OvmfPkg/VirtioFsDxe: split canon. path into last parent + last component

[mirror_edk2.git] / OvmfPkg / VirtioFsDxe / Helpers.c

/** @file\r
  Initialization and helper routines for the Virtio Filesystem device.\r
\r
  Copyright (C) 2020, Red Hat, Inc.\r
\r
  SPDX-License-Identifier: BSD-2-Clause-Patent\r
**/\r
\r
#include <Library/BaseLib.h>             // StrLen()\r
#include <Library/BaseMemoryLib.h>       // CopyMem()\r
#include <Library/MemoryAllocationLib.h> // AllocatePool()\r
#include <Library/TimeBaseLib.h>         // EpochToEfiTime()\r
#include <Library/VirtioLib.h>           // Virtio10WriteFeatures()\r
\r
#include "VirtioFsDxe.h"\r
\r
/**\r
  Read the Virtio Filesystem device configuration structure in full.\r
\r
  @param[in] Virtio   The Virtio protocol underlying the VIRTIO_FS object.\r
\r
  @param[out] Config  The fully populated VIRTIO_FS_CONFIG structure.\r
\r
  @retval EFI_SUCCESS  Config has been filled in.\r
\r
  @return              Error codes propagated from Virtio->ReadDevice(). The\r
                       contents of Config are indeterminate.\r
**/\r
STATIC\r
EFI_STATUS\r
VirtioFsReadConfig (\r
  IN  VIRTIO_DEVICE_PROTOCOL *Virtio,\r
  OUT VIRTIO_FS_CONFIG       *Config\r
  )\r
{\r
  UINTN      Idx;\r
  EFI_STATUS Status;\r
\r
  for (Idx = 0; Idx < VIRTIO_FS_TAG_BYTES; Idx++) {\r
    Status = Virtio->ReadDevice (\r
                       Virtio,                                 // This\r
                       OFFSET_OF (VIRTIO_FS_CONFIG, Tag[Idx]), // FieldOffset\r
                       sizeof Config->Tag[Idx],                // FieldSize\r
                       sizeof Config->Tag[Idx],                // BufferSize\r
                       &Config->Tag[Idx]                       // Buffer\r
                       );\r
    if (EFI_ERROR (Status)) {\r
      return Status;\r
    }\r
  }\r
\r
  Status = Virtio->ReadDevice (\r
                     Virtio,                                     // This\r
                     OFFSET_OF (VIRTIO_FS_CONFIG, NumReqQueues), // FieldOffset\r
                     sizeof Config->NumReqQueues,                // FieldSize\r
                     sizeof Config->NumReqQueues,                // BufferSize\r
                     &Config->NumReqQueues                       // Buffer\r
                     );\r
  return Status;\r
}\r
\r
/**\r
  Configure the Virtio Filesystem device underlying VirtioFs.\r
\r
  @param[in,out] VirtioFs  The VIRTIO_FS object for which Virtio communication\r
                           should be set up. On input, the caller is\r
                           responsible for VirtioFs->Virtio having been\r
                           initialized. On output, synchronous Virtio\r
                           Filesystem commands (primitives) may be submitted to\r
                           the device.\r
\r
  @retval EFI_SUCCESS      Virtio machinery has been set up.\r
\r
  @retval EFI_UNSUPPORTED  The host-side configuration of the Virtio Filesystem\r
                           is not supported by this driver.\r
\r
  @return                  Error codes from underlying functions.\r
**/\r
EFI_STATUS\r
VirtioFsInit (\r
  IN OUT VIRTIO_FS *VirtioFs\r
  )\r
{\r
  UINT8            NextDevStat;\r
  EFI_STATUS       Status;\r
  UINT64           Features;\r
  VIRTIO_FS_CONFIG Config;\r
  UINTN            Idx;\r
  UINT64           RingBaseShift;\r
\r
  //\r
  // Execute virtio-v1.1-cs01-87fa6b5d8155, 3.1.1 Driver Requirements: Device\r
  // Initialization.\r
  //\r
  // 1. Reset the device.\r
  //\r
  NextDevStat = 0;\r
  Status = VirtioFs->Virtio->SetDeviceStatus (VirtioFs->Virtio, NextDevStat);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
\r
  //\r
  // 2. Set the ACKNOWLEDGE status bit [...]\r
  //\r
  NextDevStat |= VSTAT_ACK;\r
  Status = VirtioFs->Virtio->SetDeviceStatus (VirtioFs->Virtio, NextDevStat);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
\r
  //\r
  // 3. Set the DRIVER status bit [...]\r
  //\r
  NextDevStat |= VSTAT_DRIVER;\r
  Status = VirtioFs->Virtio->SetDeviceStatus (VirtioFs->Virtio, NextDevStat);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
\r
  //\r
  // 4. Read device feature bits...\r
  //\r
  Status = VirtioFs->Virtio->GetDeviceFeatures (VirtioFs->Virtio, &Features);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
  if ((Features & VIRTIO_F_VERSION_1) == 0) {\r
    Status = EFI_UNSUPPORTED;\r
    goto Failed;\r
  }\r
  //\r
  // No device-specific feature bits have been defined in file "virtio-fs.tex"\r
  // of the virtio spec at <https://github.com/oasis-tcs/virtio-spec.git>, as\r
  // of commit 87fa6b5d8155.\r
  //\r
  Features &= VIRTIO_F_VERSION_1 | VIRTIO_F_IOMMU_PLATFORM;\r
\r
  //\r
  // ... and write the subset of feature bits understood by the [...] driver to\r
  // the device. [...]\r
  // 5. Set the FEATURES_OK status bit.\r
  // 6. Re-read device status to ensure the FEATURES_OK bit is still set [...]\r
  //\r
  Status = Virtio10WriteFeatures (VirtioFs->Virtio, Features, &NextDevStat);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
\r
  //\r
  // 7. Perform device-specific setup, including discovery of virtqueues for\r
  // the device, [...] reading [...] the device's virtio configuration space\r
  //\r
  Status = VirtioFsReadConfig (VirtioFs->Virtio, &Config);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
\r
  //\r
  // 7.a. Convert the filesystem label from UTF-8 to UCS-2. Only labels with\r
  // printable ASCII code points (U+0020 through U+007E) are supported.\r
  // NUL-terminate at either the terminator we find, or right after the\r
  // original label.\r
  //\r
  for (Idx = 0; Idx < VIRTIO_FS_TAG_BYTES && Config.Tag[Idx] != '\0'; Idx++) {\r
    if (Config.Tag[Idx] < 0x20 || Config.Tag[Idx] > 0x7E) {\r
      Status = EFI_UNSUPPORTED;\r
      goto Failed;\r
    }\r
    VirtioFs->Label[Idx] = Config.Tag[Idx];\r
  }\r
  VirtioFs->Label[Idx] = L'\0';\r
\r
  //\r
  // 7.b. We need one queue for sending normal priority requests.\r
  //\r
  if (Config.NumReqQueues < 1) {\r
    Status = EFI_UNSUPPORTED;\r
    goto Failed;\r
  }\r
\r
  //\r
  // 7.c. Fetch and remember the number of descriptors we can place on the\r
  // queue at once. We'll need two descriptors per request, as a minimum --\r
  // request header, response header.\r
  //\r
  Status = VirtioFs->Virtio->SetQueueSel (VirtioFs->Virtio,\r
                               VIRTIO_FS_REQUEST_QUEUE);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
  Status = VirtioFs->Virtio->GetQueueNumMax (VirtioFs->Virtio,\r
                               &VirtioFs->QueueSize);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
  if (VirtioFs->QueueSize < 2) {\r
    Status = EFI_UNSUPPORTED;\r
    goto Failed;\r
  }\r
\r
  //\r
  // 7.d. [...] population of virtqueues [...]\r
  //\r
  Status = VirtioRingInit (VirtioFs->Virtio, VirtioFs->QueueSize,\r
             &VirtioFs->Ring);\r
  if (EFI_ERROR (Status)) {\r
    goto Failed;\r
  }\r
\r
  Status = VirtioRingMap (VirtioFs->Virtio, &VirtioFs->Ring, &RingBaseShift,\r
             &VirtioFs->RingMap);\r
  if (EFI_ERROR (Status)) {\r
    goto ReleaseQueue;\r
  }\r
\r
  Status = VirtioFs->Virtio->SetQueueAddress (VirtioFs->Virtio,\r
                               &VirtioFs->Ring, RingBaseShift);\r
  if (EFI_ERROR (Status)) {\r
    goto UnmapQueue;\r
  }\r
\r
  //\r
  // 8. Set the DRIVER_OK status bit.\r
  //\r
  NextDevStat |= VSTAT_DRIVER_OK;\r
  Status = VirtioFs->Virtio->SetDeviceStatus (VirtioFs->Virtio, NextDevStat);\r
  if (EFI_ERROR (Status)) {\r
    goto UnmapQueue;\r
  }\r
\r
  return EFI_SUCCESS;\r
\r
UnmapQueue:\r
  VirtioFs->Virtio->UnmapSharedBuffer (VirtioFs->Virtio, VirtioFs->RingMap);\r
\r
ReleaseQueue:\r
  VirtioRingUninit (VirtioFs->Virtio, &VirtioFs->Ring);\r
\r
Failed:\r
  //\r
  // If any of these steps go irrecoverably wrong, the driver SHOULD set the\r
  // FAILED status bit to indicate that it has given up on the device (it can\r
  // reset the device later to restart if desired). [...]\r
  //\r
  // Virtio access failure here should not mask the original error.\r
  //\r
  NextDevStat |= VSTAT_FAILED;\r
  VirtioFs->Virtio->SetDeviceStatus (VirtioFs->Virtio, NextDevStat);\r
\r
  return Status;\r
}\r
\r
/**\r
  De-configure the Virtio Filesystem device underlying VirtioFs.\r
\r
  @param[in] VirtioFs  The VIRTIO_FS object for which Virtio communication\r
                       should be torn down. On input, the caller is responsible\r
