Commit Graph

497 Commits

Author SHA1 Message Date
Alejandro Colomar
709e6b4497 Add stpecpy()
strncat(3), strlcpy(3), and many other functions are often misused for
catenating strings, when they should never be used for that.  strlcat(3)
is good.  However, there's no equivalent to strlcat(3) similar to
snprintf(3).  Let's add stpecpy(), which is similar to strlcat(3), but
it is also the only function compatible with stpeprintf(), which makes
it more useful than strlcat(3).

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-16 11:29:33 +01:00
Alejandro Colomar
e0e9e57a72 Add mempcpy(3)
We'll use it for implementing stpecpy(), and may be interesting to have
it around.

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-16 11:29:33 +01:00
Alejandro Colomar
7e213cfb50 Add stpeprintf()
[v]stpeprintf() are similar to [v]snprintf(3), but they allow chaining.
[v]snprintf(3) are very dangerous for catenating strings, since the
obvious ways to do it invoke Undefined Behavior, and the ways that avoid
UB are very error-prone.

Cc: Iker Pedrosa <ipedrosa@redhat.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-16 11:29:33 +01:00
Alejandro Colomar
bddcd9b095 Remove superfluous casts
-  Every non-const pointer converts automatically to void *.
-  Every pointer converts automatically to void *.
-  void * converts to any other pointer.
-  const void * converts to any other const pointer.
-  Integer variables convert to each other.

I changed the declaration of a few variables in order to allow removing
a cast.

However, I didn't attempt to edit casts inside comparisons, since they
are very delicate.  I also kept casts in variadic functions, since they
are necessary, and in allocation functions, because I have other plans
for them.

I also changed a few casts to int that are better as ptrdiff_t.

This change has triggered some warnings about const correctness issues,
which have also been fixed in this patch (see for example src/login.c).

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-09 10:03:03 -06:00
Alejandro Colomar
b34387745a lib/defines.h: Add NORETURN attribute macro
We could use the standard (C11) _Noreturn qualifier, but it will be
deprecated in C23, and replaced by C++'s [[noreturn]], which is
compatible with the GCC attribute, so let's directly use the attribute,
and in the future we'll be able to switch to [[]].

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-08 22:01:01 -06:00
Alejandro Colomar
e762ab8b54 Assume getutent(3) exists (remove dead code)
Recently, we removed support for 'struct utmpx'.  We did it because utmp
and utmpx are identical, and while POSIX specifies utmpx (and not utmp),
GNU/Linux documentation seems to favor utmp.  Also, this project
defaulted to utmp, so changing to utmpx would be more dangerous than
keeping old defaults, even if it's supposed to be the same.

Now, I just found more code that didn't make much sense: lib/utent.c
provides definitions for getutent(3) and friends in case the system
doesn't provide them, but we don't provide prototypes for those
definitions, so code using the functions would have never compiled.

Let's just remove these definitions as dead code.

Fixes: 3be7b9d75a ("Remove traces of utmpx")
Fixes: 170b76cdd1 ("Disable utmpx permanently")
Cc: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-08 17:21:34 +01:00
Alejandro Colomar
82480995b4 Remove unused function: gr_append_member()
Reported-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-03 22:03:38 -06:00
Alejandro Colomar
1f6f1669cf Remove superfluous casts to 'void*'
Every non-const pointer converts automatically to it.

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-02 22:03:26 -06:00
Alejandro Colomar
62172f6fb5 Call NULL by its name
In variadic functions we still do the cast.  In POSIX, it's not
necessary, since NULL is required to be of type 'void *', and 'void *'
is guaranteed to have the same alignment and representation as 'char *'.
However, since ISO C still doesn't mandate that, and moreover they're
doing dubious stuff by adding nullptr, let's be on the cautious side.
Also, C++ requires that NULL is _not_ 'void *', but either plain 0 or
some magic stuff.

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-02 13:08:30 -06:00
Samanta Navarro
ffc480c2e9 Explicitly override only newlines
Override only newlines with '\0' to avoid undesired truncation of
actual line content.

