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Annotation of prex/usr/bin/head/head.c, Revision 1.1

1.1     ! nbrk        1: /*
        !             2:  * Copyright (c) 1980, 1987, 1992, 1993
        !             3:  *     The Regents of the University of California.  All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms, with or without
        !             6:  * modification, are permitted provided that the following conditions
        !             7:  * are met:
        !             8:  * 1. Redistributions of source code must retain the above copyright
        !             9:  *    notice, this list of conditions and the following disclaimer.
        !            10:  * 2. Redistributions in binary form must reproduce the above copyright
        !            11:  *    notice, this list of conditions and the following disclaimer in the
        !            12:  *    documentation and/or other materials provided with the distribution.
        !            13:  * 3. Neither the name of the University nor the names of its contributors
        !            14:  *    may be used to endorse or promote products derived from this software
        !            15:  *    without specific prior written permission.
        !            16:  *
        !            17:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            18:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            19:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            20:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            21:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            22:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            23:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            24:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            25:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            26:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            27:  * SUCH DAMAGE.
        !            28:  */
        !            29:
        !            30: #include <sys/types.h>
        !            31:
        !            32: #include <ctype.h>
        !            33: #include <err.h>
        !            34: #include <errno.h>
        !            35: #include <stdio.h>
        !            36: #include <stdlib.h>
        !            37: #include <string.h>
        !            38: #include <unistd.h>
        !            39:
        !            40: /*
        !            41:  * head - give the first few lines of a stream or of each of a set of files
        !            42:  *
        !            43:  * Bill Joy UCB August 24, 1977
        !            44:  */
        !            45:
        !            46: #ifdef CMDBOX
        !            47: #define main(argc, argv)       head_main(argc, argv)
        !            48: #endif
        !            49:
        !            50: void head(FILE *, int);
        !            51: void obsolete(char *[]);
        !            52: static void usage(void);
        !            53:
        !            54: int eval;
        !            55:
        !            56: int
        !            57: main(int argc, char *argv[])
        !            58: {
        !            59:        register int ch;
        !            60:        FILE *fp;
        !            61:        int first, linecnt;
        !            62:        char *ep;
        !            63:
        !            64:        obsolete(argv);
        !            65:        linecnt = 10;
        !            66:        while ((ch = getopt(argc, argv, "n:")) != EOF)
        !            67:                switch(ch) {
        !            68:                case 'n':
        !            69:                        linecnt = strtol(optarg, &ep, 10);
        !            70:                        if (*ep || linecnt <= 0)
        !            71:                                err(1, "illegal line count -- %s", optarg);
        !            72:                        break;
        !            73:                case '?':
        !            74:                default:
        !            75:                        usage();
        !            76:                }
        !            77:        argc -= optind;
        !            78:        argv += optind;
        !            79:
        !            80:        if (*argv)
        !            81:                for (first = 1; *argv; ++argv) {
        !            82:                        if ((fp = fopen(*argv, "r")) == NULL) {
        !            83:                                err(0, "%s: %s", *argv, strerror(errno));
        !            84:                                continue;
        !            85:                        }
        !            86:                        if (argc > 1) {
        !            87:                                (void)printf("%s==> %s <==\n",
        !            88:                                    first ? "" : "\n", *argv);
        !            89:                                first = 0;
        !            90:                        }
        !            91:                        head(fp, linecnt);
        !            92:                        (void)fclose(fp);
        !            93:                }
        !            94:        else
        !            95:                head(stdin, linecnt);
        !            96:        exit(eval);
        !            97: }
        !            98:
        !            99: void
        !           100: head(fp, cnt)
        !           101:        FILE *fp;
        !           102:        register int cnt;
        !           103: {
        !           104:        register int ch;
        !           105:
        !           106:        while (cnt--)
        !           107:                while ((ch = getc(fp)) != EOF) {
        !           108:                        if (putchar(ch) == EOF)
        !           109:                                err(1, "stdout: %s", strerror(errno));
        !           110:                        if (ch == '\n')
        !           111:                                break;
        !           112:                }
        !           113: }
        !           114:
        !           115: void
        !           116: obsolete(argv)
        !           117:        char *argv[];
        !           118: {
        !           119:        char *ap;
        !           120:
        !           121:        while ((ap = *++argv)) {
        !           122:                /* Return if "--" or not "-[0-9]*". */
        !           123:                if (ap[0] != '-' || ap[1] == '-' || !isdigit(ap[1]))
        !           124:                        return;
        !           125:                if ((ap = malloc(strlen(*argv) + 2)) == NULL)
        !           126:                        err(1, "%s", strerror(errno));
        !           127:                ap[0] = '-';
        !           128:                ap[1] = 'n';
        !           129:                (void)strcpy(ap + 2, *argv + 1);
        !           130:                *argv = ap;
        !           131:        }
        !           132: }
        !           133:
        !           134: static void
        !           135: usage()
        !           136: {
        !           137:        (void)fprintf(stderr, "usage: head [-n lines] [file ...]\n");
        !           138:        exit(1);
        !           139: }