/*
 * $Id: hex.c,v 1.2 2005/11/27 19:58:23 sms Exp $
 * www.pccl.demon.co.uk
 */

#include	<ctype.h>
#include	<errno.h>
#include	<libgen.h>
#include	<stdio.h>
#include	<stdlib.h>
#include	<string.h>
#include	<unistd.h>

#define	LINE_LEN	16
static char	*sProgName;
static int	sOffset;

static void resetDisplay (void)
{
	sOffset	= 0;
}

/*
 * Print out a block of memory as both Hex and text
 */
static void hexPrint (
	  char	*aMsg		/* Message buffer			*/
	, int	aLen		/* Message length			*/
	)
{
	int	lIdx;		/* Index through message		*/

	/*
	 * Print the offset
	 */
	printf ("  %05d: ", sOffset);
	sOffset	+= LINE_LEN;

	/*
	 * The Hex data
	 */
	for (lIdx = 0; lIdx < LINE_LEN; lIdx++)
	{
		if (lIdx < aLen)
		{
			printf ("%02x ", (unsigned char) aMsg[lIdx]);
		}
		else
		{
			printf ("   ");
		}
	}

	printf (" : ");

	/*
	 * The ASCII data
	 */
	for (lIdx = 0; lIdx < LINE_LEN; lIdx++)
	{
		char	lChar	= ' ';

		if (lIdx < aLen)
		{
			lChar	= aMsg[lIdx];
		}
		printf ("%c", (((lChar & 0x80) == 0) && isprint ((int) lChar))
				? lChar : '.'
				);
	}

	printf ("\n");
}

/*
 * Display the usage message
 */
static void usage (
	  FILE	*aFp		/* Stream to write			*/
	)
{
	fprintf (aFp, "USAGE:\n");
	fprintf (aFp, "    %s file...\n", sProgName);
	fprintf (aFp, "        -h    help\n");
	fprintf (aFp, "stdin is used as default\n");
}

/*
 * Display all data from a stream in hex/text.
*/
static void displayFp(
	  FILE	*aFp
	)
{
	char	lBuff [LINE_LEN];	/* Message buffer		*/
	int		lLen;		/* and length			*/

	while ((lLen = fread (lBuff, 1, LINE_LEN, aFp)) > 0)
	{
		hexPrint (lBuff, lLen);
	}
}

/*
 * Display a file in hex/text
 */
static void displayFile(
	  char	*aFile
	)
{
	FILE	*lFp;		/* File handle				*/

	printf ("File: %s\n", aFile);
	lFp	= fopen (aFile, "r");

	resetDisplay ();

	if (lFp != NULL)
	{
		displayFp (lFp);
		fclose (lFp);
	}
	else
	{
		fprintf (stderr
			, "Cannot open %s, %s\n"
			, aFile
			, strerror (errno)
			);
		exit (errno);
	}
}

/*
 * This program dumps out the named files in both hex and ascii.
 */
int main (
	  int	aArgc		/* Argument count			*/
	, char	*aArgv[]	/* Arguments				*/
	)
{
	char	lOpt;		/* Command line option			*/
	int	lArgIdx;	/* Index through command line		*/
	/*
	 * Parse the command line
	 */
	sProgName	= basename (aArgv[0]);

	while ((lOpt = getopt (aArgc, aArgv, "h")) != -1)
	{
		switch (lOpt)
		{
			case 'h':
				usage (stdout);
				exit (EINVAL);
				break;
			case '?':
				fprintf (stderr
					, "Unrecognised option: -%c\n"
					, optopt
					);
				usage (stderr);
				exit (EINVAL);
		}
	}

	/*
	 * Process each file
	 */
	if (optind < aArgc)
	{
		for (lArgIdx = optind; lArgIdx < aArgc; lArgIdx++)
		{
			displayFile (aArgv[lArgIdx]);
		}
	}
	else
	{
		displayFp (stdin);
	}

	exit (0);
}