Data-transfer interface should now be functionally complete.

src/core/downloader.c

@@ -115,7 +115,7 @@ static void downloader_job_start ( struct job_interface *job ) {
 		container_of ( job, struct downloader, job );
 
 	/* Start data transfer */
-	xfer_start ( &downloader->xfer );
+	xfer_request_all ( &downloader->xfer );
 }
 
 /**
@@ -152,17 +152,30 @@ static struct job_interface_operations downloader_job_operations = {
  * @v pos		New position
  * @ret rc		Return status code
  */
-static int downloader_xfer_seek ( struct xfer_interface *xfer, size_t pos ) {
+static int downloader_xfer_seek ( struct xfer_interface *xfer, off_t offset,
+				  int whence ) {
 	struct downloader *downloader =
 		container_of ( xfer, struct downloader, xfer );
+	off_t new_pos;
 	int rc;
 
-	/* Ensure that we have enough buffer space for this buffer position */
+	/* Calculate new buffer position */
-	if ( ( rc = downloader_ensure_size ( downloader, pos ) ) != 0 )
+	switch ( whence ) {
-		return rc;
+	case SEEK_SET:
+		new_pos = offset;
+		break;
+	case SEEK_CUR:
+		new_pos = ( downloader->pos + offset );
+		break;
+	default:
+		assert ( 0 );
+		return -EINVAL;
+	}
 
-	/* Update current buffer position */
+	/* Ensure that we have enough buffer space for this buffer position */
-	downloader->pos = pos;
+	if ( ( rc = downloader_ensure_size ( downloader, new_pos ) ) != 0 )
+		return rc;
+	downloader->pos = new_pos;
 
 	return 0;
 }
@@ -216,11 +229,11 @@ static void downloader_xfer_close ( struct xfer_interface *xfer, int rc ) {
 
 /** Downloader data transfer interface operations */
 static struct xfer_interface_operations downloader_xfer_operations = {
-	.start		= ignore_xfer_start,
 	.close		= downloader_xfer_close,
-	.vredirect	= default_xfer_vredirect,
+	.vredirect	= vopen,
+	.request	= ignore_xfer_request,
 	.seek		= downloader_xfer_seek,
-	.deliver	= xfer_deliver_as_raw,
+	.deliver_iob	= xfer_deliver_as_raw,
 	.deliver_raw	= downloader_xfer_deliver_raw,
 };
 

src/core/hw.c

@@ -0,0 +1,68 @@
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <gpxe/refcnt.h>
+#include <gpxe/xfer.h>
+#include <gpxe/open.h>
+
+/** @file
+ *
+ * "Hello World" data source
+ *
+ */
+
+struct hw {
+	struct refcnt refcnt;
+	struct xfer_interface xfer;
+};
+
+static const char hw_msg[] = "Hello world!\n";
+
+static void hw_finished ( struct hw *hw, int rc ) {
+	xfer_nullify ( &hw->xfer );
+	xfer_close ( &hw->xfer, rc );
+	ref_put ( &hw->refcnt );
+}
+
+static void hw_xfer_close ( struct xfer_interface *xfer, int rc ) {
+	struct hw *hw = container_of ( xfer, struct hw, xfer );
+
+	hw_finished ( hw, rc );
+}
+
+static int hw_xfer_request ( struct xfer_interface *xfer, off_t start __unused,
+			     int whence __unused, size_t len __unused ) {
+	struct hw *hw = container_of ( xfer, struct hw, xfer );
+
+	xfer_deliver_raw ( xfer, hw_msg, sizeof ( hw_msg ) );
+	hw_finished ( hw, 0 );
+	return 0;
+}
+
+static struct xfer_interface_operations hw_xfer_operations = {
+	.close		= hw_xfer_close,
+	.vredirect	= ignore_xfer_vredirect,
+	.request	= hw_xfer_request,
+	.seek		= ignore_xfer_seek,
+	.deliver_iob	= xfer_deliver_as_raw,
+	.deliver_raw	= ignore_xfer_deliver_raw,
+};
+
+static int hw_open ( struct xfer_interface *xfer, struct uri *uri __unused ) {
+	struct hw *hw;
+
+	hw = malloc ( sizeof ( *hw ) );
+	if ( ! hw )
+		return -ENOMEM;
+	memset ( hw, 0, sizeof ( *hw ) );
+	xfer_init ( &hw->xfer, &hw_xfer_operations, &hw->refcnt );
+
+	xfer_plug_plug ( &hw->xfer, xfer );
+	return 0;
+}
+
+struct uri_opener hw_uri_opener __uri_opener = {
+	.scheme = "hw",
+	.open = hw_open,
+};

src/core/xfer.c

@@ -39,19 +39,6 @@ void xfer_close ( struct xfer_interface *xfer, int rc ) {
 	xfer_unplug ( xfer );
 }
 
