59 lines
1.7 KiB
C
59 lines
1.7 KiB
C
/* Copyright (C) 1991-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <limits.h>
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#include <termios.h>
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#include <stdlib.h>
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#include "ttyname.h"
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static char *ttyname_buf = NULL;
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libc_freeres_fn (free_mem)
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{
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free (ttyname_buf);
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}
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/* Return the pathname of the terminal FD is open on, or NULL on errors.
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The returned storage is good only until the next call to this function. */
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char *
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ttyname (int fd)
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{
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/* isatty check, tcgetattr is used because it sets the correct
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errno (EBADF resp. ENOTTY) on error. Fast error path to avoid the
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allocation */
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struct termios term;
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if (__glibc_unlikely (__tcgetattr (fd, &term) < 0))
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return NULL;
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if (ttyname_buf == NULL)
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{
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ttyname_buf = malloc (PATH_MAX);
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if (ttyname_buf == NULL)
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return NULL;
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}
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int result = __ttyname_r (fd, ttyname_buf, PATH_MAX);
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if (result != 0)
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{
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__set_errno (result);
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return NULL;
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}
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return ttyname_buf;
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}
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