flag parameters: pipe

This patch introduces the new syscall pipe2 which is like pipe but it also
takes an additional parameter which takes a flag value.  This patch implements
the handling of O_CLOEXEC for the flag.  I did not add support for the new
syscall for the architectures which have a special sys_pipe implementation.  I
think the maintainers of those archs have the chance to go with the unified
implementation but that's up to them.

The implementation introduces do_pipe_flags.  I did that instead of changing
all callers of do_pipe because some of the callers are written in assembler.
I would probably screw up changing the assembly code.  To avoid breaking code
do_pipe is now a small wrapper around do_pipe_flags.  Once all callers are
changed over to do_pipe_flags the old do_pipe function can be removed.

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 <unistd.h>
#include <sys/syscall.h>

#ifndef __NR_pipe2
# ifdef __x86_64__
#  define __NR_pipe2 293
# elif defined __i386__
#  define __NR_pipe2 331
# else
#  error "need __NR_pipe2"
# endif
#endif

int
main (void)
{
  int fd[2];
  if (syscall (__NR_pipe2, fd, 0) != 0)
    {
      puts ("pipe2(0) failed");
      return 1;
    }
  for (int i = 0; i < 2; ++i)
    {
      int coe = fcntl (fd[i], F_GETFD);
      if (coe == -1)
        {
          puts ("fcntl failed");
          return 1;
        }
      if (coe & FD_CLOEXEC)
        {
          printf ("pipe2(0) set close-on-exit for fd[%d]\n", i);
          return 1;
        }
    }
  close (fd[0]);
  close (fd[1]);

  if (syscall (__NR_pipe2, fd, O_CLOEXEC) != 0)
    {
      puts ("pipe2(O_CLOEXEC) failed");
      return 1;
    }
  for (int i = 0; i < 2; ++i)
    {
      int coe = fcntl (fd[i], F_GETFD);
      if (coe == -1)
        {
          puts ("fcntl failed");
          return 1;
        }
      if ((coe & FD_CLOEXEC) == 0)
        {
          printf ("pipe2(O_CLOEXEC) does not set close-on-exit for fd[%d]\n", i);
          return 1;
        }
    }
  close (fd[0]);
  close (fd[1]);

  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>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ulrich Drepper 2008-07-23 21:29:30 -07:00 committed by Linus Torvalds
parent 336dd1f70f
commit ed8cae8ba0
15 changed files with 33 additions and 14 deletions

View File

@ -1139,7 +1139,7 @@ sys32_pipe (int __user *fd)
int retval;
int fds[2];
retval = do_pipe(fds);
retval = do_pipe_flags(fds, 0);
if (retval)
goto out;
if (copy_to_user(fd, fds, sizeof(fds)))

View File

@ -160,7 +160,7 @@ sys_pipe (void)
int fd[2];
int retval;
retval = do_pipe(fd);
retval = do_pipe_flags(fd, 0);
if (retval)
goto out;
retval = fd[0];

View File

@ -52,7 +52,7 @@ asmlinkage int sysm_pipe(nabi_no_regargs volatile struct pt_regs regs)
int fd[2];
int error, res;
error = do_pipe(fd);
error = do_pipe_flags(fd, 0);
if (error) {
res = error;
goto out;

View File

@ -448,7 +448,7 @@ int hpux_pipe(int *kstack_fildes)
int error;
lock_kernel();
error = do_pipe(kstack_fildes);
error = do_pipe_flags(kstack_fildes, 0);
unlock_kernel();
return error;
}

View File

@ -29,7 +29,7 @@ asmlinkage int sys_pipe(unsigned long r4, unsigned long r5,
int fd[2];
int error;
error = do_pipe(fd);
error = do_pipe_flags(fd, 0);
if (!error) {
regs->regs[1] = fd[1];
return fd[0];

View File

@ -97,7 +97,7 @@ asmlinkage int sparc_pipe(struct pt_regs *regs)
int fd[2];
int error;
error = do_pipe(fd);
error = do_pipe_flags(fd, 0);
if (error)
goto out;
regs->u_regs[UREG_I1] = fd[1];