                       for having called VirtioFsInit(). On output, Virtio\r
                       Filesystem commands (primitives) must no longer be\r
                       submitted to the device.\r
**/\r
VOID\r
VirtioFsUninit (\r
  IN OUT VIRTIO_FS *VirtioFs\r
  )\r
{\r
  //\r
  // Resetting the Virtio device makes it release its resources and forget its\r
  // configuration.\r
  //\r
  VirtioFs->Virtio->SetDeviceStatus (VirtioFs->Virtio, 0);\r
  VirtioFs->Virtio->UnmapSharedBuffer (VirtioFs->Virtio, VirtioFs->RingMap);\r
  VirtioRingUninit (VirtioFs->Virtio, &VirtioFs->Ring);\r
}\r
\r
/**\r
  ExitBootServices event notification function for a Virtio Filesystem object.\r
\r
  This function resets the VIRTIO_FS.Virtio device, causing it to release all\r
  references to guest-side resources. The function may only be called after\r
  VirtioFsInit() returns successfully and before VirtioFsUninit() is called.\r
\r
  @param[in] ExitBootEvent   The VIRTIO_FS.ExitBoot event that has been\r
                             signaled.\r
\r
  @param[in] VirtioFsAsVoid  Pointer to the VIRTIO_FS object, passed in as\r
                             (VOID*).\r
**/\r
VOID\r
EFIAPI\r
VirtioFsExitBoot (\r
  IN EFI_EVENT ExitBootEvent,\r
  IN VOID      *VirtioFsAsVoid\r
  )\r
{\r
  VIRTIO_FS *VirtioFs;\r
\r
  VirtioFs = VirtioFsAsVoid;\r
  DEBUG ((DEBUG_VERBOSE, "%a: VirtioFs=0x%p Label=\"%s\"\n", __FUNCTION__,\r
    VirtioFsAsVoid, VirtioFs->Label));\r
  VirtioFs->Virtio->SetDeviceStatus (VirtioFs->Virtio, 0);\r
}\r
\r
/**\r
  Validate two VIRTIO_FS_SCATTER_GATHER_LIST objects -- list of request\r
  buffers, list of response buffers -- together.\r
\r
  On input, the caller is required to populate the following fields:\r
  - VIRTIO_FS_IO_VECTOR.Buffer,\r
  - VIRTIO_FS_IO_VECTOR.Size,\r
  - VIRTIO_FS_SCATTER_GATHER_LIST.IoVec,\r
  - VIRTIO_FS_SCATTER_GATHER_LIST.NumVec.\r
\r
  On output (on successful return), the following fields will be\r
  zero-initialized:\r
  - VIRTIO_FS_IO_VECTOR.Mapped,\r
  - VIRTIO_FS_IO_VECTOR.MappedAddress,\r
  - VIRTIO_FS_IO_VECTOR.Mapping,\r
  - VIRTIO_FS_IO_VECTOR.Transferred.\r
\r
  On output (on successful return), the following fields will be calculated:\r
  - VIRTIO_FS_SCATTER_GATHER_LIST.TotalSize.\r
\r
  The function may only be called after VirtioFsInit() returns successfully and\r
  before VirtioFsUninit() is called.\r
\r
  @param[in] VirtioFs            The Virtio Filesystem device that the\r
                                 request-response exchange, expressed via\r
                                 RequestSgList and ResponseSgList, will be\r
                                 submitted to.\r
\r
  @param[in,out] RequestSgList   The scatter-gather list that describes the\r
                                 request part of the exchange -- the buffers\r
                                 that should be sent to the Virtio Filesystem\r
                                 device in the virtio transfer.\r
\r
  @param[in,out] ResponseSgList  The scatter-gather list that describes the\r
                                 response part of the exchange -- the buffers\r
                                 that the Virtio Filesystem device should\r
                                 populate in the virtio transfer. May be NULL\r
                                 if the exchange with the Virtio Filesystem\r
                                 device consists of a request only, with the\r
                                 response part omitted altogether.\r
\r
  @retval EFI_SUCCESS            RequestSgList and ResponseSgList have been\r
                                 validated, output fields have been set.\r
\r
  @retval EFI_INVALID_PARAMETER  RequestSgList is NULL.\r
\r
  @retval EFI_INVALID_PARAMETER  On input, a\r
                                 VIRTIO_FS_SCATTER_GATHER_LIST.IoVec field is\r
                                 NULL, or a\r
                                 VIRTIO_FS_SCATTER_GATHER_LIST.NumVec field is\r
                                 zero.\r
\r
  @retval EFI_INVALID_PARAMETER  On input, a VIRTIO_FS_IO_VECTOR.Buffer field\r
                                 is NULL, or a VIRTIO_FS_IO_VECTOR.Size field\r
                                 is zero.\r
\r
  @retval EFI_UNSUPPORTED        (RequestSgList->NumVec +\r
                                 ResponseSgList->NumVec) exceeds\r
                                 VirtioFs->QueueSize, meaning that the total\r
                                 list of buffers cannot be placed on the virtio\r
                                 queue in a single descriptor chain (with one\r
                                 descriptor per buffer).\r
\r
  @retval EFI_UNSUPPORTED        One of the\r
                                 VIRTIO_FS_SCATTER_GATHER_LIST.TotalSize fields\r
                                 would exceed MAX_UINT32.\r
**/\r
EFI_STATUS\r
VirtioFsSgListsValidate (\r
  IN     VIRTIO_FS                     *VirtioFs,\r
  IN OUT VIRTIO_FS_SCATTER_GATHER_LIST *RequestSgList,\r
  IN OUT VIRTIO_FS_SCATTER_GATHER_LIST *ResponseSgList OPTIONAL\r
  )\r
{\r
  VIRTIO_FS_SCATTER_GATHER_LIST *SgListParam[2];\r
  UINT16                        DescriptorsNeeded;\r
  UINTN                         ListId;\r
\r
  if (RequestSgList == NULL) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  SgListParam[0] = RequestSgList;\r
  SgListParam[1] = ResponseSgList;\r
\r
  DescriptorsNeeded = 0;\r
  for (ListId = 0; ListId < ARRAY_SIZE (SgListParam); ListId++) {\r
    VIRTIO_FS_SCATTER_GATHER_LIST *SgList;\r
    UINT32                        SgListTotalSize;\r
    UINTN                         IoVecIdx;\r
\r
    SgList = SgListParam[ListId];\r
    if (SgList == NULL) {\r
      continue;\r
    }\r
    //\r
    // Sanity-check SgList -- it must provide at least one IO Vector.\r
    //\r
    if (SgList->IoVec == NULL || SgList->NumVec == 0) {\r
      return EFI_INVALID_PARAMETER;\r
    }\r
    //\r
    // Make sure that, for each IO Vector in this SgList, a virtio descriptor\r
    // can be added to the virtio queue, after the other descriptors added\r
    // previously.\r
    //\r
    if (SgList->NumVec > (UINTN)(MAX_UINT16 - DescriptorsNeeded) ||\r
        DescriptorsNeeded + SgList->NumVec > VirtioFs->QueueSize) {\r
      return EFI_UNSUPPORTED;\r
    }\r
    DescriptorsNeeded += (UINT16)SgList->NumVec;\r
\r
    SgListTotalSize = 0;\r
    for (IoVecIdx = 0; IoVecIdx < SgList->NumVec; IoVecIdx++) {\r
      VIRTIO_FS_IO_VECTOR *IoVec;\r
\r
      IoVec = &SgList->IoVec[IoVecIdx];\r
      //\r
      // Sanity-check this IoVec -- it must describe a non-empty buffer.\r
      //\r
      if (IoVec->Buffer == NULL || IoVec->Size == 0) {\r
        return EFI_INVALID_PARAMETER;\r
      }\r
      //\r
      // Make sure the cumulative size of all IO Vectors in this SgList remains\r
      // expressible as a UINT32.\r
      //\r
      if (IoVec->Size > MAX_UINT32 - SgListTotalSize) {\r
        return EFI_UNSUPPORTED;\r
      }\r
      SgListTotalSize += (UINT32)IoVec->Size;\r
\r
      //\r
      // Initialize those fields in this IO Vector that will be updated in\r
      // relation to mapping / transfer.\r
      //\r
      IoVec->Mapped        = FALSE;\r
      IoVec->MappedAddress = 0;\r
      IoVec->Mapping       = NULL;\r
      IoVec->Transferred   = 0;\r
    }\r
\r
    //\r
    // Store the cumulative size of all IO Vectors that we have calculated in\r
    // this SgList.\r
    //\r
    SgList->TotalSize = SgListTotalSize;\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Submit a validated pair of (request buffer list, response buffer list) to the\r
  Virtio Filesystem device.\r
\r
  On input, the pair of VIRTIO_FS_SCATTER_GATHER_LIST objects must have been\r
  validated together, using the VirtioFsSgListsValidate() function.\r
\r
  On output (on successful return), the following fields will be re-initialized\r
  to zero (after temporarily setting them to different values):\r
  - VIRTIO_FS_IO_VECTOR.Mapped,\r
  - VIRTIO_FS_IO_VECTOR.MappedAddress,\r
  - VIRTIO_FS_IO_VECTOR.Mapping.\r
\r
  On output (on successful return), the following fields will be calculated:\r
  - VIRTIO_FS_IO_VECTOR.Transferred.\r
\r
  The function may only be called after VirtioFsInit() returns successfully and\r
  before VirtioFsUninit() is called.\r
\r
  @param[in,out] VirtioFs        The Virtio Filesystem device that the\r
