/**
Read data from an open file.
@param[in] This A pointer to the EFI_FILE_PROTOCOL instance that
is the file handle to read data from.
@param[in out] BufferSize On input, the size of the Buffer. On output, the
amount of data returned in Buffer. In both cases,
the size is measured in bytes.
@param[out] Buffer The buffer into which the data is read.
@retval EFI_SUCCESS The data was read.
@retval EFI_DEVICE_ERROR On entry, the current file position is
beyond the end of the file, or the semi-hosting
interface reported an error while performing the
read operation.
@retval EFI_INVALID_PARAMETER At least one of the three input pointers is NULL.
**/
EFI_STATUS
FileRead (
IN EFI_FILE *This,
IN OUT UINTN *BufferSize,
OUT VOID *Buffer
)
{
SEMIHOST_FCB *Fcb;
EFI_STATUS Status;
RETURN_STATUS Return;
if ((This == NULL) || (BufferSize == NULL) || (Buffer == NULL)) {
return EFI_INVALID_PARAMETER;
}
Fcb = SEMIHOST_FCB_FROM_THIS (This);
if (Fcb->IsRoot) {
// The semi-hosting interface does not allow to list files on the host machine.
Status = EFI_UNSUPPORTED;
} else {
Status = EFI_SUCCESS;
if (Fcb->Position >= Fcb->Info.FileSize) {
*BufferSize = 0;
if (Fcb->Position > Fcb->Info.FileSize) {
Status = EFI_DEVICE_ERROR;
}
} else {
Return = SemihostFileRead (Fcb->SemihostHandle, BufferSize, Buffer);
if (RETURN_ERROR (Return)) {
Status = EFI_DEVICE_ERROR;
} else {
Fcb->Position += *BufferSize;
}
}
}
return Status;
}
EFI_STATUS
FileRead (
IN EFI_FILE *File,
IN OUT UINTN *BufferSize,
OUT VOID *Buffer
)
{
SEMIHOST_FCB *Fcb = NULL;
EFI_STATUS Status;
Fcb = SEMIHOST_FCB_FROM_THIS(File);
if (Fcb->IsRoot == TRUE) {
// By design, the Semihosting feature does not allow to list files on the host machine.
Status = EFI_UNSUPPORTED;
} else {
Status = SemihostFileRead (Fcb->SemihostHandle, BufferSize, Buffer);
if (!EFI_ERROR (Status)) {
Fcb->Position += *BufferSize;
}
}
return Status;
}
/**
Worker function that truncate a file specified by its name to a given size.
@param[in] FileName The Null-terminated string of the name of the file to be opened.
@param[in] Size The target size for the file.
@retval EFI_SUCCESS The file was truncated.
@retval EFI_DEVICE_ERROR The last issued semi-hosting operation failed.
**/
STATIC
EFI_STATUS
TruncateFile (
IN CHAR8 *FileName,
IN UINTN Size
)
{
EFI_STATUS Status;
RETURN_STATUS Return;
UINTN FileHandle;
UINT8 *Buffer;
UINTN Remaining;
UINTN Read;
UINTN ToRead;
Status = EFI_DEVICE_ERROR;
FileHandle = 0;
Buffer = NULL;
Return = SemihostFileOpen (
FileName,
SEMIHOST_FILE_MODE_READ | SEMIHOST_FILE_MODE_BINARY,
&FileHandle
);
if (RETURN_ERROR (Return)) {
goto Error;
}
Buffer = AllocatePool (Size);
if (Buffer == NULL) {
Status = EFI_OUT_OF_RESOURCES;
goto Error;
}
Read = 0;
Remaining = Size;
while (Remaining > 0) {
ToRead = Remaining;
Return = SemihostFileRead (FileHandle, &ToRead, Buffer + Read);
if (RETURN_ERROR (Return)) {
goto Error;
}
Remaining -= ToRead;
Read += ToRead;
}
Return = SemihostFileClose (FileHandle);
FileHandle = 0;
if (RETURN_ERROR (Return)) {
goto Error;
}
Return = SemihostFileOpen (
FileName,
SEMIHOST_FILE_MODE_WRITE | SEMIHOST_FILE_MODE_BINARY,
&FileHandle
);
if (RETURN_ERROR (Return)) {
goto Error;
}
if (Size > 0) {
Return = SemihostFileWrite (FileHandle, &Size, Buffer);
if (RETURN_ERROR (Return)) {
goto Error;
}
}
Status = EFI_SUCCESS;
Error:
if (FileHandle != 0) {
SemihostFileClose (FileHandle);
}
if (Buffer != NULL) {
FreePool (Buffer);
}
return (Status);
}
