Fix ssprintf to not allocate temporary memory

The original code was written the way that it was because snprintf was not
standard and didn't work consistently across many platforms. But since C++11
std::snprintf is available and can be used to get the exact size of the
required buffer. Because of that, ssprintf can be greatly simplified.

src/RageUtil.cpp

@@ -382,87 +382,22 @@ RString ssprintf( const char *fmt, ...)
 {
 	va_list	va;
 	va_start(va, fmt);
-	return vssprintf(fmt, va);
+	RString sRet = vssprintf(fmt, va);
+	va_end(va);
+	return sRet;
 }
 
-#define FMT_BLOCK_SIZE		2048 // # of bytes to increment per try
-
 RString vssprintf( const char *szFormat, va_list argList )
 {
-	RString sStr;
+	va_list tmp;
+	va_copy( tmp, argList );
+	int iNeeded = std::vsnprintf( nullptr, 0, szFormat, tmp );
+	va_end(tmp);
 
-#if defined(WIN32)
-	char *pBuf = nullptr;
-	int iChars = 1;
-	int iUsed = 0;
-	int iTry = 0;
-
-	do
-	{
-		// Grow more than linearly (e.g. 512, 1536, 3072, etc)
-		iChars += iTry * FMT_BLOCK_SIZE;
-		pBuf = (char*) _alloca( sizeof(char)*iChars );
-		iUsed = vsnprintf( pBuf, iChars-1, szFormat, argList );
-		++iTry;
-	} while( iUsed < 0 );
-
-	// assign whatever we managed to format
-	sStr.assign( pBuf, iUsed );
-#else
-	static bool bExactSizeSupported;
-	static bool bInitialized = false;
-	if( !bInitialized )
-	{
-		/* Some systems return the actual size required when snprintf
-		 * doesn't have enough space.  This lets us avoid wasting time
-		 * iterating, and wasting memory. */
-		char ignore;
-		bExactSizeSupported = ( snprintf( &ignore, 0, "Hello World" ) == 11 );
-		bInitialized = true;
-	}
-
-	if( bExactSizeSupported )
-	{
-		va_list tmp;
-		va_copy( tmp, argList );
-		char ignore;
-		int iNeeded = vsnprintf( &ignore, 0, szFormat, tmp );
-		va_end(tmp);
-
-		char *buf = new char[iNeeded + 1];
-		std::fill(buf, buf + iNeeded + 1, '\0');
-		vsnprintf( buf, iNeeded+1, szFormat, argList );
-		RString ret(buf);
-		delete [] buf;
-		return ret;
-	}
-
-	int iChars = FMT_BLOCK_SIZE;
-	int iTry = 1;
-	for (;;)
-	{
-		// Grow more than linearly (e.g. 512, 1536, 3072, etc)
-		char *buf = new char[iChars];
-		std::fill(buf, buf + iChars, '\0');
-		int used = vsnprintf( buf, iChars - 1, szFormat, argList );
-		if ( used == -1 )
-		{
-			iChars += ( ++iTry * FMT_BLOCK_SIZE );
-		}
-		else
-		{
-			/* OK */
-			sStr.assign(buf, used);
-		}
-
-		delete [] buf;
-		if (used != -1)
-		{
-			break;
-		}
-	}
-#endif
-	return sStr;
+	RString sRet;
+	std::vsnprintf( sRet.GetBuffer(iNeeded), iNeeded+1, szFormat, argList );
+	sRet.ReleaseBuffer( iNeeded );
+	return sRet;
 }
 
 /* ISO-639-1 codes: http://www.loc.gov/standards/iso639-2/php/code_list.php

src/StdString.h

@@ -257,10 +257,6 @@ inline void ssupr(wchar_t *pT, size_t nLen)
 	MakeUpper( pT, nLen );
 }
 
-#if defined(WIN32)
-#define vsnprintf _vsnprintf
-#endif
-
 //			Now we can define the template (finally!)
 // =============================================================================
 // TEMPLATE: CStdStr