                                 request-response exchange, expressed via\r
                                 RequestSgList and ResponseSgList, should now\r
                                 be submitted to.\r
\r
  @param[in,out] RequestSgList   The scatter-gather list that describes the\r
                                 request part of the exchange -- the buffers\r
                                 that should be sent to the Virtio Filesystem\r
                                 device in the virtio transfer.\r
\r
  @param[in,out] ResponseSgList  The scatter-gather list that describes the\r
                                 response part of the exchange -- the buffers\r
                                 that the Virtio Filesystem device should\r
                                 populate in the virtio transfer. May be NULL\r
                                 if and only if NULL was passed to\r
                                 VirtioFsSgListsValidate() as ResponseSgList.\r
\r
  @retval EFI_SUCCESS       Transfer complete. The caller should investigate\r
                            the VIRTIO_FS_IO_VECTOR.Transferred fields in\r
                            ResponseSgList, to ensure coverage of the relevant\r
                            response buffers. Subsequently, the caller should\r
                            investigate the contents of those buffers.\r
\r
  @retval EFI_DEVICE_ERROR  The Virtio Filesystem device reported populating\r
                            more response bytes than ResponseSgList->TotalSize.\r
\r
  @return                   Error codes propagated from\r
                            VirtioMapAllBytesInSharedBuffer(), VirtioFlush(),\r
                            or VirtioFs->Virtio->UnmapSharedBuffer().\r
**/\r
EFI_STATUS\r
VirtioFsSgListsSubmit (\r
  IN OUT VIRTIO_FS                     *VirtioFs,\r
  IN OUT VIRTIO_FS_SCATTER_GATHER_LIST *RequestSgList,\r
  IN OUT VIRTIO_FS_SCATTER_GATHER_LIST *ResponseSgList OPTIONAL\r
  )\r
{\r
  VIRTIO_FS_SCATTER_GATHER_LIST *SgListParam[2];\r
  VIRTIO_MAP_OPERATION          SgListVirtioMapOp[ARRAY_SIZE (SgListParam)];\r
  UINT16                        SgListDescriptorFlag[ARRAY_SIZE (SgListParam)];\r
  UINTN                         ListId;\r
  VIRTIO_FS_SCATTER_GATHER_LIST *SgList;\r
  UINTN                         IoVecIdx;\r
  VIRTIO_FS_IO_VECTOR           *IoVec;\r
  EFI_STATUS                    Status;\r
  DESC_INDICES                  Indices;\r
  UINT32                        TotalBytesWrittenByDevice;\r
  UINT32                        BytesPermittedForWrite;\r
\r
  SgListParam[0]          = RequestSgList;\r
  SgListVirtioMapOp[0]    = VirtioOperationBusMasterRead;\r
  SgListDescriptorFlag[0] = 0;\r
\r
  SgListParam[1]          = ResponseSgList;\r
  SgListVirtioMapOp[1]    = VirtioOperationBusMasterWrite;\r
  SgListDescriptorFlag[1] = VRING_DESC_F_WRITE;\r
\r
  //\r
  // Map all IO Vectors.\r
  //\r
  for (ListId = 0; ListId < ARRAY_SIZE (SgListParam); ListId++) {\r
    SgList = SgListParam[ListId];\r
    if (SgList == NULL) {\r
      continue;\r
    }\r
    for (IoVecIdx = 0; IoVecIdx < SgList->NumVec; IoVecIdx++) {\r
      IoVec = &SgList->IoVec[IoVecIdx];\r
      //\r
      // Map this IO Vector.\r
      //\r
      Status = VirtioMapAllBytesInSharedBuffer (\r
                 VirtioFs->Virtio,\r
                 SgListVirtioMapOp[ListId],\r
                 IoVec->Buffer,\r
                 IoVec->Size,\r
                 &IoVec->MappedAddress,\r
                 &IoVec->Mapping\r
                 );\r
      if (EFI_ERROR (Status)) {\r
        goto Unmap;\r
      }\r
      IoVec->Mapped = TRUE;\r
    }\r
  }\r
\r
  //\r
  // Compose the descriptor chain.\r
  //\r
  VirtioPrepare (&VirtioFs->Ring, &Indices);\r
  for (ListId = 0; ListId < ARRAY_SIZE (SgListParam); ListId++) {\r
    SgList = SgListParam[ListId];\r
    if (SgList == NULL) {\r
      continue;\r
    }\r
    for (IoVecIdx = 0; IoVecIdx < SgList->NumVec; IoVecIdx++) {\r
      UINT16 NextFlag;\r
\r
      IoVec = &SgList->IoVec[IoVecIdx];\r
      //\r
      // Set VRING_DESC_F_NEXT on all except the very last descriptor.\r
      //\r
      NextFlag = VRING_DESC_F_NEXT;\r
      if (ListId == ARRAY_SIZE (SgListParam) - 1 &&\r
          IoVecIdx == SgList->NumVec - 1) {\r
        NextFlag = 0;\r
      }\r
      VirtioAppendDesc (\r
        &VirtioFs->Ring,\r
        IoVec->MappedAddress,\r
        (UINT32)IoVec->Size,\r
        SgListDescriptorFlag[ListId] | NextFlag,\r
        &Indices\r
        );\r
    }\r
  }\r
\r
  //\r
  // Submit the descriptor chain.\r
  //\r
  Status = VirtioFlush (VirtioFs->Virtio, VIRTIO_FS_REQUEST_QUEUE,\r
             &VirtioFs->Ring, &Indices, &TotalBytesWrittenByDevice);\r
  if (EFI_ERROR (Status)) {\r
    goto Unmap;\r
  }\r
\r
  //\r
  // Sanity-check: the Virtio Filesystem device should not have written more\r
  // bytes than what we offered buffers for.\r
  //\r
  if (ResponseSgList == NULL) {\r
    BytesPermittedForWrite = 0;\r
  } else {\r
    BytesPermittedForWrite = ResponseSgList->TotalSize;\r
  }\r
  if (TotalBytesWrittenByDevice > BytesPermittedForWrite) {\r
    Status = EFI_DEVICE_ERROR;\r
    goto Unmap;\r
  }\r
\r
  //\r
  // Update the transfer sizes in the IO Vectors.\r
  //\r
  for (ListId = 0; ListId < ARRAY_SIZE (SgListParam); ListId++) {\r
    SgList = SgListParam[ListId];\r
    if (SgList == NULL) {\r
      continue;\r
    }\r
    for (IoVecIdx = 0; IoVecIdx < SgList->NumVec; IoVecIdx++) {\r
      IoVec = &SgList->IoVec[IoVecIdx];\r
      if (SgListVirtioMapOp[ListId] == VirtioOperationBusMasterRead) {\r
        //\r
        // We report that the Virtio Filesystem device has read all buffers in\r
        // the request.\r
        //\r
        IoVec->Transferred = IoVec->Size;\r
      } else {\r
        //\r
        // Regarding the response, calculate how much of the current IO Vector\r
        // has been populated by the Virtio Filesystem device. In\r
        // "TotalBytesWrittenByDevice", VirtioFlush() reported the total count\r
        // across all device-writeable descriptors, in the order they were\r
        // chained on the ring.\r
        //\r
        IoVec->Transferred = MIN ((UINTN)TotalBytesWrittenByDevice,\r
                               IoVec->Size);\r
        TotalBytesWrittenByDevice -= (UINT32)IoVec->Transferred;\r
      }\r
    }\r
  }\r
\r
  //\r
  // By now, "TotalBytesWrittenByDevice" has been exhausted.\r
  //\r
  ASSERT (TotalBytesWrittenByDevice == 0);\r
\r
  //\r
  // We've succeeded; fall through.\r
  //\r
Unmap:\r
  //\r
  // Unmap all mapped IO Vectors on both the success and the error paths. The\r
  // unmapping occurs in reverse order of mapping, in an attempt to avoid\r
  // memory fragmentation.\r
  //\r
  ListId = ARRAY_SIZE (SgListParam);\r
  while (ListId > 0) {\r
    --ListId;\r
    SgList = SgListParam[ListId];\r
    if (SgList == NULL) {\r
      continue;\r
    }\r
    IoVecIdx = SgList->NumVec;\r
    while (IoVecIdx > 0) {\r
      EFI_STATUS UnmapStatus;\r
\r
      --IoVecIdx;\r
      IoVec = &SgList->IoVec[IoVecIdx];\r
      //\r
      // Unmap this IO Vector, if it has been mapped.\r
      //\r
      if (!IoVec->Mapped) {\r
        continue;\r
      }\r
      UnmapStatus = VirtioFs->Virtio->UnmapSharedBuffer (VirtioFs->Virtio,\r
                                        IoVec->Mapping);\r
      //\r
      // Re-set the following fields to the values they initially got from\r
      // VirtioFsSgListsValidate() -- the above unmapping attempt is considered\r
      // final, even if it fails.\r
      //\r
      IoVec->Mapped        = FALSE;\r
      IoVec->MappedAddress = 0;\r
      IoVec->Mapping       = NULL;\r
\r
      //\r
      // If we are on the success path, but the unmapping failed, we need to\r
      // transparently flip to the failure path -- the caller must learn they\r
      // should not consult the response buffers.\r
      //\r
      // The branch below can be taken at most once.\r
      //\r
      if (!EFI_ERROR (Status) && EFI_ERROR (UnmapStatus)) {\r
        Status = UnmapStatus;\r
      }\r
    }\r
  }\r
\r
  return Status;\r
}\r
\r
/**\r
  Set up the fields of a new VIRTIO_FS_FUSE_REQUEST object.\r
\r
  The function may only be called after VirtioFsInit() returns successfully and\r
  before VirtioFsUninit() is called.\r
\r
  @param[in,out] VirtioFs The Virtio Filesystem device that the request is\r
                          being prepared for. The "VirtioFs->RequestId" field\r
