[Lldb-commits] [PATCH] D76835: [lldb] Fix TestSettings.test_pass_host_env_vars on windows

[Pavel Labath via Phabricator via lldb-commits]

labath created this revision.
labath added reviewers: amccarth, friss.
Herald added a project: LLDB.

A defensive check in ProcessLauncherWindows meant that we would never
attempt to launch a process with a completely empty environment -- the
host environment would be used instead. Insted, I make function add an
extra null wchar_t at the end of an empty environment. The documentation
on this is a bit fuzzy, but it seems to be what is needed to make
windows accept these kinds of environments.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D76835

Files:
  lldb/source/Host/windows/ProcessLauncherWindows.cpp
  lldb/test/API/commands/settings/TestSettings.py


Index: lldb/test/API/commands/settings/TestSettings.py
===================================================================
--- lldb/test/API/commands/settings/TestSettings.py
+++ lldb/test/API/commands/settings/TestSettings.py
@@ -286,7 +286,6 @@
                 "Environment variable 'MY_ENV_VAR' successfully passed."])
 
     @skipIfRemote  # it doesn't make sense to send host env to remote target
-    @skipIf(oslist=["windows"])
     def test_pass_host_env_vars(self):
         """Test that the host env vars are passed to the launched process."""
         self.build()
Index: lldb/source/Host/windows/ProcessLauncherWindows.cpp
===================================================================
--- lldb/source/Host/windows/ProcessLauncherWindows.cpp
+++ lldb/source/Host/windows/ProcessLauncherWindows.cpp
@@ -23,10 +23,8 @@
 namespace {
 void CreateEnvironmentBuffer(const Environment &env,
                              std::vector<char> &buffer) {
-  if (env.size() == 0)
-    return;
-
-  // Environment buffer is a null terminated list of null terminated strings
+  // Environment buffer is a list of null-terminated list of strings. It ends
+  // with a double null.
   for (const auto &KV : env) {
     std::wstring warg;
     if (llvm::ConvertUTF8toWide(Environment::compose(KV), warg)) {
@@ -38,6 +36,12 @@
   // One null wchar_t (to end the block) is two null bytes
   buffer.push_back(0);
   buffer.push_back(0);
+  // If the environment was empty, we must insert an extra byte to ensure a
+  // double null.
+  if (env.empty()) {
+    buffer.push_back(0);
+    buffer.push_back(0);
+  }
 }
 
 bool GetFlattenedWindowsCommandString(Args args, std::string &command) {
@@ -94,8 +98,7 @@
 
   LPVOID env_block = nullptr;
   ::CreateEnvironmentBuffer(launch_info.GetEnvironment(), environment);
-  if (!environment.empty())
-    env_block = environment.data();
+  env_block = environment.data();
 
   executable = launch_info.GetExecutableFile().GetPath();
   GetFlattenedWindowsCommandString(launch_info.GetArguments(), commandLine);


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