usr.bin/head/head.c

   1 /*      $NetBSD: head.c,v 1.18 2004/05/04 10:57:42 mrg Exp $    */
   2
   3 /*
   4  * Copyright (c) 1980, 1987, 1992, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #ifndef lint
  34 __COPYRIGHT("@(#) Copyright (c) 1980, 1987, 1992, 1993\
  35  The Regents of the University of California.  All rights reserved.");
  36 #endif /* not lint */
  37
  38 #ifndef lint
  39 #if 0
  40 static char sccsid[] = "@(#)head.c      8.2 (Berkeley) 5/4/95";
  41 #else
  42 __RCSID("$NetBSD: head.c,v 1.18 2004/05/04 10:57:42 mrg Exp $");
  43 #endif
  44 #endif /* not lint */
  45
  46 #include <sys/types.h>
  47
  48 #include <ctype.h>
  49 #include <err.h>
  50 #include <errno.h>
  51 #include <limits.h>
  52 #include <locale.h>
  53 #include <stdio.h>
  54 #include <stdlib.h>
  55 #include <string.h>
  56 #include <unistd.h>
  57
  58 /*
  59  * head - give the first few lines of a stream or of each of a set of files
  60  *
  61  * Bill Joy UCB August 24, 1977
  62  */
  63
  64 void head __P((FILE *, long, long));
  65 void obsolete __P((char *[]));
  66 void usage __P((void));
  67 int main __P((int, char *[]));
  68
  69 int eval = 0;
  70
  71 int
  72 main(argc, argv)
  73         int argc;
  74         char *argv[];
  75 {
  76         int ch;
  77         FILE *fp;
  78         int first;
  79         long linecnt;
  80         long bytecnt;
  81         char *ep;
  82         int qflag = 0;
  83         int vflag = 0;
  84
  85         (void)setlocale(LC_ALL, "");
  86         obsolete(argv);
  87         linecnt = 10;
  88         bytecnt = 0;
  89         while ((ch = getopt(argc, argv, "c:n:qv")) != -1)
  90                 switch(ch) {
  91                 case 'c':
  92                         errno = 0;
  93                         bytecnt = strtol(optarg, &ep, 10);
  94                         if ((bytecnt == LONG_MIN || bytecnt == LONG_MAX) &&
  95                             errno == ERANGE)
  96                                 err(1, "illegal byte count -- %s", optarg);
  97                         else if (*ep || bytecnt <= 0)
  98                                 errx(1, "illegal byte count -- %s", optarg);
  99                         break;
 100
 101                 case 'n':
 102                         errno = 0;
 103                         linecnt = strtol(optarg, &ep, 10);
 104                         if ((linecnt == LONG_MIN || linecnt == LONG_MAX) &&
 105                             errno == ERANGE)
 106                                 err(1, "illegal line count -- %s", optarg);
 107                         else if (*ep || linecnt <= 0)
 108                                 errx(1, "illegal line count -- %s", optarg);
 109                         break;
 110
 111                 case 'q':
 112                         qflag = 1;
 113                         vflag = 0;
 114                         break;
 115
 116                 case 'v':
 117                         qflag = 0;
 118                         vflag = 1;
 119                         break;
 120
 121                 case '?':
 122                 default:
 123                         usage();
 124                 }
 125         argc -= optind;
 126         argv += optind;
 127
 128         if (*argv)
 129                 for (first = 1; *argv; ++argv) {
 130                         if ((fp = fopen(*argv, "r")) == NULL) {
 131                                 warn("%s", *argv);
 132                                 eval = 1;
 133                                 continue;
 134                         }
 135                         if (vflag || (qflag == 0 && argc > 1)) {
 136                                 (void)printf("%s==> %s <==\n",
 137                                     first ? "" : "\n", *argv);
 138                                 first = 0;
 139                         }
 140                         head(fp, linecnt, bytecnt);
 141                         (void)fclose(fp);
 142                 }
 143         else
 144                 head(stdin, linecnt, bytecnt);
 145         exit(eval);
 146 }
 147
 148 void
 149 head(fp, cnt, bytecnt)
 150         FILE *fp;
 151         long cnt;
 152         long bytecnt;
 153 {
 154         int ch;
 155
 156         if (bytecnt)
 157                 cnt = bytecnt;
 158         while (cnt--)
 159                 while ((ch = getc(fp)) != EOF) {
 160                         if (putchar(ch) == EOF)
 161                                 err(1, "stdout");
 162                         if (ch == '\n' || bytecnt)
 163                                 break;
 164                 }
 165 }
 166
 167 void
 168 obsolete(argv)
 169         char *argv[];
 170 {
 171         char *ap;
 172
 173         while ((ap = *++argv)) {
 174                 /* Return if "--" or not "-[0-9]*". */
 175                 if (ap[0] != '-' || ap[1] == '-' ||
 176                     !isdigit((unsigned char)ap[1]))
 177                         return;
 178                 if ((ap = malloc(strlen(*argv) + 2)) == NULL)
 179                         err(1, NULL);
 180                 ap[0] = '-';
 181                 ap[1] = 'n';
 182                 (void)strcpy(ap + 2, *argv + 1);
 183                 *argv = ap;
 184         }
 185 }
 186
 187 void
 188 usage()
 189 {
 190
 191         (void)fprintf(stderr, "usage: %s [-n lines] [file ...]\n",
 192             getprogname());
 193         exit(1);
 194 }