Factor out the context specific functions into their own file.

context.c

Index: context.c
diff --git a/context.c b/context.c
new file mode 100644
index 0000000000000000000000000000000000000000..771b7fe43d858c52019723cdfe0cb4a7b7b3b9dc
--- /dev/null
+++ b/context.c
@@ -0,0 +1,83 @@
+/**
+ * Copyright (c) 2011 NVIDIA Corporation.  All rights reserved.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include "cbootimage.h"
+#include "data_layout.h"
+#include "set.h"
+
+static int
+query_alloc(build_image_context *context,
+        nvbct_lib_id size_id,
+        u_int8_t **dst)
+{
+        u_int32_t size;
+
+        /* Note: 3rd argument not used in this particular query. */
+        if (context->bctlib.get_value(size_id,
+                        &size, context->bct) != 0)
+                return -ENODATA;
+        *dst = malloc(size);
+
+        if (*dst == NULL)
+                return -ENOMEM;
+
+        memset(*dst, 0, size);
+
+        return 0;
+}
+
+void
+cleanup_context(build_image_context *context)
+{
+        destroy_block_list(context->memory);
+        destroy_addon_list(context->addon_tbl.addon_item_list);
+        free(context->bct);
+}
+
+int
+init_context(build_image_context *context)
+{
+        int e = 0;
+
+        /* Set defaults */
+        context->memory = new_block_list();
+        context->journal_blk = 1; /* Default to 1st block */
+
+        /* Allocate space for the bct.
+         * Note that this is different from the old code which pointed directly
+         * into a memory image.
+         */
+        e = query_alloc(context, nvbct_lib_id_bct_size, &(context->bct));
+        if (e != 0)
+                goto fail;
+
+        context_set_value(context, token_page_size, 2048);
+        context_set_value(context, token_redundancy, 1);
+        context_set_value(context, token_version, 1);
+
+        return 0;
+
+ fail:
+        cleanup_context(context);
+
+        return e;
+}