source: bootcd/isolinux/syslinux-6.03/gpxe/src/core/xfer.c

/*
 * Copyright (C) 2007 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

FILE_LICENCE ( GPL2_OR_LATER );

#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <gpxe/xfer.h>

/** @file
 *
 * Data transfer interfaces
 *
 */

/**
 * Dummy transfer metadata
 *
 * This gets passed to xfer_interface::deliver_iob() and equivalents
 * when no metadata is available.
 */
static struct xfer_metadata dummy_metadata;

/**
 * Close data transfer interface
 *
 * @v xfer              Data transfer interface
 * @v rc                Reason for close
 */
void xfer_close ( struct xfer_interface *xfer, int rc ) {
        struct xfer_interface *dest = xfer_get_dest ( xfer );
        struct xfer_interface_operations *op = xfer->op;

        DBGC ( xfer, "XFER %p->%p close\n", xfer, dest );

        xfer_unplug ( xfer );
        xfer_nullify ( xfer );
        dest->op->close ( dest, rc );
        xfer->op = op;
        xfer_put ( dest );
}

/**
 * Send redirection event
 *
 * @v xfer              Data transfer interface
 * @v type              New location type
 * @v args              Remaining arguments depend upon location type
 * @ret rc              Return status code
 */
int xfer_vredirect ( struct xfer_interface *xfer, int type, va_list args ) {
        struct xfer_interface *dest = xfer_get_dest ( xfer );
        int rc;

        DBGC ( xfer, "XFER %p->%p redirect\n", xfer, dest );

        rc = dest->op->vredirect ( dest, type, args );

        if ( rc != 0 ) {
                DBGC ( xfer, "XFER %p<-%p redirect: %s\n", xfer, dest,
                       strerror ( rc ) );
        }
        xfer_put ( dest );
        return rc;
}

/**
 * Send redirection event
 *
 * @v xfer              Data transfer interface
 * @v type              New location type
 * @v ...               Remaining arguments depend upon location type
 * @ret rc              Return status code
 */
int xfer_redirect ( struct xfer_interface *xfer, int type, ... ) {
        va_list args;
        int rc;

        va_start ( args, type );
        rc = xfer_vredirect ( xfer, type, args );
        va_end ( args );
        return rc;
}

/**
 * Check flow control window
 *
 * @v xfer              Data transfer interface
 * @ret len             Length of window
 */
size_t xfer_window ( struct xfer_interface *xfer ) {
        struct xfer_interface *dest = xfer_get_dest ( xfer );
        size_t len;

        len = dest->op->window ( dest );

        xfer_put ( dest );
        return len;
}

/**
 * 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_get_dest ( xfer );
        struct io_buffer *iobuf;

        DBGC ( xfer, "XFER %p->%p alloc_iob %zd\n", xfer, dest, len );

        iobuf = dest->op->alloc_iob ( dest, len );

        if ( ! iobuf ) {
                DBGC ( xfer, "XFER %p<-%p alloc_iob failed\n", xfer, dest );
        }
        xfer_put ( dest );
        return iobuf;
}

/**
 * Deliver datagram as I/O buffer with metadata
 *
 * @v xfer              Data transfer interface
 * @v iobuf             Datagram I/O buffer
 * @v meta              Data transfer metadata
 * @ret rc              Return status code
 */
int xfer_deliver_iob_meta ( struct xfer_interface *xfer,
                            struct io_buffer *iobuf,
                            struct xfer_metadata *meta ) {
        struct xfer_interface *dest = xfer_get_dest ( xfer );
        int rc;

        DBGC ( xfer, "XFER %p->%p deliver_iob %zd\n", xfer, dest,
               iob_len ( iobuf ) );

        rc = dest->op->deliver_iob ( dest, iobuf, meta );

        if ( rc != 0 ) {
                DBGC ( xfer, "XFER %p<-%p deliver_iob: %s\n", xfer, dest,
                       strerror ( rc ) );
        }
        xfer_put ( dest );
        return rc;
}

/**
 * Deliver datagram as I/O buffer with metadata
 *
 * @v xfer              Data transfer interface
 * @v iobuf             Datagram I/O buffer
 * @ret rc              Return status code
 */
int xfer_deliver_iob ( struct xfer_interface *xfer,
                       struct io_buffer *iobuf ) {
        return xfer_deliver_iob_meta ( xfer, iobuf, &dummy_metadata );
}

/**
 * Deliver datagram as raw data
 *
 * @v xfer              Data transfer interface
 * @v iobuf             Datagram I/O buffer
 * @ret rc              Return status code
 */
int xfer_deliver_raw ( struct xfer_interface *xfer,
                       const void *data, size_t len ) {
        struct xfer_interface *dest = xfer_get_dest ( xfer );
        int rc;

        DBGC ( xfer, "XFER %p->%p deliver_raw %p+%zd\n", xfer, dest,
               data, len );

        rc = dest->op->deliver_raw ( dest, data, len );

        if ( rc != 0 ) {
                DBGC ( xfer, "XFER %p<-%p deliver_raw: %s\n", xfer, dest,
                       strerror ( rc ) );
        }
        xfer_put ( dest );
        return rc;
}

