From b7be7bd4a64fbcee890bc65ef462b4f22ff945ef Mon Sep 17 00:00:00 2001
From: DonalMe <76789979+DonalMe@users.noreply.github.com>
Date: Thu, 12 Jun 2025 10:13:16 -0400
Subject: [PATCH] Revert "Bug 1966443: Use proper length for Windows clipboard
 elements r=win-reviewers,emilio,gstoll" for causing Bug 1968744

This reverts commit cff2580bc6b540ff1bb9b890d9cf79c1bcc563a5.
---
 widget/windows/nsClipboard.cpp | 50 +++++++++++++++-------------------
 1 file changed, 22 insertions(+), 28 deletions(-)

diff --git a/widget/windows/nsClipboard.cpp b/widget/windows/nsClipboard.cpp
index dc272f1ff856..1a68aa7e39e2 100644
--- a/widget/windows/nsClipboard.cpp
+++ b/widget/windows/nsClipboard.cpp
@@ -578,7 +578,6 @@ NS_IMETHODIMP nsClipboard::SetNativeClipboardData(
 }
 
 //-------------------------------------------------------------------------
-/* static */
 nsresult nsClipboard::GetGlobalData(HGLOBAL aHGBL, void** aData,
                                     uint32_t* aLen) {
   MOZ_CLIPBOARD_LOG("%s", __FUNCTION__);
@@ -701,29 +700,6 @@ HRESULT nsClipboard::FillSTGMedium(IDataObject* aDataObject, UINT aFormat,
 }
 
 //-------------------------------------------------------------------------
-// Get the data out of the global data handle. The size we
-// return should be the size returned from GetGlobalData(), since the
-// string returned from Windows may have nulls inserted -- it may not
-// even be null-terminated.  GetGlobalData adds bytes for null
-// termination to the buffer but they are not considered in the returned
-// byte count.  We check and skip the last counted byte if it is a null
-// since Windows also appears to add null termination.  See GetGlobalData.
-template <typename CharType>
-static nsresult GetCharDataFromGlobalData(STGMEDIUM& aStm, CharType** aData,
-                                   uint32_t* aLen) {
-  uint32_t nBytes = 0;
-  MOZ_TRY(nsClipboard::GetGlobalData(aStm.hGlobal,
-                                     reinterpret_cast<void**>(aData), &nBytes));
-  auto nChars = nBytes / sizeof(CharType);
-  if (nChars < 1) {
-    *aLen = 0;
-    return NS_OK;
-  }
-  bool hasNullTerminator = (*aData)[nChars - 1] == CharType(0);
-  *aLen = hasNullTerminator ? nBytes - sizeof(CharType) : nBytes;
-  return NS_OK;
-}
-
 // If aFormat is CF_DIBV5, aMIMEImageFormat must be a type for which we have
 // an image encoder (e.g. image/png).
 // For other values of aFormat, it is OK to pass null for aMIMEImageFormat.
@@ -788,13 +764,31 @@ nsresult nsClipboard::GetNativeDataOffClipboard(IDataObject* aDataObject,
   // compile-time-constant format indicators:
   switch (fe.cfFormat) {
     case CF_TEXT: {
-      return GetCharDataFromGlobalData(stm, reinterpret_cast<char**>(aData),
-                                       aLen);
+      // Get the data out of the global data handle. The size we
+      // return should not include the null because the other
+      // platforms don't use nulls, so just return the length we get
+      // back from strlen(), since we know CF_TEXT is null
+      // terminated. Recall that GetGlobalData() returns the size of
+      // the allocated buffer, not the size of the data (on 98, these
+      // are not the same) so we can't use that.
+      uint32_t allocLen = 0;
+      MOZ_TRY(GetGlobalData(stm.hGlobal, aData, &allocLen));
+      *aLen = strlen(reinterpret_cast<char*>(*aData));
+      return NS_OK;
     }
 
     case CF_UNICODETEXT: {
-      return GetCharDataFromGlobalData(stm, reinterpret_cast<char16_t**>(aData),
-                                       aLen);
+      // Get the data out of the global data handle. The size we
+      // return should not include the null because the other
+      // platforms don't use nulls, so just return the length we get
+      // back from strlen(), since we know CF_UNICODETEXT is null
+      // terminated. Recall that GetGlobalData() returns the size of
+      // the allocated buffer, not the size of the data (on 98, these
+      // are not the same) so we can't use that.
+      uint32_t allocLen = 0;
+      MOZ_TRY(GetGlobalData(stm.hGlobal, aData, &allocLen));
+      *aLen = NS_strlen(reinterpret_cast<char16_t*>(*aData)) * 2;
+      return NS_OK;
     }
 
     case CF_DIBV5: {