[Qemu-devel] [6455] block-vpc: Adapt header structures to official documentation ( Kevin Wolf)

[Anthony Liguori]

Revision: 6455
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=6455
Author:   aliguori
Date:     2009-01-26 20:26:49 +0000 (Mon, 26 Jan 2009)

Log Message:
-----------
block-vpc: Adapt header structures to official documentation (Kevin Wolf)

The current definition of the VirtualPC headers is incomplete and partly
even wrong. This patch changes the header structs according to the
official VHD specification.

Signed-off-by: Kevin Wolf <address@hidden>
Signed-off-by: Anthony Liguori <address@hidden>

Modified Paths:
--------------
    trunk/block-vpc.c

Modified: trunk/block-vpc.c
===================================================================
--- trunk/block-vpc.c   2009-01-26 20:26:46 UTC (rev 6454)
+++ trunk/block-vpc.c   2009-01-26 20:26:49 UTC (rev 6455)
@@ -30,41 +30,87 @@
 
 //#define CACHE
 
+enum vhd_type {
+    VHD_FIXED           = 2,
+    VHD_DYNAMIC         = 3,
+    VHD_DIFFERENCING    = 4,
+};
+
 // always big-endian
 struct vhd_footer {
-    char creator[8]; // "conectix
-    uint32_t unk1[2];
-    uint32_t unk2; // always zero?
-    uint32_t subheader_offset;
-    uint32_t unk3; // some size?
-    char creator_app[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        creator[8]; // "conectix"
+    uint32_t    features;
+    uint32_t    version;
+
+    // Offset of next header structure, 0xFFFFFFFF if none
+    uint64_t    data_offset;
+
+    // Seconds since Jan 1, 2000 0:00:00 (UTC)
+    uint32_t    timestamp;
+
+    char        creator_app[4]; // "vpc "
+    uint16_t    major;
+    uint16_t    minor;
+    char        creator_os[4]; // "Wi2k"
+
+    uint64_t    orig_size;
+    uint64_t    size;
+
+    uint16_t    cyls;
+    uint8_t     heads;
+    uint8_t     secs_per_cyl;
+
+    uint32_t    type;
+
+    // Checksum of the Hard Disk Footer ("one's complement of the sum of all
+    // the bytes in the footer without the checksum field")
+    uint32_t    checksum;
+
+    // UUID used to identify a parent hard disk (backing file)
+    uint8_t     uuid[16];
+
+    uint8_t     in_saved_state;
 };
 
 struct vhd_dyndisk_header {
-    char magic[8]; // "cxsparse"
-    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        magic[8]; // "cxsparse"
+
+    // Offset of next header structure, 0xFFFFFFFF if none
+    uint64_t    data_offset;
+
+    // Offset of the Block Allocation Table (BAT)
+    uint64_t    table_offset;
+
+    uint32_t    version;
+    uint32_t    max_table_entries; // 32bit/entry
+
+    // 2 MB by default, must be a power of two
+    uint32_t    block_size;
+
+    uint32_t    checksum;
+    uint8_t     parent_uuid[16];
+    uint32_t    parent_timestamp;
+    uint32_t    reserved;
+
+    // Backing file name (in UTF-16)
+    uint8_t     parent_name[512];
+
+    struct {
+        uint32_t    platform;
+        uint32_t    data_space;
+        uint32_t    data_length;
+        uint32_t    reserved;
+        uint64_t    data_offset;
+    } parent_locator[8];
 };
 
 typedef struct BDRVVPCState {
     int fd;
 
-    int pagetable_entries;
+    int max_table_entries;
     uint32_t *pagetable;
 
-    uint32_t pageentry_size;
+    uint32_t block_size;
 #ifdef CACHE
     uint8_t *pageentry_u8;
     uint32_t *pageentry_u32;
@@ -104,7 +150,7 @@
     if (strncmp(footer->creator, "conectix", 8))
         goto fail;
 
-    lseek(s->fd, be32_to_cpu(footer->subheader_offset), SEEK_SET);
+    lseek(s->fd, be64_to_cpu(footer->data_offset), SEEK_SET);
     if (read(fd, buf, HEADER_SIZE) != HEADER_SIZE)
         goto fail;
 
@@ -114,22 +160,22 @@
     if (strncmp(dyndisk_header->magic, "cxsparse", 8))
         goto fail;
 
-    bs->total_sectors = 
((uint64_t)be32_to_cpu(dyndisk_header->pagetable_entries) *
-                       be32_to_cpu(dyndisk_header->pageentry_size)) / 512;
+    bs->total_sectors = 
((uint64_t)be32_to_cpu(dyndisk_header->max_table_entries) *
+                       be32_to_cpu(dyndisk_header->block_size)) / 512;
 
-    lseek(s->fd, be32_to_cpu(dyndisk_header->pagetable_offset), SEEK_SET);
+    lseek(s->fd, be64_to_cpu(dyndisk_header->table_offset), SEEK_SET);
 
-    s->pagetable_entries = be32_to_cpu(dyndisk_header->pagetable_entries);
-    s->pagetable = qemu_malloc(s->pagetable_entries * 4);
+    s->max_table_entries = be32_to_cpu(dyndisk_header->max_table_entries);
+    s->pagetable = qemu_malloc(s->max_table_entries * 4);
     if (!s->pagetable)
        goto fail;
-    if (read(s->fd, s->pagetable, s->pagetable_entries * 4) !=
-       s->pagetable_entries * 4)
+    if (read(s->fd, s->pagetable, s->max_table_entries * 4) !=
+       s->max_table_entries * 4)
        goto fail;
-    for (i = 0; i < s->pagetable_entries; i++)
+    for (i = 0; i < s->max_table_entries; i++)
        be32_to_cpus(&s->pagetable[i]);
 
-    s->pageentry_size = be32_to_cpu(dyndisk_header->pageentry_size);
+    s->block_size = be32_to_cpu(dyndisk_header->block_size);
 #ifdef CACHE
     s->pageentry_u8 = qemu_malloc(512);
     if (!s->pageentry_u8)
@@ -152,10 +198,10 @@
     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;
+    pagetable_index = offset / s->block_size;
+    pageentry_index = (offset % s->block_size) / 512;
 
-    if (pagetable_index > s->pagetable_entries || 
s->pagetable[pagetable_index] == 0xffffffff)
+    if (pagetable_index > s->max_table_entries || 
s->pagetable[pagetable_index] == 0xffffffff)
        return -1; // not allocated
 
     bitmap_offset = 512 * s->pagetable[pagetable_index];