flag parameters: timerfd_create
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>
diff --git a/fs/timerfd.c b/fs/timerfd.c
index 77c2bc9..c6ef5e3 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -184,7 +184,7 @@
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 @@
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);