[filedisk] Support .ISO-on-HDD scenario

Had to add a bit to the threaded filedisk in order to
allow a run-once read/write hook which attempts to find
the correct file-backed disk.  This hook used to hook
the enqueuer, but is now queued by it.

So now one can boot an .ISO file that's found on an HDD,
as long as there is a 2048-byte (OD sector) footer whose
last 512 bytes are the Microsoft .VHD footer details.

We should probably provide the convenience for adding
.VHD footers to HDD images and .ISOs in the user-land
utility.

diff --git a/src/include/filedisk.h b/src/include/filedisk.h
index 066c6d1..bcc747b 100644 (file)
--- a/src/include/filedisk.h
+++ b/src/include/filedisk.h
@@ -40,6 +40,7 @@ winvblock__def_struct ( filedisk__type )
   LIST_ENTRY req_list;
   KSPIN_LOCK req_list_lock;
   KEVENT signal;
+  disk__io_routine sync_io;
 };
 
 extern irp__handler_decl (

diff --git a/src/winvblock/filedisk/filedisk.c b/src/winvblock/filedisk/filedisk.c
index 4ced971..69e7268 100644 (file)
--- a/src/winvblock/filedisk/filedisk.c
+++ b/src/winvblock/filedisk/filedisk.c
@@ -393,8 +393,8 @@ thread (
          thread_req_ptr req;
 
          req = CONTAINING_RECORD ( walker, thread_req, list_entry );
-         io ( req->dev_ptr, req->mode, req->start_sector, req->sector_count,
-              req->buffer, req->irp );
+         filedisk_ptr->sync_io ( req->dev_ptr, req->mode, req->start_sector,
+                                 req->sector_count, req->buffer, req->irp );
          ExFreePool ( req );
        }
     }
@@ -483,6 +483,7 @@ filedisk__create_threaded (
   /*
    * Use threaded routines
    */
+  filedisk_ptr->sync_io = io;
   filedisk_ptr->disk->disk_ops.io = threaded_io;
   filedisk_ptr->disk->device->ops.free = free_threaded_filedisk;
   /*

diff --git a/src/winvblock/filedisk/grub4dos.c b/src/winvblock/filedisk/grub4dos.c
index 8ccb1e8..e1abe9d 100644 (file)
--- a/src/winvblock/filedisk/grub4dos.c
+++ b/src/winvblock/filedisk/grub4dos.c
@@ -42,7 +42,7 @@
 #include "byte.h"
 #include "msvhd.h"
 
-static disk__io_routine threaded_io;
+static disk__io_routine sync_io;
 
 /**
  * Check if a disk might be the matching backing disk for
@@ -72,12 +72,14 @@ check_disk_match (
       goto err_alloc;
     }
   /*
-   * Read in the buffer
+   * Read in the buffer.  Note that we adjust for the .VHD footer (plus
+   * prefixed padding for an .ISO) that we truncated from the reported disk
+   * size earlier when the disk mapping was found
    */
   end_part.QuadPart =
     filedisk_ptr->offset.QuadPart +
-    ( filedisk_ptr->disk->LBADiskSize * filedisk_ptr->disk->SectorSize ) -
-    sizeof ( *buf );
+    ( filedisk_ptr->disk->LBADiskSize * filedisk_ptr->disk->SectorSize ) +
+    filedisk_ptr->disk->SectorSize - sizeof ( *buf );
   status =
     ZwReadFile ( file, NULL, NULL, NULL, &io_status, buf, sizeof ( *buf ),
                 &end_part, NULL );
@@ -102,13 +104,10 @@ check_disk_match (
   if ( buf->type.val != 2 )
     status = STATUS_UNSUCCESSFUL;
   /*
-   * Match against our expected disk size, within an OD sector's worth
+   * Match against our expected disk size
    */
-  if ( filedisk_ptr->disk->LBADiskSize * filedisk_ptr->disk->SectorSize <
-       buf->orig_size.val )
-    status = STATUS_UNSUCCESSFUL;
-  if ( filedisk_ptr->disk->LBADiskSize * filedisk_ptr->disk->SectorSize -
-       buf->orig_size.val > 2048 )
+  if ( ( filedisk_ptr->disk->LBADiskSize * filedisk_ptr->disk->SectorSize ) !=
+       buf->cur_size.val )
     status = STATUS_UNSUCCESSFUL;
 
 err_read:
@@ -193,12 +192,11 @@ disk__io_decl (
    *  Use the backing disk and restore the original read/write routine
    */
   filedisk_ptr->file = file;
-  filedisk_ptr->disk->disk_ops.io = threaded_io;
+  filedisk_ptr->sync_io = sync_io;
   /*
    * Call the original read/write routine
    */
-  return threaded_io ( dev_ptr, mode, start_sector, sector_count, buffer,
-                      irp );
+  return sync_io ( dev_ptr, mode, start_sector, sector_count, buffer, irp );
 
 dud:
   irp->IoStatus.Information = 0;
@@ -288,8 +286,8 @@ filedisk_grub4dos__find (
              DBG ( "Could not create GRUB4DOS disk!\n" );
              return;
            }
-         threaded_io = filedisk_ptr->disk->disk_ops.io;
-         filedisk_ptr->disk->disk_ops.io = io;
+         sync_io = filedisk_ptr->sync_io;
+         filedisk_ptr->sync_io = io;
          /*
           * Possible precision loss
           */
@@ -314,10 +312,19 @@ filedisk_grub4dos__find (
            Grub4DosDriveMapSlotPtr[i].SectorStart *
            ( Grub4DosDriveMapSlotPtr[i].DestODD ? 2048 : 512 );
          /*
-          * Size and geometry
+          * Size and geometry.  Please note that since we require a .VHD
+          * footer, we exclude this from the LBA disk size by truncating
+          * a 512-byte sector for HDD images, or a 2048-byte sector for .ISO
           */
-         filedisk_ptr->disk->LBADiskSize =
-           ( winvblock__uint32 ) Grub4DosDriveMapSlotPtr[i].SectorCount;
+         {
+           ULONGLONG total_size =
+             Grub4DosDriveMapSlotPtr[i].SectorCount *
+             ( Grub4DosDriveMapSlotPtr[i].DestODD ? 2048 : 512 );
+           filedisk_ptr->disk->LBADiskSize =
+             ( total_size -
+               filedisk_ptr->disk->SectorSize ) /
+             filedisk_ptr->disk->SectorSize;
+         }
          filedisk_ptr->disk->Heads = Grub4DosDriveMapSlotPtr[i].MaxHead + 1;
          filedisk_ptr->disk->Sectors =
            Grub4DosDriveMapSlotPtr[i].DestMaxSector;