OvmfPkg/VirtioFsDxe/SimpleFsWrite.c

   1 /** @file
   2   EFI_FILE_PROTOCOL.Write() member function for the Virtio Filesystem driver.
   3
   4   Copyright (C) 2020, Red Hat, Inc.
   5
   6   SPDX-License-Identifier: BSD-2-Clause-Patent
   7 **/
   8
   9 #include "VirtioFsDxe.h"
  10
  11 EFI_STATUS
  12 EFIAPI
  13 VirtioFsSimpleFileWrite (
  14   IN     EFI_FILE_PROTOCOL  *This,
  15   IN OUT UINTN              *BufferSize,
  16   IN     VOID               *Buffer
  17   )
  18 {
  19   VIRTIO_FS_FILE  *VirtioFsFile;
  20   VIRTIO_FS       *VirtioFs;
  21   EFI_STATUS      Status;
  22   UINTN           Transferred;
  23   UINTN           Left;
  24
  25   VirtioFsFile = VIRTIO_FS_FILE_FROM_SIMPLE_FILE (This);
  26   VirtioFs     = VirtioFsFile->OwnerFs;
  27
  28   if (VirtioFsFile->IsDirectory) {
  29     return EFI_UNSUPPORTED;
  30   }
  31
  32   if (!VirtioFsFile->IsOpenForWriting) {
  33     return EFI_ACCESS_DENIED;
  34   }
  35
  36   Status      = EFI_SUCCESS;
  37   Transferred = 0;
  38   Left        = *BufferSize;
  39   while (Left > 0) {
  40     UINT32  WriteSize;
  41
  42     //
  43     // Honor the write buffer size limit.
  44     //
  45     WriteSize = (UINT32)MIN ((UINTN)VirtioFs->MaxWrite, Left);
  46     Status    = VirtioFsFuseWrite (
  47                   VirtioFs,
  48                   VirtioFsFile->NodeId,
  49                   VirtioFsFile->FuseHandle,
  50                   VirtioFsFile->FilePosition + Transferred,
  51                   &WriteSize,
  52                   (UINT8 *)Buffer + Transferred
  53                   );
  54     if (!EFI_ERROR (Status) && (WriteSize == 0)) {
  55       //
  56       // Progress should have been made.
  57       //
  58       Status = EFI_DEVICE_ERROR;
  59     }
  60
  61     if (EFI_ERROR (Status)) {
  62       break;
  63     }
  64
  65     Transferred += WriteSize;
  66     Left        -= WriteSize;
  67   }
  68
  69   *BufferSize                 = Transferred;
  70   VirtioFsFile->FilePosition += Transferred;
  71   //
  72   // According to the UEFI spec,
  73   //
  74   // - 'Partial writes only occur when there has been a data error during the
  75   //    write attempt (such as "file space full")', and
  76   //
  77   // - (as an example) EFI_VOLUME_FULL is returned when 'The volume is full'.
  78   //
  79   // These together imply that after a partial write, we have to return an
  80   // error. In other words, (Transferred > 0) is inconsequential for the return
  81   // value.
  82   //
  83   return Status;
  84 }