[edk2-devel] [edk2 PATCH 36/48] OvmfPkg/VirtioFsDxe: implement EFI_FILE_PROTOCOL.Read() for directories
Laszlo Ersek
lersek at redhat.com
Wed Dec 16 21:11:13 UTC 2020
Using the functions introduced previously, we can now implement
VirtioFsSimpleFileRead() for directories as well.
This patch completes the read-only support for virtio-fs. Commands like
"TYPE" and "DIR" work in the UEFI shell.
Cc: Ard Biesheuvel <ard.biesheuvel at arm.com>
Cc: Jordan Justen <jordan.l.justen at intel.com>
Cc: Philippe Mathieu-Daudé <philmd at redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3097
Signed-off-by: Laszlo Ersek <lersek at redhat.com>
---
OvmfPkg/VirtioFsDxe/SimpleFsRead.c | 343 +++++++++++++++++++-
1 file changed, 342 insertions(+), 1 deletion(-)
diff --git a/OvmfPkg/VirtioFsDxe/SimpleFsRead.c b/OvmfPkg/VirtioFsDxe/SimpleFsRead.c
index c4ad07c9aec4..d6368342a139 100644
--- a/OvmfPkg/VirtioFsDxe/SimpleFsRead.c
+++ b/OvmfPkg/VirtioFsDxe/SimpleFsRead.c
@@ -1,18 +1,359 @@
/** @file
EFI_FILE_PROTOCOL.Read() member function for the Virtio Filesystem driver.
Copyright (C) 2020, Red Hat, Inc.
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
+#include <Library/BaseMemoryLib.h> // CopyMem()
+#include <Library/MemoryAllocationLib.h> // AllocatePool()
+
#include "VirtioFsDxe.h"
+/**
+ Populate a caller-allocated EFI_FILE_INFO object from
+ VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE.
+
+ @param[in] Dirent The entry read from the directory stream. The
+ caller is responsible for ensuring that
+ Dirent->Namelen describe valid storage.
+
+ @param[in] SingleFileInfoSize The allocated size of FileInfo.
+
+ @param[out] FileInfo The EFI_FILE_INFO object to populate. On
+ success, all fields in FileInfo will be
+ updated, setting FileInfo->Size to the
+ actually used size (which will not exceed
+ SingleFileInfoSize).
+
+ @retval EFI_SUCCESS FileInfo has been filled in.
+
+ @return Error codes propagated from
+ VirtioFsFuseDirentPlusToEfiFileInfo() and
+ VirtioFsFuseAttrToEfiFileInfo(). The contents of
+ FileInfo are indeterminate.
+**/
+STATIC
+EFI_STATUS
+PopulateFileInfo (
+ IN VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE *Dirent,
+ IN UINTN SingleFileInfoSize,
+ OUT EFI_FILE_INFO *FileInfo
+ )
+{
+ EFI_STATUS Status;
+
+ //
+ // Convert the name, set the actual size.
+ //
+ FileInfo->Size = SingleFileInfoSize;
+ Status = VirtioFsFuseDirentPlusToEfiFileInfo (Dirent, FileInfo);
+ if (EFI_ERROR (Status)) {
+ return Status;
+ }
+ //
+ // Populate the scalar fields.
+ //
+ Status = VirtioFsFuseAttrToEfiFileInfo (&Dirent->AttrResp, FileInfo);
+ return Status;
+}
+
+/**
+ Refill the EFI_FILE_INFO cache from the directory stream.