                          will be copied into "Request->Unique". On output (on\r
                          successful return), "VirtioFs->RequestId" will be\r
                          incremented.\r
\r
  @param[out] Request     The VIRTIO_FS_FUSE_REQUEST object whose fields are to\r
                          be set.\r
\r
  @param[in] RequestSize  The total size of the request, including\r
                          sizeof(VIRTIO_FS_FUSE_REQUEST).\r
\r
  @param[in] Opcode       The VIRTIO_FS_FUSE_OPCODE that identifies the command\r
                          to send.\r
\r
  @param[in] NodeId       The inode number of the file that the request refers\r
                          to. When Opcode is VirtioFsFuseOpInit, NodeId is\r
                          ignored by the Virtio Filesystem device.\r
\r
  @retval EFI_INVALID_PARAMETER  RequestSize is smaller than\r
                                 sizeof(VIRTIO_FS_FUSE_REQUEST).\r
\r
  @retval EFI_OUT_OF_RESOURCES   "VirtioFs->RequestId" is MAX_UINT64, and can\r
                                 be incremented no more.\r
\r
  @retval EFI_SUCCESS            Request has been populated,\r
                                 "VirtioFs->RequestId" has been incremented.\r
**/\r
EFI_STATUS\r
VirtioFsFuseNewRequest (\r
  IN OUT VIRTIO_FS              *VirtioFs,\r
     OUT VIRTIO_FS_FUSE_REQUEST *Request,\r
  IN     UINT32                 RequestSize,\r
  IN     VIRTIO_FS_FUSE_OPCODE  Opcode,\r
  IN     UINT64                 NodeId\r
  )\r
{\r
  if (RequestSize < sizeof *Request) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  if (VirtioFs->RequestId == MAX_UINT64) {\r
    return EFI_OUT_OF_RESOURCES;\r
  }\r
\r
  Request->Len     = RequestSize;\r
  Request->Opcode  = Opcode;\r
  Request->Unique  = VirtioFs->RequestId++;\r
  Request->NodeId  = NodeId;\r
  Request->Uid     = 0;\r
  Request->Gid     = 0;\r
  Request->Pid     = 1;\r
  Request->Padding = 0;\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Check the common FUSE response format.\r
\r
  The first buffer in the response scatter-gather list is assumed a\r
  VIRTIO_FS_FUSE_RESPONSE structure. Subsequent response buffers, if any, up to\r
  and excluding the last one, are assumed fixed size. The last response buffer\r
  may or may not be fixed size, as specified by the caller.\r
\r
  This function may only be called after VirtioFsSgListsSubmit() returns\r
  successfully.\r
\r
  @param[in] ResponseSgList   The scatter-gather list that describes the\r
                              response part of the exchange -- the buffers that\r
                              the Virtio Filesystem device filled in during the\r
                              virtio transfer.\r
\r
  @param[in] RequestId        The request identifier to which the response is\r
                              expected to belong.\r
\r
  @param[out] TailBufferFill  If NULL, then the last buffer in ResponseSgList\r
                              is considered fixed size. Otherwise, the last\r
                              buffer is considered variable size, and on\r
                              successful return, TailBufferFill reports the\r
                              number of bytes in the last buffer.\r
\r
  @retval EFI_INVALID_PARAMETER  TailBufferFill is not NULL (i.e., the last\r
                                 buffer is considered variable size), and\r
                                 ResponseSgList->NumVec is 1.\r
\r
  @retval EFI_INVALID_PARAMETER  The allocated size of the first buffer does\r
                                 not match sizeof(VIRTIO_FS_FUSE_RESPONSE).\r
\r
  @retval EFI_PROTOCOL_ERROR     The VIRTIO_FS_FUSE_RESPONSE structure in the\r
                                 first buffer has not been fully populated.\r
\r
  @retval EFI_PROTOCOL_ERROR     "VIRTIO_FS_FUSE_RESPONSE.Len" in the first\r
                                 buffer does not equal the sum of the\r
                                 individual buffer sizes (as populated).\r
\r
  @retval EFI_PROTOCOL_ERROR     "VIRTIO_FS_FUSE_RESPONSE.Unique" in the first\r
                                 buffer does not equal RequestId.\r
\r
  @retval EFI_PROTOCOL_ERROR     "VIRTIO_FS_FUSE_RESPONSE.Error" in the first\r
                                 buffer is zero, but a subsequent fixed size\r
                                 buffer has not been fully populated.\r
\r
  @retval EFI_DEVICE_ERROR       "VIRTIO_FS_FUSE_RESPONSE.Error" in the first\r
                                 buffer is nonzero. The caller may investigate\r
                                 "VIRTIO_FS_FUSE_RESPONSE.Error". Note that the\r
                                 completeness of the subsequent fixed size\r
                                 buffers is not verified in this case.\r
\r
  @retval EFI_SUCCESS            Verification successful.\r
**/\r
EFI_STATUS\r
VirtioFsFuseCheckResponse (\r
  IN  VIRTIO_FS_SCATTER_GATHER_LIST *ResponseSgList,\r
  IN  UINT64                        RequestId,\r
  OUT UINTN                         *TailBufferFill\r
  )\r
{\r
  UINTN                   NumFixedSizeVec;\r
  VIRTIO_FS_FUSE_RESPONSE *CommonResp;\r
  UINT32                  TotalTransferred;\r
  UINTN                   Idx;\r
\r
  //\r
  // Ensured by VirtioFsSgListsValidate().\r
  //\r
  ASSERT (ResponseSgList->NumVec > 0);\r
\r
  if (TailBufferFill == NULL) {\r
    //\r
    // All buffers are considered fixed size.\r
    //\r
    NumFixedSizeVec = ResponseSgList->NumVec;\r
  } else {\r
    //\r
    // If the last buffer is variable size, then we need that buffer to be\r
    // different from the first buffer, which is considered a\r
    // VIRTIO_FS_FUSE_RESPONSE (fixed size) structure.\r
    //\r
    if (ResponseSgList->NumVec == 1) {\r
      return EFI_INVALID_PARAMETER;\r
    }\r
    NumFixedSizeVec = ResponseSgList->NumVec - 1;\r
  }\r
\r
  //\r
  // The first buffer is supposed to carry a (fully populated)\r
  // VIRTIO_FS_FUSE_RESPONSE structure.\r
  //\r
  if (ResponseSgList->IoVec[0].Size != sizeof *CommonResp) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
  if (ResponseSgList->IoVec[0].Transferred != ResponseSgList->IoVec[0].Size) {\r
    return EFI_PROTOCOL_ERROR;\r
  }\r
\r
  //\r
  // FUSE must report the same number of bytes, written by the Virtio\r
  // Filesystem device, as the virtio transport does.\r
  //\r
  CommonResp = ResponseSgList->IoVec[0].Buffer;\r
  TotalTransferred = 0;\r
  for (Idx = 0; Idx < ResponseSgList->NumVec; Idx++) {\r
    //\r
    // Integer overflow and truncation are not possible, based on\r
    // VirtioFsSgListsValidate() and VirtioFsSgListsSubmit().\r
    //\r
    TotalTransferred += (UINT32)ResponseSgList->IoVec[Idx].Transferred;\r
  }\r
  if (CommonResp->Len != TotalTransferred) {\r
    return EFI_PROTOCOL_ERROR;\r
  }\r
\r
  //\r
  // Enforce that FUSE match our request ID in the response.\r
  //\r
  if (CommonResp->Unique != RequestId) {\r
    return EFI_PROTOCOL_ERROR;\r
  }\r
\r
  //\r
  // If there is an explicit error report, skip checking the transfer\r
  // counts for the rest of the fixed size buffers.\r
  //\r
  if (CommonResp->Error != 0) {\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  //\r
  // There was no error reported, so we require that the Virtio Filesystem\r
  // device populate all fixed size buffers. We checked this for the very first\r
  // buffer above; let's check the rest (if any).\r
  //\r
  ASSERT (NumFixedSizeVec >= 1);\r
  for (Idx = 1; Idx < NumFixedSizeVec; Idx++) {\r
    if (ResponseSgList->IoVec[Idx].Transferred !=\r
        ResponseSgList->IoVec[Idx].Size) {\r
      return EFI_PROTOCOL_ERROR;\r
    }\r
  }\r
\r
  //\r
  // If the last buffer is considered variable size, report its filled size.\r
  //\r
  if (TailBufferFill != NULL) {\r
    *TailBufferFill = ResponseSgList->IoVec[NumFixedSizeVec].Transferred;\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  An ad-hoc function for mapping FUSE (well, Linux) "errno" values to\r
  EFI_STATUS.\r
\r
  @param[in] Errno  The "VIRTIO_FS_FUSE_RESPONSE.Error" value, returned by the\r
                    Virtio Filesystem device. The value is expected to be\r
                    negative.\r
\r
  @return                   An EFI_STATUS error code that's deemed a passable\r
                            mapping for the Errno value.\r
\r
  @retval EFI_DEVICE_ERROR  Fallback EFI_STATUS code for unrecognized Errno\r