View File

@ -418,7 +418,7 @@ asmlinkage long sparc_pipe(struct pt_regs *regs)
int fd[2];
int error;
error = do_pipe(fd);
error = do_pipe_flags(fd, 0);
if (error)
goto out;
regs->u_regs[UREG_I1] = fd[1];

View File

@ -830,4 +830,5 @@ ia32_sys_call_table:
.quad sys_eventfd2
.quad sys_epoll_create2
.quad sys_dup3 /* 330 */
.quad sys_pipe2
ia32_syscall_end:

View File

@ -238,7 +238,7 @@ asmlinkage long sys32_pipe(int __user *fd)
int retval;
int fds[2];
retval = do_pipe(fds);
retval = do_pipe_flags(fds, 0);
if (retval)
goto out;
if (copy_to_user(fd, fds, sizeof(fds)))

View File

@ -330,3 +330,4 @@ ENTRY(sys_call_table)
.long sys_eventfd2
.long sys_epoll_create2
.long sys_dup3 /* 330 */
.long sys_pipe2

View File

@ -49,7 +49,7 @@ asmlinkage long xtensa_pipe(int __user *userfds)
int fd[2];
int error;
error = do_pipe(fd);
error = do_pipe_flags(fd, 0);
if (!error) {
if (copy_to_user(userfds, fd, 2 * sizeof(int)))
error = -EFAULT;

View File

@ -1027,12 +1027,15 @@ struct file *create_read_pipe(struct file *wrf)
return f;
}
int do_pipe(int *fd)
int do_pipe_flags(int *fd, int flags)
{
struct file *fw, *fr;
int error;
int fdw, fdr;
if (flags & ~O_CLOEXEC)
return -EINVAL;
fw = create_write_pipe();
if (IS_ERR(fw))
return PTR_ERR(fw);
@ -1041,12 +1044,12 @@ int do_pipe(int *fd)
if (IS_ERR(fr))
goto err_write_pipe;
error = get_unused_fd();
error = get_unused_fd_flags(flags);
if (error < 0)
goto err_read_pipe;
fdr = error;
error = get_unused_fd();
error = get_unused_fd_flags(flags);
if (error < 0)
goto err_fdr;
fdw = error;
@ -1074,16 +1077,21 @@ int do_pipe(int *fd)
return error;
}
int do_pipe(int *fd)
{
return do_pipe_flags(fd, 0);
}
/*
* sys_pipe() is the normal C calling standard for creating
* a pipe. It's not the way Unix traditionally does this, though.
*/
asmlinkage long __weak sys_pipe(int __user *fildes)
asmlinkage long __weak sys_pipe2(int __user *fildes, int flags)
{
int fd[2];
int error;
error = do_pipe(fd);
error = do_pipe_flags(fd, flags);
if (!error) {
if (copy_to_user(fildes, fd, sizeof(fd))) {
sys_close(fd[0]);
@ -1094,6 +1102,11 @@ asmlinkage long __weak sys_pipe(int __user *fildes)
return error;
}
asmlinkage long __weak sys_pipe(int __user *fildes)
{
return sys_pipe2(fildes, 0);
}
/*
* pipefs should _never_ be mounted by userland - too much of security hassle,
* no real gain from having the whole whorehouse mounted. So we don't need

View File

@ -336,6 +336,7 @@
#define __NR_eventfd2 328
#define __NR_epoll_create2 329
#define __NR_dup3 330
#define __NR_pipe2 331
#ifdef __KERNEL__

View File

@ -649,6 +649,8 @@ __SYSCALL(__NR_eventfd2, sys_eventfd2)
__SYSCALL(__NR_epoll_create2, sys_epoll_create2)
#define __NR_dup3 292
__SYSCALL(__NR_dup3, sys_dup3)
#define __NR_pipe2 293
__SYSCALL(__NR_pipe2, sys_pipe2)
#ifndef __NO_STUBS

View File

@ -1777,6 +1777,7 @@ static inline void allow_write_access(struct file *file)
atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
}
extern int do_pipe(int *);
extern int do_pipe_flags(int *, int);
extern struct file *create_read_pipe(struct file *f);
extern struct file *create_write_pipe(void);
extern void free_write_pipe(struct file *);