+**/
+STATIC
+EFI_STATUS
+RefillFileInfoCache (
+ IN OUT VIRTIO_FS_FILE *VirtioFsFile
+ )
+{
+ VIRTIO_FS *VirtioFs;
+ EFI_STATUS Status;
+ VIRTIO_FS_FUSE_STATFS_RESPONSE FilesysAttr;
+ UINT32 DirentBufSize;
+ UINT8 *DirentBuf;
+ UINTN SingleFileInfoSize;
+ UINT8 *FileInfoArray;
+ UINT64 DirStreamCookie;
+ UINT64 CacheEndsAtCookie;
+ UINTN NumFileInfo;
+
+ //
+ // Allocate a DirentBuf that can receive at least
+ // VIRTIO_FS_FILE_MAX_FILE_INFO directory entries, based on the maximum
+ // filename length supported by the filesystem. Note that the multiplication
+ // is safe from overflow due to the VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE_SIZE()
+ // check.
+ //
+ VirtioFs = VirtioFsFile->OwnerFs;
+ Status = VirtioFsFuseStatFs (VirtioFs, VirtioFsFile->NodeId, &FilesysAttr);
+ if (EFI_ERROR (Status)) {
+ return Status;
+ }
+ DirentBufSize = (UINT32)VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE_SIZE (
+ FilesysAttr.Namelen);
+ if (DirentBufSize == 0) {
+ return EFI_UNSUPPORTED;
+ }
+ DirentBufSize *= VIRTIO_FS_FILE_MAX_FILE_INFO;
+ DirentBuf = AllocatePool (DirentBufSize);
+ if (DirentBuf == NULL) {
+ return EFI_OUT_OF_RESOURCES;
+ }
+
+ //
+ // Allocate the EFI_FILE_INFO cache. A single EFI_FILE_INFO element is sized
+ // accordingly to the maximum filename length supported by the filesystem.
+ //
+ // Note that the calculation below cannot overflow, due to the filename limit
+ // imposed by the VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE_SIZE() check above. The
+ // calculation takes the L'\0' character that we'll need to append into
+ // account.
+ //
+ SingleFileInfoSize = (OFFSET_OF (EFI_FILE_INFO, FileName) +
+ ((UINTN)FilesysAttr.Namelen + 1) * sizeof (CHAR16));
+ FileInfoArray = AllocatePool (
+ VIRTIO_FS_FILE_MAX_FILE_INFO * SingleFileInfoSize
+ );
+ if (FileInfoArray == NULL) {
+ Status = EFI_OUT_OF_RESOURCES;
+ goto FreeDirentBuf;
+ }
+
+ //
+ // Pick up reading the directory stream where the previous cache ended.
+ //
+ DirStreamCookie = VirtioFsFile->FilePosition;
+ CacheEndsAtCookie = VirtioFsFile->FilePosition;
+ NumFileInfo = 0;
+ do {
+ UINT32 Remaining;
+ UINT32 Consumed;
+
+ //
+ // Fetch a chunk of the directory stream. The chunk may hold more entries
+ // than what we can fit in the cache. The chunk may also not entirely fill
+ // the cache, especially after filtering out entries that cannot be
+ // supported under UEFI (sockets, FIFOs, filenames with backslashes, etc).
+ //
+ Remaining = DirentBufSize;
+ Status = VirtioFsFuseReadFileOrDir (
+ VirtioFs,
+ VirtioFsFile->NodeId,
+ VirtioFsFile->FuseHandle,
+ TRUE, // IsDir
+ DirStreamCookie, // Offset
+ &Remaining, // Size
+ DirentBuf // Data
+ );
+ if (EFI_ERROR (Status)) {
+ goto FreeFileInfoArray;
+ }
+
+ if (Remaining == 0) {
+ //
+ // The directory stream ends.
+ //
+ break;
+ }
+
+ //
+ // Iterate over all records in DirentBuf. Primarily, forget them all.
+ // Secondarily, if a record proves transformable to EFI_FILE_INFO, add it
+ // to the EFI_FILE_INFO cache (unless the cache is full).