Signed-off-by: Samanta Navarro <ferivoz@riseup.net>
2023-02-01 15:47:35 -06:00
Alejandro Colomar
03bbe6c418 leading_zerosul(): Fix bug
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-01 09:10:34 +01:00
Alejandro Colomar
0712b236c3 Add bit manipulation functions
We do need the unoptimized version of csrand_uniform() for high values
of `n`, since the optimized version depends on having __int128, and it's
not available on several platforms, including ARMv7, IA32, and MK68k.

This reverts commit 848f53c1d3c1362c86d3baab6906e1e4419d2634; however,
I applied some tweaks to the reverted commit.

Reported-by: Adam Sampson <ats@offog.org>
Cc: Iker Pedrosa <ipedrosa@redhat.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-01-30 18:24:15 +01:00
Alejandro Colomar
848f53c1d3 Revert "Add bit manipulation functions"
Now that we optimized csrand_uniform(), we don't need these functions.

This reverts commit 7c8fe291b1260e127c10562bfd7616961013730f.

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-01-27 21:48:37 -06:00
Alejandro Colomar
3f90eff494 Add WIDTHOF() to get the width in bits
It is common to use the expression 'sizeof(x) * CHAR_BIT' to mean the
width in bits of a type or object.  Now that there are _WIDTH macros for
some types, indicating the number of bits that they use, it makes sense
to wrap this calculation in a macro of a similar name.

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-01-27 21:48:37 -06:00
Alejandro Colomar
1db190cb66 Rewrite csrand_interval() as a wrapper around csrand_uniform()
The old code didn't produce very good random numbers.  It had a bias.
And that was from performing some unnecessary floating-point
calculations that overcomplicate the problem.

Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Cristian Rodríguez <crrodriguez@opensuse.org>
Cc: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Björn Esser <besser82@fedoraproject.org>
Cc: Yann Droneaud <ydroneaud@opteya.com>
Cc: Joseph Myers <joseph@codesourcery.com>
Cc: Sam James <sam@gentoo.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-01-27 21:48:37 -06:00
Alejandro Colomar
31375d48ca Add csrand_uniform()
This API is similar to arc4random_uniform(3).  However, for an input of
0, this function is equivalent to csrand(), while arc4random_uniform(0)
returns 0.

This function will be used to reimplement csrand_interval() as a wrapper
around this one.

The current implementation of csrand_interval() doesn't produce very good
random numbers.  It has a bias.  And that comes from performing some
unnecessary floating-point calculations that overcomplicate the problem.

Looping until the random number hits within bounds is unbiased, and
truncating unwanted bits makes the overhead of the loop very small.

We could reduce loop overhead even more, by keeping unused bits of the
random number, if the width of the mask is not greater than
ULONG_WIDTH/2, however, that complicates the code considerably, and I
prefer to be a bit slower but have simple code.

BTW, Björn really deserves the copyright for csrand() (previously known
as read_random_bytes()), since he rewrote it almost from scratch last
year, and I kept most of its contents.  Since he didn't put himself in
the copyright back then, and BSD-3-Clause doesn't allow me to attribute
derived works, I won't add his name, but if he asks, he should be put in
the copyright too.

Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Cristian Rodríguez <crrodriguez@opensuse.org>
Cc: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Björn Esser <besser82@fedoraproject.org>
Cc: Yann Droneaud <ydroneaud@opteya.com>
Cc: Joseph Myers <joseph@codesourcery.com>
Cc: Sam James <sam@gentoo.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-01-27 21:48:37 -06:00
Alejandro Colomar
4a56f2baab Add bit manipulation functions
These functions implement bit manipulation APIs, which will be added to
C23, so that in the far future, we will be able to replace our functions
by the standard ones, just by adding the stdc_ prefix, and including
<stdbit.h>.

However, we need to avoid UB for an input of 0, so slightly deviate from
C23, and use a different name (with _wrap) for distunguishing our API
from the standard one.

