Fix Windows GetEnv mangling non-ASCII environment values

On Windows, GetEnv read variables through the narrow _dupenv_s, which
returns the value in the active ANSI code page (e.g. CP-1252). Non-ASCII
values -- such as a home path with an accented username -- were then
reinterpreted as UTF-8 and came out mangled, so ~/.aws/credentials and
~/.aws/config failed to load and the profile provider fell back to an
anonymous request (GitHub issue #3865).

Read env vars through the wide _wdupenv_s and convert explicitly to
UTF-8, since Windows stores them natively as UTF-16. Mirrors the same
fix in the CRT (awslabs/aws-c-common#1260). Non-MSVC compilers keep the
existing std::getenv path.

Adds a Windows-only regression test that injects a non-ASCII value via
the wide CRT API and asserts GetEnv returns the correct UTF-8 bytes.

Author: kai-ion

src/aws-cpp-sdk-core/source/platform/windows/Environment.cpp

@@ -4,6 +4,7 @@
  */
 
 #include <aws/core/platform/Environment.h>
+#include <aws/core/utils/StringUtils.h>
 
 #include <stdio.h>
 #include <utility>
@@ -13,25 +14,19 @@ namespace Aws
 namespace Environment
 {
 
-/*
-using std::getenv generates a warning on windows so we use _dupenv_s instead.  The character array returned by this function is our responsibility to clean up, so rather than returning raw strings
-that would need to be manually freed in all the client functions, just copy it into a Aws::String instead, freeing it here.
-
-since _dupenv_s is a non-standard function, on non-Microsoft compilers we will fall back to using std::getenv instead.
-*/
 Aws::String GetEnv(const char *variableName)
 {
-#ifdef _MSC_VER    
-    char* variableValue = nullptr;
+#ifdef _MSC_VER
+    wchar_t* variableValue = nullptr;
     std::size_t valueSize = 0;
-    auto queryResult = _dupenv_s(&variableValue, &valueSize, variableName);
+    const auto queryResult = _wdupenv_s(&variableValue, &valueSize, Aws::Utils::StringUtils::ToWString(variableName).c_str());
 
     Aws::String result;
-    if(queryResult == 0 && variableValue != nullptr && valueSize > 0)
+    if(queryResult == 0 && variableValue != nullptr)
     {
-        result.assign(variableValue, valueSize - 1);  // don't copy the c-string terminator byte
-        free(variableValue);
+        result = Aws::Utils::StringUtils::FromWString(variableValue);
     }
+    free(variableValue);
 
     return result;
 #else

tests/aws-cpp-sdk-core-tests/utils/FileSystemUtilsTest.cpp

@@ -3,11 +3,15 @@
  * SPDX-License-Identifier: Apache-2.0.
  */
 
+#include <aws/core/platform/Environment.h>
 #include <aws/core/platform/FileSystem.h>
 #include <aws/core/utils/FileSystemUtils.h>
 #include <aws/core/utils/memory/stl/AWSSet.h>
 #include <aws/testing/AwsCppSdkGTestSuite.h>
 #include <fstream>
+#ifdef _MSC_VER
+#include <stdlib.h> // _wputenv_s
+#endif
 #if defined(HAS_PATHCONF)
 #include <unistd.h>
 #include <climits>
@@ -32,6 +36,20 @@ TEST_F(FileTest, HomeDirectory)
     ASSERT_EQ(Aws::FileSystem::PATH_DELIM, homeDirectory.back());
 }
 
+#ifdef _MSC_VER
+TEST_F(FileTest, GetEnvReturnsNonAsciiValueAsUtf8)
+{
+    const char* varName = "AWS_SDK_TEST_NONASCII";
+    // Set via the wide CRT API so the true Unicode value is stored, not a pre-mangled narrow one.
+    ASSERT_EQ(0, _wputenv_s(L"AWS_SDK_TEST_NONASCII", L"José"));
+
+    const auto value = Aws::Environment::GetEnv(varName);
+    _wputenv_s(L"AWS_SDK_TEST_NONASCII", L"");
+
+    ASSERT_EQ(Aws::String("Jos\xC3\xA9"), value); // "José" in UTF-8
+}
+#endif
+
 TEST_F(FileTest, TestInvalidDirectoryPath)
 {
     auto badDir = Aws::FileSystem::OpenDirectory("boogieMan");