+ //
+ Consumed = 0;
+ while (Remaining >= sizeof (VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE)) {
+ VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE *Dirent;
+ UINT32 DirentSize;
+
+ Dirent = (VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE *)(DirentBuf + Consumed);
+ DirentSize = (UINT32)VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE_SIZE (
+ Dirent->Namelen);
+ if (DirentSize == 0) {
+ //
+ // This means one of two things: (a) Dirent->Namelen is zero, or (b)
+ // (b) Dirent->Namelen is unsupportably large. (a) is just invalid for
+ // the Virtio Filesystem device to send, while (b) shouldn't happen
+ // because "FilesysAttr.Namelen" -- the maximum filename length
+ // supported by the filesystem -- proved acceptable above.
+ //
+ Status = EFI_PROTOCOL_ERROR;
+ goto FreeFileInfoArray;
+ }
+ if (DirentSize > Remaining) {
+ //
+ // Dirent->Namelen suggests that the filename byte array (plus any
+ // padding) are truncated. This should never happen; the Virtio
+ // Filesystem device is supposed to send complete entries only.
+ //
+ Status = EFI_PROTOCOL_ERROR;
+ goto FreeFileInfoArray;
+ }
+ if (Dirent->Namelen > FilesysAttr.Namelen) {
+ //
+ // This is possible without tripping the truncation check above, due to
+ // how entries are padded. The condition means that Dirent->Namelen is
+ // reportedly larger than the filesystem limit, without spilling into
+ // the next alignment bucket. Should never happen.
+ //
+ Status = EFI_PROTOCOL_ERROR;
+ goto FreeFileInfoArray;
+ }
+
+ //
+ // If we haven't filled the EFI_FILE_INFO cache yet, attempt transforming
+ // Dirent to EFI_FILE_INFO.
+ //
+ if (NumFileInfo < VIRTIO_FS_FILE_MAX_FILE_INFO) {
+ EFI_FILE_INFO *FileInfo;
+
+ FileInfo = (EFI_FILE_INFO *)(FileInfoArray +
+ (NumFileInfo * SingleFileInfoSize));
+ Status = PopulateFileInfo (Dirent, SingleFileInfoSize, FileInfo);
+ if (!EFI_ERROR (Status)) {
+ //
+ // Dirent has been transformed and cached successfully.
+ //
+ NumFileInfo++;
+ //
+ // The next time we refill the cache, restart reading the directory
+ // stream right after the entry that we've just transformed and
+ // cached.
+ //
+ CacheEndsAtCookie = Dirent->CookieForNextEntry;
+ }
+ //
+ // If Dirent wasn't transformable to an EFI_FILE_INFO, we'll just skip
+ // it.
+ //
+ }
+
+ //
+ // Make the Virtio Filesystem device forget the NodeId in this directory
+ // entry, as we'll need it no more. (The "." and ".." entries need no
+ // FUSE_FORGET requests, when returned by FUSE_READDIRPLUS -- and so the
+ // Virtio Filesystem device reports their NodeId fields as zero.)
+ //
+ if (Dirent->NodeResp.NodeId != 0) {
+ VirtioFsFuseForget (VirtioFs, Dirent->NodeResp.NodeId);
+ }
+
+ //
+ // Advance to the next entry in DirentBuf.
+ //
+ DirStreamCookie = Dirent->CookieForNextEntry;
+ Consumed += DirentSize;
+ Remaining -= DirentSize;
+ }
+
+ if (Remaining > 0) {
+ //
+ // This suggests that a VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE header was
+ // truncated. This should never happen; the Virtio Filesystem device is
+ // supposed to send complete entries only.
+ //
+ Status = EFI_PROTOCOL_ERROR;
+ goto FreeFileInfoArray;
+ }
+ //
+ // Fetch another DirentBuf from the directory stream, unless we've filled
+ // the EFI_FILE_INFO cache.
+ //
+ } while (NumFileInfo < VIRTIO_FS_FILE_MAX_FILE_INFO);
+
+ //
+ // Commit the results. (Note that the result may be an empty cache.)
