1cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project/* Return a safer copy of a file descriptor. 2cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project 305436638acc7c010349a69c3395f1a57c642dc62Ying Wang Copyright (C) 2005-2006, 2009-2012 Free Software Foundation, Inc. 4cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project 505436638acc7c010349a69c3395f1a57c642dc62Ying Wang This program is free software: you can redistribute it and/or modify 6cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project it under the terms of the GNU General Public License as published by 705436638acc7c010349a69c3395f1a57c642dc62Ying Wang the Free Software Foundation; either version 3 of the License, or 805436638acc7c010349a69c3395f1a57c642dc62Ying Wang (at your option) any later version. 9cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project 10cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project This program is distributed in the hope that it will be useful, 11cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project but WITHOUT ANY WARRANTY; without even the implied warranty of 12cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project GNU General Public License for more details. 14cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project 15cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project You should have received a copy of the GNU General Public License 1605436638acc7c010349a69c3395f1a57c642dc62Ying Wang along with this program. If not, see <http://www.gnu.org/licenses/>. */ 17cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project 18cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project/* Written by Paul Eggert. */ 19cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project 2005436638acc7c010349a69c3395f1a57c642dc62Ying Wang#include <config.h> 21cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project 22cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project#include "unistd-safer.h" 23cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project 24cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project#include <errno.h> 25cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project#include <unistd.h> 26cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project 27cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project/* Return FD, unless FD would be a copy of standard input, output, or 28cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project error; in that case, return a duplicate of FD, closing FD. On 29cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project failure to duplicate, close FD, set errno, and return -1. Preserve 30cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project errno if FD is negative, so that the caller can always inspect 31cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project errno when the returned value is negative. 32cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project 33cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project This function is usefully wrapped around functions that return file 34cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project descriptors, e.g., fd_safer (open ("file", O_RDONLY)). */ 35cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project 36cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Projectint 37cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Projectfd_safer (int fd) 38cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project{ 39cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project if (STDIN_FILENO <= fd && fd <= STDERR_FILENO) 40cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project { 41cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project int f = dup_safer (fd); 42cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project int e = errno; 43cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project close (fd); 44cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project errno = e; 45cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project fd = f; 46cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project } 47cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project 48cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project return fd; 49cea198a11f15a2eb071d98491ca9a8bc8cebfbc4The Android Open Source Project} 50