1 /* Copyright (C) 2010-2024 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 <https://www.gnu.org/licenses/>. */
20 #include <not-cancel.h>
21 #include <scratch_buffer.h>
24 static int getlogin_r_fd0 (char *name
, size_t namesize
);
25 #define __getlogin_r getlogin_r_fd0
26 #include <sysdeps/unix/getlogin_r.c>
30 /* Try to determine login name from /proc/self/loginuid and return 0
31 if successful. If /proc/self/loginuid cannot be read return -1.
32 Otherwise return the error number. */
36 __getlogin_r_loginuid (char *name
, size_t namesize
)
38 int fd
= __open_nocancel ("/proc/self/loginuid", O_RDONLY
);
42 /* We are reading a 32-bit number. 12 bytes are enough for the text
43 representation. If not, something is wrong. */
45 ssize_t n
= TEMP_FAILURE_RETRY (__read_nocancel (fd
, uidbuf
,
47 __close_nocancel_nostatus (fd
);
52 || n
== sizeof (uidbuf
)
54 uid
= strtoul (uidbuf
, &endp
, 10),
55 endp
== uidbuf
|| *endp
!= '\0'))
58 /* If there is no login uid, linux sets /proc/self/loginid to the sentinel
59 value of, (uid_t) -1, so check if that value is set and return early to
60 avoid making unneeded nss lookups. */
61 if (uid
== (uid_t
) -1)
68 struct scratch_buffer tmpbuf
;
69 scratch_buffer_init (&tmpbuf
);
71 while ((res
= __getpwuid_r (uid
, &pwd
,
72 tmpbuf
.data
, tmpbuf
.length
, &tpwd
)) == ERANGE
)
74 if (!scratch_buffer_grow (&tmpbuf
))
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
);
98 scratch_buffer_free (&tmpbuf
);
103 /* Return at most NAME_LEN characters of the login name of the user in NAME.
104 If it cannot be determined or some other error occurred, return the error
105 code. Otherwise return 0. */
108 __getlogin_r (char *name
, size_t namesize
)
110 int res
= __getlogin_r_loginuid (name
, namesize
);
114 return getlogin_r_fd0 (name
, namesize
);
116 libc_hidden_def (__getlogin_r
)
117 weak_alias (__getlogin_r
, getlogin_r
)
118 libc_hidden_weak (getlogin_r
)