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glibc/login/login.c
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/* Copyright (C) 1996-2016 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996. | |
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 | |
<http://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> | |
/* 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. */ | |
#if _HAVE_UT_TYPE - 0 | |
copy.ut_type = USER_PROCESS; | |
#endif | |
#if _HAVE_UT_PID - 0 | |
copy.ut_pid = getpid (); | |
#endif | |
/* 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, ©); | |
} |