source: bootcd/isolinux/syslinux-6.03/gpxe/src/arch/i386/image/pxe_image.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 );

/**
 * @file
 *
 * PXE image format
 *
 */

#include <pxe.h>
#include <pxe_call.h>
#include <gpxe/uaccess.h>
#include <gpxe/image.h>
#include <gpxe/segment.h>
#include <gpxe/netdevice.h>
#include <gpxe/features.h>

FEATURE ( FEATURE_IMAGE, "PXE", DHCP_EB_FEATURE_PXE, 1 );

struct image_type pxe_image_type __image_type ( PROBE_PXE );

/**
 * Execute PXE image
 *
 * @v image             PXE image
 * @ret rc              Return status code
 */
static int pxe_exec ( struct image *image ) {
        struct net_device *netdev;
        int rc;

        /* Arbitrarily pick the most recently opened network device */
        if ( ( netdev = last_opened_netdev() ) == NULL ) {
                DBGC ( image, "IMAGE %p could not locate PXE net device\n",
                       image );
                return -ENODEV;
        }

        /* Activate PXE */
        pxe_activate ( netdev );

        /* Start PXE NBP */
        rc = pxe_start_nbp();

        /* Deactivate PXE */
        pxe_deactivate();

        return rc;
}

/**
 * Load PXE image into memory
 *
 * @v image             PXE file
 * @ret rc              Return status code
 */
int pxe_load ( struct image *image ) {
        userptr_t buffer = real_to_user ( 0, 0x7c00 );
        size_t filesz = image->len;
        size_t memsz = image->len;
        int rc;

        /* Images too large to fit in base memory cannot be PXE
         * images.  We include this check to help prevent unrecognised
         * images from being marked as PXE images, since PXE images
         * have no signature we can check against.
         */
        if ( filesz > ( 0xa0000 - 0x7c00 ) )
                return -ENOEXEC;

        /* Rejecting zero-length images is also useful, since these
         * end up looking to the user like bugs in gPXE.
         */
        if ( ! filesz )
                return -ENOEXEC;

        /* There are no signature checks for PXE; we will accept anything */
        if ( ! image->type )
                image->type = &pxe_image_type;

        /* Verify and prepare segment */
        if ( ( rc = prep_segment ( buffer, filesz, memsz ) ) != 0 ) {
                DBGC ( image, "IMAGE %p could not prepare segment: %s\n",
                       image, strerror ( rc ) );
                return rc;
        }

        /* Copy image to segment */
        memcpy_user ( buffer, 0, image->data, 0, filesz );

        return 0;
}

/** PXE image type */
struct image_type pxe_image_type __image_type ( PROBE_PXE ) = {
        .name = "PXE",
        .load = pxe_load,
        .exec = pxe_exec,
};