From 135329c0790e6d33f658727be3e5439a167a7da8 Mon Sep 17 00:00:00 2001
From: Iain Patterson <me@iain.cx>
Date: Tue, 26 Nov 2013 17:21:27 +0000
Subject: [PATCH] Added test_environment().

New helper function to verify the environment by relaunching NSSM itself
with the candidate environment set.  Unless something goes horribly
wrong somewhere, CreateProcess() will succeed iff the environment is
valid.
---
 process.cpp | 36 ++++++++++++++++++++++++++++++++++++
 process.h   |  1 +
 2 files changed, 37 insertions(+)

diff --git a/process.cpp b/process.cpp
index 1cc6a73..69aea03 100644
--- a/process.cpp
+++ b/process.cpp
@@ -306,3 +306,39 @@ void kill_process_tree(nssm_service_t *service, unsigned long pid, unsigned long
 
   CloseHandle(process_handle);
 }
+
+/*
+  Verify an environment block.
+  Returns:  1 if environment is invalid.
+            0 if environment is OK.
+           -1 on error.
+*/
+int test_environment(TCHAR *env) {
+  TCHAR path[MAX_PATH];
+  GetModuleFileName(0, path, _countof(path));
+  STARTUPINFO si;
+  ZeroMemory(&si, sizeof(si));
+  si.cb = sizeof(si);
+  PROCESS_INFORMATION pi;
+  ZeroMemory(&pi, sizeof(pi));
+  unsigned long flags = CREATE_SUSPENDED;
+#ifdef UNICODE
+  flags |= CREATE_UNICODE_ENVIRONMENT;
+#endif
+
+  /*
+    Try to relaunch ourselves but with the candidate environment set.
+    Assuming no solar flare activity, the only reason this would fail is if
+    the environment were invalid.
+  */
+  if (CreateProcess(0, path, 0, 0, 0, flags, env, 0, &si, &pi)) {
+    TerminateProcess(pi.hProcess, 0);
+  }
+  else {
+    unsigned long error = GetLastError();
+    if (error == ERROR_INVALID_PARAMETER) return 1;
+    else return -1;
+  }
+
+  return 0;
+}
diff --git a/process.h b/process.h
index 3489f54..a8f2989 100644
--- a/process.h
+++ b/process.h
@@ -17,5 +17,6 @@ int kill_threads(nssm_service_t *, kill_t *);
 int kill_console(nssm_service_t *);
 int kill_process(nssm_service_t *, HANDLE, unsigned long, unsigned long);
 void kill_process_tree(nssm_service_t *, unsigned long, unsigned long, unsigned long);
+int test_environment(TCHAR *);
 
 #endif
-- 
2.20.1