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flag parameters: timerfd_create

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The timerfd_create syscall already has a flags parameter.  It just is
unused so far.  This patch changes this by introducing the TFD_CLOEXEC
flag to set the close-on-exec flag for the returned file descriptor.

A new name TFD_CLOEXEC is introduced which in this implementation must
have the same value as O_CLOEXEC.

The following test must be adjusted for architectures other than x86 and
x86-64 and in case the syscall numbers changed.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include <fcntl.h>
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <sys/syscall.h>

#ifndef __NR_timerfd_create
# ifdef __x86_64__
#  define __NR_timerfd_create 283
# elif defined __i386__
#  define __NR_timerfd_create 322
# else
#  error "need __NR_timerfd_create"
# endif
#endif

#define TFD_CLOEXEC O_CLOEXEC

int
main (void)
{
  int fd = syscall (__NR_timerfd_create, CLOCK_REALTIME, 0);
  if (fd == -1)
    {
      puts ("timerfd_create(0) failed");
      return 1;
    }
  int coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if (coe & FD_CLOEXEC)
    {
      puts ("timerfd_create(0) set close-on-exec flag");
      return 1;
    }
  close (fd);

  fd = syscall (__NR_timerfd_create, CLOCK_REALTIME, TFD_CLOEXEC);
  if (fd == -1)
    {
      puts ("timerfd_create(TFD_CLOEXEC) failed");
      return 1;
    }
  coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if ((coe & FD_CLOEXEC) == 0)
    {
      puts ("timerfd_create(TFD_CLOEXEC) set close-on-exec flag");
      return 1;
    }
  close (fd);

  puts ("OK");

  return 0;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ulrich Drepper 2008-07-23 21:29:26 -07:00 committed by Linus Torvalds
parent b087498eb5
commit 11fcb6c146
2 changed files with 8 additions and 2 deletions
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5
fs/timerfd.c
View file

@ -184,7 +184,7 @@ asmlinkage long sys_timerfd_create(int clockid, int flags)
int ufd; int ufd;
struct timerfd_ctx *ctx; struct timerfd_ctx *ctx;
if (flags) if (flags & ~TFD_CLOEXEC)
return -EINVAL; return -EINVAL;
if (clockid != CLOCK_MONOTONIC && if (clockid != CLOCK_MONOTONIC &&
clockid != CLOCK_REALTIME) clockid != CLOCK_REALTIME)
@ -198,7 +198,8 @@ asmlinkage long sys_timerfd_create(int clockid, int flags)
ctx->clockid = clockid; ctx->clockid = clockid;
hrtimer_init(&ctx->tmr, clockid, HRTIMER_MODE_ABS); hrtimer_init(&ctx->tmr, clockid, HRTIMER_MODE_ABS);
ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx, 0); ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx,
flags & O_CLOEXEC);
if (ufd < 0) if (ufd < 0)
kfree(ctx); kfree(ctx);

5
include/linux/timerfd.h
View file

@ -8,9 +8,14 @@
#ifndef _LINUX_TIMERFD_H #ifndef _LINUX_TIMERFD_H
#define _LINUX_TIMERFD_H #define _LINUX_TIMERFD_H
/* For O_CLOEXEC */
#include <linux/fcntl.h>
/* Flags for timerfd_settime. */
#define TFD_TIMER_ABSTIME (1 << 0) #define TFD_TIMER_ABSTIME (1 << 0)
/* Flags for timerfd_create. */
#define TFD_CLOEXEC O_CLOEXEC
#endif /* _LINUX_TIMERFD_H */ #endif /* _LINUX_TIMERFD_H */