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Commit 336dd1f7 authored by Ulrich Drepper's avatar Ulrich Drepper Committed by Linus Torvalds
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flag parameters: dup2 



This patch adds the new dup3 syscall.  It extends the old dup2 syscall by one
parameter which is meant to hold a flag value.  Support for the O_CLOEXEC flag
is added in this patch.

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_dup3
# ifdef __x86_64__
#  define __NR_dup3 292
# elif defined __i386__
#  define __NR_dup3 330
# else
#  error "need __NR_dup3"
# endif
#endif

int
main (void)
{
  int fd = syscall (__NR_dup3, 1, 4, 0);
  if (fd == -1)
    {
      puts ("dup3(0) failed");
      return 1;
    }
  int coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if (coe & FD_CLOEXEC)
    {
      puts ("dup3(0) set close-on-exec flag");
      return 1;
    }
  close (fd);

  fd = syscall (__NR_dup3, 1, 4, O_CLOEXEC);
  if (fd == -1)
    {
      puts ("dup3(O_CLOEXEC) failed");
      return 1;
    }
  coe = fcntl (fd, F_GETFD);
  if (coe == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if ((coe & FD_CLOEXEC) == 0)
    {
      puts ("dup3(O_CLOEXEC) set close-on-exec flag");
      return 1;
    }
  close (fd);

  puts ("OK");

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

Signed-off-by: default avatarUlrich Drepper <drepper@redhat.com>
Acked-by: default avatarDavide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a0998b50

arch/x86/ia32/ia32entry.S

+1 −0
Original line number Diff line number Diff line
@@ -829,4 +829,5 @@ ia32_sys_call_table: 
	.quad compat_sys_signalfd4

	.quad sys_eventfd2

	.quad sys_epoll_create2

	.quad sys_dup3			/* 330 */

ia32_syscall_end:

arch/x86/kernel/syscall_table_32.S

+1 −0
Original line number Diff line number Diff line
@@ -329,3 +329,4 @@ ENTRY(sys_call_table) 
	.long sys_signalfd4

	.long sys_eventfd2

	.long sys_epoll_create2

	.long sys_dup3			/* 330 */

fs/fcntl.c

+13 −2
Original line number Diff line number Diff line
@@ -125,13 +125,16 @@ static int dupfd(struct file *file, unsigned int start, int cloexec) 
	return fd;

}



asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd)

asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags)

{

	int err = -EBADF;

	struct file * file, *tofree;

	struct files_struct * files = current->files;

	struct fdtable *fdt;



	if ((flags & ~O_CLOEXEC) != 0)

		return -EINVAL;



	spin_lock(&files->file_lock);

	if (!(file = fcheck(oldfd)))

		goto out_unlock;
@@ -163,6 +166,9 @@ asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd) 


	rcu_assign_pointer(fdt->fd[newfd], file);

	FD_SET(newfd, fdt->open_fds);

	if (flags & O_CLOEXEC)

		FD_SET(newfd, fdt->close_on_exec);

	else

		FD_CLR(newfd, fdt->close_on_exec);

	spin_unlock(&files->file_lock);
@@ -181,6 +187,11 @@ asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd) 
	goto out;

}



asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd)

{

	return sys_dup3(oldfd, newfd, 0);

}



asmlinkage long sys_dup(unsigned int fildes)

{

	int ret = -EBADF;

include/asm-x86/unistd_32.h

+1 −0
Original line number Diff line number Diff line
@@ -335,6 +335,7 @@ 
#define __NR_signalfd4		327

#define __NR_eventfd2		328

#define __NR_epoll_create2	329

#define __NR_dup3		330



#ifdef __KERNEL__

include/asm-x86/unistd_64.h

+2 −0
Original line number Diff line number Diff line
@@ -647,6 +647,8 @@ __SYSCALL(__NR_signalfd4, sys_signalfd4) 
__SYSCALL(__NR_eventfd2, sys_eventfd2)

#define __NR_epoll_create2			291

__SYSCALL(__NR_epoll_create2, sys_epoll_create2)

#define __NR_dup3				292

__SYSCALL(__NR_dup3, sys_dup3)





#ifndef __NO_STUBS