                            values.\r
**/\r
EFI_STATUS\r
VirtioFsErrnoToEfiStatus (\r
  IN INT32 Errno\r
  )\r
{\r
  switch (Errno) {\r
  case   -1: // EPERM               Operation not permitted\r
    return EFI_SECURITY_VIOLATION;\r
\r
  case   -2: // ENOENT              No such file or directory\r
  case   -3: // ESRCH               No such process\r
  case   -6: // ENXIO               No such device or address\r
  case  -10: // ECHILD              No child processes\r
  case  -19: // ENODEV              No such device\r
  case  -49: // EUNATCH             Protocol driver not attached\r
  case  -65: // ENOPKG              Package not installed\r
  case  -79: // ELIBACC             Can not access a needed shared library\r
  case -126: // ENOKEY              Required key not available\r
    return EFI_NOT_FOUND;\r
\r
  case   -4: // EINTR               Interrupted system call\r
  case  -11: // EAGAIN, EWOULDBLOCK Resource temporarily unavailable\r
  case  -16: // EBUSY               Device or resource busy\r
  case  -26: // ETXTBSY             Text file busy\r
  case  -35: // EDEADLK, EDEADLOCK  Resource deadlock avoided\r
  case  -39: // ENOTEMPTY           Directory not empty\r
  case  -42: // ENOMSG              No message of desired type\r
  case  -61: // ENODATA             No data available\r
  case  -85: // ERESTART            Interrupted system call should be restarted\r
    return EFI_NOT_READY;\r
\r
  case   -5: // EIO                 Input/output error\r
  case  -45: // EL2NSYNC            Level 2 not synchronized\r
  case  -46: // EL3HLT              Level 3 halted\r
  case  -47: // EL3RST              Level 3 reset\r
  case  -51: // EL2HLT              Level 2 halted\r
  case -121: // EREMOTEIO           Remote I/O error\r
  case -133: // EHWPOISON           Memory page has hardware error\r
    return EFI_DEVICE_ERROR;\r
\r
  case   -7: // E2BIG               Argument list too long\r
  case  -36: // ENAMETOOLONG        File name too long\r
  case  -90: // EMSGSIZE            Message too long\r
    return EFI_BAD_BUFFER_SIZE;\r
\r
  case   -8: // ENOEXEC             Exec format error\r
  case  -15: // ENOTBLK             Block device required\r
  case  -18: // EXDEV               Invalid cross-device link\r
  case  -20: // ENOTDIR             Not a directory\r
  case  -21: // EISDIR              Is a directory\r
  case  -25: // ENOTTY              Inappropriate ioctl for device\r
  case  -27: // EFBIG               File too large\r
  case  -29: // ESPIPE              Illegal seek\r
  case  -38: // ENOSYS              Function not implemented\r
  case  -59: // EBFONT              Bad font file format\r
  case  -60: // ENOSTR              Device not a stream\r
  case  -83: // ELIBEXEC            Cannot exec a shared library directly\r
  case  -88: // ENOTSOCK            Socket operation on non-socket\r
  case  -91: // EPROTOTYPE          Protocol wrong type for socket\r
  case  -92: // ENOPROTOOPT         Protocol not available\r
  case  -93: // EPROTONOSUPPORT     Protocol not supported\r
  case  -94: // ESOCKTNOSUPPORT     Socket type not supported\r
  case  -95: // ENOTSUP, EOPNOTSUPP Operation not supported\r
  case  -96: // EPFNOSUPPORT        Protocol family not supported\r
  case  -97: // EAFNOSUPPORT        Address family not supported by protocol\r
  case  -99: // EADDRNOTAVAIL       Cannot assign requested address\r
  case -118: // ENOTNAM             Not a XENIX named type file\r
  case -120: // EISNAM              Is a named type file\r
  case -124: // EMEDIUMTYPE         Wrong medium type\r
    return EFI_UNSUPPORTED;\r
\r
  case   -9: // EBADF               Bad file descriptor\r
  case  -14: // EFAULT              Bad address\r
  case  -44: // ECHRNG              Channel number out of range\r
  case  -48: // ELNRNG              Link number out of range\r
  case  -53: // EBADR               Invalid request descriptor\r
  case  -56: // EBADRQC             Invalid request code\r
  case  -57: // EBADSLT             Invalid slot\r
  case  -76: // ENOTUNIQ            Name not unique on network\r
  case  -84: // EILSEQ        Invalid or incomplete multibyte or wide character\r
    return EFI_NO_MAPPING;\r
\r
  case  -12: // ENOMEM              Cannot allocate memory\r
  case  -23: // ENFILE              Too many open files in system\r
  case  -24: // EMFILE              Too many open files\r
  case  -31: // EMLINK              Too many links\r
  case  -37: // ENOLCK              No locks available\r
  case  -40: // ELOOP               Too many levels of symbolic links\r
  case  -50: // ENOCSI              No CSI structure available\r
  case  -55: // ENOANO              No anode\r
  case  -63: // ENOSR               Out of streams resources\r
  case  -82: // ELIBMAX         Attempting to link in too many shared libraries\r
  case  -87: // EUSERS              Too many users\r
  case -105: // ENOBUFS             No buffer space available\r
  case -109: // ETOOMANYREFS        Too many references: cannot splice\r
  case -119: // ENAVAIL             No XENIX semaphores available\r
  case -122: // EDQUOT              Disk quota exceeded\r
    return EFI_OUT_OF_RESOURCES;\r
\r
  case  -13: // EACCES              Permission denied\r
    return EFI_ACCESS_DENIED;\r
\r
  case  -17: // EEXIST              File exists\r
  case  -98: // EADDRINUSE          Address already in use\r
  case -106: // EISCONN             Transport endpoint is already connected\r
  case -114: // EALREADY            Operation already in progress\r
  case -115: // EINPROGRESS         Operation now in progress\r
    return EFI_ALREADY_STARTED;\r
\r
  case  -22: // EINVAL              Invalid argument\r
  case  -33: // EDOM                Numerical argument out of domain\r
    return EFI_INVALID_PARAMETER;\r
\r
  case  -28: // ENOSPC              No space left on device\r
  case  -54: // EXFULL              Exchange full\r
    return EFI_VOLUME_FULL;\r
\r
  case  -30: // EROFS               Read-only file system\r
    return EFI_WRITE_PROTECTED;\r
\r
  case  -32: // EPIPE               Broken pipe\r
  case  -43: // EIDRM               Identifier removed\r
  case  -67: // ENOLINK             Link has been severed\r
  case  -68: // EADV                Advertise error\r
  case  -69: // ESRMNT              Srmount error\r
  case  -70: // ECOMM               Communication error on send\r
  case  -73: // EDOTDOT             RFS specific error\r
  case  -78: // EREMCHG             Remote address changed\r
  case  -86: // ESTRPIPE            Streams pipe error\r
  case -102: // ENETRESET           Network dropped connection on reset\r
  case -103: // ECONNABORTED        Software caused connection abort\r
  case -104: // ECONNRESET          Connection reset by peer\r
  case -116: // ESTALE              Stale file handle\r
  case -125: // ECANCELED           Operation canceled\r
  case -128: // EKEYREVOKED         Key has been revoked\r
  case -129: // EKEYREJECTED        Key was rejected by service\r
  case -130: // EOWNERDEAD          Owner died\r
  case -131: // ENOTRECOVERABLE     State not recoverable\r
    return EFI_ABORTED;\r
\r
  case  -34: // ERANGE              Numerical result out of range\r
  case  -75: // EOVERFLOW           Value too large for defined data type\r
    return EFI_BUFFER_TOO_SMALL;\r
\r
  case  -52: // EBADE               Invalid exchange\r
  case -108: // ESHUTDOWN         Cannot send after transport endpoint shutdown\r
  case -111: // ECONNREFUSED        Connection refused\r
    return EFI_END_OF_FILE;\r
\r
  case  -62: // ETIME               Timer expired\r
  case -110: // ETIMEDOUT           Connection timed out\r
  case -127: // EKEYEXPIRED         Key has expired\r
    return EFI_TIMEOUT;\r
\r
  case  -64: // ENONET              Machine is not on the network\r
  case  -66: // EREMOTE             Object is remote\r
  case  -72: // EMULTIHOP           Multihop attempted\r
  case -100: // ENETDOWN            Network is down\r
  case -101: // ENETUNREACH         Network is unreachable\r
  case -112: // EHOSTDOWN           Host is down\r
  case -113: // EHOSTUNREACH        No route to host\r
  case -123: // ENOMEDIUM           No medium found\r
  case -132: // ERFKILL             Operation not possible due to RF-kill\r
    return EFI_NO_MEDIA;\r
\r
  case  -71: // EPROTO              Protocol error\r
    return EFI_PROTOCOL_ERROR;\r
