VirtualFs.c

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#include <Uefi.h>
 
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/BaseOverflowLib.h>
#include <Library/DebugLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/OcVirtualFsLib.h>
 
#include <Guid/FileInfo.h>
 
#include "VirtualFsInternal.h"
 
STATIC EFI_HANDLE_PROTOCOL  mOriginalHandleProtocol;
STATIC EFI_LOCATE_PROTOCOL  mOriginalLocateProtocol;
STATIC EFI_FILE_OPEN        mOpenCallback;
STATIC UINT32               mEntranceCount;
 
STATIC
VOID
VirtualFsWrapProtocol (
  IN  EFI_GUID  *Protocol,
  OUT VOID      **Interface
  )
{
  EFI_STATUS                       Status;
  EFI_SIMPLE_FILE_SYSTEM_PROTOCOL  *FileSystem;
 
  if (!CompareGuid (Protocol, &gEfiSimpleFileSystemProtocolGuid)) {
    return;
  }
 
  Status = CreateVirtualFs (*Interface, mOpenCallback, &FileSystem);
  if (!EFI_ERROR (Status)) {
    *Interface = FileSystem;
  }
}
 
STATIC
EFI_STATUS
EFIAPI
VirtualFsHandleProtocol (
  IN  EFI_HANDLE  Handle,
  IN  EFI_GUID    *Protocol,
  OUT VOID        **Interface
  )
{
  EFI_STATUS  Status;
 
  Status = mOriginalHandleProtocol (Handle, Protocol, Interface);
 
  if (!EFI_ERROR (Status) && (Interface != NULL) && (mEntranceCount == 0)) {
    ++mEntranceCount;
    VirtualFsWrapProtocol (Protocol, Interface);
    --mEntranceCount;
  }
 
  return Status;
}
 
STATIC
EFI_STATUS
EFIAPI
VirtualFsLocateProtocol (
  IN  EFI_GUID  *Protocol,
  IN  VOID      *Registration OPTIONAL,
  OUT VOID      **Interface
  )
{
  EFI_STATUS  Status;
 
  Status = mOriginalLocateProtocol (Protocol, Registration, Interface);
 
  if (!EFI_ERROR (Status) && (Interface != NULL) && (mEntranceCount == 0)) {
    ++mEntranceCount;
    VirtualFsWrapProtocol (Protocol, Interface);
    --mEntranceCount;
  }
 
  return Status;
}
 
EFI_STATUS
EnableVirtualFs (
  IN OUT EFI_BOOT_SERVICES  *BootServices,
  IN     EFI_FILE_OPEN      OpenCallback
  )
{
  if (  (mOriginalHandleProtocol != NULL)
     || (BootServices->HandleProtocol == VirtualFsHandleProtocol))
  {
    return EFI_ALREADY_STARTED;
  }
 
  //
  // Note, we should normally also hook OpenProtocol, but it results in freezes on APTIO IV and V.
  //
  mOpenCallback                = OpenCallback;
  mOriginalHandleProtocol      = BootServices->HandleProtocol;
  mOriginalLocateProtocol      = BootServices->LocateProtocol;
  BootServices->HandleProtocol = VirtualFsHandleProtocol;
  BootServices->LocateProtocol = VirtualFsLocateProtocol;
  BootServices->Hdr.CRC32      = 0;
  BootServices->CalculateCrc32 (BootServices, BootServices->Hdr.HeaderSize, &BootServices->Hdr.CRC32);
 
  return EFI_SUCCESS;
}
 
EFI_STATUS
DisableVirtualFs (
  IN OUT EFI_BOOT_SERVICES  *BootServices
  )
{
  if (  (mOriginalHandleProtocol == NULL)
     || (BootServices->HandleProtocol != VirtualFsHandleProtocol))
  {
    return EFI_ALREADY_STARTED;
  }
 
  BootServices->HandleProtocol = mOriginalHandleProtocol;
  BootServices->LocateProtocol = mOriginalLocateProtocol;
  mOpenCallback                = NULL;
  mOriginalHandleProtocol      = NULL;
  mOriginalLocateProtocol      = NULL;
  BootServices->Hdr.CRC32      = 0;
  BootServices->CalculateCrc32 (BootServices, BootServices->Hdr.HeaderSize, &BootServices->Hdr.CRC32);
 
  return EFI_SUCCESS;
}