buf should have been a register

[unix-history] / usr / src / usr.bin / look / look.c

/*
* Copyright (c) 1987 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1987 Regents of the University of California.\n\
All rights reserved.\n";
#endif not lint

#ifndef lint
static char sccsid[] = "@(#)look.c      4.4 (Berkeley) %G%";
#endif not lint

#include <sys/types.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <stdio.h>
#include <ctype.h>

#define EOS             '\0'
#define MAXLINELEN      250
#define YES             1

static int      fold, dict, len;

main(argc, argv)
       int     argc;
       char    **argv;
{
       extern char     *optarg;
       extern int      optind;
       static char     *filename = "/usr/dict/words";
       register off_t  bot, mid, top;
       register int    c;
       struct stat     sb;
       char    entry[MAXLINELEN], copy[MAXLINELEN];

       while ((c = getopt(argc, argv, "df")) != EOF)
               switch((char)c) {
               case 'd':
                       dict = YES;
                       break;
               case 'f':
                       fold = YES;
                       break;
               case '?':
               default:
                       usage();
               }
       argv += optind;
       argc -= optind;

       switch(argc) {
       case 1: /* if nothing set, default to dictionary order and folding */
               if (!dict && !fold)
                       dict = fold = YES;
               break;
       case 2:
               filename = argv[1];
               break;
       default:
               usage();
       }

       if (!freopen(filename, "r", stdin)) {
               fprintf(stderr,"look: can't read %s.\n", filename);
               exit(2);
       }
       if (fstat(fileno(stdin), &sb)) {
               perror("look: fstat");
               exit(2);
       }

       len = strlen(*argv);
       canon(*argv, *argv);
       len = strlen(*argv);            /* may have changed */
       if (len > MAXLINELEN - 1) {
               fputs("look: search string is too long.\n", stderr);
               exit(2);
       }

       for (bot = 0, top = sb.st_size;;) {
               mid = (top + bot) / 2;
               (void)fseek(stdin, mid, L_SET);

               for (++mid; (c = getchar()) != EOF && c != '\n'; ++mid);
               if (!getline(entry))
                       break;
               canon(entry, copy);
               if (strncmp(*argv, copy, len) <= 0) {
                       if (top <= mid)
                               break;
                       top = mid;
               }
               else
                       bot = mid;
       }
       (void)fseek(stdin, bot, L_SET);
       while (ftell(stdin) < top) {
               register int val;

               if (!getline(entry))
                       exit(0);
               canon(entry, copy);
               if (!(val = strncmp(*argv, copy, len))) {
                       puts(entry);
                       break;
               }
               if (val < 0)
                       exit(0);
       }
       while (getline(entry)) {
               canon(entry, copy);
               if (strncmp(*argv, copy, len))
                       break;
               puts(entry);
       }
       exit(0);
}

/*
* getline --
*      get a line
*/
static
getline(buf)
       register char   *buf;
{
       register int    c;

       for (;;) {
               if ((c = getchar()) == EOF)
                       return(0);
               if (c == '\n')
                       break;
               *buf++ = c;
       }
       *buf = EOS;
       return(1);
}

/*
* canon --
*      create canonical version of word
*/
static
canon(src, copy)
       register char   *src, *copy;
{
       register int    cnt;
       register char   c;

       for (cnt = len + 1; (c = *src++) && cnt; --cnt)
               if (!dict || isalnum(c))
                       *copy++ = fold && isupper(c) ? tolower(c) : c;
       *copy = EOS;
}

/*
* usage --
*      print a usage message and die
*/
static
usage()
{
       fputs("usage: look [-df] string [file]\n", stderr);
       exit(1);
}