47 lines
1.3 KiB
C
47 lines
1.3 KiB
C
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/* Invoke open, but return either a desired file descriptor or -1.
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Copyright (C) 2005-2020 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Paul Eggert. */
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#include <config.h>
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#include "fd-reopen.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <unistd.h>
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/* Open a file to a particular file descriptor. This is like standard
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'open', except it always returns DESIRED_FD if successful. */
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int
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fd_reopen (int desired_fd, char const *file, int flags, mode_t mode)
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{
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int fd = open (file, flags, mode);
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if (fd == desired_fd || fd < 0)
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return fd;
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else
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{
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int fd2 = dup2 (fd, desired_fd);
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int saved_errno = errno;
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close (fd);
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errno = saved_errno;
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return fd2;
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}
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}
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