-/**
- * Seek to position
- *
- * @v xfer		Data transfer interface
- * @v pos		New position
- * @ret rc		Return status code
- */
-int xfer_seek ( struct xfer_interface *xfer, size_t pos ) {
-	struct xfer_interface *dest = xfer_dest ( xfer );
-
-	return dest->op->seek ( dest, pos );
-}
-
 /**
  * Send redirection event
  *
@@ -84,6 +71,59 @@ int xfer_redirect ( struct xfer_interface *xfer, int type, ... ) {
 	return rc;
 }
 
+/**
+ * Request data
+ *
+ * @v xfer		Data transfer interface
+ * @v offset		Offset to new position
+ * @v whence		Basis for new position
+ * @v len		Length of requested data
+ * @ret rc		Return status code
+ */
+int xfer_request ( struct xfer_interface *xfer, off_t offset, int whence,
+		   size_t len ) {
+	struct xfer_interface *dest = xfer_dest ( xfer );
+
+	return dest->op->request ( dest, offset, whence, len );
+}
+
+/**
+ * Request all data
+ *
+ * @v xfer		Data transfer interface
+ * @ret rc		Return status code
+ */
+int xfer_request_all ( struct xfer_interface *xfer ) {
+	return xfer_request ( xfer, 0, SEEK_SET, ~( ( size_t ) 0 ) );
+}
+
+/**
+ * Seek to position
+ *
+ * @v xfer		Data transfer interface
+ * @v offset		Offset to new position
+ * @v whence		Basis for new position
+ * @ret rc		Return status code
+ */
+int xfer_seek ( struct xfer_interface *xfer, off_t offset, int whence ) {
+	struct xfer_interface *dest = xfer_dest ( xfer );
+
+	return dest->op->seek ( dest, offset, whence );
+}
+
+/**
+ * Allocate I/O buffer
+ *
+ * @v xfer		Data transfer interface
+ * @v len		I/O buffer payload length
+ * @ret iobuf		I/O buffer
+ */
+struct io_buffer * xfer_alloc_iob ( struct xfer_interface *xfer, size_t len ) {
+	struct xfer_interface *dest = xfer_dest ( xfer );
+
+	return dest->op->alloc_iob ( dest, len );
+}
+
 /**
  * Deliver datagram
  *
@@ -91,10 +131,10 @@ int xfer_redirect ( struct xfer_interface *xfer, int type, ... ) {
  * @v iobuf		Datagram I/O buffer
  * @ret rc		Return status code
  */
-int xfer_deliver ( struct xfer_interface *xfer, struct io_buffer *iobuf ) {
+int xfer_deliver_iob ( struct xfer_interface *xfer, struct io_buffer *iobuf ) {
 	struct xfer_interface *dest = xfer_dest ( xfer );
 
-	return dest->op->deliver ( dest, iobuf );
+	return dest->op->deliver_iob ( dest, iobuf );
 }
 
 /**
@@ -120,15 +160,6 @@ int xfer_deliver_raw ( struct xfer_interface *xfer,
  *
  */
 
-/**
- * Ignore start() event
- *
- * @v xfer		Data transfer interface
- */
-void ignore_xfer_start ( struct xfer_interface *xfer __unused ) {
-	/* Nothing to do */
-}
-
 /**
  * Ignore close() event
  *
@@ -153,18 +184,46 @@ int ignore_xfer_vredirect ( struct xfer_interface *xfer __unused,
 	return 0;
 }
 
