Bochs disk image support (Alex Beregszaszi)

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@1409 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 224 insertions, 0 deletions

diff --git a/block-bochs.c b/block-bochs.c
new file mode 100644
index 0000000..62317af
--- /dev/null
+++ b/block-bochs.c
@@ -0,0 +1,224 @@
+/*
+ * Block driver for the various disk image formats used by Bochs
+ * Currently only for "growing" type in read-only mode
+ * 
+ * Copyright (c) 2005 Alex Beregszaszi
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "vl.h"
+#include "block_int.h"
+
+/**************************************************************/
+
+#define HEADER_MAGIC "Bochs Virtual HD Image"
+#define HEADER_VERSION 0x00010000
+#define HEADER_SIZE 512
+
+#define REDOLOG_TYPE "Redolog"
+#define GROWING_TYPE "Growing"
+
+// not allocated: 0xffffffff
+
+// always little-endian
+struct bochs_header {
+    char magic[32]; // "Bochs Virtual HD Image"
+    char type[16]; // "Redolog"
+    char subtype[16]; // "Undoable" / "Volatile" / "Growing"
+    uint32_t version;
+    uint32_t header; // size of header
+    
+    union {
+	struct {
+	    uint32_t catalog; // num of entries
+	    uint32_t bitmap; // bitmap size
+	    uint32_t extent; // extent size
+	    uint64_t disk; // disk size
+	    char padding[HEADER_SIZE - 64 - 8 - 20];
+	} redolog;
+	char padding[HEADER_SIZE - 64 - 8];
+    } extra;
+};
+
+typedef struct BDRVBochsState {
+    int fd;
+
+    uint32_t *catalog_bitmap;
+    int catalog_size;
+    
+    int data_offset;
+    
+    int bitmap_blocks;
+    int extent_blocks;
+    int extent_size;
+} BDRVBochsState;
+
+static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
+{
+    const struct bochs_header *bochs = (const void *)buf;
+    
+    if (buf_size < HEADER_SIZE)
+	return 0;
+
+    if (!strcmp(bochs->magic, HEADER_MAGIC) &&
+	!strcmp(bochs->type, REDOLOG_TYPE) &&
+	!strcmp(bochs->subtype, GROWING_TYPE) &&
+	(le32_to_cpu(bochs->version) == HEADER_VERSION))
+	return 100;
+
+    return 0;
+}
+
+static int bochs_open(BlockDriverState *bs, const char *filename)
+{
+    BDRVBochsState *s = bs->opaque;
+    int fd, i;
+    struct bochs_header bochs;
+
+    fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
+    if (fd < 0) {
+        fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
+        if (fd < 0)
+            return -1;
+    }
+    
+    bs->read_only = 1; // no write support yet
+    
+    s->fd = fd;
+
+    if (read(fd, &bochs, sizeof(bochs)) != sizeof(bochs)) {
+        goto fail;
+    }
+
+    if (strcmp(bochs.magic, HEADER_MAGIC) ||
+        strcmp(bochs.type, REDOLOG_TYPE) ||
+        strcmp(bochs.subtype, GROWING_TYPE) ||
+	(le32_to_cpu(bochs.version) != HEADER_VERSION)) {
+        goto fail;
+    }
+
+    bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
+
+    lseek(s->fd, le32_to_cpu(bochs.header), SEEK_SET);
+
+    s->catalog_size = le32_to_cpu(bochs.extra.redolog.catalog);
+    s->catalog_bitmap = qemu_malloc(s->catalog_size * 4);
+    if (!s->catalog_bitmap)
+	goto fail;
+    if (read(s->fd, s->catalog_bitmap, s->catalog_size * 4) !=
+	s->catalog_size * 4)
+	goto fail;
+    for (i = 0; i < s->catalog_size; i++)
+	le32_to_cpus(&s->catalog_bitmap[i]);
+
+    s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
+
+    s->bitmap_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.bitmap) - 1) / 512;
+    s->extent_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.extent) - 1) / 512;
+    
+    s->extent_size = le32_to_cpu(bochs.extra.redolog.extent);
+
+    return 0;
+ fail:
+    close(fd);
+    return -1;
+}
+
+static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)
+{
+    BDRVBochsState *s = bs->opaque;
+    int64_t offset = sector_num * 512;
+    int64_t extent_index, extent_offset, bitmap_offset, block_offset;
+    char bitmap_entry;
+
+    // seek to sector
+    extent_index = offset / s->extent_size;
+    extent_offset = (offset % s->extent_size) / 512;
+    
+    if (s->catalog_bitmap[extent_index] == 0xffffffff)
+    {
+//	fprintf(stderr, "page not allocated [%x - %x:%x]\n",
+//	    sector_num, extent_index, extent_offset);
+	return -1; // not allocated
+    }
+
+    bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] *
+	(s->extent_blocks + s->bitmap_blocks));
+    block_offset = bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
+    
+//    fprintf(stderr, "sect: %x [ext i: %x o: %x] -> %x bitmap: %x block: %x\n",
+//	sector_num, extent_index, extent_offset,
+//	le32_to_cpu(s->catalog_bitmap[extent_index]),
+//	bitmap_offset, block_offset);
+    
+    // read in bitmap for current extent
+    lseek(s->fd, bitmap_offset + (extent_offset / 8), SEEK_SET);
+    
+    read(s->fd, &bitmap_entry, 1);
+    
+    if (!((bitmap_entry >> (extent_offset % 8)) & 1))
+    {
+//	fprintf(stderr, "sector (%x) in bitmap not allocated\n",
+//	    sector_num);
+	return -1; // not allocated
+    }
+
+    lseek(s->fd, block_offset, SEEK_SET);
+    
+    return 0;
+}
+
+static int bochs_read(BlockDriverState *bs, int64_t sector_num, 
+                    uint8_t *buf, int nb_sectors)
+{
+    BDRVBochsState *s = bs->opaque;
+    int ret;
+
+    while (nb_sectors > 0) {
+	if (!seek_to_sector(bs, sector_num))
+	{
+	    ret = read(s->fd, buf, 512);
+	    if (ret != 512)
+		return -1;
+	}
+	else
+            memset(buf, 0, 512);
+        nb_sectors--;
+        sector_num++;
+        buf += 512;
+    }
+    return 0;
+}
+
+static void bochs_close(BlockDriverState *bs)
+{
+    BDRVBochsState *s = bs->opaque;
+    qemu_free(s->catalog_bitmap);
+    close(s->fd);
+}
+
+BlockDriver bdrv_bochs = {
+    "bochs",
+    sizeof(BDRVBochsState),
+    bochs_probe,
+    bochs_open,
+    bochs_read,
+    NULL,
+    bochs_close,
+};