98 lines
2.1 KiB
C
98 lines
2.1 KiB
C
/* $Id$ */
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/* Copyright (c) 2009 Pierre Pronchery <khorben@defora.org> */
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/* This file is part of DeforaOS Unix utils */
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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, version 3 of the License.
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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
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* GNU 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, see <http://www.gnu.org/licenses/>. */
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#include <unistd.h>
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#include <stdlib.h>
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#include <stdio.h>
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/* head */
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static int _head_error(char const * message, int ret);
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static int _head_do(int flgn, char const * filename);
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static int _head(int flgn, int filec, char * filev[])
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{
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int ret = 0;
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int i;
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if(filec == 0)
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return _head_do(flgn, NULL);
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for(i = 0; i < filec; i++)
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if(_head_do(flgn, filev[i]) != 0)
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ret = 1;
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return ret;
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}
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static int _head_error(char const * message, int ret)
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{
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fputs("head: ", stderr);
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perror(message);
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return ret;
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}
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static int _head_do(int flgn, char const * filename)
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{
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FILE * fp;
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int n = 0;
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int c;
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if(filename == NULL)
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fp = stdin;
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else if((fp = fopen(filename, "r")) == NULL)
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return _head_error(filename, 1);
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while((c = fgetc(fp)) != EOF && n < flgn)
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{
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if(c == '\n')
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n++;
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fwrite(&c, sizeof(char), 1, stdout);
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}
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if(filename != NULL && fclose(fp) != 0)
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return _head_error(filename, 1);
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return 0;
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}
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/* usage */
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static int _usage(void)
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{
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fputs("Usage: head [-n number][file...]\n\
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-n Print first number lines on standard output\n", stderr);
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return 1;
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}
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/* main */
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int main(int argc, char * argv[])
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{
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int flgn = 10;
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int o;
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char * p;
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while((o = getopt(argc, argv, "n:")) != -1)
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switch(o)
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{
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case 'n':
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flgn = strtol(optarg, &p, 10);
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if(*optarg == '\0' || *p != '\0')
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return _usage();
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break;
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default:
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return _usage();
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}
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return _head(flgn, argc - optind, &argv[optind]) == 0 ? 0 : 2;
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}
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