105436638acc7c010349a69c3395f1a57c642dc62Ying Wang/* Adjust a file descriptor result so that it avoids clobbering 205436638acc7c010349a69c3395f1a57c642dc62Ying Wang STD{IN,OUT,ERR}_FILENO, with specific flags. 305436638acc7c010349a69c3395f1a57c642dc62Ying Wang 405436638acc7c010349a69c3395f1a57c642dc62Ying Wang Copyright (C) 2005-2006, 2009-2012 Free Software Foundation, Inc. 505436638acc7c010349a69c3395f1a57c642dc62Ying Wang 605436638acc7c010349a69c3395f1a57c642dc62Ying Wang This program is free software: you can redistribute it and/or modify 705436638acc7c010349a69c3395f1a57c642dc62Ying Wang it under the terms of the GNU General Public License as published by 805436638acc7c010349a69c3395f1a57c642dc62Ying Wang the Free Software Foundation; either version 3 of the License, or 905436638acc7c010349a69c3395f1a57c642dc62Ying Wang (at your option) any later version. 1005436638acc7c010349a69c3395f1a57c642dc62Ying Wang 1105436638acc7c010349a69c3395f1a57c642dc62Ying Wang This program is distributed in the hope that it will be useful, 1205436638acc7c010349a69c3395f1a57c642dc62Ying Wang but WITHOUT ANY WARRANTY; without even the implied warranty of 1305436638acc7c010349a69c3395f1a57c642dc62Ying Wang MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 1405436638acc7c010349a69c3395f1a57c642dc62Ying Wang GNU General Public License for more details. 1505436638acc7c010349a69c3395f1a57c642dc62Ying Wang 1605436638acc7c010349a69c3395f1a57c642dc62Ying Wang You should have received a copy of the GNU General Public License 1705436638acc7c010349a69c3395f1a57c642dc62Ying Wang along with this program. If not, see <http://www.gnu.org/licenses/>. */ 1805436638acc7c010349a69c3395f1a57c642dc62Ying Wang 1905436638acc7c010349a69c3395f1a57c642dc62Ying Wang/* Written by Paul Eggert and Eric Blake. */ 2005436638acc7c010349a69c3395f1a57c642dc62Ying Wang 2105436638acc7c010349a69c3395f1a57c642dc62Ying Wang#include <config.h> 2205436638acc7c010349a69c3395f1a57c642dc62Ying Wang 2305436638acc7c010349a69c3395f1a57c642dc62Ying Wang/* Specification. */ 2405436638acc7c010349a69c3395f1a57c642dc62Ying Wang#include "unistd-safer.h" 2505436638acc7c010349a69c3395f1a57c642dc62Ying Wang 2605436638acc7c010349a69c3395f1a57c642dc62Ying Wang#include <errno.h> 2705436638acc7c010349a69c3395f1a57c642dc62Ying Wang#include <unistd.h> 2805436638acc7c010349a69c3395f1a57c642dc62Ying Wang 2905436638acc7c010349a69c3395f1a57c642dc62Ying Wang/* Return FD, unless FD would be a copy of standard input, output, or 3005436638acc7c010349a69c3395f1a57c642dc62Ying Wang error; in that case, return a duplicate of FD, closing FD. If FLAG 3105436638acc7c010349a69c3395f1a57c642dc62Ying Wang contains O_CLOEXEC, the returned FD will have close-on-exec 3205436638acc7c010349a69c3395f1a57c642dc62Ying Wang semantics. On failure to duplicate, close FD, set errno, and 3305436638acc7c010349a69c3395f1a57c642dc62Ying Wang return -1. Preserve errno if FD is negative, so that the caller 3405436638acc7c010349a69c3395f1a57c642dc62Ying Wang can always inspect errno when the returned value is negative. 3505436638acc7c010349a69c3395f1a57c642dc62Ying Wang 3605436638acc7c010349a69c3395f1a57c642dc62Ying Wang This function is usefully wrapped around functions that return file 3705436638acc7c010349a69c3395f1a57c642dc62Ying Wang descriptors, e.g., fd_safer_flag (open ("file", O_RDONLY | flag), flag). */ 3805436638acc7c010349a69c3395f1a57c642dc62Ying Wang 3905436638acc7c010349a69c3395f1a57c642dc62Ying Wangint 4005436638acc7c010349a69c3395f1a57c642dc62Ying Wangfd_safer_flag (int fd, int flag) 4105436638acc7c010349a69c3395f1a57c642dc62Ying Wang{ 4205436638acc7c010349a69c3395f1a57c642dc62Ying Wang if (STDIN_FILENO <= fd && fd <= STDERR_FILENO) 4305436638acc7c010349a69c3395f1a57c642dc62Ying Wang { 4405436638acc7c010349a69c3395f1a57c642dc62Ying Wang int f = dup_safer_flag (fd, flag); 4505436638acc7c010349a69c3395f1a57c642dc62Ying Wang int e = errno; 4605436638acc7c010349a69c3395f1a57c642dc62Ying Wang close (fd); 4705436638acc7c010349a69c3395f1a57c642dc62Ying Wang errno = e; 4805436638acc7c010349a69c3395f1a57c642dc62Ying Wang fd = f; 4905436638acc7c010349a69c3395f1a57c642dc62Ying Wang } 5005436638acc7c010349a69c3395f1a57c642dc62Ying Wang 5105436638acc7c010349a69c3395f1a57c642dc62Ying Wang return fd; 5205436638acc7c010349a69c3395f1a57c642dc62Ying Wang} 53