/*
 * Copyright 2009-2011, Ingo Weinhold, ingo_weinhold@gmx.de.
 * Distributed under the terms of the MIT License.
 */

#include <io_requests.h>

#include "IORequest.h"


// #pragma mark - static helpers


static status_t
transfer_io_request_data(io_request* request, void* buffer, size_t size,
        bool writeToRequest)
{
        if (writeToRequest == request->IsWrite()
                || request->RemainingBytes() < size) {
                return B_BAD_VALUE;
        }

        // lock the request buffer memory, if it is user memory
        IOBuffer* ioBuffer = request->Buffer();
        if (ioBuffer->IsUser() && !ioBuffer->IsMemoryLocked()) {
                status_t error = ioBuffer->LockMemory(request->TeamID(),
                        !writeToRequest);
                if (error != B_OK)
                        return error;
        }

        // read/write
        off_t offset = request->Offset() + request->TransferredBytes();
        status_t error = writeToRequest
                ? request->CopyData(buffer, offset, size)
                : request->CopyData(offset, buffer, size);
        if (error != B_OK)
                return error;

        request->Advance(size);
        return B_OK;
}


// #pragma mark - public API


/*!     Returns whether the given I/O request is a write request. */
bool
io_request_is_write(const io_request* request)
{
        return request->IsWrite();
}


/*!     Returns whether the I/O request has VIP status. */
bool
io_request_is_vip(const io_request* request)
{
        return (request->Flags() & B_VIP_IO_REQUEST) != 0;
}


/*!     Returns the read/write offset of the given I/O request.
        This is the immutable offset the request was created with;
        read_from_io_request() and write_to_io_request() don't change it.
*/
off_t
io_request_offset(const io_request* request)
{
        return request->Offset();
}


/*!     Returns the read/write length of the given I/O request.
        This is the immutable length the request was created with;
        read_from_io_request() and write_to_io_request() don't change it.
*/
off_t
io_request_length(const io_request* request)
{
        return request->Length();
}


/*!     Reads data from the given I/O request into the given buffer and advances
        the request's transferred data pointer.
        Multiple calls to read_from_io_request() are allowed, but the total size
        must not exceed io_request_length(request).
*/
status_t
read_from_io_request(io_request* request, void* buffer, size_t size)
{
        return transfer_io_request_data(request, buffer, size, false);
}


/*!     Writes data from the given buffer to the given I/O request and advances
        the request's transferred data pointer.
        Multiple calls to write_to_io_request() are allowed, but the total size
        must not exceed io_request_length(request).
*/
status_t
write_to_io_request(io_request* request, const void* buffer, size_t size)
{
        return transfer_io_request_data(request, (void*)buffer, size, true);
}


/*!     Sets the given I/O request's status and notifies listeners that the request
        is finished.
*/
void
notify_io_request(io_request* request, status_t status)
{
        request->SetStatusAndNotify(status);
}