Cc: Joseph Myers <joseph@codesourcery.com>
Cc: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-01-27 21:48:37 -06:00
Alejandro Colomar
be1f4f7972 Move csrand() to a new file csrand.c
A set of APIs similar to arc4random(3) is complex enough to deserve its
own file.

Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Cristian Rodríguez <crrodriguez@opensuse.org>
Cc: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Björn Esser <besser82@fedoraproject.org>
Cc: Yann Droneaud <ydroneaud@opteya.com>
Cc: Joseph Myers <joseph@codesourcery.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-01-27 21:48:37 -06:00
Samanta Navarro
b312bc0b4d Fix typos
Typos found with codespell.

Signed-off-by: Samanta Navarro <ferivoz@riseup.net>
2023-01-26 22:44:39 -06:00
Christian Göttsche
194014678e Declare constant data structure const
./lib/pam_defs.h:18:24: warning: ‘conv’ defined but not used [-Wunused-variable]
       18 | static struct pam_conv conv = {
          |                        ^~~~
2023-01-25 12:31:17 +01:00
Christian Göttsche
89be7c0465 Provide strlcpy declaration
strlcpy(3) might not be visible since it is declared in <bsd/string.h>.
This can lead to warnings, like:

    fields.c: In function 'change_field':
    fields.c:103:17: warning: implicit declaration of function 'strlcpy'; did you mean 'strncpy'? [-Wimplicit-function-declaration]
      103 |                 strlcpy (buf, cp, maxsize);
          |                 ^~~~~~~
          |                 strncpy

    ../lib/fields.c:103:17: warning: type of 'strlcpy' does not match original declaration [-Wlto-type-mismatch]
      103 |                 strlcpy (buf, cp, maxsize);
          |                 ^
    /usr/include/bsd/string.h:44:8: note: return value type mismatch
       44 | size_t strlcpy(char *dst, const char *src, size_t siz);
          |        ^
    /usr/include/bsd/string.h:44:8: note: type 'size_t' should match type 'int'
    /usr/include/bsd/string.h:44:8: note: 'strlcpy' was previously declared here
    /usr/include/bsd/string.h:44:8: note: code may be misoptimized unless '-fno-strict-aliasing' is used
2023-01-25 12:31:17 +01:00
Christian Göttsche
e0d79ee032 Modernize manual memzero implementation
Instead of using volatile pointers to prevent the compiler from
optimizing the call away, use a memory barrier.
This requires support for embedded assembly, which should be fine after
the recent requirement bumps.
2023-01-25 11:07:25 +01:00
Christian Göttsche
90ead3cfb8 Replace flawed memset_s usage
memset_s() has a different signature than memset(3) or explicit_bzero(),
thus the current code would not compile.  Also memset_s()
implementations are quite rare.
Use the C23 standardized version memset_explicit(3).

Fixes: 7a799ebb ("Ensure memory cleaning")
2023-01-25 11:07:25 +01:00
Alejandro Colomar
b2bed465e8 Use getnameinfo(3) instead of our own equivalent
I didn't know getnameinfo(3) existed, so I implemented it, or something
similar to it called inet_sockaddr2str().  Let's use the standard API.

Link: <https://inbox.sourceware.org/libc-alpha/0f25d60f-f183-b518-b6c1-6d46aa63ee57@gmail.com/T/>
Link: <https://stackoverflow.com/a/42190913/6872717>
Link: <https://github.com/shadow-maint/shadow/pull/617>
Link: <https://software.codidact.com/posts/287748>
Cc: Zack Weinberg <zack@owlfolio.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-01-20 10:23:03 -06:00
Christian Göttsche
1d936c968a Warn if failed to read existing /etc/nsswitch.conf
Commit 90424e7c ("Don't warn when failed to open /etc/nsswitch.conf")
removed the logging for failing to read /etc/nsswitch.conf to reduce the
noise in the case the file does not exists (e.g. musl based systems).

Reintroduce a warning if /etc/nsswitch.conf exists but we failed to read
it (e.g. permission denied).

