diff options
Diffstat (limited to 'lib/fd-reopen.c')
-rw-r--r-- | lib/fd-reopen.c | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/lib/fd-reopen.c b/lib/fd-reopen.c new file mode 100644 index 000000000..a33d23d45 --- /dev/null +++ b/lib/fd-reopen.c @@ -0,0 +1,46 @@ +/* Invoke open, but return either a desired file descriptor or -1. + + Copyright (C) 2005 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software Foundation, + Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ + +/* Written by Paul Eggert. */ + +#include "fd-reopen.h" + +#include <errno.h> +#include <fcntl.h> + +/* Open a file to a particular file descriptor. This is like standard + `open', except it always returns DESIRED_FD if successful. */ + +int +fd_reopen (int desired_fd, char const *file, int flags, mode_t mode) +{ + int fd; + + close (desired_fd); + fd = open (file, flags, mode); + if (fd == desired_fd || fd < 0) + return fd; + else + { + int fd2 = fcntl (fd, F_DUPFD, desired_fd); + int saved_errno = errno; + close (fd); + errno = saved_errno; + return fd2; + } +} |