[edk2 PATCH 26/48] OvmfPkg/VirtioFsDxe: implement EFI_FILE_PROTOCOL.Open()

["Laszlo Ersek" <lersek@redhat.com>]

Using the functions introduced previously, we can now implement
VirtioFsSimpleFileOpen().

This lets the "MKDIR" command to work in the UEFI shell, for example.

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3097
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 OvmfPkg/VirtioFsDxe/SimpleFsOpen.c | 480 +++++++++++++++++++-
 1 file changed, 479 insertions(+), 1 deletion(-)

diff --git a/OvmfPkg/VirtioFsDxe/SimpleFsOpen.c b/OvmfPkg/VirtioFsDxe/SimpleFsOpen.c
index f0e249184079..2649c796ac97 100644
--- a/OvmfPkg/VirtioFsDxe/SimpleFsOpen.c
+++ b/OvmfPkg/VirtioFsDxe/SimpleFsOpen.c
@@ -1,22 +1,500 @@
 /** @file
   EFI_FILE_PROTOCOL.Open() member function for the Virtio Filesystem driver.
 
   Copyright (C) 2020, Red Hat, Inc.
 
   SPDX-License-Identifier: BSD-2-Clause-Patent
 **/
 
+#include <Library/BaseLib.h>             // AsciiStrCmp()
+#include <Library/MemoryAllocationLib.h> // AllocatePool()
+
 #include "VirtioFsDxe.h"
 
