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flag parameters: signalfd

This patch adds the new signalfd4 syscall.  It extends the old signalfd
syscall by one parameter which is meant to hold a flag value.  In this
patch the only flag support is SFD_CLOEXEC which causes the close-on-exec
flag for the returned file descriptor to be set.

A new name SFD_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 <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>

#ifndef __NR_signalfd4
# ifdef __x86_64__
#  define __NR_signalfd4 289
# elif defined __i386__
#  define __NR_signalfd4 327
# else
#  error "need __NR_signalfd4"
# endif
#endif

#define SFD_CLOEXEC O_CLOEXEC

int
main (void)
{
  sigset_t ss;
  sigemptyset (&ss);
  sigaddset (&ss, SIGUSR1);
  int fd = syscall (__NR_signalfd4, -1, &ss, 8, 0);
  if (fd == -1)
    {
      puts ("signalfd4(0) failed");
      return 1;
    }
  int coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if (coe & FD_CLOEXEC)
    {
      puts ("signalfd4(0) set close-on-exec flag");
      return 1;
    }
  close (fd);

  fd = syscall (__NR_signalfd4, -1, &ss, 8, SFD_CLOEXEC);
  if (fd == -1)
    {
      puts ("signalfd4(SFD_CLOEXEC) failed");
      return 1;
    }
  coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if ((coe & FD_CLOEXEC) == 0)
    {
      puts ("signalfd4(SFD_CLOEXEC) does not set close-on-exec flag");
      return 1;
    }
  close (fd);

  puts ("OK");

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

[akpm@linux-foundation.org: add sys_ni stub]
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
master
Ulrich Drepper 14 years ago
committed by Linus Torvalds
parent
commit
9deb27baed
  1. 1
      arch/x86/ia32/ia32entry.S
  2. 1
      arch/x86/kernel/syscall_table_32.S
  3. 14
      fs/compat.c
  4. 14
      fs/signalfd.c
  5. 1
      include/asm-x86/unistd_32.h
  6. 2
      include/asm-x86/unistd_64.h
  7. 5
      include/linux/signalfd.h
  8. 1
      include/linux/syscalls.h
  9. 1
      kernel/sys_ni.c

1
arch/x86/ia32/ia32entry.S

@ -826,4 +826,5 @@ ia32_sys_call_table:
.quad sys32_fallocate
.quad compat_sys_timerfd_settime /* 325 */
.quad compat_sys_timerfd_gettime
.quad compat_sys_signalfd4
ia32_syscall_end:

1
arch/x86/kernel/syscall_table_32.S

@ -326,3 +326,4 @@ ENTRY(sys_call_table)
.long sys_fallocate
.long sys_timerfd_settime /* 325 */
.long sys_timerfd_gettime
.long sys_signalfd4

14
fs/compat.c

@ -2131,9 +2131,9 @@ asmlinkage long compat_sys_epoll_pwait(int epfd,
#ifdef CONFIG_SIGNALFD
asmlinkage long compat_sys_signalfd(int ufd,
const compat_sigset_t __user *sigmask,
compat_size_t sigsetsize)
asmlinkage long compat_sys_signalfd4(int ufd,
const compat_sigset_t __user *sigmask,
compat_size_t sigsetsize, int flags)
{
compat_sigset_t ss32;
sigset_t tmp;
@ -2148,9 +2148,15 @@ asmlinkage long compat_sys_signalfd(int ufd,
if (copy_to_user(ksigmask, &tmp, sizeof(sigset_t)))
return -EFAULT;
return sys_signalfd(ufd, ksigmask, sizeof(sigset_t));
return sys_signalfd4(ufd, ksigmask, sizeof(sigset_t), flags);
}
asmlinkage long compat_sys_signalfd(int ufd,
const compat_sigset_t __user *sigmask,
compat_size_t sigsetsize)
{
return compat_sys_signalfd4(ufd, sigmask, sigsetsize, 0);
}
#endif /* CONFIG_SIGNALFD */
#ifdef CONFIG_TIMERFD

14
fs/signalfd.c

@ -205,11 +205,15 @@ static const struct file_operations signalfd_fops = {
.read = signalfd_read,
};
asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemask)
asmlinkage long sys_signalfd4(int ufd, sigset_t __user *user_mask,
size_t sizemask, int flags)
{
sigset_t sigmask;
struct signalfd_ctx *ctx;
if (flags & ~SFD_CLOEXEC)
return -EINVAL;
if (sizemask != sizeof(sigset_t) ||
copy_from_user(&sigmask, user_mask, sizeof(sigmask)))
return -EINVAL;
@ -228,7 +232,7 @@ asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemas
* anon_inode_getfd() will install the fd.
*/
ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
0);
flags & O_CLOEXEC);
if (ufd < 0)
kfree(ctx);
} else {
@ -250,3 +254,9 @@ asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemas
return ufd;
}
asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask,
size_t sizemask)
{
return sys_signalfd4(ufd, user_mask, sizemask, 0);
}

1
include/asm-x86/unistd_32.h

@ -332,6 +332,7 @@
#define __NR_fallocate 324
#define __NR_timerfd_settime 325
#define __NR_timerfd_gettime 326
#define __NR_signalfd4 327
#ifdef __KERNEL__

2
include/asm-x86/unistd_64.h

@ -641,6 +641,8 @@ __SYSCALL(__NR_timerfd_settime, sys_timerfd_settime)
__SYSCALL(__NR_timerfd_gettime, sys_timerfd_gettime)
#define __NR_paccept 288
__SYSCALL(__NR_paccept, sys_paccept)
#define __NR_signalfd4 289
__SYSCALL(__NR_signalfd4, sys_signalfd4)
#ifndef __NO_STUBS

5
include/linux/signalfd.h

@ -8,6 +8,11 @@
#ifndef _LINUX_SIGNALFD_H
#define _LINUX_SIGNALFD_H
/* For O_CLOEXEC */
#include <linux/fcntl.h>
/* Flags for signalfd4. */
#define SFD_CLOEXEC O_CLOEXEC
struct signalfd_siginfo {
__u32 ssi_signo;

1
include/linux/syscalls.h

@ -610,6 +610,7 @@ asmlinkage long sys_set_robust_list(struct robust_list_head __user *head,
size_t len);
asmlinkage long sys_getcpu(unsigned __user *cpu, unsigned __user *node, struct getcpu_cache __user *cache);
asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemask);
asmlinkage long sys_signalfd4(int ufd, sigset_t __user *user_mask, size_t sizemask, int flags);
asmlinkage long sys_timerfd_create(int clockid, int flags);
asmlinkage long sys_timerfd_settime(int ufd, int flags,
const struct itimerspec __user *utmr,

1
kernel/sys_ni.c

@ -156,6 +156,7 @@ cond_syscall(sys_ioprio_get);
/* New file descriptors */
cond_syscall(sys_signalfd);
cond_syscall(sys_signalfd4);
cond_syscall(compat_sys_signalfd);
cond_syscall(sys_timerfd_create);
cond_syscall(sys_timerfd_settime);

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