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
......@@ -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:
......@@ -329,3 +329,4 @@ ENTRY(sys_call_table)
.long sys_signalfd4
.long sys_eventfd2
.long sys_epoll_create2
.long sys_dup3 /* 330 */
......@@ -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;
......@@ -163,7 +166,10 @@ asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd)
rcu_assign_pointer(fdt->fd[newfd], file);
FD_SET(newfd, fdt->open_fds);
FD_CLR(newfd, fdt->close_on_exec);
if (flags & O_CLOEXEC)
FD_SET(newfd, fdt->close_on_exec);
else
FD_CLR(newfd, fdt->close_on_exec);
spin_unlock(&files->file_lock);
if (tofree)
......@@ -181,6 +187,11 @@ out_fput:
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;
......
......@@ -335,6 +335,7 @@
#define __NR_signalfd4 327
#define __NR_eventfd2 328
#define __NR_epoll_create2 329
#define __NR_dup3 330
#ifdef __KERNEL__
......
......@@ -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
......
......@@ -305,6 +305,7 @@ asmlinkage long sys_fcntl64(unsigned int fd,
#endif
asmlinkage long sys_dup(unsigned int fildes);
asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd);
asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags);
asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int on);
asmlinkage long sys_ioctl(unsigned int fd, unsigned int cmd,
unsigned long arg);
......
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