/* hd.c   by Michael Thorpe   2009-02-01 */

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

#define BUFSIZE 8192
unsigned char buffer[BUFSIZE];
size_t bufstart,bufstop;
int infile=0;
unsigned int breakchar=-1;
unsigned int linelen=16;
unsigned int maxline=16;

/*
 * I wrote a replacement read function for two reasons:
 *   1. I want to flush stdout before calling read(2).
 *   2. stdio usually line-buffers even on a short read.
 */
size_t myread(int fd,void *buf,size_t count) {
	size_t l;

	if(!infile) {
		bufstart=bufstop=0;
		infile=1;
	}
	l=bufstop-bufstart;
	if(l==0) {
		if(bufstart==BUFSIZE)
			bufstart=0;
		fflush(stdout);
		l=read(fd,buffer+bufstart,BUFSIZE-bufstart);
		if(l==-1 || l==0) {
			infile=0;
			return(l);
		}
		bufstop=bufstart+l;
	}
	if(l<count)
		count=l;
	memcpy(buf,buffer+bufstart,count);
	bufstart+=count;
	return(count);
}

int doit(int fd) {
	int done=0;
	size_t j,l=0,linepos=0,semidone=0,semistart=0;
	unsigned char *s;

	s=(unsigned char *)malloc(linelen);
	if(!s) {
		perror("malloc");
		return(1);
	}
	while(!done) {
		j=myread(fd,s+linepos,linelen-linepos);
		if(j==0)
			done=1;
		if(j==-1) {
			j=0;
			done=-1;
		}
		if(j && !linepos)
next_line:
			printf("%8.8ZX: ",l);
		j+=linepos;
		while(linepos<j) {
			if(!(linepos&1))
				putchar(' ');
			printf("%2.2X",s[linepos++]);
			if(linepos<j && breakchar==s[linepos-1]) {
				semistart=linepos;
				semidone=j;
				j=linepos;
			}
		}
		if(maxline<linepos)
			maxline=linepos;
		if(semidone || linepos==linelen || (done && linepos)) {
			while(linepos<maxline) {
				if(++linepos&1)
					putchar(' ');
				putchar(' ');
				putchar(' ');
			}
			putchar(' ');
			putchar(' ');
			for(linepos=0;linepos<j;linepos++) {
				if(isprint(s[linepos]))
					putchar(s[linepos]);
				else
					putchar('.');
			}
			putchar('\n');
			l+=linepos;
			linepos=0;
			if(semidone) {
				j=semidone-semistart;
				memmove(s,s+semistart,j);
				linepos=0;
				semidone=0;
				goto next_line;
			}
		}
	}
	if(done<0) {
		perror("read");
		return(-1);
	}
	return(0);
}

int main(int argc,char **argv) {
	int didone=0,i;
	FILE *f;

	for(i=1;i<argc;i++) {
		if(argv[i][0]=='-') {
			if(argv[i][1]=='\0') {
				didone=1;
				if(doit(0))
					return(1);
			} else if(argv[i][1]=='l' && argv[i][2]=='\0' && (i+1)<argc) {
				linelen=strtoul(argv[++i],0,0);
				if(linelen==0) {
					fprintf(stderr,"Invalid line length\n");
					return(1);
				}
				maxline=linelen;
			} else if(argv[i][1]=='c' && argv[i][2]=='\0' && (i+1)<argc) {
				breakchar=strtoul(argv[++i],0,0);
				if(linelen<BUFSIZE)
					linelen=BUFSIZE;
				maxline=0;
			} else if(argv[i][1]=='c' && argv[i][2] && argv[i][3]=='\0') {
				breakchar=argv[i][2];
				if(linelen<BUFSIZE)
					linelen=BUFSIZE;
				maxline=0;
			} else {
				fprintf(stderr,"usage: %s [-c <breakchar>] [-l <linelen>] [<file1> [<file2>...]]\n",argv[0]);
				return(1);
			}
		} else {
			didone=1;
			f=fopen(argv[i],"rb");
			if(!f)
				fprintf(stderr,"%s: couldn't open %s\n",argv[0],argv[i]);
			else {
				if(doit(fileno(f)))
					return(1);
				if(fclose(f)) {
					perror("close");
					return(1);
				}
			}
		}
	}
	if(!didone)
		if(doit(0))
			return(1);
	return(0);
}