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/* Copyright (C) 2010-2021 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 <pwd.h>
#include <unistd.h>
#include <not-cancel.h>
#include <scratch_buffer.h>
#define STATIC static
static int getlogin_r_fd0 (char *name, size_t namesize);
#define __getlogin_r getlogin_r_fd0
#include <sysdeps/unix/getlogin_r.c>
#undef __getlogin_r
/* Try to determine login name from /proc/self/loginuid and return 0
if successful. If /proc/self/loginuid cannot be read return -1.
Otherwise return the error number. */
int
attribute_hidden
__getlogin_r_loginuid (char *name, size_t namesize)
{
int fd = __open_nocancel ("/proc/self/loginuid", O_RDONLY);
if (fd == -1)
return -1;
/* We are reading a 32-bit number. 12 bytes are enough for the text
representation. If not, something is wrong. */
char uidbuf[12];
ssize_t n = TEMP_FAILURE_RETRY (__read_nocancel (fd, uidbuf,
sizeof (uidbuf)));
__close_nocancel_nostatus (fd);
uid_t uid;
char *endp;
if (n <= 0
|| n == sizeof (uidbuf)
|| (uidbuf[n] = '\0',
uid = strtoul (uidbuf, &endp, 10),
endp == uidbuf || *endp != '\0'))
return -1;
/* If there is no login uid, linux sets /proc/self/loginid to the sentinel
value of, (uid_t) -1, so check if that value is set and return early to
avoid making unneeded nss lookups. */
if (uid == (uid_t) -1)
{
__set_errno (ENXIO);
return ENXIO;
}
struct passwd pwd;
struct passwd *tpwd;
int result = 0;
int res;
struct scratch_buffer tmpbuf;
scratch_buffer_init (&tmpbuf);
while ((res = __getpwuid_r (uid, &pwd,
tmpbuf.data, tmpbuf.length, &tpwd)) == ERANGE)
{
if (!scratch_buffer_grow (&tmpbuf))
{
result = ENOMEM;
goto out;
}
}
if (res != 0 || tpwd == NULL)
{
result = -1;
goto out;
}
size_t needed = strlen (pwd.pw_name) + 1;
if (needed > namesize)
{
__set_errno (ERANGE);
result = ERANGE;
goto out;
}
memcpy (name, pwd.pw_name, needed);
out:
scratch_buffer_free (&tmpbuf);
return result;
}
/* 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. */
int
__getlogin_r (char *name, size_t namesize)
{
int res = __getlogin_r_loginuid (name, namesize);
if (res >= 0)
return res;
return getlogin_r_fd0 (name, namesize);
}
libc_hidden_def (__getlogin_r)
weak_alias (__getlogin_r, getlogin_r)
libc_hidden_weak (getlogin_r)
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