cmd/head/head.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */
/*
 * Copyright (c) 2014, Joyent, Inc.  All rights reserved.
 */


#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <locale.h>
#include <string.h>
#include <ctype.h>

#define DEF_LINE_COUNT  10

static  void    copyout(off_t, int);
static  void    Usage();
static  FILE    *input;


/*
 * head - give the first few lines of a stream or of each of a set of files.
 * Optionally shows a specific number of bytes instead.
 */
int
main(int argc, char **argv)
{
    int fileCount;
    int around = 0;
    int i;
    int opt;
    off_t   linecnt = DEF_LINE_COUNT;
    int isline = 1;
    int error = 0;
    int quiet = 0;

    (void) setlocale(LC_ALL, "");
#if !defined(TEXT_DOMAIN)   /* Should be defined by cc -D */
#define TEXT_DOMAIN "SYS_TEST"  /* Use this only if it weren't */
#endif
    (void) textdomain(TEXT_DOMAIN);

    /* check for non-standard "-line-count" option */
    for (i = 1; i < argc; i++) {
        if (strcmp(argv[i], "--") == 0)
            break;

        if ((argv[i][0] == '-') && isdigit(argv[i][1])) {
            if (strlen(&argv[i][1]) !=
                strspn(&argv[i][1], "0123456789")) {
                (void) fprintf(stderr, gettext(
                    "%s: Badly formed number\n"), argv[0]);
                Usage();
            }

            linecnt = (off_t)strtoll(&argv[i][1], (char **)NULL,
                10);
            while (i < argc) {
                argv[i] = argv[i + 1];
                i++;
            }
            argc--;
        }
    }

    /* get options */
    while ((opt = getopt(argc, argv, "qvn:c:")) != EOF) {
        switch (opt) {
        case 'n':
        case 'c':
            if ((strcmp(optarg, "--") == 0) || (optind > argc)) {
                (void) fprintf(stderr, gettext(
                    "%s: Missing -%c argument\n"), argv[0],
                    optopt);
                Usage();
            }
            linecnt = (off_t)strtoll(optarg, (char **)NULL, 10);
            if (linecnt <= 0) {
                (void) fprintf(stderr, gettext(
                    "%s: Invalid \"-%c %s\" option\n"),
                    argv[0], optopt, optarg);
                Usage();
            }
            isline = optopt != 'c';
            break;
        case 'q':
            quiet = 1;
            break;
        case 'v':
            quiet = 0;
            break;
        default:
            Usage();
        }
    }

    fileCount = argc - optind;

    do {
        if ((argv[optind] == NULL) && around)
            break;

        if (argv[optind] != NULL) {
            if (input != NULL)
                (void) fclose(input);
            if ((input = fopen(argv[optind], "r")) == NULL) {
                perror(argv[optind]);
                error = 1;
                optind++;
                continue;
            }
        } else {
            input = stdin;
        }

        if (quiet == 0) {
            if (around)
                (void) putchar('\n');

            if (fileCount > 1)
                (void) printf("==> %s <==\n", argv[optind]);
        }

        if (argv[optind] != NULL)
            optind++;

        copyout(linecnt, isline);
        (void) fflush(stdout);
        around++;

    } while (argv[optind] != NULL);

    return (error);
}

static void
copyout(off_t cnt, int isline)
{
    char lbuf[BUFSIZ];
    size_t len;

    while (cnt > 0 && fgets(lbuf, sizeof (lbuf), input) != 0) {
        len = strlen(lbuf);
        if (isline) {
            (void) printf("%s", lbuf);
            /*
             * only count as a line if buffer read ends with newline
             */
            if (len > 0) {
                if (lbuf[len - 1] == '\n') {
                    (void) fflush(stdout);
                    cnt--;
                }
            }
        } else {
            if (len > cnt) {
                lbuf[cnt] = '\0';
                len = cnt;
            }
            (void) printf("%s", lbuf);
            cnt -= len;
            (void) fflush(stdout);
        }
    }
}

static void
Usage()
{
    (void) printf(gettext("usage: head [-q] [-v] [-n #] [-c #] [-#] "
        "[filename...]\n"));
    exit(1);
}