Add open() and close() skeletons that only recognize the image as a correct one.

src/close.c

@@ -0,0 +1,62 @@
+// /***************************************************************************
+// The Disc Image Chef
+// ----------------------------------------------------------------------------
+//
+// Filename       : close.c
+// Author(s)      : Natalia Portillo <claunia@claunia.com>
+//
+// Component      : libdicformat.
+//
+// --[ Description ] ----------------------------------------------------------
+//
+//     Handles closing DiscImageChef format disk images.
+//
+// --[ License ] --------------------------------------------------------------
+//
+//     This library is free software; you can redistribute it and/or modify
+//     it under the terms of the GNU Lesser General Public License as
+//     published by the Free Software Foundation; either version 2.1 of the
+//     License, or (at your option) any later version.
+//
+//     This library is distributed in the hope that it will be useful, but
+//     WITHOUT ANY WARRANTY; without even the implied warranty of
+//     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+//     Lesser General Public License for more details.
+//
+//     You should have received a copy of the GNU Lesser General Public
+//     License along with this library; if not, see <http://www.gnu.org/licenses/>.
+//
+// ----------------------------------------------------------------------------
+// Copyright © 2011-2019 Natalia Portillo
+// ****************************************************************************/
+
+#include <stdio.h>
+#include <dicformat.h>
+#include <malloc.h>
+#include <errno.h>
+
+int close(void *context)
+{
+    if(context == NULL)
+    {
+        errno = EINVAL;
+        return -1;
+    }
+
+    dicformatContext *ctx = context;
+
+    // TODO: Cast this field without casting the whole structure, as this can buffer overlow
+    // Not a libdicformat context
+    if(ctx->magic != DIC_MAGIC)
+    {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if(ctx->imageStream != NULL)
+        fclose(ctx->imageStream);
+
+    free(context);
+
+    return 0;
+}