engine: prevent extra malloc in exec by checking if cfg already contains newline at EOL and appending it to cbuf if required

engine/common/cmd.c

@@ -142,28 +142,33 @@ void Cbuf_AddFilteredText( const char *text )
 Cbuf_InsertText
 
 Adds command text immediately after the current command
-Adds a \n to the text
 ============
 */
-static void Cbuf_InsertTextToBuffer( cmdbuf_t *buf, const char *text )
+static void Cbuf_InsertTextToBuffer( cmdbuf_t *buf, const char *text, size_t len, size_t requested_len )
 {
-	int	l = Q_strlen( text );
+	if(( buf->cursize + requested_len ) >= buf->maxsize )
-
-	if(( buf->cursize + l ) >= buf->maxsize )
 	{
 		Con_Reportf( S_WARN "%s: overflow\n", __func__ );
 	}
 	else
 	{
-		memmove( buf->data + l, buf->data, buf->cursize );
+		memmove( buf->data + len, buf->data, buf->cursize );
-		memcpy( buf->data, text, l );
+		memcpy( buf->data, text, len );
-		buf->cursize += l;
+		buf->cursize += len;
 	}
 }
 
+void Cbuf_InsertTextLen( const char *text, size_t len, size_t requested_len )
+{
+	// sometimes we need to insert more data than we have
+	// but also prevent overflow
+	Cbuf_InsertTextToBuffer( &cmd_text, text, len, requested_len );
+}
+
 void Cbuf_InsertText( const char *text )
 {
-	Cbuf_InsertTextToBuffer( &cmd_text, text );
+	size_t l = Q_strlen( text );
+	Cbuf_InsertTextToBuffer( &cmd_text, text, l, l );
 }
 
 /*
@@ -1010,9 +1015,10 @@ static void Cmd_ExecuteStringWithPrivilegeCheck( const char *text, qboolean isPr
 
 		if( a )
 		{
+			size_t len = Q_strlen( a->value );
 			Cbuf_InsertTextToBuffer(
 				isPrivileged ? &cmd_text : &filteredcmd_text,
-				a->value );
+				a->value, len, len );
 			return;
 		}
 	}

engine/common/common.h

@@ -425,6 +425,7 @@ void Cbuf_AddText( const char *text );
 void Cbuf_AddTextf( const char *text, ... ) FORMAT_CHECK( 1 );
 void Cbuf_AddFilteredText( const char *text );
 void Cbuf_InsertText( const char *text );
+void Cbuf_InsertTextLen( const char *text, size_t len, size_t requested_len );
 void Cbuf_ExecStuffCmds( void );
 void Cbuf_Execute (void);
 qboolean Cmd_CurrentCommandIsPrivileged( void );

engine/common/host.c

@@ -418,7 +418,6 @@ static void Host_Exec_f( void )
 {
 	string cfgpath;
 	byte *f;
-	char *txt;
 	fs_offset_t len;
 
 	if( Cmd_Argc() != 2 )
@@ -474,20 +473,29 @@ static void Host_Exec_f( void )
 		return;
 	}
 
+	// len is fs_offset_t, which can be larger than size_t
+	if( len >= SIZE_MAX )
+	{
+		Con_Reportf( "%s: %s is too long\n", __func__, Cmd_Argv( 1 ));
+		return;
+	}
+
 	if( !Q_stricmp( "config.cfg", cfgpath ))
 		host.config_executed = true;
 
-	// adds \n\0 at end of the file
-	txt = Z_Calloc( len + 2 );
-	memcpy( txt, f, len );
-	txt[len] = '\n';
-	txt[len + 1] = '\0';
-	Mem_Free( f );
-
 	if( !host.apply_game_config )
 		Con_Printf( "execing %s\n", Cmd_Argv( 1 ));
-	Cbuf_InsertText( txt );
+
-	Mem_Free( txt );
+	// adds \n at end of the file
+	// FS_LoadFile always null terminates
+	if( f[len - 1] != '\n' )
+	{
+		Cbuf_InsertTextLen( f, len, len + 1 );
+		Cbuf_InsertTextLen( "\n", 1, 1 );
+	}
+	else Cbuf_InsertTextLen( f, len, len );
+
+	Mem_Free( f );
 }
 
 /*