[edk2-devel] [edk2 PATCH 33/48] OvmfPkg/VirtioFsDxe: implement EFI_FILE_PROTOCOL.Read() for regular files
Laszlo Ersek
lersek at redhat.com
Wed Dec 16 21:11:10 UTC 2020
Using the functions introduced previously, we can now implement
VirtioFsSimpleFileRead(); for regular files at first.
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 | 75 +++++++++++++++++++-
1 file changed, 74 insertions(+), 1 deletion(-)
diff --git a/OvmfPkg/VirtioFsDxe/SimpleFsRead.c b/OvmfPkg/VirtioFsDxe/SimpleFsRead.c
index e737d5e33204..c4ad07c9aec4 100644
--- a/OvmfPkg/VirtioFsDxe/SimpleFsRead.c
+++ b/OvmfPkg/VirtioFsDxe/SimpleFsRead.c
@@ -3,18 +3,91 @@
Copyright (C) 2020, Red Hat, Inc.
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "VirtioFsDxe.h"
+/**
+ Read from a regular file.
+**/
+STATIC
+EFI_STATUS
+ReadRegularFile (
+ IN OUT VIRTIO_FS_FILE *VirtioFsFile,
+ IN OUT UINTN *BufferSize,
+ OUT VOID *Buffer
+ )
+{
+ VIRTIO_FS *VirtioFs;
+ EFI_STATUS Status;
+ VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE FuseAttr;
+ UINTN Transferred;
+ UINTN Left;
+
+ VirtioFs = VirtioFsFile->OwnerFs;
+ //
+ // The UEFI spec forbids reads that start beyond the end of the file.
+ //
+ Status = VirtioFsFuseGetAttr (VirtioFs, VirtioFsFile->NodeId, &FuseAttr);
+ if (EFI_ERROR (Status) || VirtioFsFile->FilePosition > FuseAttr.Size) {
+ return EFI_DEVICE_ERROR;
+ }
+
+ Status = EFI_SUCCESS;
+ Transferred = 0;
+ Left = *BufferSize;
+ while (Left > 0) {
+ UINT32 ReadSize;
+
+ //
+ // FUSE_READ cannot express a >=4GB buffer size.
+ //
+ ReadSize = (UINT32)MIN ((UINTN)MAX_UINT32, Left);
+ Status = VirtioFsFuseReadFileOrDir (
+ VirtioFs,
+ VirtioFsFile->NodeId,
+ VirtioFsFile->FuseHandle,
+ FALSE, // IsDir
+ VirtioFsFile->FilePosition + Transferred,
+ &ReadSize,
+ (UINT8 *)Buffer + Transferred
+ );
+ if (EFI_ERROR (Status) || ReadSize == 0) {
+ break;
+ }
+ Transferred += ReadSize;
+ Left -= ReadSize;
+ }
+
+ *BufferSize = Transferred;
+ VirtioFsFile->FilePosition += Transferred;
+ //
+ // If we managed to read some data, return success. If zero bytes were
+ // transferred due to zero-sized buffer on input or due to EOF on first read,
+ // return SUCCESS. Otherwise, return the error due to which zero bytes were
+ // transferred.
+ //
+ return (Transferred > 0) ? EFI_SUCCESS : Status;
+}
+
EFI_STATUS
EFIAPI
VirtioFsSimpleFileRead (
IN EFI_FILE_PROTOCOL *This,
IN OUT UINTN *BufferSize,
OUT VOID *Buffer
)
{
- return EFI_NO_MEDIA;
+ VIRTIO_FS_FILE *VirtioFsFile;
+ EFI_STATUS Status;
+
+ VirtioFsFile = VIRTIO_FS_FILE_FROM_SIMPLE_FILE (This);
+
+ if (VirtioFsFile->IsDirectory) {
+ Status = EFI_NO_MEDIA;
+ } else {
+ Status = ReadRegularFile (VirtioFsFile, BufferSize, Buffer);
+ }
+ return Status;
}
--
2.19.1.3.g30247aa5d201
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