[block] Add generic block device translator

Add a generic mechanism for providing block devices on top of a data
transfer interface (such as HTTP).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/blocktrans.c

@@ -0,0 +1,261 @@
+/*
+ * Copyright (C) 2015 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 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 );
+
+/**
+ * @file
+ *
+ * Block device translator
+ *
+ */
+
+#include <stdlib.h>
+#include <errno.h>
+#include <assert.h>
+#include <ipxe/iobuf.h>
+#include <ipxe/xfer.h>
+#include <ipxe/blockdev.h>
+#include <ipxe/blocktrans.h>
+
+/**
+ * Reallocate block device translator data buffer
+ *
+ * @v xferbuf		Data transfer buffer
+ * @v len		New length (or zero to free buffer)
+ * @ret rc		Return status code
+ */
+static int blktrans_xferbuf_realloc ( struct xfer_buffer *xferbuf,
+				      size_t len ) {
+	struct block_translator *blktrans =
+		container_of ( xferbuf, struct block_translator, xferbuf );
+
+	/* Record length, if applicable */
+	if ( blktrans->buffer ) {
+
+		/* We have a (non-reallocatable) data buffer */
+		return -ENOTSUP;
+
+	} else {
+
+		/* Record length (for block device capacity) */
+		xferbuf->len = len;
+		return 0;
+	}
+}
+
+/**
+ * Write data to block device translator data buffer
+ *
+ * @v xferbuf		Data transfer buffer
+ * @v offset		Starting offset
+ * @v data		Data to copy
+ * @v len		Length of data
+ */
+static void blktrans_xferbuf_write ( struct xfer_buffer *xferbuf, size_t offset,
+				     const void *data, size_t len ) {
+	struct block_translator *blktrans =
+		container_of ( xferbuf, struct block_translator, xferbuf );
+
+	/* Write data to buffer, if applicable */
+	if ( blktrans->buffer ) {
+
+		/* Write data to buffer */
+		copy_to_user ( blktrans->buffer, offset, data, len );
+
+	} else {
+
+		/* Sanity check */
+		assert ( len == 0 );
+	}
+}
+
+/**
+ * Read data from block device translator data buffer
+ *
+ * @v xferbuf		Data transfer buffer
+ * @v offset		Starting offset
+ * @v data		Data to read
+ * @v len		Length of data
+ */
+static void blktrans_xferbuf_read ( struct xfer_buffer *xferbuf, size_t offset,
+				    void *data, size_t len ) {
+	struct block_translator *blktrans =
+		container_of ( xferbuf, struct block_translator, xferbuf );
+
+	/* Read data from buffer, if applicable */
+	if ( blktrans->buffer ) {
+
+		/* Read data from buffer */
+		copy_from_user ( data, blktrans->buffer, offset, len );
+
+	} else {
+
+		/* Sanity check */
+		assert ( len == 0 );
+	}
+}
+
+/** Block device translator data transfer buffer operations */
+static struct xfer_buffer_operations blktrans_xferbuf_operations = {
+	.realloc = blktrans_xferbuf_realloc,
+	.write = blktrans_xferbuf_write,
+	.read = blktrans_xferbuf_read,
+};
+
+/**
+ * Close block device translator
+ *
+ * @v blktrans		Block device translator
+ * @v rc		Reason for close
+ */
+static void blktrans_close ( struct block_translator *blktrans, int rc ) {
+	struct block_device_capacity capacity;
+
+	/* Report block device capacity, if applicable */
+	if ( ( rc == 0 ) && ( blktrans->blksize ) ) {
+
+		/* Construct block device capacity */
+		capacity.blocks =
+			( blktrans->xferbuf.len / blktrans->blksize );
+		capacity.blksize = blktrans->blksize;
+		capacity.max_count = -1U;
+
+		/* Report block device capacity */
+		block_capacity ( &blktrans->block, &capacity );
+	}
+
+	/* Shut down interfaces */
+	intf_shutdown ( &blktrans->xfer, rc );
+	intf_shutdown ( &blktrans->block, rc );
+}
+
+/**
+ * Deliver data
+ *
+ * @v blktrans		Block device translator
+ * @v iobuf		I/O buffer
+ * @v meta		Data transfer metadata
+ * @ret rc		Return status code
+ */
+static int blktrans_deliver ( struct block_translator *blktrans,
+			      struct io_buffer *iobuf,
+			      struct xfer_metadata *meta ) {
+	int rc;
+
+	/* Deliver to buffer */
+	if ( ( rc = xferbuf_deliver ( &blktrans->xferbuf, iob_disown ( iobuf ),
+				      meta ) ) != 0 ) {
+		DBGC ( blktrans, "BLKTRANS %p could not deliver: %s\n",
+		       blktrans, strerror ( rc ) );
+		goto err;
+	}
+
+	return 0;
+
+ err:
+	blktrans_close ( blktrans, rc );
+	return rc;
+}
+
+/**
+ * Get underlying data transfer buffer
+ *
+ * @v blktrans		Block device translator
+ * @ret xferbuf		Data transfer buffer
+ */
+static struct xfer_buffer *
+blktrans_buffer ( struct block_translator *blktrans ) {
+
+	return &blktrans->xferbuf;
+}
+
+/** Block device translator block device interface operations */
+static struct interface_operation blktrans_block_operations[] = {
+	INTF_OP ( intf_close, struct block_translator *, blktrans_close ),
+};
+
+/** Block device translator block device interface descriptor */
+static struct interface_descriptor blktrans_block_desc =
+	INTF_DESC_PASSTHRU ( struct block_translator, block,
+			     blktrans_block_operations, xfer );
+
+/** Block device translator data transfer interface operations */
+static struct interface_operation blktrans_xfer_operations[] = {
+	INTF_OP ( xfer_deliver, struct block_translator *, blktrans_deliver ),
+	INTF_OP ( xfer_buffer, struct block_translator *, blktrans_buffer ),
+	INTF_OP ( intf_close, struct block_translator *, blktrans_close ),
+};
+
+/** Block device translator data transfer interface descriptor */
+static struct interface_descriptor blktrans_xfer_desc =
+	INTF_DESC_PASSTHRU ( struct block_translator, xfer,
+			     blktrans_xfer_operations, block );
+
+/**
+ * Insert block device translator
+ *
+ * @v block		Block device interface
+ * @v buffer		Data buffer (or UNULL)
+ * @v size		Length of data buffer, or block size
+ * @ret rc		Return status code
+ */
+int block_translate ( struct interface *block, userptr_t buffer, size_t size ) {
+	struct block_translator *blktrans;
+	int rc;
+
+	/* Allocate and initialise structure */
+	blktrans = zalloc ( sizeof ( *blktrans ) );
+	if ( ! blktrans ) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+	ref_init ( &blktrans->refcnt, NULL );
+	intf_init ( &blktrans->block, &blktrans_block_desc, &blktrans->refcnt );
+	intf_init ( &blktrans->xfer, &blktrans_xfer_desc, &blktrans->refcnt );
+	blktrans->xferbuf.op = &blktrans_xferbuf_operations;
+	blktrans->buffer = buffer;
+	if ( buffer ) {
+		blktrans->xferbuf.len = size;
+	} else {
+		blktrans->blksize = size;
+	}
+
+	/* Attach to interfaces, mortalise self, and return */
+	assert ( block->dest != &null_intf );
+	intf_plug_plug ( &blktrans->xfer, block->dest );
+	intf_plug_plug ( &blktrans->block, block );
+	ref_put ( &blktrans->refcnt );
+
+	DBGC2 ( blktrans, "BLKTRANS %p created", blktrans );
+	if ( buffer ) {
+		DBGC2 ( blktrans, " for %#lx+%#zx",
+			user_to_phys ( buffer, 0 ), size );
+	}
+	DBGC2 ( blktrans, "\n" );
+	return 0;
+
+	ref_put ( &blktrans->refcnt );
+ err_alloc:
+	return rc;
+}

