Changeset 96587 in vbox for trunk/src/VBox/Runtime/r3/win

Timestamp:

Sep 3, 2022 2:37:15 AM (2 years ago)

Author:

vboxsync

Message:

IPRT/env-win.cpp: GetEnvironmentVariableW doesn't set ERROR_ENVVAR_NOT_FOUND on older windows versions (pre NT4?), added workaround for that. bugref:10261

File:

• trunk/src/VBox/Runtime/r3/win/env-win.cpp (modified) (3 diffs)

trunk/src/VBox/Runtime/r3/win/env-win.cpp

@@ -72 +72 @@
 int rtEnvSetUtf8Worker(const char *pchVar, size_t cchVar, const char *pszValue);
 
+
+#if defined(RT_ARCH_X86) && defined(RT_OS_WINDOWS)
+/**
+ * This is a workaround for NT 3.x not setting the last error.
+ */
+static DWORD rtEnvNt31CheckEmpty(PCRTUTF16 pwszVar)
+{
+    /* Check the version first: */
+    DWORD dwVersion = GetVersion();
+    if (RT_BYTE1(dwVersion) != 3)
+        return 0;
+
+    /* When called with an empty buffer, we should get 1 if empty value
+       and 0 if not found:  */
+    DWORD cwcNeeded = GetEnvironmentVariableW(pwszVar, NULL, 0);
+    return cwcNeeded == 0 ? ERROR_ENVVAR_NOT_FOUND : NO_ERROR;
+}
+#endif
 
 
@@ -173 +191 @@
     for (unsigned iTry = 0;; iTry++)
     {
-        /* This API is weird, it didn't always set ERROR_BUFFER_OVERFLOW.
+        /* This API is weird, it didn't always set ERROR_BUFFER_OVERFLOW nor ERROR_ENVVAR_NOT_FOUND.
            Note! Assume that the CRT transparently updates the process
                  environment and that we don't need to use _wgetenv_s here. */
         SetLastError(NO_ERROR);
         DWORD const cwcValueRet = GetEnvironmentVariableW(pwszVar, pwszValue, cwcValueBuf);
-        DWORD const dwErr       = GetLastError();
+        DWORD       dwErr       = GetLastError();
 
         if (cwcValueRet < cwcValueBuf)
         {
+#ifdef RT_ARCH_X86
+            if (cwcValueRet == 0 && dwErr == NO_ERROR)
+                dwErr = rtEnvNt31CheckEmpty(pwszVar);
+#endif
             if (cwcValueRet > 0 || dwErr == NO_ERROR) /* In case of empty values we have to see if last error was set or not. */
             {
@@ -241 +263 @@
     for (unsigned iTry = 0;; iTry++)
     {
-        /* This API is weird, it didn't always set ERROR_BUFFER_OVERFLOW.
+        /* This API is weird, it didn't always set ERROR_BUFFER_OVERFLOW nor ERROR_ENVVAR_NOT_FOUND.
            Note! Assume that the CRT transparently updates the process
                  environment and that we don't need to use _wgetenv_s here. */
         SetLastError(NO_ERROR);
         DWORD const cwcValueRet = GetEnvironmentVariableW(pwszVar, pwszValue, cwcValueBuf);
-        DWORD const dwErr       = GetLastError();
+        DWORD       dwErr       = GetLastError();
 
         if (cwcValueRet < cwcValueBuf)
         {
+#ifdef RT_ARCH_X86
+            if (cwcValueRet == 0 && dwErr == NO_ERROR)
+                dwErr = rtEnvNt31CheckEmpty(pwszVar);
+#endif
             if (cwcValueRet > 0 || dwErr == NO_ERROR) /* In case of empty values we have to see if last error was set or not. */
             {