//----------------------------------------------------------------
//	fileview.cpp
//
//	This program displays the contents of a specified file
//	in hexadecimal and ascii formats (including any device 
//	special files representing storage media).  A user may 
//	navigate the file's content using cursor-key commands,
//	or may adjust the format of the hexadecimal display to
//	select from among four data-sizes: byte (B), word (W), 
//	doubleword (D) or quadword (Q).
//
//	compile using:
//		root# g++ -o fileview fileview.cpp -lncurses 
//		root# chmod a+s fileview
//
//	execute using:
//		user$ fileview <filename>
//	e.g., 	user$ fileview /dev/hda
//
//	NOTE: Developed and tested using Linux kernel 2.4.19.
//
//	programmer: ALLAN CRUSE
//	date begun: 25 OCT 2002
//	completion: 26 OCT 2002
//	revised on: 01 NOV 2002 
//----------------------------------------------------------------

#include <curses.h>		// for initscr(), endwin()
#include <string.h>		// for strncpy()
#include <unistd.h>		// for close()
#include <stdlib.h>		// for exit()
#include <fcntl.h>		// for open(), O_RDONLY
#include <sys/types.h>		// for loff_t
#include <linux/unistd.h>	// for _syscall5

#define MAXNAME		79
#define BUFHIGH 	16
#define BUFWIDE		16
#define	BUFSIZE	BUFHIGH*BUFWIDE
#define ROW		5
#define COL		2
#define KEY_RET		10
#define KEY_ESC		27

#define __NR_llseek 	140	// documented in "Linux Internals"

_syscall5(int,llseek,uint,fd,ulong,hi,ulong,lo,loff_t*,result,uint,wh);

loff_t my_llseek( int fd, loff_t where, int whence )
{
	unsigned long	hi = ( where >> 32 );
	unsigned long	lo = ( where >>  0 );
	loff_t		result = ~0;

	llseek( fd, hi, lo, &result, whence );

	return	result;
}

char progname[ ] = "FILEVIEW";
char filename[ 1+MAXNAME ] = "/proc/kcore";
char buffer[ BUFSIZE ];
char outline[ 80 ];

int main( int argc, char **argv )
{
	if ( argc > 1 ) strncpy( filename, argv[1], MAXNAME );
	
	int	fd = open( filename, O_RDONLY );
	if ( fd < 0 ) { perror( "fopen" ); exit(1); }

	loff_t 	filesize = my_llseek( fd, 0LL, SEEK_END );
	loff_t	posmax = my_llseek( fd, -241LL, SEEK_END )&~0xF;
	loff_t	posmin = my_llseek( fd, 0LL, SEEK_SET );
	loff_t	incmax = ( 1LL << 36 );
	loff_t	incmin = ( 1LL <<  8 );

	initscr();
	cbreak();
	noecho();
	keypad( stdscr, TRUE );
	clear();

	int	i, j, k;
	k = ( 77 - strlen( progname ) )/2;
	mvprintw( 0, 35, "%s", progname );
	k = ( 77 - strlen( filename ) )/2;
	mvprintw( 2, k, "\'%s\'", filename );
	char	infomsg[ 80 ];
	sprintf( infomsg,"filesize: %lld (=0x%08llX)", filesize, filesize );
	k = ( 78 - strlen( infomsg ) );
	mvprintw( 23, k, "%s", infomsg );
	refresh();

	loff_t	pageincr = incmin;
	loff_t	lineincr = 16;
	loff_t	format = 1;
	loff_t	position = 0LL;
	while( 1 )
		{	
		for (j = 0; j < BUFSIZE; j++) buffer[ j ] = ~0; 

		if ( pageincr == 0 ) pageincr = incmax;
		else if ( pageincr < incmin ) pageincr = incmin;
		else if ( pageincr > incmax ) pageincr = incmax;
		
		loff_t	location = my_llseek( fd, position, SEEK_SET );
		read( fd, buffer, BUFSIZE );
		
		int	len;
		for (i = 0; i < BUFHIGH; i++)
			{
			len = 0;
			location = position + i*BUFWIDE;
			len += sprintf( outline+len, "%010llX ", location );

			unsigned char		*bp;
			unsigned short		*wp;
			unsigned long		*lp;
			unsigned long long	*qp;

			len += sprintf( outline+len, " " );
			switch( format )
				{
				case 1:
				bp = (unsigned char *)&buffer[ i*BUFWIDE ];
				for (j = 0; j < BUFWIDE; j++)
				len += sprintf(outline+len,"%02X ", bp[j] );
				break;

				case 2:
				wp = (unsigned short *)&buffer[ i*BUFWIDE ];
				for (j = 0; j < BUFWIDE/2; j++)
				len += sprintf(outline+len," %04X ", wp[j] );
				break;

				case 4:
				lp = (unsigned long *)&buffer[ i*BUFWIDE ];
				for (j = 0; j < BUFWIDE/4; j++)
				len += sprintf(outline+len,"  %08X  ",lp[j] );
				break;

				case 8:
				lp = (unsigned long *)&buffer[ i*BUFWIDE ];
				for (j = 0; j < BUFWIDE/4; j+=2)
				len += sprintf(outline+len,"    %08X%08X    ",
						lp[j+1], lp[j] );
				break;
				}

			len += sprintf( outline+len, " " );
			for (j = 0; j < BUFWIDE; j++)
				{
				char	ch = buffer[ i*BUFWIDE + j ];
				if (( ch < 0x20 )||( ch > 0x7E )) ch = '.';
				len += sprintf( outline+len, "%c", ch );
				}			

			mvprintw( ROW+i, COL, "%s", outline ); 
			}
		move( 23, COL );
		refresh();

		int	inch = getch();
		if (( inch == 'x' )||( inch == KEY_ESC )) break;
		mvprintw( 22, COL, "%75s", " " );
		refresh();

		switch( inch )
			{
			case KEY_RIGHT:	pageincr /= 0x10; break;
			case KEY_LEFT:	pageincr *= 0x10; break;
			case KEY_UP:	position -= BUFWIDE; break;
			case KEY_DOWN:	position += BUFWIDE; break;
			case KEY_NPAGE:	position += pageincr; break; 
			case KEY_PPAGE:	position -= pageincr; break; 
			case KEY_HOME:	position = posmin; break; 
			case KEY_END:	position = posmax; break; 

			case 'H': case 'h': position = posmin; break;
			case 'E': case 'e': position = posmax; break;
					
			case 'B': case 'b': 	format = 1; break;
			case 'W': case 'w': 	format = 2; break;
			case 'D': case 'd': 	format = 4; break;
			case 'Q': case 'q': 	format = 8; break;

			case KEY_RET:
				{
				char	inbuf[40];
				mvprintw( 22, COL, "Address: " );
				refresh();
				echo();
				getstr( inbuf );
				noecho();
				sscanf( inbuf, "%x", &position ); 
				position &= ~0xFLL;
				}
				break;
			}
		if ( position < posmin ) position = posmin;
		if ( position > posmax ) position = posmax;



		}

	mvprintw( 24, 0, "%-79s", " " );
	refresh();
	endwin();
	close( fd );
}