/** @file | |
FUSE_READ / FUSE_READDIRPLUS wrapper for the Virtio Filesystem device. | |
Copyright (C) 2020, Red Hat, Inc. | |
SPDX-License-Identifier: BSD-2-Clause-Patent | |
**/ | |
#include "VirtioFsDxe.h" | |
/** | |
Read a chunk from a regular file or a directory stream, by sending the | |
FUSE_READ / FUSE_READDIRPLUS request to the Virtio Filesystem device. | |
The function may only be called after VirtioFsFuseInitSession() returns | |
successfully and before VirtioFsUninit() is called. | |
@param[in,out] VirtioFs The Virtio Filesystem device to send the FUSE_READ | |
or FUSE_READDIRPLUS request to. On output, the FUSE | |
request counter "VirtioFs->RequestId" will have been | |
incremented. | |
@param[in] NodeId The inode number of the regular file or directory | |
stream to read from. | |
@param[in] FuseHandle The open handle to the regular file or directory | |
stream to read from. | |
@param[in] IsDir TRUE if NodeId and FuseHandle refer to a directory, | |
FALSE if NodeId and FuseHandle refer to a regular | |
file. | |
@param[in] Offset If IsDir is FALSE: the absolute file position at | |
which to start reading. | |
If IsDir is TRUE: the directory stream cookie at | |
which to start or continue reading. The zero-valued | |
cookie identifies the start of the directory stream. | |
Further positions in the directory stream can be | |
passed in from the CookieForNextEntry field of | |
VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE. | |
@param[in,out] Size On input, the number of bytes to read. On successful | |
return, the number of bytes actually read, which may | |
be smaller than the value on input. | |
When reading a regular file (i.e., when IsDir is | |
FALSE), EOF can be detected by passing in a nonzero | |
Size, and finding a zero Size on output. | |
When reading a directory stream (i.e., when IsDir is | |
TRUE), Data consists of a sequence of variably-sized | |
records (directory entries). A read operation | |
returns the maximal sequence of records that fits in | |
Size, without having to truncate a record. In order | |
to guarantee progress, call | |
VirtioFsFuseStatFs (VirtioFs, NodeId, | |
&FilesysAttr) | |
first, to learn the maximum Namelen for the | |
directory stream. Then assign Size at least | |
VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE_SIZE ( | |
FilesysAttr.Namelen) | |
on input. (Remember that | |
VIRTIO_FS_FUSE_DIRENTPLUS_RESPONSE_SIZE() may return | |
0 if its Namelen argument is invalid.) EOF can be | |
detected if Size is set on input like described | |
above, and Size is zero on output. | |
@param[out] Data Buffer to read the bytes from the regular file or | |
the directory stream into. The caller is responsible | |
for providing room for (at least) as many bytes in | |
Data as Size is on input. | |
@retval EFI_SUCCESS Read successful. The caller is responsible for checking | |
Size to learn the actual byte count transferred. | |
@return The "errno" value mapped to an EFI_STATUS code, if the | |
Virtio Filesystem device explicitly reported an error. | |
@return Error codes propagated from VirtioFsSgListsValidate(), | |
VirtioFsFuseNewRequest(), VirtioFsSgListsSubmit(), | |
VirtioFsFuseCheckResponse(). | |
**/ | |
EFI_STATUS | |
VirtioFsFuseReadFileOrDir ( | |
IN OUT VIRTIO_FS *VirtioFs, | |
IN UINT64 NodeId, | |
IN UINT64 FuseHandle, | |
IN BOOLEAN IsDir, | |
IN UINT64 Offset, | |
IN OUT UINT32 *Size, | |
OUT VOID *Data | |
) | |
{ | |
VIRTIO_FS_FUSE_REQUEST CommonReq; | |
VIRTIO_FS_FUSE_READ_REQUEST ReadReq; | |
VIRTIO_FS_IO_VECTOR ReqIoVec[2]; | |
VIRTIO_FS_SCATTER_GATHER_LIST ReqSgList; | |
VIRTIO_FS_FUSE_RESPONSE CommonResp; | |
VIRTIO_FS_IO_VECTOR RespIoVec[2]; | |
VIRTIO_FS_SCATTER_GATHER_LIST RespSgList; | |
EFI_STATUS Status; | |
UINTN TailBufferFill; | |
// | |
// Set up the scatter-gather lists. | |
// | |
ReqIoVec[0].Buffer = &CommonReq; | |
ReqIoVec[0].Size = sizeof CommonReq; | |
ReqIoVec[1].Buffer = &ReadReq; | |
ReqIoVec[1].Size = sizeof ReadReq; | |
ReqSgList.IoVec = ReqIoVec; | |
ReqSgList.NumVec = ARRAY_SIZE (ReqIoVec); | |
RespIoVec[0].Buffer = &CommonResp; | |
RespIoVec[0].Size = sizeof CommonResp; | |
RespIoVec[1].Buffer = Data; | |
RespIoVec[1].Size = *Size; | |
RespSgList.IoVec = RespIoVec; | |
RespSgList.NumVec = ARRAY_SIZE (RespIoVec); | |
// | |
// Validate the scatter-gather lists; calculate the total transfer sizes. | |
// | |
Status = VirtioFsSgListsValidate (VirtioFs, &ReqSgList, &RespSgList); | |
if (EFI_ERROR (Status)) { | |
return Status; | |
} | |
// | |
// Populate the common request header. | |
// | |
Status = VirtioFsFuseNewRequest ( | |
VirtioFs, | |
&CommonReq, | |
ReqSgList.TotalSize, | |
IsDir ? VirtioFsFuseOpReadDirPlus : VirtioFsFuseOpRead, | |
NodeId | |
); | |
if (EFI_ERROR (Status)) { | |
return Status; | |
} | |
// | |
// Populate the FUSE_READ- / FUSE_READDIRPLUS-specific fields. | |
// | |
ReadReq.FileHandle = FuseHandle; | |
ReadReq.Offset = Offset; | |
ReadReq.Size = *Size; | |
ReadReq.ReadFlags = 0; | |
ReadReq.LockOwner = 0; | |
ReadReq.Flags = 0; | |
ReadReq.Padding = 0; | |
// | |
// Submit the request. | |
// | |
Status = VirtioFsSgListsSubmit (VirtioFs, &ReqSgList, &RespSgList); | |
if (EFI_ERROR (Status)) { | |
return Status; | |
} | |
// | |
// Verify the response. Note that TailBufferFill is variable. | |
// | |
Status = VirtioFsFuseCheckResponse ( | |
&RespSgList, | |
CommonReq.Unique, | |
&TailBufferFill | |
); | |
if (EFI_ERROR (Status)) { | |
if (Status == EFI_DEVICE_ERROR) { | |
DEBUG (( | |
DEBUG_ERROR, | |
"%a: Label=\"%s\" NodeId=%Lu FuseHandle=%Lu " | |
"IsDir=%d Offset=0x%Lx Size=0x%x Data@%p Errno=%d\n", | |
__func__, | |
VirtioFs->Label, | |
NodeId, | |
FuseHandle, | |
IsDir, | |
Offset, | |
*Size, | |
Data, | |
CommonResp.Error | |
)); | |
Status = VirtioFsErrnoToEfiStatus (CommonResp.Error); | |
} | |
return Status; | |
} | |
// | |
// Report the actual transfer size. | |
// | |
// Integer overflow in the (UINT32) cast below is not possible; the | |
// VIRTIO_FS_SCATTER_GATHER_LIST functions would have caught that. | |
// | |
*Size = (UINT32)TailBufferFill; | |
return EFI_SUCCESS; | |
} |