__throw* functions seem to be available in LLVM 4.0 or above.

[folly.git] / folly / portability / Environment.cpp

diff --git a/folly/portability/Environment.cpp b/folly/portability/Environment.cpp
index 34f91217883e2f1dbe26a7699507ed73433c2261..ba3105967803bd1dc85d88955df91de43cf94f1f 100755 (executable)
--- a/folly/portability/Environment.cpp
+++ b/folly/portability/Environment.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,10 +26,52 @@ int setenv(const char* name, const char* value, int overwrite) {
     return 0;
   }
 
+  if (*value != '\0') {
+    auto e = _putenv_s(name, value);
+    if (e != 0) {
+      errno = e;
+      return -1;
+    }
+    return 0;
+  }
+
+  // We are trying to set the value to an empty string, but
   // _putenv_s deletes entries if the value is an empty string,
-  // so we have to call the windows API function to safely assign
-  // these.
-  if (SetEnvironmentVariableA(name, value) != 0) {
+  // and just calling SetEnvironmentVariableA doesn't update
+  // _environ, so we have to do these terrible things.
+  if (_putenv_s(name, "  ") != 0) {
+    errno = EINVAL;
+    return -1;
+  }
+
+  // Here lies the documentation we blatently ignore to make
+  // this work >_>...
+  *getenv(name) = '\0';
+  // This would result in a double null termination, which
+  // normally signifies the end of the environment variable
+  // list, so we stick a completely empty environment variable
+  // into the list instead.
+  *(getenv(name) + 1) = '=';
+
+  // If _wenviron is null, the wide environment has not been initialized
+  // yet, and we don't need to try to update it.
+  // We have to do this otherwise we'd be forcing the initialization and
+  // maintenance of the wide environment even though it's never actually
+  // used in most programs.
+  if (_wenviron != nullptr) {
+    wchar_t buf[_MAX_ENV + 1];
+    size_t len;
+    if (mbstowcs_s(&len, buf, _MAX_ENV + 1, name, _MAX_ENV) != 0) {
+      errno = EINVAL;
+      return -1;
+    }
+    *_wgetenv(buf) = u'\0';
+    *(_wgetenv(buf) + 1) = u'=';
+  }
+
+  // And now, we have to update the outer environment to have
+  // a proper empty value.
+  if (!SetEnvironmentVariableA(name, value)) {
     errno = EINVAL;
     return -1;
   }