Improves: 90424e7c ("Don't warn when failed to open /etc/nsswitch.conf")
2023-01-04 14:21:43 -06:00
Alejandro Colomar
bb3a89577c Add inet_sockaddr2str() to wrap inet_ntop(3)
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-01-02 08:20:43 +01:00
ed neville
65470e5c7d changing lock mechanism
Systems can suffer power interruptions whilst .lock files are in /etc,
preventing scripts and other automation tools from updating shadow's
files which persist across boots.

This commit replaces that mechanism with file locking to avoid problems
of power interruption/crashing.

Minor tweak to groupmems man page, requested by 'xx' on IRC.

Signed-off-by: ed neville <ed@s5h.net>
2022-12-29 13:58:49 -06:00
Alejandro Colomar
eb164165f6 Add NITEMS(arr) to get the number of elements of an array
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-22 18:20:02 -06:00
Alejandro Colomar
220b352b70 Use strlcpy(3) instead of its pattern
-  Since strncpy(3) is not designed to write strings, but rather
   (null-padded) character sequences (a.k.a. unterminated strings), we
   had to manually append a '\0'.  strlcpy(3) creates strings, so they
   are always terminated.  This removes dependencies between lines, and
   also removes chances of accidents.

-  Repurposing strncpy(3) to create strings requires calculating the
   location of the terminating null byte, which involves a '-1'
   calculation.  This is a source of off-by-one bugs.  The new code has
   no '-1' calculations, so there's almost-zero chance of these bugs.

-  strlcpy(3) doesn't padd with null bytes.  Padding is relevant when
   writing fixed-width buffers to binary files, when interfacing certain
   APIs (I believe utmpx requires null padding at lease in some
   systems), or when sending them to other processes or through the
   network.  This is not the case, so padding is effectively ignored.

-  strlcpy(3) requires that the input string is really a string;
   otherwise it crashes (SIGSEGV).  Let's check if the input strings are
   really strings:

   -  lib/fields.c:
      -  'cp' was assigned from 'newft', and 'newft' comes from fgets(3).

   -  lib/gshadow.c:
      -  strlen(string) is calculated a few lines above.

   -  libmisc/console.c:
      -  'cons' comes from getdef_str, which is a bit cryptic, but seems
         to generate strings, I guess.1

   -  libmisc/date_to_str.c:
      -  It receives a string literal.  :)

   -  libmisc/utmp.c:
      -  'tname' comes from ttyname(3), which returns a string.

   -  src/su.c:
      -  'tmp_name' has been passed to strcmp(3) a few lines above.

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-22 18:03:39 -06:00
Alejandro Colomar
5d7a3b80e9 Remove USE_SYSLOG preprocessor conditional, which was always defined
Reported-by: Iker Pedrosa <ipedrosa@redhat.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-22 11:44:36 +01:00
Alejandro Colomar
e2df287aad Don't redefine errno(3)
It is Undefined Behavior to declare errno (see NOTES in its manual page).
Instead of using the errno dummy declaration, use one that doesn't need
a comment.

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-22 11:43:29 +01:00
Alejandro Colomar
3be7b9d75a Remove traces of utmpx
-  USER_NAME_MAX_LENGTH was being calculated in terms of utmpx.  Do it
   in terms of utmp.
-  Remove utmpx support from the whishlist.
-  Remove unused tests about utmpx members.

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-22 10:31:43 +01:00
Alejandro Colomar
170b76cdd1 Disable utmpx permanently
On Linux, utmpx and utmp are identical.  However, documentation (manual
pages) covers utmp, and just says about utmpx that it's identical to
utmp.  It seems that it's preferred to use utmp, at least by reading the
manual pages.

Moreover, we were defaulting to utmp (utmpx had to be explicitly enabled
at configuration time).  So, it seems safer to just make it permanent,
which should not affect default builds.

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-22 10:31:43 +01:00
Alejandro Colomar
54847a76da Remove preprocessor conditionals that are always true
In a previous commit, we made USE_TERMIOS unconditionally defined.
Let's just remove it, and remove the condition everywhere.

Reported-by: Iker Pedrosa <ipedrosa@redhat.com>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-15 16:22:05 -06:00
Alejandro Colomar
0e0c55aeca Assume F_* and SEEK_* macros are defined
They are required by POSIX.1-2001.

