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git.ipfire.org Git - thirdparty/glibc.git/blob - sysdeps/unix/sysv/linux/getlogin_r.c
1 /* Copyright (C) 2010-2018 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <http://www.gnu.org/licenses/>. */
20 #include <not-cancel.h>
23 static int getlogin_r_fd0 (char *name
, size_t namesize
);
24 #define __getlogin_r getlogin_r_fd0
25 #include <sysdeps/unix/getlogin_r.c>
29 /* Try to determine login name from /proc/self/loginuid and return 0
30 if successful. If /proc/self/loginuid cannot be read return -1.
31 Otherwise return the error number. */
35 __getlogin_r_loginuid (char *name
, size_t namesize
)
37 int fd
= __open_nocancel ("/proc/self/loginuid", O_RDONLY
);
41 /* We are reading a 32-bit number. 12 bytes are enough for the text
42 representation. If not, something is wrong. */
44 ssize_t n
= TEMP_FAILURE_RETRY (__read_nocancel (fd
, uidbuf
,
46 __close_nocancel_nostatus (fd
);
51 || n
== sizeof (uidbuf
)
53 uid
= strtoul (uidbuf
, &endp
, 10),
54 endp
== uidbuf
|| *endp
!= '\0'))
58 char *buf
= alloca (buflen
);
59 bool use_malloc
= false;
65 while ((res
= __getpwuid_r (uid
, &pwd
, buf
, buflen
, &tpwd
)) == ERANGE
)
66 if (__libc_use_alloca (2 * buflen
))
67 buf
= extend_alloca (buf
, buflen
, 2 * buflen
);
71 char *newp
= realloc (use_malloc
? buf
: NULL
, buflen
);
81 if (res
!= 0 || tpwd
== NULL
)
87 size_t needed
= strlen (pwd
.pw_name
) + 1;
88 if (needed
> namesize
)
95 memcpy (name
, pwd
.pw_name
, needed
);
105 /* Return at most NAME_LEN characters of the login name of the user in NAME.
106 If it cannot be determined or some other error occurred, return the error
107 code. Otherwise return 0. */
110 __getlogin_r (char *name
, size_t namesize
)
112 int res
= __getlogin_r_loginuid (name
, namesize
);
116 return getlogin_r_fd0 (name
, namesize
);
118 libc_hidden_def (__getlogin_r
)
119 weak_alias (__getlogin_r
, getlogin_r
)
120 libc_hidden_weak (getlogin_r
)