+/**
+  Open the root directory, possibly for writing.
+
+  @param[in,out] VirtioFs    The Virtio Filesystem device whose root directory
+                             should be opened.
+
+  @param[out] NewHandle      The new EFI_FILE_PROTOCOL instance through which
+                             the root directory can be accessed.
+
+  @param[in] OpenForWriting  TRUE if the root directory should be opened for
+                             read-write access. FALSE if the root directory
+                             should be opened for read-only access. Opening the
+                             root directory for read-write access is useful for
+                             calling EFI_FILE_PROTOCOL.Flush() or
+                             EFI_FILE_PROTOCOL.SetInfo() later, for syncing or
+                             touching the root directory, respectively.
+
+  @retval EFI_SUCCESS        The root directory has been opened successfully.
+
+  @retval EFI_ACCESS_DENIED  OpenForWriting is TRUE, but the root directory is
+                             marked as read-only.
+
+  @return                    Error codes propagated from underlying functions.
+**/
+STATIC
+EFI_STATUS
+OpenRootDirectory (
+  IN OUT VIRTIO_FS         *VirtioFs,
+     OUT EFI_FILE_PROTOCOL **NewHandle,
+  IN     BOOLEAN           OpenForWriting
+  )
+{
+  EFI_STATUS     Status;
+  VIRTIO_FS_FILE *NewVirtioFsFile;
+
+  //
+  // VirtioFsOpenVolume() opens the root directory for read-only access. If the
+  // current request is to open the root directory for read-write access, so
+  // that EFI_FILE_PROTOCOL.Flush() or EFI_FILE_PROTOCOL.SetInfo()+timestamps
+  // can be used on the root directory later, then we have to check for write
+  // permission first.
+  //
+  if (OpenForWriting) {
+    VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE FuseAttr;
+    EFI_FILE_INFO                      FileInfo;
+
+    Status = VirtioFsFuseGetAttr (VirtioFs, VIRTIO_FS_FUSE_ROOT_DIR_NODE_ID,
+               &FuseAttr);
+    if (EFI_ERROR (Status)) {
+      return Status;
+    }
+    Status = VirtioFsFuseAttrToEfiFileInfo (&FuseAttr, &FileInfo);
+    if (EFI_ERROR (Status)) {
+      return Status;
+    }
+    if ((FileInfo.Attribute & EFI_FILE_READ_ONLY) != 0) {
+      return EFI_ACCESS_DENIED;
+    }
+  }
+
+  Status = VirtioFsOpenVolume (&VirtioFs->SimpleFs, NewHandle);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  NewVirtioFsFile = VIRTIO_FS_FILE_FROM_SIMPLE_FILE (*NewHandle);
+  NewVirtioFsFile->IsOpenForWriting = OpenForWriting;
+  return EFI_SUCCESS;
+}
+
+/**
+  Open an existent regular file or non-root directory.
+
+  @param[in,out] VirtioFs      The Virtio Filesystem device on which the
+                               regular file or directory should be opened.
+
+  @param[in] DirNodeId         The inode number of the immediate parent
+                               directory of the regular file or directory to
+                               open.
+
+  @param[in] Name              The single-component filename of the regular
+                               file or directory to open, under the immediate
+                               parent directory identified by DirNodeId.
+
+  @param[in] OpenForWriting    TRUE if the regular file or directory should be
+                               opened for read-write access. FALSE if the
+                               regular file or directory should be opened for
+                               read-only access. Opening a directory for
+                               read-write access is useful for deleting,
+                               renaming, syncing or touching the directory
+                               later.
+
+  @param[out] NodeId           The inode number of the regular file or
+                               directory, returned by the Virtio Filesystem
+                               device.
+
+  @param[out] FuseHandle       The open handle to the regular file or
+                               directory, returned by the Virtio Filesystem
+                               device.
+
+  @param[out] NodeIsDirectory  Set to TRUE on output if Name was found to refer
+                               to a directory. Set to FALSE if Name was found
