/usr.bin/head/head.c
https://bitbucket.org/freebsd/freebsd-head/ · C · 182 lines · 130 code · 18 blank · 34 comment · 42 complexity · 99019213985945ee06def305f9aeb9b2 MD5 · raw file
- /*
- * Copyright (c) 1980, 1987, 1992, 1993
- * The Regents of the University of California. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 4. Neither the name of the University nor the names of its contributors
- * may be used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
- #ifndef lint
- static const char copyright[] =
- "@(#) Copyright (c) 1980, 1987, 1992, 1993\n\
- The Regents of the University of California. All rights reserved.\n";
- #endif /* not lint */
- #ifndef lint
- #if 0
- static char sccsid[] = "@(#)head.c 8.2 (Berkeley) 5/4/95";
- #endif
- #endif /* not lint */
- #include <sys/cdefs.h>
- __FBSDID("$FreeBSD$");
- #include <sys/types.h>
- #include <ctype.h>
- #include <err.h>
- #include <inttypes.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <unistd.h>
- /*
- * head - give the first few lines of a stream or of each of a set of files
- *
- * Bill Joy UCB August 24, 1977
- */
- static void head(FILE *, int);
- static void head_bytes(FILE *, off_t);
- static void obsolete(char *[]);
- static void usage(void);
- int
- main(int argc, char *argv[])
- {
- int ch;
- FILE *fp;
- int first, linecnt = -1, eval = 0;
- off_t bytecnt = -1;
- char *ep;
- obsolete(argv);
- while ((ch = getopt(argc, argv, "n:c:")) != -1)
- switch(ch) {
- case 'c':
- bytecnt = strtoimax(optarg, &ep, 10);
- if (*ep || bytecnt <= 0)
- errx(1, "illegal byte count -- %s", optarg);
- break;
- case 'n':
- linecnt = strtol(optarg, &ep, 10);
- if (*ep || linecnt <= 0)
- errx(1, "illegal line count -- %s", optarg);
- break;
- case '?':
- default:
- usage();
- }
- argc -= optind;
- argv += optind;
- if (linecnt != -1 && bytecnt != -1)
- errx(1, "can't combine line and byte counts");
- if (linecnt == -1 )
- linecnt = 10;
- if (*argv) {
- for (first = 1; *argv; ++argv) {
- if ((fp = fopen(*argv, "r")) == NULL) {
- warn("%s", *argv);
- eval = 1;
- continue;
- }
- if (argc > 1) {
- (void)printf("%s==> %s <==\n",
- first ? "" : "\n", *argv);
- first = 0;
- }
- if (bytecnt == -1)
- head(fp, linecnt);
- else
- head_bytes(fp, bytecnt);
- (void)fclose(fp);
- }
- } else if (bytecnt == -1)
- head(stdin, linecnt);
- else
- head_bytes(stdin, bytecnt);
- exit(eval);
- }
- static void
- head(FILE *fp, int cnt)
- {
- char *cp;
- size_t error, readlen;
- while (cnt && (cp = fgetln(fp, &readlen)) != NULL) {
- error = fwrite(cp, sizeof(char), readlen, stdout);
- if (error != readlen)
- err(1, "stdout");
- cnt--;
- }
- }
- static void
- head_bytes(FILE *fp, off_t cnt)
- {
- char buf[4096];
- size_t readlen;
- while (cnt) {
- if ((uintmax_t)cnt < sizeof(buf))
- readlen = cnt;
- else
- readlen = sizeof(buf);
- readlen = fread(buf, sizeof(char), readlen, fp);
- if (readlen == 0)
- break;
- if (fwrite(buf, sizeof(char), readlen, stdout) != readlen)
- err(1, "stdout");
- cnt -= readlen;
- }
- }
- static void
- obsolete(char *argv[])
- {
- char *ap;
- while ((ap = *++argv)) {
- /* Return if "--" or not "-[0-9]*". */
- if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1]))
- return;
- if ((ap = malloc(strlen(*argv) + 2)) == NULL)
- err(1, NULL);
- ap[0] = '-';
- ap[1] = 'n';
- (void)strcpy(ap + 2, *argv + 1);
- *argv = ap;
- }
- }
- static void
- usage(void)
- {
- (void)fprintf(stderr, "usage: head [-n lines | -c bytes] [file ...]\n");
- exit(1);
- }