Extended the public I/O request C API.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34121 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/drivers/io_requests.h

@@ -19,8 +19,14 @@ typedef struct IORequest io_request;
 extern "C" {
 #endif
 
-bool io_request_is_write(const io_request* request);
+bool		io_request_is_write(const io_request* request);
-void notify_io_request(io_request* request, status_t status);
+off_t		io_request_offset(const io_request* request);
+off_t		io_request_length(const io_request* request);
+status_t	read_from_io_request(io_request* request, void* buffer,
+				size_t size);
+status_t	write_to_io_request(io_request* request, const void* buffer,
+				size_t size);
+void		notify_io_request(io_request* request, status_t status);
 
 #ifdef __cplusplus
 }

src/system/kernel/device_manager/io_requests.cpp

@@ -8,6 +8,41 @@
 #include "IORequest.h"
 
 
+// #pragma mark - static helpers
+
+
+status_t
+transfer_io_request_data(io_request* request, void* buffer, size_t size,
+	bool isWrite)
+{
+	if (isWrite != 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->Team(), isWrite);
+		if (error != B_OK)
+			return error;
+	}
+
+	// read/write
+	off_t offset = request->Offset() + request->TransferredBytes();
+	status_t error = isWrite
+		? 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)
 {
@@ -15,9 +50,57 @@ io_request_is_write(const io_request* request)
 }
 
 
+/*!	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);
 }
-