Fix a bug in LoadNativeStringResource to honor the contract properly when the buffer is not big enough (#12051)

* Return last error properly

* adjust pcwchUsed if ERROR_INSUFFICIENT_BUFFER

* return hr

* ERROR_INSUFFICIENT_BUFFER is a win32 error....

1 files changed, 12 insertions, 0 deletions

diff --git a/src/nativeresources/resourcestring.cpp b/src/nativeresources/resourcestring.cpp
index 236a2a3ca7..1c3f50a1c4 100644
--- a/src/nativeresources/resourcestring.cpp
+++ b/src/nativeresources/resourcestring.cpp
@@ -38,6 +38,16 @@ int LoadNativeStringResource(const NativeStringResourceTable &nativeStringResour
         if (resourceEntry != NULL)
         {
             len = PAL_GetResourceString(NULL, resourceEntry->resourceString, szBuffer, iMax);
+            if (len == 0)
+            {
+                int hr = HRESULT_FROM_GetLastError();
+
+                // Tell the caller if the buffer isn't big enough
+                if (hr == HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER) && pcwchUsed)
+                    *pcwchUsed = iMax;
+                    
+                return hr;
+            }
         }
         else
         {
@@ -47,6 +57,8 @@ int LoadNativeStringResource(const NativeStringResourceTable &nativeStringResour
             {   
                 // The only possible failure is that that string didn't fit the buffer. So the buffer contains 
                 // partial string terminated by '\0'
+                // We could return ERROR_INSUFFICIENT_BUFFER, but we'll error on the side of caution here and
+                // actually show something (given that this is likely a scenario involving a bug/deployment issue)
                 len = iMax - 1;
             }
         }