Strings owned by local stack objects can't be returned.

The BString is destroyed when the function returns and takes the
storage pointed to by BString::String() with it, so returning such a
pointer is bogus. Instead the return type is now a BString which takes
over ownership of the string.

src/apps/screenshot/ScreenshotWindow.cpp

@@ -713,7 +713,7 @@ ScreenshotWindow::_FindValidFileName(const char* name)
 	if (orgPath == NULL)
 		return baseName;
 
-	fExtension = BString(fUtility.GetFileNameExtension(fImageFileType));
+	fExtension = fUtility.GetFileNameExtension(fImageFileType);
 
 	BPath outputPath = orgPath;
 	BString fileName;

src/apps/screenshot/Utility.cpp

@@ -120,7 +120,7 @@ Utility::Save(BBitmap** screenshot, const char* fileName, uint32 imageType)
 	if (nodeInfo.InitCheck() != B_OK)
 		return B_ERROR;
 
-	nodeInfo.SetType(_GetMimeString(imageType));
+	nodeInfo.SetType(_GetMimeString(imageType).String());
 
 	return B_OK;
 }
@@ -187,10 +187,10 @@ Utility::MakeScreenshot(bool includeMouse, bool activeWindow,
 }
 
 
-const char*
+BString
 Utility::GetFileNameExtension(uint32 imageType) const
 {
-	BMimeType mimeType(_GetMimeString(imageType));
+	BMimeType mimeType(_GetMimeString(imageType).String());
 	BString extension("");
 
 	BMessage message;
@@ -203,11 +203,11 @@ Utility::GetFileNameExtension(uint32 imageType) const
 			extension.SetTo("");
 	}
 
-	return extension.String();
+	return extension;
 }
 
 
-const char*
+BString
 Utility::_GetMimeString(uint32 imageType) const
 {
 	const char *dummy = "";

src/apps/screenshot/Utility.h

@@ -8,6 +8,7 @@
 
 #include <Point.h>
 #include <Rect.h>
+#include <String.h>
 
 
 class BBitmap;
@@ -27,7 +28,7 @@ public:
 							uint32 imageType) const;
 			BBitmap*	MakeScreenshot(bool includeCursor, bool activeWindow,
 							bool includeBorder) const;
-			const char*	GetFileNameExtension(uint32 imageType) const;
+			BString		GetFileNameExtension(uint32 imageType) const;
 
 			BBitmap*	wholeScreen;
 			BBitmap*	cursorBitmap;
@@ -42,7 +43,7 @@ public:
 private:
 			void		_MakeTabSpaceTransparent(BBitmap* screenshot,
 							BRect frame) const;
-			const char*	_GetMimeString(uint32 imageType) const;
+			BString		_GetMimeString(uint32 imageType) const;
 };