+                               to refer to a regular file.
+
+  @retval EFI_SUCCESS        The regular file or directory has been looked up
+                             and opened successfully.
+
+  @retval EFI_ACCESS_DENIED  OpenForWriting is TRUE, but the regular file or
+                             directory is marked read-only.
+
+  @retval EFI_NOT_FOUND      A directory entry called Name was not found in the
+                             directory identified by DirNodeId. (EFI_NOT_FOUND
+                             is not returned for any other condition.)
+
+  @return                    Errors propagated from underlying functions. If
+                             the error code to propagate were EFI_NOT_FOUND, it
+                             is remapped to EFI_DEVICE_ERROR.
+**/
+STATIC
+EFI_STATUS
+OpenExistentFileOrDirectory (
+  IN OUT VIRTIO_FS *VirtioFs,
+  IN     UINT64    DirNodeId,
+  IN     CHAR8     *Name,
+  IN     BOOLEAN   OpenForWriting,
+     OUT UINT64    *NodeId,
+     OUT UINT64    *FuseHandle,
+     OUT BOOLEAN   *NodeIsDirectory
+  )
+{
+  EFI_STATUS                         Status;
+  UINT64                             ResolvedNodeId;
+  VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE FuseAttr;
+  EFI_FILE_INFO                      FileInfo;
+  BOOLEAN                            IsDirectory;
+  UINT64                             NewFuseHandle;
+
+  Status = VirtioFsFuseLookup (VirtioFs, DirNodeId, Name, &ResolvedNodeId,
+             &FuseAttr);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+  Status = VirtioFsFuseAttrToEfiFileInfo (&FuseAttr, &FileInfo);
+  if (EFI_ERROR (Status)) {
+    goto ForgetResolvedNodeId;
+  }
+
+  if (OpenForWriting && (FileInfo.Attribute & EFI_FILE_READ_ONLY) != 0) {
+    Status = EFI_ACCESS_DENIED;
+    goto ForgetResolvedNodeId;
+  }
+
+  IsDirectory = (BOOLEAN)((FileInfo.Attribute & EFI_FILE_DIRECTORY) != 0);
+  if (IsDirectory) {
+    //
+    // If OpenForWriting is TRUE here, that's not passed to
+    // VirtioFsFuseOpenDir(); it does not affect the FUSE_OPENDIR request we
+    // send. OpenForWriting=TRUE will only permit attempts to delete, rename,
+    // flush (sync), and touch the directory.
+    //
+    Status = VirtioFsFuseOpenDir (VirtioFs, ResolvedNodeId, &NewFuseHandle);
+  } else {
+    Status = VirtioFsFuseOpen (VirtioFs, ResolvedNodeId, OpenForWriting,
+               &NewFuseHandle);
+  }
+  if (EFI_ERROR (Status)) {
+    goto ForgetResolvedNodeId;
+  }
+
+  *NodeId          = ResolvedNodeId;
+  *FuseHandle      = NewFuseHandle;
+  *NodeIsDirectory = IsDirectory;
+  return EFI_SUCCESS;
+
+ForgetResolvedNodeId:
+  VirtioFsFuseForget (VirtioFs, ResolvedNodeId);
+  return (Status == EFI_NOT_FOUND) ? EFI_DEVICE_ERROR : Status;
+}
+
+/**
+  Create a directory.
+
+  @param[in,out] VirtioFs  The Virtio Filesystem device on which the directory
+                           should be created.
+
+  @param[in] DirNodeId     The inode number of the immediate parent directory
+                           of the directory to create.
+
+  @param[in] Name          The single-component filename of the directory to
+                           create, under the immediate parent directory
+                           identified by DirNodeId.
+
+  @param[out] NodeId       The inode number of the directory created, returned
+                           by the Virtio Filesystem device.
+
+  @param[out] FuseHandle   The open handle to the directory created, returned
+                           by the Virtio Filesystem device.
+
+  @retval EFI_SUCCESS  The directory has been created successfully.
+
+  @return              Errors propagated from underlying functions.
+**/
+STATIC
+EFI_STATUS
+CreateDirectory (
+  IN OUT VIRTIO_FS *VirtioFs,
+  IN     UINT64    DirNodeId,
+  IN     CHAR8     *Name,
+     OUT UINT64    *NodeId,
+     OUT UINT64    *FuseHandle
+  )
+{
+  EFI_STATUS Status;
+  UINT64     NewChildDirNodeId;
+  UINT64     NewFuseHandle;
+
+  Status = VirtioFsFuseMkDir (VirtioFs, DirNodeId, Name, &NewChildDirNodeId);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  Status = VirtioFsFuseOpenDir (VirtioFs, NewChildDirNodeId, &NewFuseHandle);
+  if (EFI_ERROR (Status)) {
+    goto RemoveNewChildDir;
+  }
+
