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

src/open.c

@@ -0,0 +1,95 @@
+// /***************************************************************************
+// The Disc Image Chef
+// ----------------------------------------------------------------------------
+//
+// Filename       : open.c
+// Author(s)      : Natalia Portillo <claunia@claunia.com>
+//
+// Component      : libdicformat.
+//
+// --[ Description ] ----------------------------------------------------------
+//
+//     Handles opening 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>
+
+void *open(const char *filepath)
+{
+    dicformatContext *ctx = malloc(sizeof(dicformatContext));
+    int              errorNo;
+    size_t           readBytes;
+
+    if(ctx == NULL)
+        return NULL;
+
+    ctx->imageStream = fopen(filepath, "rb");
+
+    if(ctx->imageStream == NULL)
+    {
+        errorNo = errno;
+        free(ctx);
+        errno = errorNo;
+
+        return NULL;
+    }
+
+    fseek(ctx->imageStream, 0, SEEK_SET);
+    readBytes = fread(&ctx->header, sizeof(DicHeader), 1, ctx->imageStream);
+
+    if(readBytes != sizeof(DicHeader))
+    {
+        free(ctx);
+        errno = DICF_ERROR_FILE_TOO_SMALL;
+
+        return NULL;
+    }
+
+    if(ctx->header.identifier != DIC_MAGIC)
+    {
+        free(ctx);
+        errno = DICF_ERROR_NOT_DICFORMAT;
+
+        return NULL;
+    }
+
+    if(ctx->header.imageMajorVersion > DICF_VERSION)
+    {
+        free(ctx);
+        errno = DICF_ERROR_INCOMPATIBLE_VERSION;
+
+        return NULL;
+    }
+
+    ctx->magic               = DIC_MAGIC;
+    ctx->libraryMajorVersion = LIBDICFORMAT_MAJOR_VERSION;
+    ctx->libraryMinorVersion = LIBDICFORMAT_MINOR_VERSION;
+
+    fprintf(stderr,
+            "libdicformat: Opened image version %d.%d",
+            ctx->header.imageMajorVersion,
+            ctx->header.imageMinorVersion);
+
+    return ctx;
+}