+/**
+ * Ignore request() event
+ *
+ * @v xfer		Data transfer interface
+ * @v offset		Offset to new position
+ * @v whence		Basis for new position
+ * @v len		Length of requested data
+ * @ret rc		Return status code
+ */
+int ignore_xfer_request ( struct xfer_interface *xfer __unused,
+			  off_t offset __unused, int whence __unused, 
+			  size_t len __unused ) {
+	return 0;
+}
+
 /**
  * Ignore seek() event
  *
  * @v xfer		Data transfer interface
- * @v pos		New position
+ * @v offset		Offset to new position
+ * @v whence		Basis for new position
  * @ret rc		Return status code
  */
 int ignore_xfer_seek ( struct xfer_interface *xfer __unused,
-		       size_t pos __unused ) {
+		       off_t offset __unused, int whence __unused ) {
 	return 0;
 }
 
+/**
+ * Allocate I/O buffer
+ *
+ * @v xfer		Data transfer interface
+ * @v len		I/O buffer payload length
+ * @ret iobuf		I/O buffer
+ */
+struct io_buffer *
+default_xfer_alloc_iob ( struct xfer_interface *xfer __unused, size_t len ) {
+	return alloc_iob ( len );
+}
+
 /**
  * Deliver datagram as raw data
  *
@@ -195,16 +254,16 @@ int xfer_deliver_as_raw ( struct xfer_interface *xfer,
  * This function is intended to be used as the deliver_raw() method
  * for data transfer interfaces that prefer to handle I/O buffers.
  */
-int xfer_deliver_as_iobuf ( struct xfer_interface *xfer,
+int xfer_deliver_as_iob ( struct xfer_interface *xfer,
 			  const void *data, size_t len ) {
 	struct io_buffer *iobuf;
 
-	iobuf = alloc_iob ( len );
+	iobuf = xfer->op->alloc_iob ( xfer, len );
 	if ( ! iobuf )
 		return -ENOMEM;
 
 	memcpy ( iob_put ( iobuf, len ), data, len );
-	return xfer->op->deliver ( xfer, iobuf );
+	return xfer->op->deliver_iob ( xfer, iobuf );
 }
 
 /**
@@ -225,11 +284,12 @@ int ignore_xfer_deliver_raw ( struct xfer_interface *xfer,
 
 /** Null data transfer interface operations */
 struct xfer_interface_operations null_xfer_ops = {
-	.start		= ignore_xfer_start,
 	.close		= ignore_xfer_close,
 	.vredirect	= ignore_xfer_vredirect,
+	.request	= ignore_xfer_request,
 	.seek		= ignore_xfer_seek,
-	.deliver	= xfer_deliver_as_raw,
+	.alloc_iob	= default_xfer_alloc_iob,
+	.deliver_iob	= xfer_deliver_as_raw,
 	.deliver_raw	= ignore_xfer_deliver_raw,
 };
 

src/include/gpxe/xfer.h

@@ -16,22 +16,6 @@ struct xfer_interface;
 
 /** Data transfer interface operations */
 struct xfer_interface_operations {
-
-	/* Missing features:
-	 *
-	 * notification of non-close status - e.g. connected/opened, ...
-	 *
-	 * prompt for data delivery
-	 *
-	 * I/O buffer preparation
-	 *
-	 */
-
-	/** Start data transfer
-	 *
-	 * @v xfer		Data transfer interface
-	 */
-	void ( * start ) ( struct xfer_interface *xfer );
 	/** Close interface
 	 *
 	 * @v xfer		Data transfer interface
@@ -47,14 +31,39 @@ struct xfer_interface_operations {
 	 */
 	int ( * vredirect ) ( struct xfer_interface *xfer, int type,
 			      va_list args );
+	/** Request data
+	 *
+	 * @v xfer		Data transfer interface
+	 * @v offset		Offset to new position
+	 * @v whence		Basis for new position
+	 * @v len		Length of requested data
+	 * @ret rc		Return status code
+	 */
+	int ( * request ) ( struct xfer_interface *xfer, off_t offset,
+			    int whence, size_t len );
 	/** Seek to position
 	 *
 	 * @v xfer		Data transfer interface
-	 * @v pos		New position
+	 * @v offset		Offset to new position
+	 * @v whence		Basis for new position
 	 * @ret rc		Return status code
+	 *
+	 * @c whence must be one of @c SEEK_SET or @c SEEK_CUR.  A
+	 * successful return indicates that the interface is ready to
+	 * immediately accept datagrams; return -EAGAIN if this is not
+	 * the case.
 	 */
-	int ( * seek ) ( struct xfer_interface *xfer, size_t pos );
+	int ( * seek ) ( struct xfer_interface *xfer, off_t offset,
-	/** Deliver datagram
+			 int whence );
+	/** Allocate I/O buffer
+	 *
+	 * @v xfer		Data transfer interface
+	 * @v len		I/O buffer payload length
+	 * @ret iobuf		I/O buffer
+	 */
+	struct io_buffer * ( * alloc_iob ) ( struct xfer_interface *xfer,
+					     size_t len );
+	/** Deliver datagram as I/O buffer
 	 *
 	 * @v xfer		Data transfer interface
 	 * @v iobuf		Datagram I/O buffer
@@ -63,8 +72,12 @@ struct xfer_interface_operations {
 	 * A data transfer interface that wishes to support only raw
 	 * data delivery should set this method to
 	 * xfer_deliver_as_raw().
+	 *
+	 * Interfaces may not temporarily refuse to accept data by
+	 * returning -EAGAIN; such a response may be treated as a
+	 * fatal error.
 	 */
-	int ( * deliver ) ( struct xfer_interface *xfer,
+	int ( * deliver_iob ) ( struct xfer_interface *xfer,
 				struct io_buffer *iobuf );
 	/** Deliver datagram as raw data
 	 *
@@ -75,7 +88,11 @@ struct xfer_interface_operations {
 	 *
 	 * A data transfer interface that wishes to support only I/O
 	 * buffer delivery should set this method to
-	 * xfer_deliver_as_iobuf().
+	 * xfer_deliver_as_iob().
+	 *
+	 * Interfaces may not temporarily refuse to accept data by
+	 * returning -EAGAIN; such a response may be treated as a
+	 * fatal error.
 	 */
 	int ( * deliver_raw ) ( struct xfer_interface *xfer,
 				const void *data, size_t len );
@@ -89,30 +106,42 @@ struct xfer_interface {
 	struct xfer_interface_operations *op;
 };
 