+  *NodeId     = NewChildDirNodeId;
+  *FuseHandle = NewFuseHandle;
+  return EFI_SUCCESS;
+
+RemoveNewChildDir:
+  VirtioFsFuseRemoveFileOrDir (VirtioFs, DirNodeId, Name, TRUE /* IsDir */);
+  VirtioFsFuseForget (VirtioFs, NewChildDirNodeId);
+  return Status;
+}
+
+/**
+  Create a regular file.
+
+  @param[in,out] VirtioFs  The Virtio Filesystem device on which the regular
+                           file should be created.
+
+  @param[in] DirNodeId     The inode number of the immediate parent directory
+                           of the regular file to create.
+
+  @param[in] Name          The single-component filename of the regular file to
+                           create, under the immediate parent directory
+                           identified by DirNodeId.
+
+  @param[out] NodeId       The inode number of the regular file created,
+                           returned by the Virtio Filesystem device.
+
+  @param[out] FuseHandle   The open handle to the regular file created,
+                           returned by the Virtio Filesystem device.
+
+  @retval EFI_SUCCESS  The regular file has been created successfully.
+
+  @return              Errors propagated from underlying functions.
+**/
+STATIC
+EFI_STATUS
+CreateRegularFile (
+  IN OUT VIRTIO_FS *VirtioFs,
+  IN     UINT64    DirNodeId,
+  IN     CHAR8     *Name,
+     OUT UINT64    *NodeId,
+     OUT UINT64    *FuseHandle
+  )
+{
+  return VirtioFsFuseOpenOrCreate (VirtioFs, DirNodeId, Name, NodeId,
+           FuseHandle);
+}
+
 EFI_STATUS
 EFIAPI
 VirtioFsSimpleFileOpen (
   IN     EFI_FILE_PROTOCOL *This,
      OUT EFI_FILE_PROTOCOL **NewHandle,
   IN     CHAR16            *FileName,
   IN     UINT64            OpenMode,
   IN     UINT64            Attributes
   )
 {
-  return EFI_NO_MEDIA;
+  VIRTIO_FS_FILE *VirtioFsFile;
+  VIRTIO_FS      *VirtioFs;
+  BOOLEAN        OpenForWriting;
+  BOOLEAN        PermitCreation;
+  BOOLEAN        CreateDirectoryIfCreating;
+  VIRTIO_FS_FILE *NewVirtioFsFile;
+  EFI_STATUS     Status;
+  CHAR8          *NewCanonicalPath;
+  BOOLEAN        RootEscape;
+  UINT64         DirNodeId;
+  CHAR8          *LastComponent;
+  UINT64         NewNodeId;
+  UINT64         NewFuseHandle;
+  BOOLEAN        NewNodeIsDirectory;
+
+  VirtioFsFile = VIRTIO_FS_FILE_FROM_SIMPLE_FILE (This);
+  VirtioFs     = VirtioFsFile->OwnerFs;
+
+  //
+  // Validate OpenMode.
+  //
+  switch (OpenMode) {
+  case EFI_FILE_MODE_READ:
+    OpenForWriting = FALSE;
+    PermitCreation = FALSE;
+    break;
+  case EFI_FILE_MODE_READ | EFI_FILE_MODE_WRITE:
+    OpenForWriting = TRUE;
+    PermitCreation = FALSE;
+    break;
+  case EFI_FILE_MODE_READ | EFI_FILE_MODE_WRITE | EFI_FILE_MODE_CREATE:
+    OpenForWriting = TRUE;
+    PermitCreation = TRUE;
+    break;
+  default:
+    return EFI_INVALID_PARAMETER;
+  }
+
+  //
+  // Validate the Attributes requested for the case when the file ends up being
+  // created, provided creation is permitted.
+  //
+  if (PermitCreation) {
+    if ((Attributes & ~EFI_FILE_VALID_ATTR) != 0) {
+      //
+      // Unknown attribute requested.
+      //
+      return EFI_INVALID_PARAMETER;
+    }
+
+    ASSERT (OpenForWriting);
+    if ((Attributes & EFI_FILE_READ_ONLY) != 0) {
+      DEBUG ((
+        DEBUG_ERROR,
+        ("%a: Label=\"%s\" CanonicalPathname=\"%a\" FileName=\"%s\" "
+         "OpenMode=0x%Lx Attributes=0x%Lx: nonsensical request to possibly "
+         "create a file marked read-only, for read-write access\n"),
+        __FUNCTION__,
+        VirtioFs->Label,
+        VirtioFsFile->CanonicalPathname,
+        FileName,
+        OpenMode,
+        Attributes
+        ));
+      return EFI_INVALID_PARAMETER;
+    }
+    CreateDirectoryIfCreating = (BOOLEAN)((Attributes &
+                                           EFI_FILE_DIRECTORY) != 0);
+  }
+
+  //
+  // Referring to a file relative to a regular file makes no sense (or at least
+  // it cannot be implemented consistently with how a file is referred to
+  // relative to a directory).
+  //
+  if (!VirtioFsFile->IsDirectory) {
+    DEBUG ((
+      DEBUG_ERROR,
+      ("%a: Label=\"%s\" CanonicalPathname=\"%a\" FileName=\"%s\": "
+       "nonsensical request to open a file or directory relative to a regular "
