[Bug libc/16437] [x86_64] struct timespec definition is non-conforming on x32 and perhaps other archs

["hjl.tools at gmail dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=16437

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |hjl.tools at gmail dot com
         Resolution|---                         |WONTFIX

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Rich Felker from comment #0)
> glibc's definition of struct timespec is wrong: it's using __syscall_slong_t
> rather than long. This violates the requirements of both POSIX and C11. See
> C11 7.27.1 Components of time, paragraph 4:
> 
> "The range and precision of times representable in clock_t and time_t are
> implementation-defined. The timespec structure shall contain at least the
> following members, in any order.
> 
>          time_t tv_sec; // whole seconds -- >= 0
>          long   tv_nsec; // nanoseconds -- [0, 999999999]"
> 
> This breaks conforming code such as:
> 
> struct timespec ts;
> sscanf("42", "%ld", &ts.tv_nsec);
> 

Both clang and GCC will complain:

[hjl@gnu-6 tmp]$ cat t.c
#include <stdio.h>
#include <sys/time.h>

long
foo (const char *str)
{
  struct timespec ts;
  sscanf(str, "%ld", &ts.tv_nsec);
  return ts.tv_nsec;
}
[hjl@gnu-6 tmp]$ /opt/llvm/x32/bin/clang -c -mx32 t.c
t.c:8:22: warning: format specifies type 'long *' but the argument has type
      '__syscall_slong_t *' (aka 'long long *') [-Wformat]
  sscanf(str, "%ld", &ts.tv_nsec);
               ~~~   ^~~~~~~~~~~
               %lld
1 warning generated.
[hjl@gnu-6 tmp]$ gcc -Wall -c  -mx32 t.c
t.c: In function âfooâ:
t.c:8:3: warning: format â%ldâ expects argument of type âlong int *â, but
argument 3 has type â__syscall_slong_t *â [-Wformat=]
   sscanf(str, "%ld", &ts.tv_nsec);
   ^
[hjl@gnu-6 tmp]$ 

This issue has been discussed in March, 2012:

https://sourceware.org/ml/libc-alpha/2012-03/msg00438.html

I won't change x32.  I consider this issue is closed.

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