187 lines
4.7 KiB
C
187 lines
4.7 KiB
C
/*
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* Copyright (c) 1980, 1987, 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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static const char copyright[] =
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"@(#) Copyright (c) 1980, 1987, 1992, 1993\n\
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The Regents of the University of California. All rights reserved.\n";
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#endif /* not lint */
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)head.c 8.2 (Berkeley) 5/4/95";
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#endif
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#endif /* not lint */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/types.h>
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#include <ctype.h>
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#include <err.h>
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#include <inttypes.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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/*
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* head - give the first few lines of a stream or of each of a set of files
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*
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* Bill Joy UCB August 24, 1977
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*/
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static void head(FILE *, int);
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static void head_bytes(FILE *, off_t);
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static void obsolete(char *[]);
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static void usage(void);
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int
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main(int argc, char *argv[])
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{
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int ch;
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FILE *fp;
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int first, linecnt = -1, eval = 0;
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off_t bytecnt = -1;
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char *ep;
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obsolete(argv);
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while ((ch = getopt(argc, argv, "n:c:")) != -1)
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switch(ch) {
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case 'c':
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bytecnt = strtoimax(optarg, &ep, 10);
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if (*ep || bytecnt <= 0)
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errx(1, "illegal byte count -- %s", optarg);
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break;
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case 'n':
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linecnt = strtol(optarg, &ep, 10);
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if (*ep || linecnt <= 0)
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errx(1, "illegal line count -- %s", optarg);
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break;
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case '?':
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default:
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usage();
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}
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argc -= optind;
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argv += optind;
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if (linecnt != -1 && bytecnt != -1)
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errx(1, "can't combine line and byte counts");
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if (linecnt == -1 )
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linecnt = 10;
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if (*argv) {
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for (first = 1; *argv; ++argv) {
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if ((fp = fopen(*argv, "r")) == NULL) {
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warn("%s", *argv);
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eval = 1;
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continue;
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}
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if (argc > 1) {
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(void)printf("%s==> %s <==\n",
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first ? "" : "\n", *argv);
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first = 0;
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}
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if (bytecnt == -1)
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head(fp, linecnt);
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else
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head_bytes(fp, bytecnt);
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(void)fclose(fp);
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}
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} else if (bytecnt == -1)
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head(stdin, linecnt);
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else
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head_bytes(stdin, bytecnt);
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exit(eval);
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}
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static void
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head(FILE *fp, int cnt)
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{
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char *cp;
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size_t error, readlen;
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while (cnt && (cp = fgetln(fp, &readlen)) != NULL) {
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error = fwrite(cp, sizeof(char), readlen, stdout);
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if (error != readlen)
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err(1, "stdout");
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cnt--;
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}
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}
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static void
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head_bytes(FILE *fp, off_t cnt)
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{
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char buf[4096];
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size_t readlen;
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while (cnt) {
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if ((uintmax_t)cnt < sizeof(buf))
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readlen = cnt;
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else
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readlen = sizeof(buf);
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readlen = fread(buf, sizeof(char), readlen, fp);
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if (readlen == 0)
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break;
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if (fwrite(buf, sizeof(char), readlen, stdout) != readlen)
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err(1, "stdout");
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cnt -= readlen;
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}
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}
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static void
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obsolete(char *argv[])
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{
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char *ap;
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while ((ap = *++argv)) {
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/* Return if "--" or not "-[0-9]*". */
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if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1]))
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return;
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if ((ap = malloc(strlen(*argv) + 2)) == NULL)
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err(1, NULL);
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ap[0] = '-';
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ap[1] = 'n';
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(void)strcpy(ap + 2, *argv + 1);
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*argv = ap;
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}
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}
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static void
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usage(void)
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{
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(void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n");
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exit(1);
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}
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