src/include/ipxe/blocktrans.h

@@ -0,0 +1,38 @@
+#ifndef _IPXE_BLOCKTRANS_H
+#define _IPXE_BLOCKTRANS_H
+
+/** @file
+ *
+ * Block device translator
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <stdint.h>
+#include <ipxe/refcnt.h>
+#include <ipxe/interface.h>
+#include <ipxe/xferbuf.h>
+#include <ipxe/uaccess.h>
+
+/** A block device translator */
+struct block_translator {
+	/** Reference count */
+	struct refcnt refcnt;
+	/** Block device interface */
+	struct interface block;
+	/** Data transfer interface */
+	struct interface xfer;
+
+	/** Data transfer buffer */
+	struct xfer_buffer xferbuf;
+	/** Data buffer */
+	userptr_t buffer;
+	/** Block size */
+	size_t blksize;
+};
+
+extern int block_translate ( struct interface *block,
+			     userptr_t buffer, size_t size );
+
+#endif /* _IPXE_BLOCKTRANS_H */

src/include/ipxe/errfile.h

@@ -69,6 +69,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define ERRFILE_ansicol		       ( ERRFILE_CORE | 0x001d0000 )
 #define ERRFILE_ansicoldef	       ( ERRFILE_CORE | 0x001e0000 )
 #define ERRFILE_fault		       ( ERRFILE_CORE | 0x001f0000 )
+#define ERRFILE_blocktrans	       ( ERRFILE_CORE | 0x00200000 )
 
 #define ERRFILE_eisa		     ( ERRFILE_DRIVER | 0x00000000 )
 #define ERRFILE_isa		     ( ERRFILE_DRIVER | 0x00010000 )