mirror of
https://sourceware.org/git/glibc.git
synced 2025-12-21 17:31:10 +03:00
6b7067460f
Clang issues a warning for double alias redirection, indicating that thei
original symbol is used even if a weak definition attempts to override it.
For instance, in the construction:
int __internal_impl (...) {}
weak_alias (__internal_impl, external_impl);
#if SOMETHING
weak_alias (external_impl, another_external_impl)
#endif
Clang warns that another_external_impl always resolves to __internal_impl,
even if external_impl is a weak reference. Using the internal symbol for
both aliases resolves this warning.
This issue also occurs with certain libc_hidden_def usage:
int __internal_impl (...) {}
weak_alias (__internal_impl, __internal_alias)
libc_hidden_weak (__internal_alias)
In this case, using a strong_alias is sufficient to avoid the warning
(since the alias is internal, there is no need to use a weak alias).
However, for the constructions like:
int __internal_impl (...) {}
weak_alias (__internal_impl, __internal_alias)
libc_hidden_def (__internal_alias)
weak_alias (__internal_impl, external_alias)
libc_hidden_def (external_alias)
Clang warns that the internal external_alias will always resolve to
__GI___internal_impl, even if a weak definition of __GI_internal_impl is
overridden. For this case, a new macro named static_weak_alias is used
to create a strong alias for SHARED, or a weak_alias otherwise.
With these changes, there is no need to check and enable the
-Wno-ignored-attributes suppression when using clang.
Checked with a build on affected ABIs, and a full check on aarch64,
armhf, i686, and x86_64.
Reviewed-by: Sam James <sam@gentoo.org>
119 lines
3.2 KiB
C
119 lines
3.2 KiB
C
/* Copyright (C) 2010-2025 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)
|
|
return -1;
|
|
|
|
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)
|
|
static_weak_alias (__getlogin_r, getlogin_r)
|
|
libc_hidden_weak (getlogin_r)
|