+ //
+ if (VirtioFsFile->FileInfoArray != NULL) {
+ FreePool (VirtioFsFile->FileInfoArray);
+ }
+ VirtioFsFile->FileInfoArray = FileInfoArray;
+ VirtioFsFile->SingleFileInfoSize = SingleFileInfoSize;
+ VirtioFsFile->NumFileInfo = NumFileInfo;
+ VirtioFsFile->NextFileInfo = 0;
+ VirtioFsFile->FilePosition = CacheEndsAtCookie;
+
+ FreePool (DirentBuf);
+ return EFI_SUCCESS;
+
+FreeFileInfoArray:
+ FreePool (FileInfoArray);
+
+FreeDirentBuf:
+ FreePool (DirentBuf);
+
+ return Status;
+}
+
+/**
+ Read an entry from the EFI_FILE_INFO cache.
+**/
+STATIC
+EFI_STATUS
+ReadFileInfoCache (
+ IN OUT VIRTIO_FS_FILE *VirtioFsFile,
+ IN OUT UINTN *BufferSize,
+ OUT VOID *Buffer
+ )
+{
+ EFI_FILE_INFO *FileInfo;
+ UINTN CallerAllocated;
+
+ //
+ // Refill the cache if needed. If the refill doesn't produce any new
+ // EFI_FILE_INFO, report End of Directory, by setting (*BufferSize) to 0.
+ //
+ if (VirtioFsFile->NextFileInfo == VirtioFsFile->NumFileInfo) {
+ EFI_STATUS Status;
+
+ Status = RefillFileInfoCache (VirtioFsFile);
+ if (EFI_ERROR (Status)) {
+ return (Status == EFI_BUFFER_TOO_SMALL) ? EFI_DEVICE_ERROR : Status;
+ }
+ if (VirtioFsFile->NumFileInfo == 0) {
+ *BufferSize = 0;
+ return EFI_SUCCESS;
+ }
+ }
+ FileInfo = (EFI_FILE_INFO *)(VirtioFsFile->FileInfoArray +
+ (VirtioFsFile->NextFileInfo *
+ VirtioFsFile->SingleFileInfoSize));
+
+ //
+ // Check if the caller is ready to accept FileInfo. If not, we'll just
+ // present the required size for now.
+ //
+ // (The (UINTN) cast below is safe because FileInfo->Size has been reduced
+ // from VirtioFsFile->SingleFileInfoSize, in
+ //
+ // RefillFileInfoCache()
+ // PopulateFileInfo()
+ // VirtioFsFuseDirentPlusToEfiFileInfo()
+ //
+ // and VirtioFsFile->SingleFileInfoSize was computed from
+ // FilesysAttr.Namelen, which had been accepted by
+ // VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE_SIZE().)
+ //
+ CallerAllocated = *BufferSize;
+ *BufferSize = (UINTN)FileInfo->Size;
+ if (CallerAllocated < *BufferSize) {
+ return EFI_BUFFER_TOO_SMALL;
+ }
+ //
+ // Output FileInfo, and remove it from the cache.
+ //
+ CopyMem (Buffer, FileInfo, *BufferSize);
+ VirtioFsFile->NextFileInfo++;
+ return EFI_SUCCESS;
+}
+
/**
Read from a regular file.
**/
STATIC
EFI_STATUS
ReadRegularFile (
IN OUT VIRTIO_FS_FILE *VirtioFsFile,
IN OUT UINTN *BufferSize,
@@ -80,14 +421,14 @@ VirtioFsSimpleFileRead (
)
{
VIRTIO_FS_FILE *VirtioFsFile;
EFI_STATUS Status;
VirtioFsFile = VIRTIO_FS_FILE_FROM_SIMPLE_FILE (This);
if (VirtioFsFile->IsDirectory) {
- Status = EFI_NO_MEDIA;
+ Status = ReadFileInfoCache (VirtioFsFile, BufferSize, Buffer);
} else {
Status = ReadRegularFile (VirtioFsFile, BufferSize, Buffer);
}
return Status;
}
--
2.19.1.3.g30247aa5d201
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