BSD 2 development

[unix-history] / src / cr3.c

/* Copyright (c) 1979 Regents of the University of California */
#include <retrofit.h>
#include <stdio.h>
#include <sgtty.h>
/*
* cr3 - simulate chuck haley's cr3
* Bill Joy UCB July 1, 1977
*
* This filter simulates chuck haleys cr3,
* stopping output after each page (22 lines) to wait for
* a carriage return, sending 22 more lines, or a EOF, sending 10 more lines.
*
* Typing in a positive number will cause that many lines to be sent,
* a negative number that many lines to be skipped.
*/

struct  sgttyb otty, ntty;
int     left, nxtleft, onintr();
char    ch;
char    obuf[BUFSIZ];

main(argc, argv)
       int argc;
       char *argv[];
{
       register c;
       FILE *f;

       setbuf(stdout, obuf);
       gtty(1, &otty);
       gtty(1, &ntty);
       ntty.sg_flags &= ~ECHO;
       signal(2, onintr);
       stty(1, &ntty);
       left = 23;
       argc--;
       argv++;
       f = stdin;
       do {
               if (argc > 0) {
                       close(0);
                       if ((f=fopen(argv[0], "r")) == NULL) {
                               fflush(stdout);
                               perror(argv[0]);
                               fflush(stdout);
                               onintr();
                       }
                       argc--;
                       argv++;
               }
               for (;;) {
                       c = getc(f);
                       if (c == -1)
                               break;
                       if (left < 0) {
                               left++;
                               if (left == 0)
                                       left = nxtleft;
                       } else {
                               left--;
                               if (left == 0) {
                                       fflush(stdout);
                                       getleft();
                               }
                       }
                       if (left > 0)
                               putchar(c);
                       while (c != '\n') {
                               c = getc(f);
                               if (c == -1)
                                       goto endfile;
                               if (left > 0)
                                       putchar(c);
                       }
                       fflush(stdout);
               }
endfile:
               fflush(stdout);
       } while (argc > 0);
       stty(1, &otty);
       exit(0);
}

onintr()
{

       signal(2, 1);
       stty(1, &otty);
       exit(1);
}

getleft()
{
       int i;

       i = number();
       if (i == 0) {
               left = 22;
               return;
       }
       left = i;
       if (i < 0) {
               if (ch == '\n')
                       nxtleft = 11;
               else {
                       i = number();
                       nxtleft = i == 0 ? 11 : i;
               }
       }
}

char ch;

number()
{
       int i, sign;

       i = 0;
       sign = 0;
       while (read(2, &ch, 1) == 1) {
               switch (ch) {
                       case ' ':
                               if (sign == 0)
                                       continue;
                       case '\n':
                               return (i * sign);
                       case '-':
                               sign = -1;
                               continue;
                       default:
                               if (ch < '0' || ch > '9')
                                       continue;
                               i *= 10;
                               i += ch - '0';
                               if (sign == 0)
                                       sign = 1;
                               continue;
               }
       }
       return (11);
}