(homedir) {
   r = uv_os_homedir(homedir, &len);
   ASSERT_EQ(r, UV_EINVAL);
 
+#ifdef _WIN32
+  /* Test empty environment variable */
+  r = uv_os_setenv("USERPROFILE", "");
+  ASSERT_EQ(r, 0);
+  len = sizeof homedir;
+  r = uv_os_homedir(homedir, &len);
+  ASSERT_EQ(r, UV_ENOENT);
+#endif
+
   return 0;
 }
diff --git a/test/test-tmpdir.c b/test/test-tmpdir.c
index a4e9ce95..c8fc8e06 100644
--- a/test/test-tmpdir.c
+++ b/test/test-tmpdir.c
@@ -76,6 +76,13 @@ TEST_IMPL(tmpdir) {
   size_t lenx = sizeof tmpdirx;
   r = uv_os_tmpdir(tmpdirx, &lenx);
   ASSERT_OK(r);
+
+  /* Test empty environment variable */
+  r = uv_os_setenv("TMP", "");
+  ASSERT_EQ(r, 0);
+  len = sizeof tmpdir;
+  r = uv_os_tmpdir(tmpdir, &len);
+  ASSERT_EQ(r, UV_ENOENT);
 #endif
 
   return 0;