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https://github.com/topjohnwu/ndk-busybox.git
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107 lines
2.5 KiB
C
107 lines
2.5 KiB
C
/*
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* Mini head implementation for busybox
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*
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*
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* Copyright (C) 1999 by Lineo, inc.
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* Written by John Beppu <beppu@lineo.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include "internal.h"
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#include <errno.h>
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#include <stdio.h>
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const char head_usage[] =
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"Usage: head [FILE]...\n\n"
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"Print first 10 lines of each FILE to standard output.\n"
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"With more than one FILE, precede each with a header giving the\n"
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"file name. With no FILE, or when FILE is -, read standard input.\n";
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int
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head(int len, FILE *src)
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{
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int i;
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char buffer[1024];
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for (i = 0; i < len; i++) {
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fgets(buffer, 1024, src);
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if (feof(src)) { break; }
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fputs(buffer, stdout);
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}
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return 0;
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}
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/* BusyBoxed head(1) */
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int
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head_main(int argc, char **argv)
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{
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int i = 1;
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char opt;
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int len = 10;
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/* 1st option is potentially special */
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if ((argc > 1) && (argv[1][0] == '-') && isDecimal(argv[1][1])) {
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int tmplen = atoi(&argv[1][1]);
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if (tmplen) { len = tmplen; }
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i = 2;
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}
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/* parse argv[] */
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for ( ; i < argc; i++) {
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if (argv[i][0] == '-') {
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opt = argv[i][1];
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switch (opt) {
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case '-':
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case 'h':
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usage(head_usage);
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default:
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fprintf(stderr, "head: invalid option -- %c\n", opt);
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usage(head_usage);
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}
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} else {
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break;
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}
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}
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/* get rest of argv[] or stdin if nothing's left */
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if (i >= argc) {
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head(len, stdin);
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} else {
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int need_headers = ((argc - i) > 1);
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for ( ; i < argc; i++) {
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FILE *src;
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src = fopen(argv[i], "r");
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if (!src) {
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fprintf(stderr,"head: %s: %s\n", argv[i], strerror(errno));
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} else {
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/* emulating GNU behaviour */
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if (need_headers) {
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fprintf(stdout, "==> %s <==\n", argv[i]);
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}
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head(len, src);
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if (i < argc - 1) {
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fprintf(stdout, "\n");
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}
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}
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}
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}
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exit(0);
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}
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/* $Id: head.c,v 1.4 1999/12/17 18:52:06 erik Exp $ */
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