From 6197413ba058f1f17d80d6df67a263121932ef08 Mon Sep 17 00:00:00 2001
From: espes <nielkie2@gmail.com>
Date: Thu, 18 Apr 2013 12:57:57 +1000
Subject: [PATCH] add address-space block device

---
 block/Makefile.objs       |   1 +
 block/blkmemory.c         | 126 ++++++++++++++++++++++++++++++++++++++
 include/block/blkmemory.h |   9 +++
 3 files changed, 136 insertions(+)
 create mode 100644 block/blkmemory.c
 create mode 100644 include/block/blkmemory.h

diff --git a/block/Makefile.objs b/block/Makefile.objs
index c067f38e1d..04157e01b5 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -18,5 +18,6 @@ endif
 common-obj-y += stream.o
 common-obj-y += commit.o
 common-obj-y += mirror.o
+common-obj-y += blkmemory.o
 
 $(obj)/curl.o: QEMU_CFLAGS+=$(CURL_CFLAGS)
diff --git a/block/blkmemory.c b/block/blkmemory.c
new file mode 100644
index 0000000000..2ff8a0f7f9
--- /dev/null
+++ b/block/blkmemory.c
@@ -0,0 +1,126 @@
+/*
+ * MemoryRegion backed block driver
+ *
+ * Copyright (c) 2013 espes
+ *
+ * Based on "Add an in-memory block device" patch
+ * Copyright IBM, Corp. 2007
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * 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 or
+ * (at your option) version 3 of the License.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu-common.h"
+#include "exec/memory.h"
+#include "block/block_int.h"
+
+#include "block/blkmemory.h"
+
+
+typedef struct BDRVMemoryState {
+    uint64_t size;
+    AddressSpace *as;
+} BDRVMemoryState;
+
+static int memory_open(BlockDriverState *bs, QDict *options, int flags)
+{
+    /* We're kinda unique in that we're inited with a MemoryRegion instead
+     * of a file. A MemoryRegion pointer can't be put in QDict, so we have
+     * to be inited by hand. If something tries to init us normally, better
+     * to fail than crash.
+     */
+    return -1;
+}
+
+static void memory_close(BlockDriverState *bs)
+{
+    /* nothing to do..? */
+}
+
+static int64_t memory_getlength(BlockDriverState *bs)
+{
+    BDRVMemoryState *s = bs->opaque;
+
+    return s->size / BDRV_SECTOR_SIZE;
+}
+
+static int memory_read(BlockDriverState *bs, int64_t sector_num,
+                       uint8_t *buf, int nb_sectors)
+{
+    BDRVMemoryState *s = bs->opaque;
+    
+    sector_num = MIN(sector_num, bs->total_sectors - 1);
+    size_t size = MIN(s->size - sector_num * BDRV_SECTOR_SIZE,
+                      nb_sectors * BDRV_SECTOR_SIZE);
+
+    address_space_read(s->as, sector_num * BDRV_SECTOR_SIZE, buf, size);
+
+    return 0;
+}
+
+static int memory_write(BlockDriverState *bs, int64_t sector_num,
+                        const uint8_t *buf, int nb_sectors)
+{
+    BDRVMemoryState *s = bs->opaque;
+
+    sector_num = MIN(sector_num, bs->total_sectors - 1);
+    size_t size = MIN(s->size - sector_num * BDRV_SECTOR_SIZE,
+                      nb_sectors * BDRV_SECTOR_SIZE);
+
+    address_space_write(s->as, sector_num * BDRV_SECTOR_SIZE, buf, size);
+
+    return 0;
+}
+
+static BlockDriver bdrv_memory = {
+    .format_name = "memory",
+    .instance_size = sizeof(BDRVMemoryState),
+    .bdrv_open = memory_open,
+    .bdrv_close = memory_close,
+    .bdrv_getlength = memory_getlength,
+
+    .bdrv_read = memory_read,
+    .bdrv_write = memory_write,
+};
+
+static void bdrv_memory_init(void)
+{
+    bdrv_register(&bdrv_memory);
+}
+
+block_init(bdrv_memory_init);
+
+
+int bdrv_memory_open(BlockDriverState *bs, AddressSpace *as, uint64_t size)
+{
+    bs->total_sectors = (size + BDRV_SECTOR_SIZE-1) / BDRV_SECTOR_SIZE;
+    bs->read_only = false;
+    bs->is_temporary = false;
+    bs->encrypted = false;
+
+    pstrcpy(bs->filename, sizeof(bs->filename), "<mem>");
+
+    bs->drv = &bdrv_memory;
+    bs->opaque = g_malloc0(bdrv_memory.instance_size);
+    if (!bs->opaque) {
+        return -1;
+    }
+
+    BDRVMemoryState *s = bs->opaque;
+    s->as = as;
+    s->size = size;
+
+    return 0;
+}
\ No newline at end of file
diff --git a/include/block/blkmemory.h b/include/block/blkmemory.h
new file mode 100644
index 0000000000..732a06e42a
--- /dev/null
+++ b/include/block/blkmemory.h
@@ -0,0 +1,9 @@
+#ifndef BLKMEMORY_H
+#define BLKMEMORY_H
+
+#include "block/block_int.h"
+#include "exec/memory.h"
+
+int bdrv_memory_open(BlockDriverState *bs, AddressSpace *as, uint64_t size);
+
+#endif
\ No newline at end of file