/*
dvdimagecmp.

Copyright (C) Jan Panteltje  2002-always

Usage: dvdimagecmp /dev/dvd imagefile

dvdimagecmp 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, or (at your option)
any later version.
  
dvdimagecmp 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 GNU Make; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 
*/



#define VERSION "0.3"

#define _FILE_OFFSET_BITS	64

#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <ctype.h>
#include <time.h>

#define MAX_RETRIES 1
#define BUFFER_SIZE	2048*16
#define DVD_SPEED_1X 11080000

int debug_flag;


char *strsave(char *s) /* save string s somewhere */
{
char *p;

p = malloc(strlen(s) + 1);
if(!p) return 0;
strcpy(p, s);
return p;
} /* end function strsave */


int print_usage()
{
fprintf(stdout, "\
Usage:  dvdimagecmp -a file1 -b file [-d] [-h] [-o offset in file 1] [-p offset in file 2]\n\n\
-d      debug mode, print functuons and arguments.\n\
-h      help (this help)\n\
-a      filename of first input file.\n\
-b      filename of second input file.\n\
-o      offset from start in bytes in first input file (default 0).\n\
-p      offset from start in bytes in second input file (default 0).\n\
");

return 1;
} /* end function print_usage */




int main(int argc, char **argv)
{
int a, c, d, i;
unsigned long long count;
unsigned long long errors;
unsigned long long last_error_position;
int bytes1, bytes2;
unsigned char buffer1[BUFFER_SIZE], buffer2[BUFFER_SIZE];
unsigned char error_buffer1[BUFFER_SIZE], error_buffer2[BUFFER_SIZE];
FILE *fin1;
FILE *fin2;
int error_flag;
int eof_flag;
time_t start_time, stop_time;
int bytes;
double mega_bytes;
double bits_per_second, kilo_bits_per_second;
double speed;
int block_errors;
int retries;
int rerror1, rerror2;
long unsigned defective_blocks;
unsigned long long difference;
unsigned long long block;
off_t offset1, offset2;
char *filename1, *filename2;


/* program identification */
fprintf(stdout, "\nPanteltje (c) dvdimagecmp-%s\n\n", VERSION);

/* defaults */
debug_flag = 0;
offset1 = 0;
offset2 = 0;
filename1 = 0;
filename2 = 0;
/* end defaults */

while(1)
	{
	a = getopt(argc, argv, "a:b:dho:p:");
	if(a == -1) break;

	switch(a)
		{
		case 'a':
			filename1 = strsave(optarg);
			if(! filename1)
				{
				fprintf(stderr, "Could not allocate space for filename1, aborting.\n");

				exit(1);
				}
			break;
		case 'b':
			filename2 = strsave(optarg);
			if(! filename2)
				{
				fprintf(stderr, "Could not allocate space for filename2, aborting.\n");

				exit(1);
				}
			break;
		case 'd':
			debug_flag = 1;
			break;
		case 'h':
			print_usage();
			exit(1);
			break;
		case 'o':
			sscanf(optarg, "%llu", &offset1);
			break;
		case 'p':
			sscanf(optarg, "%llu", &offset2);
			break;
        case -1:
        	break;
		case '?':
			if (isprint(optopt) )
 				{
 				fprintf(stdout, "Unknown option `-%c'.\n", optopt);
 				}
			else
				{
				fprintf(stdout, "Unknown option character `\\x%x'.\n",\
				optopt);
				}
			print_usage();

			exit(1);
			break;			
		default:
			print_usage();

			exit(1);
			break;
		}/* end switch a */
	}/* end while getopt() */


if(debug_flag)
	{
	fprintf(stderr,\
	"filename1=%s filename2=%s offset1=%llu offset2=%llu\n",\
	filename1, filename2, offset1, offset2);
	}

if(! filename1)
	{
	fprintf(stderr, "No filename1 specified, use -a filename, aborting\n");
	
	print_usage();
	exit(1);
	}

if(! filename2)
	{
	fprintf(stderr, "No filename2 specified, use -b filename, aborting\n");
	
	print_usage();
	exit(1);
	}


fin1 = fopen(filename1, "r");
if(! fin1)
	{
	fprintf(stderr, "dvdimagecmp(): could not open first input file %s, aborting.\n", filename1);

	exit(1);
	}

fin2 = fopen(filename2, "r");
if(! fin2)
	{
	fprintf(stderr, "dvdimagecmp(): could not open second input file %s, aborting.\n", filename2);

	exit(1);
	}

if(offset1 != 0)
	{
	errno = 0;
	a = fseeko(fin1, offset1, SEEK_SET);
	if(a == -1)
		{
		perror("seek in file1 ");
		fprintf(stderr, "fseek to offset %llu failed in %s, aborting.\n", (long long int)offset1, filename1);

		exit(1);
		}
	}


if(offset2 != 0)
	{
	errno = 0;
	a = fseeko(fin2, offset2, SEEK_CUR);
	if(a == -1)
		{
		perror("seek in file 2 ");
		fprintf(stderr, "fseek to offset %llu failed in %s, aborting.\n", (long long int)offset2, filename2);

		exit(1);
		}
	}

if(debug_flag)
	{
	fprintf(stderr, "real file1 offset = %llu\n", (unsigned long long) ftello(fin1) );
	fprintf(stderr, "real file2 offset = %llu\n", (unsigned long long) ftello(fin2) );
	}

