• Ulrich Drepper's avatar
    flag parameters: pipe · ed8cae8b
    Ulrich Drepper authored
    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: 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>
    ed8cae8b
pipe.c 25 KB