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glibc/sysdeps/unix/getlogin_r.c
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/* Reentrant function to return the current login name. Unix version. | |
Copyright (C) 1991-2016 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 | |
<http://www.gnu.org/licenses/>. */ | |
#include <errno.h> | |
#include <unistd.h> | |
#include <string.h> | |
#include <stdio.h> | |
#include <limits.h> | |
#include <fcntl.h> | |
#include <utmp.h> | |
#include "../login/utmp-private.h" | |
/* Return at most NAME_LEN characters of the login name of the user in NAME. | |
If it cannot be determined or some other error occurred, return the error | |
code. Otherwise return 0. */ | |
#ifdef STATIC | |
STATIC | |
#endif | |
int | |
__getlogin_r (char *name, size_t name_len) | |
{ | |
char tty_pathname[2 + 2 * NAME_MAX]; | |
char *real_tty_path = tty_pathname; | |
int result; | |
struct utmp *ut, line, buffer; | |
/* Get name of tty connected to fd 0. Return if not a tty or | |
if fd 0 isn't open. Note that a lot of documentation says that | |
getlogin() is based on the controlling terminal---what they | |
really mean is "the terminal connected to standard input". The | |
getlogin() implementation of DEC Unix, SunOS, Solaris, HP-UX all | |
return NULL if fd 0 has been closed, so this is the compatible | |
thing to do. Note that ttyname(open("/dev/tty")) on those | |
systems returns /dev/tty, so that is not a possible solution for | |
getlogin(). */ | |
result = __ttyname_r (0, real_tty_path, sizeof (tty_pathname)); | |
if (result != 0) | |
return result; | |
real_tty_path += 5; /* Remove "/dev/". */ | |
strncpy (line.ut_line, real_tty_path, sizeof line.ut_line); | |
/* We don't use the normal entry points __setutent et al, because we | |
want setutent + getutline_r + endutent all to happen with the lock | |
held so that our search is thread-safe. */ | |
__libc_lock_lock (__libc_utmp_lock); | |
(*__libc_utmp_jump_table->setutent) (); | |
result = (*__libc_utmp_jump_table->getutline_r) (&line, &buffer, &ut); | |
if (result < 0) | |
{ | |
if (errno == ESRCH) | |
/* The caller expects ENOENT if nothing is found. */ | |
result = ENOENT; | |
else | |
result = errno; | |
} | |
(*__libc_utmp_jump_table->endutent) (); | |
__libc_utmp_jump_table = &__libc_utmp_unknown_functions; | |
__libc_lock_unlock (__libc_utmp_lock); | |
if (result == 0) | |
{ | |
size_t needed = strlen (ut->ut_user) + 1; | |
if (needed > name_len) | |
{ | |
__set_errno (ERANGE); | |
result = ERANGE; | |
} | |
else | |
{ | |
memcpy (name, ut->ut_user, needed); | |
result = 0; | |
} | |
} | |
return result; | |
} | |
#ifndef STATIC | |
libc_hidden_def (__getlogin_r) | |
weak_alias (__getlogin_r, getlogin_r) | |
libc_hidden_weak (getlogin_r) | |
#endif |