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/* $OpenBSD: head.c,v 1.21 2016/03/20 17:14:51 tb Exp $ */ |
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/* |
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* Copyright (c) 1980, 1987 Regents of the University of California. |
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* 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. 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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#include <stdio.h> |
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#include <stdlib.h> |
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#include <ctype.h> |
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#include <limits.h> |
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#include <err.h> |
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#include <errno.h> |
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#include <unistd.h> |
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static void usage(void); |
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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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int |
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main(int argc, char *argv[]) |
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{ |
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FILE *fp; |
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long cnt; |
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int ch, firsttime; |
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long linecnt = 10; |
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char *p = NULL; |
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int status = 0; |
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✗✓ |
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if (pledge("stdio rpath flock cpath wpath", NULL) == -1) |
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err(1, "pledge"); |
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/* handle obsolete -number syntax */ |
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✓✗✓✗ ✓✓ |
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if (argc > 1 && argv[1][0] == '-' && |
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isdigit((unsigned char)argv[1][1])) { |
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p = argv[1] + 1; |
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argc--; |
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argv++; |
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} |
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✓✓ |
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while ((ch = getopt(argc, argv, "n:")) != -1) { |
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✓✗ |
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switch (ch) { |
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case 'n': |
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p = optarg; |
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break; |
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default: |
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usage(); |
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} |
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} |
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argc -= optind, argv += optind; |
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✓✗ |
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if (p) { |
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const char *errstr; |
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linecnt = strtonum(p, 1, LONG_MAX, &errstr); |
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✗✓ |
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if (errstr) |
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errx(1, "line count %s: %s", errstr, p); |
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} |
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for (firsttime = 1; ; firsttime = 0) { |
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✓✗ |
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if (!*argv) { |
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✓✓ |
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if (!firsttime) |
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exit(status); |
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fp = stdin; |
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✗✓ |
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if (pledge("stdio flock rpath cpath wpath", NULL) == -1) |
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err(1, "pledge"); |
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} else { |
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if ((fp = fopen(*argv, "r")) == NULL) { |
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warn("%s", *argv++); |
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status = 1; |
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continue; |
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} |
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if (argc > 1) { |
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if (!firsttime) |
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putchar('\n'); |
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printf("==> %s <==\n", *argv); |
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} |
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++argv; |
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} |
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✓✓✓✗ ✓✓ |
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for (cnt = linecnt; cnt && !feof(fp); --cnt) |
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✓✗✓✓ ✓✓ |
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while ((ch = getc(fp)) != EOF) |
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✓✗✓✓
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if (putchar(ch) == '\n') |
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break; |
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fclose(fp); |
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} |
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/*NOTREACHED*/ |
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} |
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static void |
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usage(void) |
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{ |
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fputs("usage: head [-count | -n count] [file ...]\n", stderr); |
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exit(1); |
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} |