53 lines
1.7 KiB
C
53 lines
1.7 KiB
C
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/* Adjust a file descriptor result so that it avoids clobbering
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STD{IN,OUT,ERR}_FILENO, with specific flags.
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Copyright (C) 2005-2006, 2009-2020 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 and Eric Blake. */
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#include <config.h>
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/* Specification. */
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#include "unistd-safer.h"
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#include <errno.h>
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#include <unistd.h>
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/* Return FD, unless FD would be a copy of standard input, output, or
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error; in that case, return a duplicate of FD, closing FD. If FLAG
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contains O_CLOEXEC, the returned FD will have close-on-exec
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semantics. On failure to duplicate, close FD, set errno, and
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return -1. Preserve errno if FD is negative, so that the caller
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can always inspect errno when the returned value is negative.
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This function is usefully wrapped around functions that return file
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descriptors, e.g., fd_safer_flag (open ("file", O_RDONLY | flag), flag). */
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int
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fd_safer_flag (int fd, int flag)
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{
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if (STDIN_FILENO <= fd && fd <= STDERR_FILENO)
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{
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int f = dup_safer_flag (fd, flag);
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int e = errno;
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close (fd);
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errno = e;
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fd = f;
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}
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return fd;
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}
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