\r
  case  -74: // EBADMSG             Bad message\r
  case  -77: // EBADFD              File descriptor in bad state\r
  case  -80: // ELIBBAD             Accessing a corrupted shared library\r
  case  -81: // ELIBSCN             .lib section in a.out corrupted\r
  case -117: // EUCLEAN             Structure needs cleaning\r
    return EFI_VOLUME_CORRUPTED;\r
\r
  case  -89: // EDESTADDRREQ        Destination address required\r
  case -107: // ENOTCONN            Transport endpoint is not connected\r
    return EFI_NOT_STARTED;\r
\r
  default:\r
    break;\r
  }\r
\r
  return EFI_DEVICE_ERROR;\r
}\r
\r
//\r
// Parser states for canonicalizing a POSIX pathname.\r
//\r
typedef enum {\r
  ParserInit,   // just starting\r
  ParserEnd,    // finished\r
  ParserSlash,  // slash(es) seen\r
  ParserDot,    // one dot seen since last slash\r
  ParserDotDot, // two dots seen since last slash\r
  ParserNormal, // a different sequence seen\r
} PARSER_STATE;\r
\r
/**\r
  Strip the trailing slash from the parser's output buffer, unless the trailing\r
  slash stands for the root directory.\r
\r
  @param[in] Buffer        The parser's output buffer. Only used for\r
                           sanity-checking.\r
\r
  @param[in,out] Position  On entry, points at the next character to produce\r
                           (i.e., right past the end of the output written by\r
                           the parser thus far). The last character in the\r
                           parser's output buffer is a slash. On return, the\r
                           slash is stripped, by decrementing Position by one.\r
                           If this action would remove the slash character\r
                           standing for the root directory, then the function\r
                           has no effect.\r
**/\r
STATIC\r
VOID\r
ParserStripSlash (\r
  IN     CHAR8 *Buffer,\r
  IN OUT UINTN *Position\r
  )\r
{\r
  ASSERT (*Position >= 1);\r
  ASSERT (Buffer[*Position - 1] == '/');\r
  if (*Position == 1) {\r
    return;\r
  }\r
  (*Position)--;\r
}\r
\r
/**\r
  Produce one character in the parser's output buffer.\r
\r
  @param[out] Buffer       The parser's output buffer. On return, Char8 will\r
                           have been written.\r
\r
  @param[in,out] Position  On entry, points at the next character to produce\r
                           (i.e., right past the end of the output written by\r
                           the parser thus far). On return, Position is\r
                           incremented by one.\r
\r
  @param[in] Size          Total allocated size of the parser's output buffer.\r
                           Used for sanity-checking.\r
\r
  @param[in] Char8         The character to place in the output buffer.\r
**/\r
STATIC\r
VOID\r
ParserCopy (\r
     OUT CHAR8 *Buffer,\r
  IN OUT UINTN *Position,\r
  IN     UINTN Size,\r
  IN     CHAR8 Char8\r
  )\r
{\r
  ASSERT (*Position < Size);\r
  Buffer[(*Position)++] = Char8;\r
}\r
\r
/**\r
  Rewind the last single-dot in the parser's output buffer.\r
\r
  @param[in] Buffer        The parser's output buffer. Only used for\r
                           sanity-checking.\r
\r
  @param[in,out] Position  On entry, points at the next character to produce\r
                           (i.e., right past the end of the output written by\r
                           the parser thus far); the parser's output buffer\r
                           ends with the characters ('/', '.'). On return, the\r
                           dot is rewound by decrementing Position by one; a\r
                           slash character will reside at the new end of the\r
                           parser's output buffer.\r
**/\r
STATIC\r
VOID\r
ParserRewindDot (\r
  IN     CHAR8 *Buffer,\r
  IN OUT UINTN *Position\r
  )\r
{\r
  ASSERT (*Position >= 2);\r
  ASSERT (Buffer[*Position - 1] == '.');\r
  ASSERT (Buffer[*Position - 2] == '/');\r
  (*Position)--;\r
}\r
\r
/**\r
  Rewind the last dot-dot in the parser's output buffer.\r
\r
  @param[in] Buffer        The parser's output buffer. Only used for\r
                           sanity-checking.\r
\r
  @param[in,out] Position  On entry, points at the next character to produce\r
                           (i.e., right past the end of the output written by\r
                           the parser thus far); the parser's output buffer\r
                           ends with the characters ('/', '.', '.'). On return,\r
                           the ('.', '.') pair is rewound unconditionally, by\r
                           decrementing Position by two; a slash character\r
                           resides at the new end of the parser's output\r
                           buffer.\r
\r
                           If this slash character stands for the root\r
                           directory, then RootEscape is set to TRUE.\r
\r
                           Otherwise (i.e., if this slash character is not the\r
                           one standing for the root directory), then the slash\r
                           character, and the pathname component preceding it,\r
                           are removed by decrementing Position further. In\r
                           this case, the slash character preceding the removed\r
                           pathname component will reside at the new end of the\r
                           parser's output buffer.\r
\r
  @param[out] RootEscape   Set to TRUE on output if the dot-dot component tries\r
                           to escape the root directory, as described above.\r
                           Otherwise, RootEscape is not modified.\r
**/\r
STATIC\r
VOID\r
ParserRewindDotDot (\r
  IN     CHAR8   *Buffer,\r
  IN OUT UINTN   *Position,\r
     OUT BOOLEAN *RootEscape\r
\r
  )\r
{\r
  ASSERT (*Position >= 3);\r
  ASSERT (Buffer[*Position - 1] == '.');\r
  ASSERT (Buffer[*Position - 2] == '.');\r
  ASSERT (Buffer[*Position - 3] == '/');\r
  (*Position) -= 2;\r
\r
  if (*Position == 1) {\r
    //\r
    // Root directory slash reached; don't try to climb higher.\r
    //\r
    *RootEscape = TRUE;\r
    return;\r
  }\r
\r
  //\r
  // Skip slash.\r
  //\r
  (*Position)--;\r
  //\r
  // Scan until next slash to the left.\r
  //\r
  do {\r
    ASSERT (*Position > 0);\r
    (*Position)--;\r
  } while (Buffer[*Position] != '/');\r
  (*Position)++;\r
}\r
\r
/**\r
  Append the UEFI-style RhsPath16 to the POSIX-style, canonical format\r
  LhsPath8. Output the POSIX-style, canonical format result in ResultPath, as a\r
  dynamically allocated string.\r
\r
  Canonicalization (aka sanitization) establishes the following properties:\r
  - ResultPath is absolute (starts with "/"),\r
  - dot (.) and dot-dot (..) components are resolved/eliminated in ResultPath,\r
    with the usual semantics,\r
  - ResultPath uses forward slashes,\r
  - sequences of slashes are squashed in ResultPath,\r
  - the printable ASCII character set covers ResultPath,\r
  - CHAR8 encoding is used in ResultPath,\r
  - no trailing slash present in ResultPath except for the standalone root\r
    directory,\r
  - the length of ResultPath is at most VIRTIO_FS_MAX_PATHNAME_LENGTH.\r
\r
  Any dot-dot in RhsPath16 that would remove the root directory is dropped, and\r
  reported through RootEscape, without failing the function call.\r
\r
  @param[in] LhsPath8      Identifies the base directory. The caller is\r
                           responsible for ensuring that LhsPath8 conform to\r
                           the above canonical pathname format on entry.\r
\r
  @param[in] RhsPath16     Identifies the desired file with a UEFI-style CHAR16\r
                           pathname. If RhsPath16 starts with a backslash, then\r
                           RhsPath16 is considered absolute, and LhsPath8 is\r
                           ignored; RhsPath16 is sanitized in isolation, for\r
                           producing ResultPath8. Otherwise (i.e., if RhsPath16\r
                           is relative), RhsPath16 is transliterated to CHAR8,\r
                           and naively appended to LhsPath8. The resultant\r
                           fused pathname is then sanitized, to produce\r
                           ResultPath8.\r
\r
  @param[out] ResultPath8  The POSIX-style, canonical format pathname that\r
                           leads to the file desired by the caller. After use,\r
