1/* Duplicate an open file descriptor to a specified file descriptor. 2 Copyright (C) 1999, 2004 Free Software Foundation, Inc. 3 4 This program is free software; you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 2, or (at your option) 7 any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program; if not, write to the Free Software Foundation, 16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ 17 18/* written by Paul Eggert */ 19 20#ifdef HAVE_CONFIG_H 21# include <config.h> 22#endif 23 24#include <errno.h> 25 26#include <fcntl.h> 27 28#if HAVE_UNISTD_H 29# include <unistd.h> 30#endif 31 32#ifndef F_DUPFD 33static int 34dupfd (int fd, int desired_fd) 35{ 36 int duplicated_fd = dup (fd); 37 if (duplicated_fd < 0 || duplicated_fd == desired_fd) 38 return duplicated_fd; 39 else 40 { 41 int r = dupfd (fd, desired_fd); 42 int e = errno; 43 close (duplicated_fd); 44 errno = e; 45 return r; 46 } 47} 48#endif 49 50int 51dup2 (int fd, int desired_fd) 52{ 53 if (fd == desired_fd) 54 return fd; 55 close (desired_fd); 56#ifdef F_DUPFD 57 return fcntl (fd, F_DUPFD, desired_fd); 58#else 59 return dupfd (fd, desired_fd); 60#endif 61} 62