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glibc/sysdeps/unix/sysv/linux/getlogin_r.c
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/* Copyright (C) 2010-2016 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 <pwd.h> | |
#include <unistd.h> | |
#include <not-cancel.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_not_cancel_2 ("/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_not_cancel (fd, uidbuf, | |
sizeof (uidbuf))); | |
close_not_cancel_no_status (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; | |
size_t buflen = 1024; | |
char *buf = alloca (buflen); | |
bool use_malloc = false; | |
struct passwd pwd; | |
struct passwd *tpwd; | |
int result = 0; | |
int res; | |
while ((res = __getpwuid_r (uid, &pwd, buf, buflen, &tpwd)) == ERANGE) | |
if (__libc_use_alloca (2 * buflen)) | |
buf = extend_alloca (buf, buflen, 2 * buflen); | |
else | |
{ | |
buflen *= 2; | |
char *newp = realloc (use_malloc ? buf : NULL, buflen); | |
if (newp == NULL) | |
{ | |
result = ENOMEM; | |
goto out; | |
} | |
buf = newp; | |
use_malloc = true; | |
} | |
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: | |
if (use_malloc) | |
free (buf); | |
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) |