1/* Duplicate an open file descriptor to a specified file descriptor. 2 3 Copyright (C) 1999, 2004, 2005, 2006, 2007 Free Software Foundation, Inc. 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 2, or (at your option) 8 any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program; if not, write to the Free Software Foundation, 17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ 18 19/* written by Paul Eggert */ 20 21#include <config.h> 22 23/* Specification. */ 24#include <unistd.h> 25 26#include <errno.h> 27#include <fcntl.h> 28 29#ifndef F_DUPFD 30static int 31dupfd (int fd, int desired_fd) 32{ 33 int duplicated_fd = dup (fd); 34 if (duplicated_fd < 0 || duplicated_fd == desired_fd) 35 return duplicated_fd; 36 else 37 { 38 int r = dupfd (fd, desired_fd); 39 int e = errno; 40 close (duplicated_fd); 41 errno = e; 42 return r; 43 } 44} 45#endif 46 47int 48dup2 (int fd, int desired_fd) 49{ 50 if (fd == desired_fd) 51 return fd; 52 close (desired_fd); 53#ifdef F_DUPFD 54 return fcntl (fd, F_DUPFD, desired_fd); 55#else 56 return dupfd (fd, desired_fd); 57#endif 58} 59