ipxe/src/image/script.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
 *
 * gPXE scripts
 *
 */

#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <gpxe/image.h>

struct image_type script_image_type __image_type ( PROBE_NORMAL );

/**
 * Execute script
 *
 * @v image		Script
 * @ret rc		Return status code
 */
static int script_exec ( struct image *image ) {
	char cmdbuf[256];
	size_t offset = 0;
	size_t remaining;
	size_t len;
	char *eol;
	int rc;

	/* Temporarily de-register image, so that a "boot" command
	 * doesn't throw us into an execution loop.  Hold a reference
	 * to avoid the image's being freed.
	 */
	image_get ( image );
	unregister_image ( image );

	while ( offset < image->len ) {
	
		/* Read up to cmdbuf bytes from script into buffer */
		remaining = ( image->len - offset );
		len = sizeof ( cmdbuf );
		if ( len > remaining )
			len = remaining;
		copy_from_user ( cmdbuf, image->data, offset, len );

		/* Find end of line */
		eol = memchr ( cmdbuf, '\n', sizeof ( cmdbuf ) );
		if ( ! eol )
			eol = memchr ( cmdbuf, '\0', sizeof ( cmdbuf ) );
		if ( ! eol ) {
			DBG ( "Script line too long (max %d bytes)\n",
			      sizeof ( cmdbuf ) );
			rc = -ENOEXEC;
			goto done;
		}

		/* Mark end of line and execute command */
		*eol = '\0';
		DBG ( "$ %s\n", cmdbuf );
		if ( ( rc = system ( cmdbuf ) ) != 0 ) {
			DBG ( "Command \"%s\" exited with status %d\n",
			      cmdbuf, rc );
			goto done;
		}
		
		/* Move to next line */
		offset += ( ( eol - cmdbuf ) + 1 );
	}

	rc = 0;
 done:
	/* Re-register image and return */
	register_image ( image );
	image_put ( image );
	return rc;
}

/**
 * Load script into memory
 *
 * @v image		Script
 * @ret rc		Return status code
 */
static int script_load ( struct image *image ) {
	static const char magic[] = "#!gpxe\n";
	char test[ sizeof ( magic ) - 1 ];

	/* Check for magic signature */
	copy_from_user ( test, image->data, 0, sizeof ( test ) );
	if ( memcmp ( test, magic, sizeof ( test ) ) != 0 ) {
		DBG ( "Invalid magic signature\n" );
		return -ENOEXEC;
	}

	/* This is a script */
	image->type = &script_image_type;

	/* We don't actually load it anywhere; we will pick the lines
	 * out of the image as we need them.
	 */

	return 0;
}

/** Script image type */
struct image_type script_image_type __image_type ( PROBE_NORMAL ) = {
	.name = "script",
	.load = script_load,
	.exec = script_exec,
};