                           the caller is responsible for freeing ResultPath8.\r
\r
  @param[out] RootEscape   Set to TRUE if at least one dot-dot component in\r
                           RhsPath16 attempted to escape the root directory;\r
                           set to FALSE otherwise.\r
\r
  @retval EFI_SUCCESS            ResultPath8 has been produced. RootEscape has\r
                                 been output.\r
\r
  @retval EFI_INVALID_PARAMETER  RhsPath16 is zero-length.\r
\r
  @retval EFI_INVALID_PARAMETER  RhsPath16 failed the\r
                                 VIRTIO_FS_MAX_PATHNAME_LENGTH check.\r
\r
  @retval EFI_OUT_OF_RESOURCES   Memory allocation failed.\r
\r
  @retval EFI_OUT_OF_RESOURCES   ResultPath8 would have failed the\r
                                 VIRTIO_FS_MAX_PATHNAME_LENGTH check.\r
\r
  @retval EFI_UNSUPPORTED        RhsPath16 contains a character that either\r
                                 falls outside of the printable ASCII set, or\r
                                 is a forward slash.\r
**/\r
EFI_STATUS\r
VirtioFsAppendPath (\r
  IN     CHAR8   *LhsPath8,\r
  IN     CHAR16  *RhsPath16,\r
     OUT CHAR8   **ResultPath8,\r
     OUT BOOLEAN *RootEscape\r
  )\r
{\r
  UINTN        RhsLen;\r
  CHAR8        *RhsPath8;\r
  UINTN        Idx;\r
  EFI_STATUS   Status;\r
  UINTN        SizeToSanitize;\r
  CHAR8        *BufferToSanitize;\r
  CHAR8        *SanitizedBuffer;\r
  PARSER_STATE State;\r
  UINTN        SanitizedPosition;\r
\r
  //\r
  // Appending an empty pathname is not allowed.\r
  //\r
  RhsLen = StrLen (RhsPath16);\r
  if (RhsLen == 0) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
  //\r
  // Enforce length restriction on RhsPath16.\r
  //\r
  if (RhsLen > VIRTIO_FS_MAX_PATHNAME_LENGTH) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  //\r
  // Transliterate RhsPath16 to RhsPath8 by:\r
  // - rejecting RhsPath16 if a character outside of printable ASCII is seen,\r
  // - rejecting RhsPath16 if a forward slash is seen,\r
  // - replacing backslashes with forward slashes,\r
  // - casting the characters from CHAR16 to CHAR8.\r
  //\r
  RhsPath8 = AllocatePool (RhsLen + 1);\r
  if (RhsPath8 == NULL) {\r
    return EFI_OUT_OF_RESOURCES;\r
  }\r
  for (Idx = 0; RhsPath16[Idx] != L'\0'; Idx++) {\r
    if (RhsPath16[Idx] < 0x20 || RhsPath16[Idx] > 0x7E ||\r
        RhsPath16[Idx] == L'/') {\r
      Status = EFI_UNSUPPORTED;\r
      goto FreeRhsPath8;\r
    }\r
    RhsPath8[Idx] = (CHAR8)((RhsPath16[Idx] == L'\\') ? L'/' : RhsPath16[Idx]);\r
  }\r
  RhsPath8[Idx++] = '\0';\r
\r
  //\r
  // Now prepare the input for the canonicalization (squashing of sequences of\r
  // forward slashes, and eliminating . (dot) and .. (dot-dot) pathname\r
  // components).\r
  //\r
  // The sanitized path can never be longer than the naive concatenation of the\r
  // left hand side and right hand side paths, so we'll use the catenated size\r
  // for allocating the sanitized output too.\r
  //\r
  if (RhsPath8[0] == '/') {\r
    //\r
    // If the right hand side path is absolute, then it is not appended to the\r
    // left hand side path -- it *replaces* the left hand side path.\r
    //\r
    SizeToSanitize = RhsLen + 1;\r
    BufferToSanitize = RhsPath8;\r
  } else {\r
    //\r
    // If the right hand side path is relative, then it is appended (naively)\r
    // to the left hand side.\r
    //\r
    UINTN LhsLen;\r
\r
    LhsLen = AsciiStrLen (LhsPath8);\r
    SizeToSanitize = LhsLen + 1 + RhsLen + 1;\r
    BufferToSanitize = AllocatePool (SizeToSanitize);\r
    if (BufferToSanitize == NULL) {\r
      Status = EFI_OUT_OF_RESOURCES;\r
      goto FreeRhsPath8;\r
    }\r
    CopyMem (BufferToSanitize, LhsPath8, LhsLen);\r
    BufferToSanitize[LhsLen] = '/';\r
    CopyMem (BufferToSanitize + LhsLen + 1, RhsPath8, RhsLen + 1);\r
  }\r
\r
  //\r
  // Allocate the output buffer.\r
  //\r
  SanitizedBuffer = AllocatePool (SizeToSanitize);\r
  if (SanitizedBuffer == NULL) {\r
    Status = EFI_OUT_OF_RESOURCES;\r
    goto FreeBufferToSanitize;\r
  }\r
\r
  //\r
  // State machine for parsing the input and producing the canonical output\r
  // follows.\r
  //\r
  *RootEscape       = FALSE;\r
  Idx               = 0;\r
  State             = ParserInit;\r
  SanitizedPosition = 0;\r
  do {\r
    CHAR8 Chr8;\r
\r
    ASSERT (Idx < SizeToSanitize);\r
    Chr8 = BufferToSanitize[Idx++];\r
\r
    switch (State) {\r
    case ParserInit: // just starting\r
      ASSERT (Chr8 == '/');\r
      ParserCopy (SanitizedBuffer, &SanitizedPosition, SizeToSanitize, Chr8);\r
      State = ParserSlash;\r
      break;\r
\r
    case ParserSlash: // slash(es) seen\r
      switch (Chr8) {\r
      case '\0':\r
        ParserStripSlash (SanitizedBuffer, &SanitizedPosition);\r
        ParserCopy (SanitizedBuffer, &SanitizedPosition, SizeToSanitize, Chr8);\r
        State = ParserEnd;\r
        break;\r
      case '/':\r
        //\r
        // skip & stay in same state\r
        //\r
        break;\r
      case '.':\r
        ParserCopy (SanitizedBuffer, &SanitizedPosition, SizeToSanitize, Chr8);\r
        State = ParserDot;\r
        break;\r
      default:\r
        ParserCopy (SanitizedBuffer, &SanitizedPosition, SizeToSanitize, Chr8);\r
        State = ParserNormal;\r
        break;\r
      }\r
      break;\r
\r
    case ParserDot: // one dot seen since last slash\r
      switch (Chr8) {\r
      case '\0':\r
        ParserRewindDot (SanitizedBuffer, &SanitizedPosition);\r
        ParserStripSlash (SanitizedBuffer, &SanitizedPosition);\r
        ParserCopy (SanitizedBuffer, &SanitizedPosition, SizeToSanitize, Chr8);\r
        State = ParserEnd;\r
        break;\r
      case '/':\r
        ParserRewindDot (SanitizedBuffer, &SanitizedPosition);\r
        State = ParserSlash;\r
        break;\r
      case '.':\r
        ParserCopy (SanitizedBuffer, &SanitizedPosition, SizeToSanitize, Chr8);\r
        State = ParserDotDot;\r
        break;\r
      default:\r
        ParserCopy (SanitizedBuffer, &SanitizedPosition, SizeToSanitize, Chr8);\r
        State = ParserNormal;\r
        break;\r
      }\r
      break;\r
\r
    case ParserDotDot: // two dots seen since last slash\r
      switch (Chr8) {\r
      case '\0':\r
        ParserRewindDotDot (SanitizedBuffer, &SanitizedPosition, RootEscape);\r
        ParserStripSlash (SanitizedBuffer, &SanitizedPosition);\r
        ParserCopy (SanitizedBuffer, &SanitizedPosition, SizeToSanitize, Chr8);\r
        State = ParserEnd;\r
        break;\r
      case '/':\r
        ParserRewindDotDot (SanitizedBuffer, &SanitizedPosition, RootEscape);\r
        State = ParserSlash;\r
        break;\r
      case '.':\r
        //\r
        // fall through\r
        //\r
      default:\r
        ParserCopy (SanitizedBuffer, &SanitizedPosition, SizeToSanitize, Chr8);\r
        State = ParserNormal;\r
        break;\r
      }\r
      break;\r
\r
    case ParserNormal: // a different sequence seen\r
      switch (Chr8) {\r
      case '\0':\r
        ParserCopy (SanitizedBuffer, &SanitizedPosition, SizeToSanitize, Chr8);\r
        State = ParserEnd;\r
        break;\r
      case '/':\r
        ParserCopy (SanitizedBuffer, &SanitizedPosition, SizeToSanitize, Chr8);\r
        State = ParserSlash;\r
        break;\r
      case '.':\r
        //\r
        // fall through\r
        //\r
      default:\r
        //\r
        // copy and stay in same state\r
        //\r
        ParserCopy (SanitizedBuffer, &SanitizedPosition, SizeToSanitize, Chr8);\r
        break;\r
      }\r
      break;\r
\r
    default:\r
      ASSERT (FALSE);\r
      break;\r
    }\r
  } while (State != ParserEnd);\r
\r
  //\r
  // Ensure length invariant on ResultPath8.\r
  //\r
  ASSERT (SanitizedPosition >= 2);\r
  if (SanitizedPosition - 1 > VIRTIO_FS_MAX_PATHNAME_LENGTH) {\r
    Status = EFI_OUT_OF_RESOURCES;\r
    goto FreeSanitizedBuffer;\r
  }\r
\r
  *ResultPath8    = SanitizedBuffer;\r
  SanitizedBuffer = NULL;\r
  Status          = EFI_SUCCESS;\r
  //\r
  // Fall through.\r
  //\r
FreeSanitizedBuffer:\r
  if (SanitizedBuffer != NULL) {\r
    FreePool (SanitizedBuffer);\r
  }\r
\r
FreeBufferToSanitize:\r
  if (RhsPath8[0] != '/') {\r
    FreePool (BufferToSanitize);\r
  }\r
\r
FreeRhsPath8:\r
  FreePool (RhsPath8);\r
  return Status;\r
}\r
\r
/**\r
  For a given canonical pathname (as defined at VirtioFsAppendPath()), look up\r
  the NodeId of the most specific parent directory, plus output a pointer to\r
