/* $Id: UWvbiosdump.c,v 1.1 2012/07/06 00:00:09 khorben Exp $ */
/* Copyright (c) 2012 khorben of UberWall <khorben@uberwall.org> */
/* This file is part of UWvbiosdump
 * Video BIOS dumper
 * UberWall security team \../. .\../ */
/* 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, version 3 of the License.
 *
 * 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, see <http://www.gnu.org/licenses/>. */



#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>


/* UWvbiosdump */
/* private */
/* prototypes */
static int _UWvbiosdump(char const * filename);

static int _error(char const * message, int ret);
static int _usage(void);


/* functions */
/* UWvbiosdump */
static int _UWvbiosdump(char const * filename)
{
	int ret = 0;
	FILE * fp;
	int fd;
	size_t base = 0xc0000;
	size_t size;
	char * p;

	/* open /dev/mem */
	fprintf(stderr, "[*] %s\n", "Opening /dev/mem");
	if((fd = open("/dev/mem", O_RDONLY)) < 0)
		return _error("/dev/mem", 1);
	/* obtain the size */
	fprintf(stderr, "[*] %s\n", "Mapping /dev/mem in memory");
	if((p = mmap(0, 32, PROT_READ, MAP_SHARED, fd, base)) == MAP_FAILED)
	{
		close(fd);
		return _error("mmap", 1);
	}
	size = p[2] * 512;
	if(size == 0) /* XXX also bailout if it is too big */
	{
		/* the size is invalid */
		munmap(p, 32);
		close(fd);
		fprintf(stderr, "[!] %s\n", "The Video BIOS is not available");
		return 1;
	}
	fprintf(stderr, "[+] %s%lu\n", "Mapped, size is ", size);
	/* remap to the complete size */
	fprintf(stderr, "[*] %s\n", "Remapping /dev/mem with the new size");
	if((p = mremap(p, 32, p, size, 0)) == MAP_FAILED)
	{
		close(fd);
		return _error("mmap", 1);
	}
	fprintf(stderr, "[+] %s\n", "Remapped /dev/mem");
	/* dump the Video BIOS */
	fprintf(stderr, "[*] %s\n", "Dumping the Video BIOS");
	if(filename == NULL)
		fp = stdout;
	else if((fp = fopen(filename, "wb")) == NULL)
	{
		close(fd);
		return _error(filename, 1);
	}
	if(fwrite(p, size, 1, fp) != 1)
		ret = _error((filename != NULL) ? filename : "stdout", 1);
	else
		fprintf(stderr, "[+] %s\n", "Dumped the Video BIOS");
	/* cleanup */
	if(filename != NULL)
		fclose(fp);
	if(munmap(p, size) != 0)
		ret = _error("/dev/mem", 1);
	close(fd);
	return ret;
}


/* error */
static int _error(char const * message, int ret)
{
	fputs("UWvbiosdump: ", stderr);
	perror(message);
	return ret;
}


/* usage */
static int _usage(void)
{
	fputs("Usage: UWvbiosdump [-o output]\n", stderr);
	return 1;
}


/* public */
/* functions */
/* main */
int main(int argc, char * argv[])
{
	int o;
	char * filename = NULL;

	while((o = getopt(argc, argv, "o:")) != -1)
		switch(o)
		{
			case 'o':
				filename = optarg;
				break;
			default:
				return _usage();
		}
	if(optind != argc)
		return _usage();
	return (_UWvbiosdump(filename) == 0) ? 0 : 2;
}