+       "file\n"),
+      __FUNCTION__,
+      VirtioFs->Label,
+      VirtioFsFile->CanonicalPathname,
+      FileName
+      ));
+    return EFI_INVALID_PARAMETER;
+  }
+
+  //
+  // Allocate the new VIRTIO_FS_FILE object.
+  //
+  NewVirtioFsFile = AllocatePool (sizeof *NewVirtioFsFile);
+  if (NewVirtioFsFile == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  //
+  // Create the canonical pathname at which the desired file is expected to
+  // exist.
+  //
+  Status = VirtioFsAppendPath (VirtioFsFile->CanonicalPathname, FileName,
+             &NewCanonicalPath, &RootEscape);
+  if (EFI_ERROR (Status)) {
+    goto FreeNewVirtioFsFile;
+  }
+  if (RootEscape) {
+    Status = EFI_ACCESS_DENIED;
+    goto FreeNewCanonicalPath;
+  }
+
+  //
+  // If the desired file is the root directory, just open the volume one more
+  // time, without looking up anything.
+  //
+  if (AsciiStrCmp (NewCanonicalPath, "/") == 0) {
+    FreePool (NewCanonicalPath);
+    FreePool (NewVirtioFsFile);
+    return OpenRootDirectory (VirtioFs, NewHandle, OpenForWriting);
+  }
+
+  //
+  // Split the new canonical pathname into most specific parent directory
+  // (given by DirNodeId) and last pathname component (i.e., immediate child
+  // within that parent directory).
+  //
+  Status = VirtioFsLookupMostSpecificParentDir (VirtioFs, NewCanonicalPath,
+             &DirNodeId, &LastComponent);
+  if (EFI_ERROR (Status)) {
+    goto FreeNewCanonicalPath;
+  }
+
+  //
+  // Try to open LastComponent directly under DirNodeId, as an existent regular
+  // file or directory.
+  //
+  Status = OpenExistentFileOrDirectory (VirtioFs, DirNodeId, LastComponent,
+             OpenForWriting, &NewNodeId, &NewFuseHandle, &NewNodeIsDirectory);
+  //
+  // If LastComponent could not be found under DirNodeId, but the request
+  // allows us to create a new entry, attempt creating the requested regular
+  // file or directory.
+  //
+  if (Status == EFI_NOT_FOUND && PermitCreation) {
+    ASSERT (OpenForWriting);
+    if (CreateDirectoryIfCreating) {
+      Status = CreateDirectory (VirtioFs, DirNodeId, LastComponent, &NewNodeId,
+                 &NewFuseHandle);
+    } else {
+      Status = CreateRegularFile (VirtioFs, DirNodeId, LastComponent,
+                 &NewNodeId, &NewFuseHandle);
+    }
+    NewNodeIsDirectory = CreateDirectoryIfCreating;
+  }
+
+  //
+  // Regardless of the branch taken, we're done with DirNodeId.
+  //
+  if (DirNodeId != VIRTIO_FS_FUSE_ROOT_DIR_NODE_ID) {
+    VirtioFsFuseForget (VirtioFs, DirNodeId);
+  }
+
+  if (EFI_ERROR (Status)) {
+    goto FreeNewCanonicalPath;
+  }
+
+  //
+  // Populate the new VIRTIO_FS_FILE object.
+  //
+  NewVirtioFsFile->Signature              = VIRTIO_FS_FILE_SIG;
+  NewVirtioFsFile->SimpleFile.Revision    = EFI_FILE_PROTOCOL_REVISION;
+  NewVirtioFsFile->SimpleFile.Open        = VirtioFsSimpleFileOpen;
+  NewVirtioFsFile->SimpleFile.Close       = VirtioFsSimpleFileClose;
+  NewVirtioFsFile->SimpleFile.Delete      = VirtioFsSimpleFileDelete;
+  NewVirtioFsFile->SimpleFile.Read        = VirtioFsSimpleFileRead;
+  NewVirtioFsFile->SimpleFile.Write       = VirtioFsSimpleFileWrite;
+  NewVirtioFsFile->SimpleFile.GetPosition = VirtioFsSimpleFileGetPosition;
+  NewVirtioFsFile->SimpleFile.SetPosition = VirtioFsSimpleFileSetPosition;
+  NewVirtioFsFile->SimpleFile.GetInfo     = VirtioFsSimpleFileGetInfo;
+  NewVirtioFsFile->SimpleFile.SetInfo     = VirtioFsSimpleFileSetInfo;
+  NewVirtioFsFile->SimpleFile.Flush       = VirtioFsSimpleFileFlush;
+  NewVirtioFsFile->IsDirectory            = NewNodeIsDirectory;
+  NewVirtioFsFile->IsOpenForWriting       = OpenForWriting;
+  NewVirtioFsFile->OwnerFs                = VirtioFs;
+  NewVirtioFsFile->CanonicalPathname      = NewCanonicalPath;
+  NewVirtioFsFile->NodeId                 = NewNodeId;
+  NewVirtioFsFile->FuseHandle             = NewFuseHandle;
+
+  //
+  // One more file is now open for the filesystem.
+  //
+  InsertTailList (&VirtioFs->OpenFiles, &NewVirtioFsFile->OpenFilesEntry);
+
+  *NewHandle = &NewVirtioFsFile->SimpleFile;
+  return EFI_SUCCESS;
+
+FreeNewCanonicalPath:
+  FreePool (NewCanonicalPath);
+
+FreeNewVirtioFsFile:
+  FreePool (NewVirtioFsFile);
+
+  return Status;
 }
-- 
2.19.1.3.g30247aa5d201