OvmfPkg/VirtioFsDxe/SimpleFsDelete.c

   1 /** @file
   2   EFI_FILE_PROTOCOL.Delete() 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 <Library/BaseLib.h>             // RemoveEntryList()
  10 #include <Library/MemoryAllocationLib.h> // FreePool()
  11
  12 #include "VirtioFsDxe.h"
  13
  14 EFI_STATUS
  15 EFIAPI
  16 VirtioFsSimpleFileDelete (
  17   IN EFI_FILE_PROTOCOL  *This
  18   )
  19 {
  20   VIRTIO_FS_FILE  *VirtioFsFile;
  21   VIRTIO_FS       *VirtioFs;
  22   EFI_STATUS      Status;
  23
  24   VirtioFsFile = VIRTIO_FS_FILE_FROM_SIMPLE_FILE (This);
  25   VirtioFs     = VirtioFsFile->OwnerFs;
  26
  27   //
  28   // All actions in this function are "best effort"; the UEFI spec requires
  29   // EFI_FILE_PROTOCOL.Delete() to release resources unconditionally. If a step
  30   // related to removing the file fails, it's only reflected in the return
  31   // status (EFI_WARN_DELETE_FAILURE rather than EFI_SUCCESS).
  32   //
  33   // Release, remove, and (if needed) forget. We don't waste time flushing and
  34   // syncing; if the EFI_FILE_PROTOCOL user cares enough, they should keep the
  35   // parent directory open until after this function call returns, and then
  36   // force a sync on *that* EFI_FILE_PROTOCOL instance, using either the
  37   // Flush() member function, or the Close() member function.
  38   //
  39   // If any action fails below, we still try the others.
  40   //
  41   VirtioFsFuseReleaseFileOrDir (
  42     VirtioFs,
  43     VirtioFsFile->NodeId,
  44     VirtioFsFile->FuseHandle,
  45     VirtioFsFile->IsDirectory
  46     );
  47
  48   //
  49   // VirtioFsFile->FuseHandle is gone at this point, but VirtioFsFile->NodeId
  50   // is still valid. Continue with removing the file or directory. The result
  51   // of this operation determines the return status of the function.
  52   //
  53   if (VirtioFsFile->IsOpenForWriting) {
  54     UINT64  ParentNodeId;
  55     CHAR8   *LastComponent;
  56
  57     //
  58     // Split our canonical pathname into most specific parent directory
  59     // (identified by NodeId), and single-component filename within that
  60     // directory. If This stands for the root directory "/", then the following
  61     // function call will gracefully fail.
  62     //
  63     Status = VirtioFsLookupMostSpecificParentDir (
  64                VirtioFs,
  65                VirtioFsFile->CanonicalPathname,
  66                &ParentNodeId,
  67                &LastComponent
  68                );
  69     if (!EFI_ERROR (Status)) {
  70       //
  71       // Attempt the actual removal. Regardless of the outcome, ParentNodeId
  72       // must be forgotten right after (unless it stands for the root
  73       // directory).
  74       //
  75       Status = VirtioFsFuseRemoveFileOrDir (
  76                  VirtioFs,
  77                  ParentNodeId,
  78                  LastComponent,
  79                  VirtioFsFile->IsDirectory
  80                  );
  81       if (ParentNodeId != VIRTIO_FS_FUSE_ROOT_DIR_NODE_ID) {
  82         VirtioFsFuseForget (VirtioFs, ParentNodeId);
  83       }
  84     }
  85
  86     if (EFI_ERROR (Status)) {
  87       //
  88       // Map any failure to the spec-mandated warning code.
  89       //
  90       Status = EFI_WARN_DELETE_FAILURE;
  91     }
  92   } else {
  93     Status = EFI_WARN_DELETE_FAILURE;
  94   }
  95
  96   //
  97   // Finally, if we've known VirtioFsFile->NodeId from a lookup, then we should
  98   // also ask the server to forget it *once*.
  99   //
 100   if (VirtioFsFile->NodeId != VIRTIO_FS_FUSE_ROOT_DIR_NODE_ID) {
 101     VirtioFsFuseForget (VirtioFs, VirtioFsFile->NodeId);
 102   }
 103
 104   //
 105   // One fewer file left open for the owner filesystem.
 106   //
 107   RemoveEntryList (&VirtioFsFile->OpenFilesEntry);
 108
 109   FreePool (VirtioFsFile->CanonicalPathname);
 110   if (VirtioFsFile->FileInfoArray != NULL) {
 111     FreePool (VirtioFsFile->FileInfoArray);
 112   }
 113
 114   FreePool (VirtioFsFile);
 115   return Status;
 116 }