text: /*
   * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation; either version 2 of the
   * License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   * 02110-1301, USA.
   *
   * You can also choose to distribute this program under the terms of
   * the Unmodified Binary Distribution Licence (as given in the file
   * COPYING.UBDL), provided that you have satisfied its requirements.
   */
  
  FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  
  #include <stdlib.h>
  #include <string.h>
  #include <errno.h>
  #include <ipxe/xfer.h>
  #include <ipxe/iobuf.h>
  #include <ipxe/umalloc.h>
  #include <ipxe/profile.h>
  #include <ipxe/xferbuf.h>
  
  /** @file
   *
   * Data transfer buffer
   *
   */
  
  /** Data delivery profiler */
  static struct profiler xferbuf_deliver_profiler __profiler =
  	{ .name = "xferbuf.deliver" };
  
  /** Data write profiler */
  static struct profiler xferbuf_write_profiler __profiler =
  	{ .name = "xferbuf.write" };
  
  /** Data read profiler */
  static struct profiler xferbuf_read_profiler __profiler =
  	{ .name = "xferbuf.read" };
  
  /**
   * Free data transfer buffer
   *
   * @v xferbuf		Data transfer buffer
   */
  void xferbuf_free ( struct xfer_buffer *xferbuf ) {
  
  	xferbuf->op->realloc ( xferbuf, 0 );
  	xferbuf->len = 0;
  	xferbuf->pos = 0;
  }
  
  /**
   * Ensure that data transfer buffer is large enough for the specified size
   *
   * @v xferbuf		Data transfer buffer
   * @v len		Required minimum size
   * @ret rc		Return status code
   */
  static int xferbuf_ensure_size ( struct xfer_buffer *xferbuf, size_t len ) {
  	int rc;
  
  	/* If buffer is already large enough, do nothing */
  	if ( len <= xferbuf->len )
  		return 0;
  
  	/* Extend buffer */
  	if ( ( rc = xferbuf->op->realloc ( xferbuf, len ) ) != 0 ) {
  		DBGC ( xferbuf, "XFERBUF %p could not extend buffer to "
  		       "%zd bytes: %s\n", xferbuf, len, strerror ( rc ) );
  		return rc;
  	}
  	xferbuf->len = len;
  
  	return 0;
  }
  
  /**
   * Write to data transfer buffer
   *
   * @v xferbuf		Data transfer buffer
   * @v offset		Starting offset
   * @v data		Data to write
   * @v len		Length of data
   */
  int xferbuf_write ( struct xfer_buffer *xferbuf, size_t offset,
  		    const void *data, size_t len ) {
  	size_t max_len;
  	int rc;
  
  	/* Check for overflow */
  	max_len = ( offset + len );
  	if ( max_len < offset )
  		return -EOVERFLOW;
  
  	/* Ensure buffer is large enough to contain this write */
  	if ( ( rc = xferbuf_ensure_size ( xferbuf, max_len ) ) != 0 )
  		return rc;
  
  	/* Copy data to buffer */
  	profile_start ( &xferbuf_write_profiler );
  	xferbuf->op->write ( xferbuf, offset, data, len );
  	profile_stop ( &xferbuf_write_profiler );
  
  	return 0;
  }
  
  /**
   * Read from data transfer buffer
   *
   * @v xferbuf		Data transfer buffer
   * @v offset		Starting offset
   * @v data		Data to write
   * @v len		Length of data
   */
  int xferbuf_read ( struct xfer_buffer *xferbuf, size_t offset,
  		   void *data, size_t len ) {
  
  	/* Check that read is within buffer range */
  	if ( ( offset > xferbuf->len ) ||
  	     ( len > ( xferbuf->len - offset ) ) )
  		return -ENOENT;
  
  	/* Copy data from buffer */
  	profile_start ( &xferbuf_read_profiler );
  	xferbuf->op->read ( xferbuf, offset, data, len );
  	profile_stop ( &xferbuf_read_profiler );
  
  	return 0;
  }
  
  /**
   * Add received data to data transfer buffer
   *
   * @v xferbuf		Data transfer buffer
   * @v iobuf		I/O buffer
   * @v meta		Data transfer metadata
   * @ret rc		Return status code
   */
  int xferbuf_deliver ( struct xfer_buffer *xferbuf, struct io_buffer *iobuf,
  		      struct xfer_metadata *meta ) {
  	size_t len = iob_len ( iobuf );
  	size_t pos;
  	int rc;
  
  	/* Start profiling */
  	profile_start ( &xferbuf_deliver_profiler );
  
  	/* Calculate new buffer position */
  	pos = xferbuf->pos;
  	if ( meta->flags & XFER_FL_ABS_OFFSET )
  		pos = 0;
  	pos += meta->offset;
  
  	/* Write data to buffer */
  	if ( ( rc = xferbuf_write ( xferbuf, pos, iobuf->data, len ) ) != 0 )
  		goto done;
  
