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;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/timerfd.c | 5 +++--
include/linux/timerfd.h | 5 +++++
2 files changed, 8 insertions(+), 2 deletions(-)
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
diff --git a/fs/timerfd.c b/fs/timerfd.c
index 77c2bc9..8a59036 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -184,7 +184,7 @@ asmlinkage long sys_timerfd_create(int clockid, int flags)
int ufd;
struct timerfd_ctx *ctx;
- if (flags)
+ if (flags & ~TFD_CLOEXEC)
return -EINVAL;
if (clockid != CLOCK_MONOTONIC &&
clockid != CLOCK_REALTIME)
@@ -198,7 +198,8 @@ asmlinkage long sys_timerfd_create(int clockid, int flags)
ctx->clockid = clockid;
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)
kfree(ctx);
diff --git a/include/linux/timerfd.h b/include/linux/timerfd.h
index cf2b10d..96ed97d 100644
--- a/include/linux/timerfd.h
+++ b/include/linux/timerfd.h
@@ -8,9 +8,14 @@
#ifndef _LINUX_TIMERFD_H
#define _LINUX_TIMERFD_H
+/* For O_CLOEXEC */
+#include <linux/fcntl.h>
+/* Flags for timerfd_settime. */
#define TFD_TIMER_ABSTIME (1 << 0)
+/* Flags for timerfd_create. */
+#define TFD_CLOEXEC O_CLOEXEC
#endif /* _LINUX_TIMERFD_H */
--