/**
 * Deliver formatted string
 *
 * @v xfer              Data transfer interface
 * @v format            Format string
 * @v args              Arguments corresponding to the format string
 * @ret rc              Return status code
 */
int xfer_vprintf ( struct xfer_interface *xfer, const char *format,
                   va_list args ) {
        size_t len;
        va_list args_tmp;

        va_copy ( args_tmp, args );
        len = vsnprintf ( NULL, 0, format, args );
        {
                char buf[len + 1];
                vsnprintf ( buf, sizeof ( buf ), format, args_tmp );
                va_end ( args_tmp );
                return xfer_deliver_raw ( xfer, buf, len );
        }
}

/**
 * Deliver formatted string
 *
 * @v xfer              Data transfer interface
 * @v format            Format string
 * @v ...               Arguments corresponding to the format string
 * @ret rc              Return status code
 */
int xfer_printf ( struct xfer_interface *xfer, const char *format, ... ) {
        va_list args;
        int rc;

        va_start ( args, format );
        rc = xfer_vprintf ( xfer, format, args );
        va_end ( args );
        return rc;
}

/**
 * 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 io_buffer *iobuf;
        struct xfer_metadata meta = {
                .offset = offset,
                .whence = whence,
        };

        DBGC ( xfer, "XFER %p seek %s+%ld\n", xfer,
               whence_text ( whence ), offset );

        /* Allocate and send a zero-length data buffer */
        iobuf = xfer_alloc_iob ( xfer, 0 );
        if ( ! iobuf )
                return -ENOMEM;
        return xfer_deliver_iob_meta ( xfer, iobuf, &meta );
}

/****************************************************************************
 *
 * Helper methods
 *
 * These functions are designed to be used as methods in the
 * xfer_interface_operations table.
 *
 */

/**
 * Ignore close() event
 *
 * @v xfer              Data transfer interface
 * @v rc                Reason for close
 */
void ignore_xfer_close ( struct xfer_interface *xfer __unused,
                         int rc __unused ) {
        /* Nothing to do */
}

/**
 * Ignore vredirect() event
 *
 * @v xfer              Data transfer interface
 * @v type              New location type
 * @v args              Remaining arguments depend upon location type
 * @ret rc              Return status code
 */
int ignore_xfer_vredirect ( struct xfer_interface *xfer __unused,
                            int type __unused, va_list args __unused ) {
        return 0;
}

/**
 * Unlimited flow control window
 *
 * @v xfer              Data transfer interface
 * @ret len             Length of window
 *
 * This handler indicates that the interface is always ready to accept
 * data.
 */
size_t unlimited_xfer_window ( struct xfer_interface *xfer __unused ) {
        return ~( ( size_t ) 0 );
}

/**
 * No flow control window
 *
 * @v xfer              Data transfer interface
 * @ret len             Length of window
 *
 * This handler indicates that the interface is never ready to accept
 * data.
 */
size_t no_xfer_window ( struct xfer_interface *xfer __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
 *
 * @v xfer              Data transfer interface
 * @v iobuf             Datagram I/O buffer
 * @v meta              Data transfer metadata
 * @ret rc              Return status code
 *
 * This function is intended to be used as the deliver() method for
 * data transfer interfaces that prefer to handle raw data.
 */
int xfer_deliver_as_raw ( struct xfer_interface *xfer,
                          struct io_buffer *iobuf,
                          struct xfer_metadata *meta __unused ) {
        int rc;

        rc = xfer->op->deliver_raw ( xfer, iobuf->data, iob_len ( iobuf ) );
        free_iob ( iobuf );
        return rc;
}

/**
 * Deliver datagram as I/O buffer
 *
 * @v xfer              Data transfer interface
 * @v data              Data buffer
 * @v len               Length of data buffer
 * @ret rc              Return status code
 *
 * 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_iob ( struct xfer_interface *xfer,
                          const void *data, size_t len ) {
        struct io_buffer *iobuf;

        iobuf = xfer->op->alloc_iob ( xfer, len );
        if ( ! iobuf )
                return -ENOMEM;

        memcpy ( iob_put ( iobuf, len ), data, len );
        return xfer->op->deliver_iob ( xfer, iobuf, &dummy_metadata );
}

/**
 * Ignore datagram as raw data event
 *
 * @v xfer              Data transfer interface
 * @v data              Data buffer
 * @v len               Length of data buffer
 * @ret rc              Return status code
 */
int ignore_xfer_deliver_raw ( struct xfer_interface *xfer,
                              const void *data __unused, size_t len ) {
        DBGC ( xfer, "XFER %p %zd bytes delivered %s\n", xfer, len,
               ( ( xfer == &null_xfer ) ?
                 "before connection" : "after termination" ) );
        return 0;
}

/** Null data transfer interface operations */
struct xfer_interface_operations null_xfer_ops = {
        .close          = ignore_xfer_close,
        .vredirect      = ignore_xfer_vredirect,
        .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = ignore_xfer_deliver_raw,
};

/**
 * Null data transfer interface
 *
 * This is the interface to which data transfer interfaces are
 * connected when unplugged.  It will never generate messages, and
 * will silently absorb all received messages.
 */
struct xfer_interface null_xfer = XFER_INIT ( &null_xfer_ops );