Windows: fix potential memory curruption bug in unicode.c

Also add ffStrbufInitWS

Author: CarterLi

CHANGELOG.md

@@ -10,6 +10,7 @@ Bugfixes:
 * Fix iTerm being detected as iTermServer-* sometimes
 * Fix sound device volume being incorrectly detected as muted sometimes (Sound)
 * Fix memleaks reported by LeakSanitizer (Linux)
+* Fix potential memory curruption bug in unicode.c (Windows)
 
 Logo:
 * Update Windows 11 ASCII logo to look more visually consistent (#445)

src/util/windows/unicode.c

@@ -17,20 +17,17 @@ void ffStrbufSetNWS(FFstrbuf* result, uint32_t length, const wchar_t* source)
     result->chars[size_needed] = '\0';
 }
 
-FFstrbuf ffStrbufCreateNWS(uint32_t length, const wchar_t* source)
+void ffStrbufInitNWS(FFstrbuf* result, uint32_t length, const wchar_t* source)
 {
-    FFstrbuf result;
-
-    if(length == 0)
-        ffStrbufInit(&result);
-    else
+    if(!length)
     {
-        int size_needed = WideCharToMultiByte(CP_UTF8, 0, source, (int)length, NULL, 0, NULL, NULL);
-        ffStrbufInitA(&result, (uint32_t)size_needed);
-        WideCharToMultiByte(CP_UTF8, 0, source, (int)length, result.chars, size_needed, NULL, NULL);
-        result.length = (uint32_t)size_needed;
-        result.chars[size_needed] = '\0';
+        ffStrbufInit(result);
+        return;
     }
 
-    return result;
+    int size_needed = WideCharToMultiByte(CP_UTF8, 0, source, (int)length, NULL, 0, NULL, NULL);
+    ffStrbufInitA(result, (uint32_t)size_needed + 1);
+    WideCharToMultiByte(CP_UTF8, 0, source, (int)length, result->chars, size_needed, NULL, NULL);
+    result->length = (uint32_t)size_needed;
+    result->chars[size_needed] = '\0';
 }

src/util/windows/unicode.h

@@ -13,7 +13,19 @@ static inline void ffStrbufSetWS(FFstrbuf* result, const wchar_t* source)
     return ffStrbufSetNWS(result, (uint32_t)wcslen(source), source);
 }
 
-FFstrbuf ffStrbufCreateNWS(uint32_t length, const wchar_t* source);
+void ffStrbufInitNWS(FFstrbuf* result, uint32_t length, const wchar_t* source);
+
+static inline void ffStrbufInitWS(FFstrbuf* result, const wchar_t* source)
+{
+    return ffStrbufInitNWS(result, (uint32_t)wcslen(source), source);
+}
+
+static inline FFstrbuf ffStrbufCreateNWS(uint32_t length, const wchar_t* source)
+{
+    FFstrbuf result;
+    ffStrbufInitNWS(&result, length, source);
+    return result;
+}
 
 static inline FFstrbuf ffStrbufCreateWS(const wchar_t* source)
 {