1/* vi: set sw=4 ts=4: */ 2/* 3 * Mini head implementation for busybox 4 * 5 * 6 * Copyright (C) 1999,2000,2001 by Lineo, inc. 7 * Written by John Beppu <beppu@lineo.com> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License as published by 11 * the Free Software Foundation; either version 2 of the License, or 12 * (at your option) any later version. 13 * 14 * This program is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 17 * General Public License for more details. 18 * 19 * You should have received a copy of the GNU General Public License 20 * along with this program; if not, write to the Free Software 21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 22 * 23 */ 24 25#include <errno.h> 26#include <stdio.h> 27#include <getopt.h> 28#include <stdlib.h> 29#include <string.h> 30#include "busybox.h" 31 32static int head(int len, FILE *fp) 33{ 34 int i; 35 char *input; 36 37 for (i = 0; i < len; i++) { 38 if ((input = get_line_from_file(fp)) == NULL) 39 break; 40 fputs(input, stdout); 41 free(input); 42 } 43 return 0; 44} 45 46/* BusyBoxed head(1) */ 47int head_main(int argc, char **argv) 48{ 49 FILE *fp; 50 int need_headers, opt, len = 10, status = EXIT_SUCCESS; 51 52 /* parse argv[] */ 53 while ((opt = getopt(argc, argv, "n:")) > 0) { 54 switch (opt) { 55 case 'n': 56 len = atoi(optarg); 57 if (len >= 1) 58 break; 59 /* fallthrough */ 60 default: 61 show_usage(); 62 } 63 } 64 65 /* get rest of argv[] or stdin if nothing's left */ 66 if (argv[optind] == NULL) { 67 head(len, stdin); 68 return status; 69 } 70 71 need_headers = optind != (argc - 1); 72 while (argv[optind]) { 73 if (strcmp(argv[optind], "-") == 0) { 74 fp = stdin; 75 argv[optind] = "standard input"; 76 } else { 77 if ((fp = wfopen(argv[optind], "r")) == NULL) 78 status = EXIT_FAILURE; 79 } 80 if (fp) { 81 if (need_headers) { 82 printf("==> %s <==\n", argv[optind]); 83 } 84 head(len, fp); 85 if (errno) { 86 perror_msg("%s", argv[optind]); 87 status = EXIT_FAILURE; 88 errno = 0; 89 } 90 if (optind < argc - 1) 91 putchar('\n'); 92 if (fp != stdin) 93 fclose(fp); 94 } 95 optind++; 96 } 97 98 return status; 99} 100