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   if (!VirtioFsFile->IsOpenForWriting) {
  32     return EFI_ACCESS_DENIED;
  33   }
  34
  35   Status      = EFI_SUCCESS;
  36   Transferred = 0;
  37   Left        = *BufferSize;
  38   while (Left > 0) {
  39     UINT32 WriteSize;
  40
  41     //
  42     // Honor the write buffer size limit.
  43     //
  44     WriteSize = (UINT32)MIN ((UINTN)VirtioFs->MaxWrite, Left);
  45     Status = VirtioFsFuseWrite (
  46                VirtioFs,
  47                VirtioFsFile->NodeId,
  48                VirtioFsFile->FuseHandle,
  49                VirtioFsFile->FilePosition + Transferred,
  50                &WriteSize,
  51                (UINT8 *)Buffer + Transferred
  52                );
  53     if (!EFI_ERROR (Status) && WriteSize == 0) {
  54       //
  55       // Progress should have been made.
  56       //
  57       Status = EFI_DEVICE_ERROR;
  58     }
  59     if (EFI_ERROR (Status)) {
  60       break;
  61     }
  62     Transferred += WriteSize;
  63     Left        -= WriteSize;
  64   }
  65
  66   *BufferSize = Transferred;
  67   VirtioFsFile->FilePosition += Transferred;
  68   //
  69   // According to the UEFI spec,
  70   //
  71   // - 'Partial writes only occur when there has been a data error during the
  72   //    write attempt (such as "file space full")', and
  73   //
  74   // - (as an example) EFI_VOLUME_FULL is returned when 'The volume is full'.
  75   //
  76   // These together imply that after a partial write, we have to return an
  77   // error. In other words, (Transferred > 0) is inconsequential for the return
  78   // value.
  79   //
  80   return Status;
  81 }