  the last pathname component (which is therefore a direct child of said parent\r
  directory).\r
\r
  The function may only be called after VirtioFsFuseInitSession() returns\r
  successfully and before VirtioFsUninit() is called.\r
\r
  @param[in,out] VirtioFs    The Virtio Filesystem device to send FUSE_LOOKUP\r
                             and FUSE_FORGET requests to. On output, the FUSE\r
                             request counter "VirtioFs->RequestId" will have\r
                             been incremented several times.\r
\r
  @param[in,out] Path        The canonical pathname (as defined in the\r
                             description of VirtioFsAppendPath()) to split.\r
                             Path is modified in-place temporarily; however, on\r
                             return (successful or otherwise), Path reassumes\r
                             its original contents.\r
\r
  @param[out] DirNodeId      The NodeId of the most specific parent directory\r
                             identified by Path. The caller is responsible for\r
                             sending a FUSE_FORGET request to the Virtio\r
                             Filesystem device for DirNodeId -- unless\r
                             DirNodeId equals VIRTIO_FS_FUSE_ROOT_DIR_NODE_ID\r
                             --, when DirNodeId's use ends.\r
\r
  @param[out] LastComponent  A pointer into Path, pointing at the start of the\r
                             last pathname component.\r
\r
  @retval EFI_SUCCESS            Splitting successful.\r
\r
  @retval EFI_INVALID_PARAMETER  Path is "/".\r
\r
  @retval EFI_ACCESS_DENIED      One of the components on Path before the last\r
                                 is not a directory.\r
\r
  @return                        Error codes propagated from\r
                                 VirtioFsFuseLookup() and\r
                                 VirtioFsFuseAttrToEfiFileInfo().\r
**/\r
EFI_STATUS\r
VirtioFsLookupMostSpecificParentDir (\r
  IN OUT VIRTIO_FS *VirtioFs,\r
  IN OUT CHAR8     *Path,\r
     OUT UINT64    *DirNodeId,\r
     OUT CHAR8     **LastComponent\r
  )\r
{\r
  UINT64     ParentDirNodeId;\r
  CHAR8      *Slash;\r
  EFI_STATUS Status;\r
  UINT64     NextDirNodeId;\r
\r
  if (AsciiStrCmp (Path, "/") == 0) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  ParentDirNodeId = VIRTIO_FS_FUSE_ROOT_DIR_NODE_ID;\r
  Slash           = Path;\r
  for (;;) {\r
    CHAR8                              *NextSlash;\r
    VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE FuseAttr;\r
    EFI_FILE_INFO                      FileInfo;\r
\r
    //\r
    // Find the slash (if any) that terminates the next pathname component.\r
    //\r
    NextSlash = AsciiStrStr (Slash + 1, "/");\r
    if (NextSlash == NULL) {\r
      break;\r
    }\r
\r
    //\r
    // Temporarily replace the found slash character with a NUL in-place, for\r
    // easy construction of the single-component filename that we need to look\r
    // up.\r
    //\r
    *NextSlash = '\0';\r
    Status = VirtioFsFuseLookup (VirtioFs, ParentDirNodeId, Slash + 1,\r
               &NextDirNodeId, &FuseAttr);\r
    *NextSlash = '/';\r
\r
    //\r
    // We're done with the directory inode that was the basis for the lookup.\r
    //\r
    if (ParentDirNodeId != VIRTIO_FS_FUSE_ROOT_DIR_NODE_ID) {\r
      VirtioFsFuseForget (VirtioFs, ParentDirNodeId);\r
    }\r
\r
    //\r
    // If we couldn't look up the next *non-final* pathname component, bail.\r
    //\r
    if (EFI_ERROR (Status)) {\r
      return Status;\r
    }\r
\r
    //\r
    // Lookup successful; now check if the next (non-final) component is a\r
    // directory. If not, bail.\r
    //\r
    Status = VirtioFsFuseAttrToEfiFileInfo (&FuseAttr, &FileInfo);\r
    if (EFI_ERROR (Status)) {\r
      goto ForgetNextDirNodeId;\r
    }\r
    if ((FileInfo.Attribute & EFI_FILE_DIRECTORY) == 0) {\r
      Status = EFI_ACCESS_DENIED;\r
      goto ForgetNextDirNodeId;\r
    }\r
\r
    //\r
    // Advance.\r
    //\r
    ParentDirNodeId = NextDirNodeId;\r
    Slash           = NextSlash;\r
  }\r
\r
  //\r
  // ParentDirNodeId corresponds to the last containing directory. The\r
  // remaining single-component filename represents a direct child under that\r
  // directory. Said filename starts at (Slash + 1).\r
  //\r
  *DirNodeId     = ParentDirNodeId;\r
  *LastComponent = Slash + 1;\r
  return EFI_SUCCESS;\r
\r
ForgetNextDirNodeId:\r
  VirtioFsFuseForget (VirtioFs, NextDirNodeId);\r
  return Status;\r
}\r
\r
/**\r
  Convert select fields of a VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE object to\r
  corresponding fields in EFI_FILE_INFO.\r
\r
  @param[in] FuseAttr   The VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE object to\r
                        convert the relevant fields from.\r
\r
  @param[out] FileInfo  The EFI_FILE_INFO structure to modify. Importantly, the\r
                        FileInfo->Size and FileInfo->FileName fields are not\r
                        overwritten.\r
\r
  @retval EFI_SUCCESS      Conversion successful.\r
\r
  @retval EFI_UNSUPPORTED  The allocated size of the file is inexpressible in\r
                           EFI_FILE_INFO.\r
\r
  @retval EFI_UNSUPPORTED  One of the file access times is inexpressible in\r
                           EFI_FILE_INFO.\r
\r
  @retval EFI_UNSUPPORTED  The file type is inexpressible in EFI_FILE_INFO.\r
\r
  @retval EFI_UNSUPPORTED  The file is a regular file that has multiple names\r
                           on the host side (i.e., its hard link count is\r
                           greater than one).\r
**/\r
EFI_STATUS\r
VirtioFsFuseAttrToEfiFileInfo (\r
  IN     VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE *FuseAttr,\r
     OUT EFI_FILE_INFO                      *FileInfo\r
  )\r
{\r
  UINT64   EpochTime[3];\r
  EFI_TIME *ConvertedTime[ARRAY_SIZE (EpochTime)];\r
  UINTN    Idx;\r
\r
  FileInfo->FileSize = FuseAttr->Size;\r
\r
  //\r
  // The unit for FuseAttr->Blocks is 512B.\r
  //\r
  if (FuseAttr->Blocks >= BIT55) {\r
    return EFI_UNSUPPORTED;\r
  }\r
  FileInfo->PhysicalSize = LShiftU64 (FuseAttr->Blocks, 9);\r
\r
  //\r
  // Convert the timestamps. File creation time is not tracked by the Virtio\r
  // Filesystem device, so set FileInfo->CreateTime from FuseAttr->Mtime as\r
  // well.\r
  //\r
  EpochTime[0]     = FuseAttr->Mtime;\r
  EpochTime[1]     = FuseAttr->Atime;\r
  EpochTime[2]     = FuseAttr->Mtime;\r
  ConvertedTime[0] = &FileInfo->CreateTime;\r
  ConvertedTime[1] = &FileInfo->LastAccessTime;\r
  ConvertedTime[2] = &FileInfo->ModificationTime;\r
\r
  for (Idx = 0; Idx < ARRAY_SIZE (EpochTime); Idx++) {\r
    //\r
    // EpochToEfiTime() takes a UINTN for seconds.\r
    //\r
    if (EpochTime[Idx] > MAX_UINTN) {\r
      return EFI_UNSUPPORTED;\r
    }\r
    //\r
    // Set the following fields in the converted time: Year, Month, Day, Hour,\r
    // Minute, Second, Nanosecond.\r
    //\r
    EpochToEfiTime ((UINTN)EpochTime[Idx], ConvertedTime[Idx]);\r
    //\r
    // The times are all expressed in UTC. Consequently, they are not affected\r
    // by daylight saving.\r
    //\r
    ConvertedTime[Idx]->TimeZone = 0;\r
    ConvertedTime[Idx]->Daylight = 0;\r
    //\r
    // Clear the padding fields.\r
    //\r
    ConvertedTime[Idx]->Pad1 = 0;\r
    ConvertedTime[Idx]->Pad2 = 0;\r
  }\r
\r
  //\r
  // Set the attributes.\r
  //\r
  switch (FuseAttr->Mode & VIRTIO_FS_FUSE_MODE_TYPE_MASK) {\r
  case VIRTIO_FS_FUSE_MODE_TYPE_DIR:\r
    FileInfo->Attribute = EFI_FILE_DIRECTORY;\r
    break;\r
  case VIRTIO_FS_FUSE_MODE_TYPE_REG:\r
    FileInfo->Attribute = 0;\r
    break;\r
  default:\r
    //\r
    // Other file types are not supported.\r
    //\r
    return EFI_UNSUPPORTED;\r
  }\r
  //\r
  // Report the regular file or directory as read-only if all classes lack\r
  // write permission.\r
  //\r
  if ((FuseAttr->Mode & (VIRTIO_FS_FUSE_MODE_PERM_WUSR |\r
                         VIRTIO_FS_FUSE_MODE_PERM_WGRP |\r
                         VIRTIO_FS_FUSE_MODE_PERM_WOTH)) == 0) {\r
    FileInfo->Attribute |= EFI_FILE_READ_ONLY;\r
  }\r
\r
  //\r
  // A hard link count greater than 1 is not supported for regular files.\r
  //\r
  if ((FileInfo->Attribute & EFI_FILE_DIRECTORY) == 0 && FuseAttr->Nlink > 1) {\r
    return EFI_UNSUPPORTED;\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r