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From: "simon.chopin at canonical dot com"
 <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug time/31510] New: Wrong type for timeval.tv_usec on 32-bit archs
 with _TIME_BITS=64
Date: Tue, 19 Mar 2024 11:24:14 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D31510

            Bug ID: 31510
           Summary: Wrong type for timeval.tv_usec on 32-bit archs with
                    _TIME_BITS=3D64
           Product: glibc
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: time
          Assignee: unassigned at sourceware dot org
          Reporter: simon.chopin at canonical dot com
  Target Milestone: ---

POSIX documents struct timeval as follows:

struct timeval {
    time_t      tv_sec;         /* seconds */
    suseconds_t tv_usec;        /* microseconds */
};
Since bdc4782744df73a8c0559985c54b5b6b9c7a4a74 ("y2038: Add __USE_TIME_BITS=
64
support for struct timeval") tv_usec can have __suseconds64_t when using 64=
-bit
time, however suseconds_t is unconditionally typedefed to __suseconds_t.

That leads to the following:

ubuntu@mantic-armhf:~$ cat test.c
#include <sys/time.h>
#include <stdio.h>
#include <assert.h>

int main(void)
{
        struct timeval tv;
        printf("tv_usec: %d, suseconds_t: %d\n", sizeof(tv.tv_usec),
sizeof(suseconds_t));
        assert(sizeof(tv.tv_usec) =3D=3D sizeof(suseconds_t));
        return 0;
}
ubuntu@mantic-armhf:~$ gcc test.c && ./a.out
tv_usec: 4, suseconds_t: 4
ubuntu@mantic-armhf:~$ gcc -D_TIME_BITS=3D64 -D_FILE_OFFSET_BITS=3D64 test.=
c &&
./a.out
tv_usec: 8, suseconds_t: 4
a.out: test.c:9: main: Assertion `sizeof(tv.tv_usec) =3D=3D sizeof(susecond=
s_t)'
failed.
Aborted (core dumped)

We noticed this when running the conformance tests on Ubuntu Noble, where w=
e've
set _TIME_BITS=3D64 in the default GCC flags as part of the ongoing t64
transition.

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