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/* Copyright (C) 1996-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <utmp.h>
#include <shlib-compat.h>
/* Return the result of ttyname in the buffer pointed to by TTY, which should
be of length BUF_LEN. If it is too long to fit in this buffer, a
sufficiently long buffer is allocated using malloc, and returned in TTY.
0 is returned upon success, -1 otherwise. */
static int
tty_name (int fd, char **tty, size_t buf_len)
{
int rv; /* Return value. 0 = success. */
char *buf = *tty; /* Buffer for ttyname, initially the user's. */
for (;;)
{
char *new_buf;
if (buf_len)
{
rv = __ttyname_r (fd, buf, buf_len);
if (rv != 0 || memchr (buf, '\0', buf_len))
/* We either got an error, or we succeeded and the
returned name fit in the buffer. */
break;
/* Try again with a longer buffer. */
buf_len += buf_len; /* Double it */
}
else
/* No initial buffer; start out by mallocing one. */
buf_len = 128; /* First time guess. */
if (buf != *tty)
/* We've already malloced another buffer at least once. */
new_buf = realloc (buf, buf_len);
else
new_buf = malloc (buf_len);
if (! new_buf)
{
rv = -1;
__set_errno (ENOMEM);
break;
}
buf = new_buf;
}
if (rv == 0)
*tty = buf; /* Return buffer to the user. */
else if (buf != *tty)
free (buf); /* Free what we malloced when returning an error. */
return rv;
}
void
__login (const struct utmp *ut)
{
#ifdef PATH_MAX
char _tty[PATH_MAX + UT_LINESIZE];
#else
char _tty[512 + UT_LINESIZE];
#endif
char *tty = _tty;
int found_tty;
const char *ttyp;
struct utmp copy = *ut;
/* Fill in those fields we supply. */
copy.ut_type = USER_PROCESS;
copy.ut_pid = getpid ();
/* Seek tty. */
found_tty = tty_name (STDIN_FILENO, &tty, sizeof (_tty));
if (found_tty < 0)
found_tty = tty_name (STDOUT_FILENO, &tty, sizeof (_tty));
if (found_tty < 0)
found_tty = tty_name (STDERR_FILENO, &tty, sizeof (_tty));
if (found_tty >= 0)
{
/* We only want to insert the name of the tty without path.
But take care of name like /dev/pts/3. */
if (strncmp (tty, "/dev/", 5) == 0)
ttyp = tty + 5; /* Skip the "/dev/". */
else
ttyp = basename (tty);
/* Position to record for this tty. */
strncpy (copy.ut_line, ttyp, UT_LINESIZE);
/* Tell that we want to use the UTMP file. */
if (__utmpname (_PATH_UTMP) == 0)
{
/* Open UTMP file. */
__setutent ();
/* Write the entry. */
__pututline (©);
/* Close UTMP file. */
__endutent ();
}
if (tty != _tty)
free (tty); /* Free buffer malloced by tty_name. */
}
else
/* We provide a default value so that the output does not contain
an random bytes in this field. */
strncpy (copy.ut_line, "???", UT_LINESIZE);
/* Update the WTMP file. Here we have to add a new entry. */
__updwtmp (_PATH_WTMP, ©);
}
versioned_symbol (libc, __login, login, GLIBC_2_34);
libc_hidden_ver (__login, login)
#if OTHER_SHLIB_COMPAT (libutil, GLIBC_2_0, GLIBC_2_34)
compat_symbol (libutil, __login, login, GLIBC_2_0);
#endif
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