//exit(1);


bytes = 0;
kilo_bits_per_second = 0;
speed = 0;
block = 0;
last_error_position = 0;
defective_blocks = 0;
retries = 0;
start_time = time(0);
eof_flag = 0;
count = 0;
errors = 0;
while(1)
	{
	bytes1 = fread(buffer1, 1, BUFFER_SIZE, fin1);
	if(ferror(fin1) )
		{
		perror("dvdimagecmp(): fread file 1():");

		break;
		}
	if(feof(fin1) )
		{
		fprintf(stderr, "EOF found in file1 at %llu\n", count);

		eof_flag = 1;
		}

	bytes2 = fread(buffer2, 1, BUFFER_SIZE, fin2);
	if(ferror(fin2) )
		{
		perror("dvdimagecmp(): fread file 2():");

		break;
		}
	if(feof(fin2) )
		{
		fprintf(stderr, "EOF found in file2 at %llu\n", count);

		eof_flag = 1;
		}

	/* total MB */
	mega_bytes = (double)count / 1000000.0;

	/* kbps */
	stop_time = time(0);
	if(stop_time - start_time >= 1)
		{
		if(stop_time - start_time == 1)
			{
			bits_per_second = bytes * 8.0;
			kilo_bits_per_second = bits_per_second / 1000.0;

			speed = bits_per_second / DVD_SPEED_1X;
			}
			
		start_time = stop_time;
		bytes = 0;
		}

	/* progress report to stdout */
	fprintf(stdout,\
"count=%llu (%.2fMB), speed=%.0fkbps (%.2fx) errors=%llu dblocks=%lu %08llx\033[K\r",\
	count, mega_bytes, kilo_bits_per_second, speed,\
	errors, defective_blocks, count);

	if(eof_flag) break;

	block_errors = 0;
	error_flag = 0;
	for(i = 0; i < bytes1; i++)
		{
		c = buffer1[i];
		d = buffer2[i];

		if(c != d)
			{
			if(! error_flag) fprintf(stderr, "\n");
			error_flag = 1;

			/*
			errors to stderr, so we can do
			./dvdimagecmp /dev/dvd /video/dvd_images/dvd_image 2> error-log.txt
			*/

			fprintf(stderr,\
"DIFFERENCE count=%llu  file1=%d (0x%02x)  file2=%d (0x%02x)  errors=%llu i=%d block=%llu\n",\
			count, c, c, d, d, errors, i, block);

			block_errors++;
			errors++;
			}
		count++;
		}

	/*
	since we do not know if it is a read or write error, try same area
	again.
	*/
	if(error_flag)
		{
		fprintf(stderr, "retries=%d read block\n", retries);

		/* if not first read, compare to previous read */
		if(retries != 0)
			{
			rerror1 = 0;
			rerror2 = 0;
			for(i = 0; i < BUFFER_SIZE; i++)
				{
				if(error_buffer1[i] != buffer1[i]) rerror1++;
				if(error_buffer2[i] != buffer2[i]) rerror2++;
				}
			if( (rerror1 == 0) && (rerror2 == 0) )
				{
				difference = count - last_error_position;

				fprintf(stderr, "\n");
				fprintf(stdout, "\n");

				if(last_error_position != 0)
					{			
					fprintf(stderr,\
					"High probability WRITE error!!!!! previous at -%llu\n",\
					 difference);

					fprintf(stdout,\
					"High probability WRITE error!!!!! previous at -%llu\n",\
					difference);
					}
				else
					{
					fprintf(stderr,\
					"High probability WRITE error!!!!!\n");

					fprintf(stdout,\
					"High probability WRITE error!!!!!\n");
					}
				}
			else
				{
				fprintf(stderr, "High probability READ error.\n");
				}
			last_error_position = bytes;
			} /* end if not first retry */

		retries++;
		if(retries < MAX_RETRIES)
			{
			/* move back to beginning of block */
			a = fseek(fin1, -BUFFER_SIZE, SEEK_CUR);
			if(a == -1)
				{
				fprintf(stderr, "fseek to previous block failed in file1.\n");
				exit(1);
				}

			a = fseek(fin2, -BUFFER_SIZE, SEEK_CUR);
			if(a == -1)
				{
				fprintf(stderr, "fseek to previous block failed in file2.\n");
				exit(1);
				}

			/* correct values for reporting */
			bytes -= bytes1;
			count -= bytes1;
			errors -= block_errors;		

			/* store buffers */
			for(i = 0; i < BUFFER_SIZE; i++)
				{
				error_buffer1[i] = buffer1[i];
				error_buffer2[i] = buffer2[i];
				}

			/* try read and compare same block again */
			continue;
			} /* end if les then max retries */

		defective_blocks++;

		/* must be write error, or persistent read error, test next block */
		retries = 0;
		} /* end if error in block */

	block++;
	bytes += bytes1;
	} /* end while read bytes */

fclose(fin1);
fclose(fin2);

fprintf(stderr,\
"\n\nReady, %llu bytes read, %llu errors found, %lu defective blocks\n",\
count, errors, defective_blocks);

if(errors == 0) exit(0);
else exit(1);

} /* end main */