From cc4dae5c0f418d304a44bb10c87c624b478b6441 Mon Sep 17 00:00:00 2001
From: "jan.nijtmans" <nijtmans@users.sourceforge.net>
Date: Sun, 7 Oct 2018 20:26:33 +0000
Subject: Streamline: Tcl_WinTCharToUtf/Tcl_WinUtfToTChar(): Always initialize
 DString, and let it return NULL when imput is NULL. That's what seem to
 assume the callers.

---
 generic/tclStubInit.c | 14 ++++++++++----
 win/tclWin32Dll.c     | 14 ++++++++++----
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/generic/tclStubInit.c b/generic/tclStubInit.c
index 50bb4a2..cbf4084 100644
--- a/generic/tclStubInit.c
+++ b/generic/tclStubInit.c
@@ -189,6 +189,9 @@ Tcl_WinUtfToTChar(
     Tcl_DString *dsPtr)
 {
     Tcl_DStringInit(dsPtr);
+    if (!string) {
+	return NULL;
+    }
     return (char *)Tcl_UtfToUniCharDString(string, len, dsPtr);
 }
 
@@ -198,12 +201,15 @@ Tcl_WinTCharToUtf(
     int len,
     Tcl_DString *dsPtr)
 {
-    if (len > 0) {
-	len /= 2;
-    } else if (len == -1) {
+    Tcl_DStringInit(dsPtr);
+    if (!string) {
+	return NULL;
+    }
+    if (len < 0) {
 	len = wcslen((wchar_t *)string);
+    } else {
+	len /= 2;
     }
-    Tcl_DStringInit(dsPtr);
     return Tcl_UniCharToUtfDString((Tcl_UniChar *)string, len, dsPtr);
 }
 
diff --git a/win/tclWin32Dll.c b/win/tclWin32Dll.c
index ca1c856..6fc2401 100644
--- a/win/tclWin32Dll.c
+++ b/win/tclWin32Dll.c
@@ -548,6 +548,9 @@ Tcl_WinUtfToTChar(
 				 * converted string is stored. */
 {
     Tcl_DStringInit(dsPtr);
+    if (!string) {
+	return NULL;
+    }
     return Tcl_UtfToUniCharDString(string, len, dsPtr);
 }
 
@@ -559,12 +562,15 @@ Tcl_WinTCharToUtf(
     Tcl_DString *dsPtr)		/* Uninitialized or free DString in which the
 				 * converted string is stored. */
 {
-    if (len > 0) {
-	len /= 2;
-    } else if (len < 0) {
+    Tcl_DStringInit(dsPtr);
+    if (!string) {
+	return NULL;
+    }
+    if (len < 0) {
 	len = wcslen(string);
+    } else {
+	len /= 2;
     }
-    Tcl_DStringInit(dsPtr);
     return Tcl_UniCharToUtfDString(string, len, dsPtr);
 }
 
-- 
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