src/system/kernel/device_manager/io_requests.cpp

   1 /*
   2  * Copyright 2009-2011, Ingo Weinhold, ingo_weinhold@gmx.de.
   3  * Distributed under the terms of the MIT License.
   4  */
   5
   6 #include <io_requests.h>
   7
   8 #include "IORequest.h"
   9
  10
  11 // #pragma mark - static helpers
  12
  13
  14 static status_t
  15 transfer_io_request_data(io_request* request, void* buffer, size_t size,
  16         bool writeToRequest)
  17 {
  18         if (writeToRequest == request->IsWrite()
  19                 || request->RemainingBytes() < size) {
  20                 return B_BAD_VALUE;
  21         }
  22
  23         // lock the request buffer memory, if it is user memory
  24         IOBuffer* ioBuffer = request->Buffer();
  25         if (ioBuffer->IsUser() && !ioBuffer->IsMemoryLocked()) {
  26                 status_t error = ioBuffer->LockMemory(request->TeamID(),
  27                         !writeToRequest);
  28                 if (error != B_OK)
  29                         return error;
  30         }
  31
  32         // read/write
  33         off_t offset = request->Offset() + request->TransferredBytes();
  34         status_t error = writeToRequest
  35                 ? request->CopyData(buffer, offset, size)
  36                 : request->CopyData(offset, buffer, size);
  37         if (error != B_OK)
  38                 return error;
  39
  40         request->Advance(size);
  41         return B_OK;
  42 }
  43
  44
  45 // #pragma mark - public API
  46
  47
  48 /*!     Returns whether the given I/O request is a write request. */
  49 bool
  50 io_request_is_write(const io_request* request)
  51 {
  52         return request->IsWrite();
  53 }
  54
  55
  56 /*!     Returns whether the I/O request has VIP status. */
  57 bool
  58 io_request_is_vip(const io_request* request)
  59 {
  60         return (request->Flags() & B_VIP_IO_REQUEST) != 0;
  61 }
  62
  63
  64 /*!     Returns the read/write offset of the given I/O request.
  65         This is the immutable offset the request was created with;
  66         read_from_io_request() and write_to_io_request() don't change it.
  67 */
  68 off_t
  69 io_request_offset(const io_request* request)
  70 {
  71         return request->Offset();
  72 }
  73
  74
  75 /*!     Returns the read/write length of the given I/O request.
  76         This is the immutable length the request was created with;
  77         read_from_io_request() and write_to_io_request() don't change it.
  78 */
  79 off_t
  80 io_request_length(const io_request* request)
  81 {
  82         return request->Length();
  83 }
  84
  85
  86 /*!     Reads data from the given I/O request into the given buffer and advances
  87         the request's transferred data pointer.
  88         Multiple calls to read_from_io_request() are allowed, but the total size
  89         must not exceed io_request_length(request).
  90 */
  91 status_t
  92 read_from_io_request(io_request* request, void* buffer, size_t size)
  93 {
  94         return transfer_io_request_data(request, buffer, size, false);
  95 }
  96
  97
  98 /*!     Writes data from the given buffer to the given I/O request and advances
  99         the request's transferred data pointer.
 100         Multiple calls to write_to_io_request() are allowed, but the total size
 101         must not exceed io_request_length(request).
 102 */
 103 status_t
 104 write_to_io_request(io_request* request, const void* buffer, size_t size)
 105 {
 106         return transfer_io_request_data(request, (void*)buffer, size, true);
 107 }
 108
 109
 110 /*!     Sets the given I/O request's status and notifies listeners that the request
 111         is finished.
 112 */
 113 void
 114 notify_io_request(io_request* request, status_t status)
 115 {
 116         request->SetStatusAndNotify(status);
 117 }