+/** Basis positions for seek() events */
+enum seek_whence {
+	SEEK_SET = 0,
+	SEEK_CUR,
+};
+
 extern struct xfer_interface null_xfer;
 extern struct xfer_interface_operations null_xfer_ops;
 
-extern void xfer_start ( struct xfer_interface *xfer );
 extern void xfer_close ( struct xfer_interface *xfer, int rc );
-extern int xfer_seek ( struct xfer_interface *xfer, size_t pos );
 extern int xfer_vredirect ( struct xfer_interface *xfer, int type,
 			    va_list args );
 extern int xfer_redirect ( struct xfer_interface *xfer, int type, ... );
-extern int xfer_deliver ( struct xfer_interface *xfer,
+extern int xfer_request ( struct xfer_interface *xfer, off_t offset,
+			  int whence, size_t len );
+extern int xfer_request_all ( struct xfer_interface *xfer );
+extern int xfer_seek ( struct xfer_interface *xfer, off_t offset, int whence );
+extern struct io_buffer * xfer_alloc_iob ( struct xfer_interface *xfer,
+					   size_t len );
+extern int xfer_deliver_iob ( struct xfer_interface *xfer,
 			      struct io_buffer *iobuf );
 extern int xfer_deliver_raw ( struct xfer_interface *xfer,
 			      const void *data, size_t len );
 
-extern void ignore_xfer_start ( struct xfer_interface *xfer );
 extern void ignore_xfer_close ( struct xfer_interface *xfer, int rc );
 extern int ignore_xfer_vredirect ( struct xfer_interface *xfer,
 				   int type, va_list args );
-extern int default_xfer_vredirect ( struct xfer_interface *xfer,
+extern int ignore_xfer_request ( struct xfer_interface *xfer, off_t offset,
-				    int type, va_list args );
+				 int whence, size_t len );
-extern int ignore_xfer_seek ( struct xfer_interface *xfer, size_t pos );
+extern int ignore_xfer_seek ( struct xfer_interface *xfer, off_t offset,
+			      int whence );
+extern struct io_buffer * default_xfer_alloc_iob ( struct xfer_interface *xfer,
+						   size_t len );
 extern int xfer_deliver_as_raw ( struct xfer_interface *xfer,
 				 struct io_buffer *iobuf );
-extern int xfer_deliver_as_iobuf ( struct xfer_interface *xfer,
+extern int xfer_deliver_as_iob ( struct xfer_interface *xfer,
 				 const void *data, size_t len );
 extern int ignore_xfer_deliver_raw ( struct xfer_interface *xfer,
 				     const void *data __unused, size_t len );