efi_cmdline.c

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/*
 * Copyright (C) 2023 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_SECBOOT ( PERMITTED );

/** @file
 *
 * EFI command line
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <ipxe/init.h>
#include <ipxe/image.h>
#include <ipxe/script.h>
#include <ipxe/uaccess.h>
#include <ipxe/efi/efi.h>
#include <ipxe/efi/efi_cmdline.h>

/** EFI command line (may not be wNUL-terminated */
const wchar_t *efi_cmdline;

/** Length of EFI command line (in bytes) */
size_t efi_cmdline_len;

/** Internal copy of the command line */
static char *efi_cmdline_copy;

/**
 * Free command line image
 *
 * @v refcnt            Reference count
 */
static void efi_cmdline_free ( struct refcnt *refcnt ) {
        struct image *image = container_of ( refcnt, struct image, refcnt );

        DBGC ( image, "CMDLINE freeing command line\n" );
        free_image ( refcnt );
        free ( efi_cmdline_copy );
}

/** Embedded script representing the command line */
static struct image efi_cmdline_image = {
        .refcnt = REF_INIT ( efi_cmdline_free ),
        .name = "<CMDLINE>",
        .flags = ( IMAGE_STATIC | IMAGE_STATIC_NAME ),
        .type = &script_image_type,
};

/** Colour for debug messages */
#define colour &efi_cmdline_image

/**
 * Initialise EFI command line
 *
 * @ret rc              Return status code
 */
static int efi_cmdline_init ( void ) {
        char *cmdline;
        size_t len;
        int rc;

        /* Do nothing if no command line was specified */
        if ( ! efi_cmdline_len ) {
                DBGC ( colour, "CMDLINE found no command line\n" );
                return 0;
        }

        /* Allocate ASCII copy of command line */
        len = ( ( efi_cmdline_len / sizeof ( efi_cmdline[0] ) ) + 1 /* NUL */ );
        efi_cmdline_copy = malloc ( len );
        if ( ! efi_cmdline_copy ) {
                rc = -ENOMEM;
                goto err_alloc;
        }
        cmdline = efi_cmdline_copy;
        snprintf ( cmdline, len, "%ls", efi_cmdline );
        DBGC ( colour, "CMDLINE found command line \"%s\"\n", cmdline );

        /* Mark command line as consumed */
        efi_cmdline_len = 0;

        /* Strip image name and surrounding whitespace */
        while ( isspace ( *cmdline ) )
                cmdline++;
        while ( *cmdline && ( ! isspace ( *cmdline ) ) )
                cmdline++;
        while ( isspace ( *cmdline ) )
                cmdline++;
        DBGC ( colour, "CMDLINE using command line \"%s\"\n", cmdline );

        /* Prepare and register image */
        efi_cmdline_image.data = cmdline;
        efi_cmdline_image.len = strlen ( cmdline );
        if ( efi_cmdline_image.len &&
             ( ( rc = register_image ( &efi_cmdline_image ) ) != 0 ) ) {
                DBGC ( colour, "CMDLINE could not register command line: %s\n",
                       strerror ( rc ) );
                goto err_register_image;
        }

        /* Drop our reference to the image */
        image_put ( &efi_cmdline_image );

        return 0;

 err_register_image:
        image_put ( &efi_cmdline_image );
 err_alloc:
        return rc;
}

/**
 * EFI command line startup function
 *
 */
static void efi_cmdline_startup ( void ) {
        int rc;

        /* Initialise command line */
        if ( ( rc = efi_cmdline_init() ) != 0 ) {
                /* No way to report failure */
                return;
        }
}

/** Command line and initrd initialisation function */
struct startup_fn efi_cmdline_startup_fn __startup_fn ( STARTUP_NORMAL ) = {
        .name = "efi_cmdline",
        .startup = efi_cmdline_startup,
};