  	/* Update current buffer position */
  	xferbuf->pos = ( pos + len );
  
   done:
  	free_iob ( iobuf );
  	profile_stop ( &xferbuf_deliver_profiler );
  	return rc;
  }
  
  /**
   * Reallocate malloc()-based data buffer
   *
   * @v xferbuf		Data transfer buffer
   * @v len		New length (or zero to free buffer)
   * @ret rc		Return status code
   */
  static int xferbuf_malloc_realloc ( struct xfer_buffer *xferbuf, size_t len ) {
  	void *new_data;
  
  	new_data = realloc ( xferbuf->data, len );
  	if ( ! new_data )
  		return -ENOSPC;
  	xferbuf->data = new_data;
  	return 0;
  }
  
  /**
   * Write data to malloc()-based data buffer
   *
   * @v xferbuf		Data transfer buffer
   * @v offset		Starting offset
   * @v data		Data to copy
   * @v len		Length of data
   */
  static void xferbuf_malloc_write ( struct xfer_buffer *xferbuf, size_t offset,
  				   const void *data, size_t len ) {
  
  	memcpy ( ( xferbuf->data + offset ), data, len );
  }
  
  /**
   * Read data from malloc()-based data buffer
   *
   * @v xferbuf		Data transfer buffer
   * @v offset		Starting offset
   * @v data		Data to read
   * @v len		Length of data
   */
  static void xferbuf_malloc_read ( struct xfer_buffer *xferbuf, size_t offset,
  				  void *data, size_t len ) {
  
  	memcpy ( data, ( xferbuf->data + offset ), len );
  }
  
  /** malloc()-based data buffer operations */
  struct xfer_buffer_operations xferbuf_malloc_operations = {
  	.realloc = xferbuf_malloc_realloc,
  	.write = xferbuf_malloc_write,
  	.read = xferbuf_malloc_read,
  };
  
  /**
   * Reallocate umalloc()-based data buffer
   *
   * @v xferbuf		Data transfer buffer
   * @v len		New length (or zero to free buffer)
   * @ret rc		Return status code
   */
  static int xferbuf_umalloc_realloc ( struct xfer_buffer *xferbuf, size_t len ) {
  	userptr_t *udata = xferbuf->data;
  	userptr_t new_udata;
  
  	new_udata = urealloc ( *udata, len );
  	if ( ! new_udata )
  		return -ENOSPC;
  	*udata = new_udata;
  	return 0;
  }
  
  /**
   * Write data to umalloc()-based data buffer
   *
   * @v xferbuf		Data transfer buffer
   * @v offset		Starting offset
   * @v data		Data to copy
   * @v len		Length of data
   */
  static void xferbuf_umalloc_write ( struct xfer_buffer *xferbuf, size_t offset,
  				    const void *data, size_t len ) {
  	userptr_t *udata = xferbuf->data;
  
  	copy_to_user ( *udata, offset, data, len );
  }
  
  /**
   * Read data from umalloc()-based data buffer
   *
   * @v xferbuf		Data transfer buffer
   * @v offset		Starting offset
   * @v data		Data to read
   * @v len		Length of data
   */
  static void xferbuf_umalloc_read ( struct xfer_buffer *xferbuf, size_t offset,
  				   void *data, size_t len ) {
  	userptr_t *udata = xferbuf->data;
  
  	copy_from_user ( data, *udata, offset, len );
  }
  
  /** umalloc()-based data buffer operations */
  struct xfer_buffer_operations xferbuf_umalloc_operations = {
  	.realloc = xferbuf_umalloc_realloc,
  	.write = xferbuf_umalloc_write,
  	.read = xferbuf_umalloc_read,
  };
  
  /**
   * Get underlying data transfer buffer
   *
   * @v interface		Data transfer interface
   * @ret xferbuf		Data transfer buffer, or NULL on error
   *
   * This call will check that the xfer_buffer() handler belongs to the
   * destination interface which also provides xfer_deliver() for this
   * interface.
   *
   * This is done to prevent accidental accesses to a data transfer
   * buffer which may be located behind a non-transparent datapath via a
   * series of pass-through interfaces.
   */
  struct xfer_buffer * xfer_buffer ( struct interface *intf ) {
  	struct interface *dest;
  	xfer_buffer_TYPE ( void * ) *op =
  		intf_get_dest_op ( intf, xfer_buffer, &dest );
  	void *object = intf_object ( dest );
  	struct interface *xfer_deliver_dest;
  	struct xfer_buffer *xferbuf;
  
  	/* Check that this operation is provided by the same interface
  	 * which handles xfer_deliver().
  	 */
  	( void ) intf_get_dest_op ( intf, xfer_deliver, &xfer_deliver_dest );
  
  	if ( op && ( dest == xfer_deliver_dest ) ) {
  		xferbuf = op ( object );
  	} else {
  		/* Default is to not have a data transfer buffer */
  		xferbuf = NULL;
  	}
  
  	intf_put ( xfer_deliver_dest );
  	intf_put ( dest );
  	return xferbuf;
  }
  