[PATCH v2 05/14] linux: Add time64 select support

[Alistair Francis]

On Tue, Sep 8, 2020 at 7:59 AM Adhemerval Zanella via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> The syscall __NR_pselect6_time64 (32-bit) or __NR_pselect6 (64-bit)
> is used as default.  For architectures with __ASSUME_TIME64_SYSCALLS
> the 32-bit fallback uses __NR_select/__NR__newselect or __NR_pselect6
> (it should cover the microblaze case where older kernels do not
> provide __NR_pselect6).
>
> Checked on x86_64-linux-gnu and i686-linux-gnu (on 5.4 and on 4.15
> kernel).

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  include/sys/select.h             |  8 +++
>  include/time.h                   |  6 +++
>  sysdeps/unix/sysv/linux/select.c | 92 ++++++++++++++++++++++++--------
>  3 files changed, 83 insertions(+), 23 deletions(-)
>
> diff --git a/include/sys/select.h b/include/sys/select.h
> index b5ae9af861..ec073deeba 100644
> --- a/include/sys/select.h
> +++ b/include/sys/select.h
> @@ -5,8 +5,11 @@
>  /* Now define the internal interfaces.  */
>  # if __TIMESIZE == 64
>  #  define __pselect64 __pselect
> +#  define __select64  __select
>  #else
>  # include <struct___timespec64.h>
> +# include <struct___timeval64.h>
> +
>  extern int __pselect64 (int __nfds, fd_set *__readfds,
>                         fd_set *__writefds, fd_set *__exceptfds,
>                         const struct __timespec64 *__timeout,
> @@ -18,6 +21,11 @@ extern int __pselect32 (int __nfds, fd_set *__readfds,
>                         const struct __timespec64 *__timeout,
>                         const __sigset_t *__sigmask)
>    attribute_hidden;
> +
> +extern int __select64 (int __nfds, fd_set *__readfds,
> +                      fd_set *__writefds, fd_set *__exceptfds,
> +                      struct __timeval64 *__timeout);
> +libc_hidden_proto (__select64)
>  #endif
>  extern int __pselect (int __nfds, fd_set *__readfds,
>                       fd_set *__writefds, fd_set *__exceptfds,
> diff --git a/include/time.h b/include/time.h
> index fe4da9ca10..936486e206 100644
> --- a/include/time.h
> +++ b/include/time.h
> @@ -464,6 +464,12 @@ valid_timespec_to_timeval32 (const struct timespec ts)
>    return (struct __timeval32) { (time_t) ts.tv_sec, ts.tv_nsec / 1000 };
>  }
>
> +static inline struct __timeval64
> +valid_timespec_to_timeval64 (const struct timespec ts)
> +{
> +  return (struct __timeval64) { (time_t) ts.tv_sec, ts.tv_nsec / 1000 };
> +}
> +
>  /* Check if a value is in the valid nanoseconds range. Return true if
>     it is, false otherwise.  */
>  static inline bool
> diff --git a/sysdeps/unix/sysv/linux/select.c b/sysdeps/unix/sysv/linux/select.c
> index 54c50edba2..bed52fbda2 100644
> --- a/sysdeps/unix/sysv/linux/select.c
> +++ b/sysdeps/unix/sysv/linux/select.c
> @@ -21,6 +21,7 @@
>  #include <sys/select.h>
>  #include <errno.h>
>  #include <sysdep-cancel.h>
> +#include <time64-support.h>
>
>  /* Check the first NFDS descriptors each in READFDS (if not NULL) for read
>     readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
> @@ -28,43 +29,88 @@
>     after waiting the interval specified therein.  Returns the number of ready
>     descriptors, or -1 for errors.  */
>
> -#ifdef __NR__newselect
> -# undef __NR_select
> -# define __NR_select __NR__newselect
> -#endif
> -
>  int
> -__select (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
> -         struct timeval *timeout)
> +__select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
> +           struct __timeval64 *timeout)
>  {
> -#ifdef __NR_select
> -  return SYSCALL_CANCEL (select, nfds, readfds, writefds, exceptfds,
> -                        timeout);
> -#else
> -  int result;
> -  struct timespec ts, *tsp = NULL;
> -
> -  if (timeout)
> +  struct __timespec64 ts64, *pts64 = NULL;
> +  if (timeout != NULL)
>      {
> -      TIMEVAL_TO_TIMESPEC (timeout, &ts);
> -      tsp = &ts;
> +      ts64 = timeval64_to_timespec64 (*timeout);
> +      pts64 = &ts64;
>      }
>
> -  result = SYSCALL_CANCEL (pselect6, nfds, readfds, writefds, exceptfds, tsp,
> -                          NULL);
> -
> -  if (timeout)
> +#ifndef __NR_pselect6_time64
> +# define __NR_pselect6_time64 __NR_pselect6
> +#endif
> +  int r;
> +  if (supports_time64 ())
>      {
> +      r = SYSCALL_CANCEL (pselect6_time64, nfds, readfds, writefds, exceptfds,
> +                         pts64, NULL);
>        /* Linux by default will update the timeout after a pselect6 syscall
>           (though the pselect() glibc call suppresses this behavior).
>           Since select() on Linux has the same behavior as the pselect6
>           syscall, we update the timeout here.  */
> -      TIMESPEC_TO_TIMEVAL (timeout, &ts);
> +      if (r == 0 || errno != ENOSYS)
> +       {
> +         if (timeout != NULL)
> +           TIMEVAL_TO_TIMESPEC (timeout, &ts64);
> +         return r;
> +       }
> +
> +      mark_time64_unsupported ();
>      }
>
> -  return result;
> +#ifndef __ASSUME_TIME64_SYSCALLS
> +  struct timespec ts32, *pts32 = NULL;
> +  if (timeout != NULL)
> +    {
> +      if (! in_time_t_range (timeout->tv_sec))
> +       {
> +         __set_errno (EINVAL);
> +         return -1;
> +       }
> +      ts32 = valid_timespec64_to_timespec (ts64);
> +      pts32 = &ts32;
> +    }
> +# ifndef __ASSUME_PSELECT
> +#  ifdef __NR__newselect
> +#   undef __NR_select
> +#   define __NR_select __NR__newselect
> +#  endif
> +  r = SYSCALL_CANCEL (select, nfds, readfds, writefds, exceptfds, pts32);
> +# else
> +  r = SYSCALL_CANCEL (pselect6, nfds, readfds, writefds, exceptfds, pts32,
> +                     NULL);
> +# endif
> +  if (r >= 0 && timeout != NULL)
> +    *timeout = valid_timespec_to_timeval64 (ts32);
>  #endif
> +
> +  return r;
>  }
> +
> +#if __TIMESIZE != 64
> +libc_hidden_def (__select64)
> +
> +int
> +__select (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
> +         struct timeval *timeout)
> +{
> +  struct __timeval64 tv64, *ptv64 = NULL;
> +  if (timeout != NULL)
> +    {
> +      tv64 = valid_timeval_to_timeval64 (*timeout);
> +      ptv64 = &tv64;
> +    }
> +  int r = __select64 (nfds, readfds, writefds, exceptfds, ptv64);
> +  if (r >= 0 && timeout != NULL)
> +    /* The remanining timeout will be always less the input TIMEOUT.  */
> +    *timeout = valid_timeval64_to_timeval (tv64);
> +  return r;
> +}
> +#endif
>  libc_hidden_def (__select)
>
>  weak_alias (__select, select)
> --
> 2.25.1
>