Link: <https://github.com/shadow-maint/shadow/pull/600>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Iker Pedrosa <ipedrosa@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-15 16:22:05 -06:00
Alejandro Colomar
9dfa71f71c Remove code conditional on S_SPLINT_S
I don't know for sure what that is, but it's redefining setlocale(3)
and LC_ALL, which is are defined by C99, so it's supect of being some
variety of an extinct dynosaur.  Maybe related to the Dodo.

Link: <https://github.com/shadow-maint/shadow/pull/600>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Iker Pedrosa <ipedrosa@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-15 16:22:05 -06:00
Alejandro Colomar
143e346dd5 Assume strdup(3) exists
It is required by POSIX.1-2001.

Link: <https://github.com/shadow-maint/shadow/pull/600>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Iker Pedrosa <ipedrosa@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-15 16:22:05 -06:00
Alejandro Colomar
a082a3975f Assume fsync(2) exists
It is required by POSIX.1-2001.

Cc: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-15 16:22:05 -06:00
Alejandro Colomar
e71c23586a Assume fchown(2) exists
It is required by POSIX.1-2001.

Cc: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-15 16:22:05 -06:00
Alejandro Colomar
9c86e07067 Assume fchmod(2) exists
It is required by POSIX.1-2001.

Cc: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-15 16:22:05 -06:00
Alejandro Colomar
5777e583cd Assume <termios.h> exists
It is required by POSIX.1-2001.

Cc: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-15 16:22:05 -06:00
Alejandro Colomar
b47aa1e9aa Assume <utmpx.h> exists
It is required by POSIX.1-2001.

Cc: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-15 16:22:05 -06:00
Alejandro Colomar
578f286215 Assume <unistd.h> exists
It is required by POSIX.1-2001.

Cc: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-15 16:22:05 -06:00
Alejandro Colomar
9d8c3df93c Assume NULL exists
ISO C99 requires NULL.

Link: <https://github.com/shadow-maint/shadow/pull/600>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Iker Pedrosa <ipedrosa@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-12 09:16:43 +01:00
Alejandro Colomar
3a32f5278d Assume strerror(3) exists
ISO C99 requires strerror(3).

Link: <https://github.com/shadow-maint/shadow/pull/600>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Iker Pedrosa <ipedrosa@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-12 09:16:43 +01:00
Alejandro Colomar
5e8df2b2b5 Assume fputs(3) exists
ISO C99 requires fputs(3).

Link: <https://github.com/shadow-maint/shadow/pull/600>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Iker Pedrosa <ipedrosa@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-12 09:16:43 +01:00
Alejandro Colomar
c26b682381 Assume <locale.h> exists
ISO C99 requires <locale.h>.

Other files in the project already include <locale.h> unconditionally,
so it's reasonable to assume that it is always available.

Link: <https://github.com/shadow-maint/shadow/pull/600>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Iker Pedrosa <ipedrosa@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-12 09:16:43 +01:00
Alejandro Colomar
1eaa30756e Assume <errno.h> exists
ISO C99 requires <errno.h>.

Many files in the project already include <errno.h> unconditionally,
so it's reasonable to assume that it is always available.

Link: <https://github.com/shadow-maint/shadow/pull/600>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Iker Pedrosa <ipedrosa@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-12 09:16:43 +01:00
Alejandro Colomar
c4d9dcacc9 Assume <stdbool.h> exists
ISO C99 requires <stdbool.h>.

Many files in the project already include <stdbool.h> unconditionally,
so it's reasonable to assume that it is always available.

Link: <https://github.com/shadow-maint/shadow/pull/600>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Iker Pedrosa <ipedrosa@redhat.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-12 09:16:43 +01:00
Alejandro Colomar
ab91ec10b4 Hide [[gnu::malloc(deallocator)]] in a macro
Clang doesn't implement this attribute and reports an error.  Work
around it by hiding it in a macro that will be empty in clang.

Reported-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-05 10:47:19 +01:00