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

/*
 * Copyright (C) 2006 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 <stddef.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <assert.h>
#include <libgen.h>
#include <gpxe/list.h>
#include <gpxe/umalloc.h>
#include <gpxe/uri.h>
#include <gpxe/image.h>

/** @file
 *
 * Executable/loadable images
 *
 */

/** List of registered images */
struct list_head images = LIST_HEAD_INIT ( images );

/**
 * Free executable/loadable image
 *
 * @v refcnt            Reference counter
 */
static void free_image ( struct refcnt *refcnt ) {
        struct image *image = container_of ( refcnt, struct image, refcnt );

        uri_put ( image->uri );
        ufree ( image->data );
        image_put ( image->replacement );
        free ( image );
        DBGC ( image, "IMAGE %p freed\n", image );
}

/**
 * Allocate executable/loadable image
 *
 * @ret image           Executable/loadable image
 */
struct image * alloc_image ( void ) {
        struct image *image;

        image = zalloc ( sizeof ( *image ) );
        if ( image ) {
                image->refcnt.free = free_image;
        }
        return image;
}

/**
 * Set image URI
 *
 * @v image             Image
 * @v URI               New image URI
 * @ret rc              Return status code
 *
 * If no name is set, the name will be updated to the base name of the
 * URI path (if any).
 */
int image_set_uri ( struct image *image, struct uri *uri ) {
        const char *path = uri->path;

        /* Replace URI reference */
        uri_put ( image->uri );
        image->uri = uri_get ( uri );

        /* Set name if none already specified */
        if ( path && ( ! image->name[0] ) )
                image_set_name ( image, basename ( ( char * ) path ) );

        return 0;
}

/**
 * Set image command line
 *
 * @v image             Image
 * @v cmdline           New image command line
 * @ret rc              Return status code
 */
int image_set_cmdline ( struct image *image, const char *cmdline ) {
        free ( image->cmdline );
        image->cmdline = strdup ( cmdline );
        if ( ! image->cmdline )
                return -ENOMEM;
        return 0;
}

/**
 * Register executable/loadable image
 *
 * @v image             Executable/loadable image
 * @ret rc              Return status code
 */
int register_image ( struct image *image ) {
        static unsigned int imgindex = 0;

        /* Create image name if it doesn't already have one */
        if ( ! image->name[0] ) {
                snprintf ( image->name, sizeof ( image->name ), "img%d",
                           imgindex++ );
        }

        /* Add to image list */
        image_get ( image );
        list_add_tail ( &image->list, &images );
        DBGC ( image, "IMAGE %p at [%lx,%lx) registered as %s\n",
               image, user_to_phys ( image->data, 0 ),
               user_to_phys ( image->data, image->len ), image->name );

        return 0;
}

/**
 * Unregister executable/loadable image
 *
 * @v image             Executable/loadable image
 */
void unregister_image ( struct image *image ) {
        DBGC ( image, "IMAGE %p unregistered\n", image );
        list_del ( &image->list );
        image_put ( image );
}

/**
 * Find image by name
 *
 * @v name              Image name
 * @ret image           Executable/loadable image, or NULL
 */
struct image * find_image ( const char *name ) {
        struct image *image;

        list_for_each_entry ( image, &images, list ) {
                if ( strcmp ( image->name, name ) == 0 )
                        return image;
        }

        return NULL;
}

/**
 * Load executable/loadable image into memory
 *
 * @v image             Executable/loadable image
 * @v type              Executable/loadable image type
 * @ret rc              Return status code
 */
static int image_load_type ( struct image *image, struct image_type *type ) {
        int rc;

        /* Check image is actually loadable */
        if ( ! type->load )
                return -ENOEXEC;

        /* Try the image loader */
        if ( ( rc = type->load ( image ) ) != 0 ) {
                DBGC ( image, "IMAGE %p could not load as %s: %s\n",
                       image, type->name, strerror ( rc ) );
                return rc;
        }

        /* Flag as loaded */
        image->flags |= IMAGE_LOADED;
        return 0;
}

/**
 * Load executable/loadable image into memory
 *
 * @v image             Executable/loadable image
 * @ret rc              Return status code
 */
int image_load ( struct image *image ) {

        assert ( image->type != NULL );

        return image_load_type ( image, image->type );
}

/**
 * Autodetect image type and load executable/loadable image into memory
 *
 * @v image             Executable/loadable image
 * @ret rc              Return status code
 */
int image_autoload ( struct image *image ) {
        struct image_type *type;
        int rc;

        /* If image already has a type, use it */
        if ( image->type )
                return image_load ( image );

        /* Otherwise probe for a suitable type */
        for_each_table_entry ( type, IMAGE_TYPES ) {
                DBGC ( image, "IMAGE %p trying type %s\n", image, type->name );
                rc = image_load_type ( image, type );
                if ( image->type == NULL )
                        continue;
                return rc;
        }

        DBGC ( image, "IMAGE %p format not recognised\n", image );
        return -ENOEXEC;
}

/**
 * Execute loaded image
 *
 * @v image             Loaded image
 * @ret rc              Return status code
 */
int image_exec ( struct image *image ) {
        struct image *replacement;
        struct uri *old_cwuri;
        int rc;

        /* Image must be loaded first */
        if ( ! ( image->flags & IMAGE_LOADED ) ) {
                DBGC ( image, "IMAGE %p could not execute: not loaded\n",
                       image );
                return -ENOTTY;
        }

        assert ( image->type != NULL );

        /* Check that image is actually executable */
        if ( ! image->type->exec )
                return -ENOEXEC;

        /* Switch current working directory to be that of the image itself */
        old_cwuri = uri_get ( cwuri );
        churi ( image->uri );

        /* Take out a temporary reference to the image.  This allows
         * the image to unregister itself if necessary, without
         * automatically freeing itself.
         */
        image_get ( image );

        /* Try executing the image */
        if ( ( rc = image->type->exec ( image ) ) != 0 ) {
                DBGC ( image, "IMAGE %p could not execute: %s\n",
                       image, strerror ( rc ) );
                /* Do not return yet; we still have clean-up to do */
        }

        /* Pick up replacement image before we drop the original
         * image's temporary reference.
         */
        replacement = image->replacement;

        /* Drop temporary reference to the original image */
        image_put ( image );

        /* Reset current working directory */
        churi ( old_cwuri );
        uri_put ( old_cwuri );

        /* Tail-recurse into replacement image, if one exists */
        if ( replacement ) {
                DBGC ( image, "IMAGE %p replacing self with IMAGE %p\n",
                       image, replacement );
                if ( ( rc = image_exec ( replacement ) ) != 0 )
                        return rc;
        }

        return rc;
}

/**
 * Register and autoload an image
 *
 * @v image             Image
 * @ret rc              Return status code
 */
int register_and_autoload_image ( struct image *image ) {
        int rc;

        if ( ( rc = register_image ( image ) ) != 0 )
                return rc;

        if ( ( rc = image_autoload ( image ) ) != 0 )
                return rc;

        return 0;
}

/**
 * Register and autoexec an image
 *
 * @v image             Image
 * @ret rc              Return status code
 */
int register_and_autoexec_image ( struct image *image ) {
        int rc;

        if ( ( rc = register_and_autoload_image ( image ) ) != 0 )
                return rc;

        if ( ( rc = image_exec ( image ) ) != 0 )
                return rc;

        return 0;
}