Virtual PC read-only disk image support (Alex Beregszaszi)

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@1417 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 243 insertions, 0 deletions

diff --git a/block-vpc.c b/block-vpc.c
new file mode 100644
index 0000000..88ad575
--- /dev/null
+++ b/block-vpc.c
@@ -0,0 +1,243 @@
+/*
+ * Block driver for Conectix/Microsoft Virtual PC images
+ * 
+ * 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_SIZE 512
+
+//#define CACHE
+
+// always big-endian
+struct vpc_subheader {
+    char magic[8]; // "conectix" / "cxsparse"
+    union {
+	struct {
+	    uint32_t unk1[2];
+	    uint32_t unk2; // always zero?
+	    uint32_t subheader_offset;
+	    uint32_t unk3; // some size?
+	    char creator[4]; // "vpc "
+	    uint16_t major;
+	    uint16_t minor;
+	    char guest[4]; // "Wi2k"
+	    uint32_t unk4[7];
+	    uint8_t vnet_id[16]; // virtual network id, purpose unknown
+	    // next 16 longs are used, but dunno the purpose
+	    // next 6 longs unknown, following 7 long maybe a serial
+	    char padding[HEADER_SIZE - 84];
+	} main;
+	struct {
+	    uint32_t unk1[2]; // all bits set
+	    uint32_t unk2; // always zero?
+	    uint32_t pagetable_offset;
+	    uint32_t unk3;
+	    uint32_t pagetable_entries; // 32bit/entry
+	    uint32_t pageentry_size; // 512*8*512
+	    uint32_t nb_sectors;
+	    char padding[HEADER_SIZE - 40];
+	} sparse;
+	char padding[HEADER_SIZE - 8];
+    } type;
+};
+
+typedef struct BDRVVPCState {
+    int fd;
+    
+    int pagetable_entries;
+    uint32_t *pagetable;
+
+    uint32_t pageentry_size;
+#ifdef CACHE
+    uint8_t *pageentry_u8;
+    uint32_t *pageentry_u32;
+    uint16_t *pageentry_u16;
+    
+    uint64_t last_bitmap;
+#endif
+} BDRVVPCState;
+
+static int vpc_probe(const uint8_t *buf, int buf_size, const char *filename)
+{
+    if (!strncmp(buf, "conectix", 8))
+	return 100;
+
+    return 0;
+}
+
+static int vpc_open(BlockDriverState *bs, const char *filename)
+{
+    BDRVVPCState *s = bs->opaque;
+    int fd, i;
+    struct vpc_subheader header;
+
+    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, &header, HEADER_SIZE) != HEADER_SIZE)
+        goto fail;
+
+    if (strncmp(header.magic, "conectix", 8))
+        goto fail;
+    lseek(s->fd, be32_to_cpu(header.type.main.subheader_offset), SEEK_SET);
+
+    if (read(fd, &header, HEADER_SIZE) != HEADER_SIZE)
+        goto fail;
+
+    if (strncmp(header.magic, "cxsparse", 8))
+	goto fail;
+
+    bs->total_sectors = ((uint64_t)be32_to_cpu(header.type.sparse.pagetable_entries) *
+			be32_to_cpu(header.type.sparse.pageentry_size)) / 512;
+
+    lseek(s->fd, be32_to_cpu(header.type.sparse.pagetable_offset), SEEK_SET);
+
+    s->pagetable_entries = be32_to_cpu(header.type.sparse.pagetable_entries);
+    s->pagetable = qemu_malloc(s->pagetable_entries * 4);
+    if (!s->pagetable)
+	goto fail;
+    if (read(s->fd, s->pagetable, s->pagetable_entries * 4) !=
+	s->pagetable_entries * 4)
+	goto fail;
+    for (i = 0; i < s->pagetable_entries; i++)
+	be32_to_cpus(&s->pagetable[i]);
+
+    s->pageentry_size = be32_to_cpu(header.type.sparse.pageentry_size);
+#ifdef CACHE
+    s->pageentry_u8 = qemu_malloc(512);
+    if (!s->pageentry_u8)
+	goto fail;
+    s->pageentry_u32 = s->pageentry_u8;
+    s->pageentry_u16 = s->pageentry_u8;
+    s->last_pagetable = -1;
+#endif
+
+    return 0;
+ fail:
+    close(fd);
+    return -1;
+}
+
+static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)
+{
+    BDRVVPCState *s = bs->opaque;
+    uint64_t offset = sector_num * 512;
+    uint64_t bitmap_offset, block_offset;
+    uint32_t pagetable_index, pageentry_index;
+
+    pagetable_index = offset / s->pageentry_size;
+    pageentry_index = (offset % s->pageentry_size) / 512;
+    
+    if (pagetable_index > s->pagetable_entries || s->pagetable[pagetable_index] == 0xffffffff)
+	return -1; // not allocated
+
+    bitmap_offset = 512 * s->pagetable[pagetable_index];
+    block_offset = bitmap_offset + 512 + (512 * pageentry_index);
+    
+//    printf("sector: %llx, index: %x, offset: %x, bioff: %llx, bloff: %llx\n",
+//	sector_num, pagetable_index, pageentry_index,
+//	bitmap_offset, block_offset);
+
+// disabled by reason
+#if 0
+#ifdef CACHE
+    if (bitmap_offset != s->last_bitmap)
+    {
+	lseek(s->fd, bitmap_offset, SEEK_SET);
+
+	s->last_bitmap = bitmap_offset;
+	
+	// Scary! Bitmap is stored as big endian 32bit entries,
+	// while we used to look it up byte by byte
+	read(s->fd, s->pageentry_u8, 512);
+	for (i = 0; i < 128; i++)
+	    be32_to_cpus(&s->pageentry_u32[i]);
+    }
+
+    if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1)
+	return -1;
+#else
+    lseek(s->fd, bitmap_offset + (pageentry_index / 8), SEEK_SET);
+	
+    read(s->fd, &bitmap_entry, 1);
+
+    if ((bitmap_entry >> (pageentry_index % 8)) & 1)
+	return -1; // not allocated
+#endif
+#endif
+    lseek(s->fd, block_offset, SEEK_SET);
+
+    return 0;
+}
+
+static int vpc_read(BlockDriverState *bs, int64_t sector_num, 
+                    uint8_t *buf, int nb_sectors)
+{
+    BDRVVPCState *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 vpc_close(BlockDriverState *bs)
+{
+    BDRVVPCState *s = bs->opaque;
+    qemu_free(s->pagetable);
+#ifdef CACHE
+    qemu_free(s->pageentry_u8);
+#endif
+    close(s->fd);
+}
+
+BlockDriver bdrv_vpc = {
+    "vpc",
+    sizeof(BDRVVPCState),
+    vpc_probe,
+    vpc_open,
+    vpc_read,
+    NULL,
+    vpc_close,
+};