[llvm] r311174 - [Support] env vars with empty values on windows

[Ben Dunbobbin via llvm-commits]

Author: bd1976llvm
Date: Fri Aug 18 09:55:44 2017
New Revision: 311174

URL: http://llvm.org/viewvc/llvm-project?rev=311174&view=rev
Log:
[Support] env vars with empty values on windows

An environment variable can be in one of three states:

1. undefined.
2. defined with a non-empty value.
3. defined but with an empty value.

The windows implementation did not support case 3
(it was not handling errors). The Linux implementation
is already correct.

Differential Revision: https://reviews.llvm.org/D36394

Modified:
    llvm/trunk/lib/Support/Windows/Process.inc
    llvm/trunk/unittests/Support/ProcessTest.cpp

Modified: llvm/trunk/lib/Support/Windows/Process.inc
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Windows/Process.inc?rev=311174&r1=311173&r2=311174&view=diff
==============================================================================
--- llvm/trunk/lib/Support/Windows/Process.inc (original)
+++ llvm/trunk/lib/Support/Windows/Process.inc Fri Aug 18 09:55:44 2017
@@ -129,9 +129,10 @@ Optional<std::string> Process::GetEnv(St
   size_t Size = MAX_PATH;
   do {
     Buf.reserve(Size);
+    SetLastError(NO_ERROR);
     Size =
-        GetEnvironmentVariableW(NameUTF16.data(), Buf.data(), Buf.capacity());
-    if (Size == 0)
+      GetEnvironmentVariableW(NameUTF16.data(), Buf.data(), Buf.capacity());
+    if (Size == 0 && GetLastError() == ERROR_ENVVAR_NOT_FOUND)
       return None;
 
     // Try again with larger buffer.

Modified: llvm/trunk/unittests/Support/ProcessTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/ProcessTest.cpp?rev=311174&r1=311173&r2=311174&view=diff
==============================================================================
--- llvm/trunk/unittests/Support/ProcessTest.cpp (original)
+++ llvm/trunk/unittests/Support/ProcessTest.cpp Fri Aug 18 09:55:44 2017
@@ -42,10 +42,18 @@ TEST(ProcessTest, None) {
   Optional<std::string> val(
       Process::GetEnv("__LLVM_TEST_ENVIRON_NO_SUCH_VAR__"));
   EXPECT_FALSE(val.hasValue());
-}
+} 
 #endif
 
 #ifdef LLVM_ON_WIN32
+
+TEST(ProcessTest, EmptyVal) {
+  SetEnvironmentVariableA("__LLVM_TEST_ENVIRON_VAR__", "");
+  Optional<std::string> val(Process::GetEnv("__LLVM_TEST_ENVIRON_VAR__"));
+  EXPECT_TRUE(val.hasValue());
+  EXPECT_STREQ("", val->c_str());
+}
+
 TEST(ProcessTest, Wchar) {
   SetEnvironmentVariableW(L"__LLVM_TEST_ENVIRON_VAR__", L"abcdefghijklmnopqrs");
   Optional<std::string> val(Process::GetEnv("__LLVM_TEST_ENVIRON_VAR__"));