Re: [fuse-devel] [PATCH] set close-on-exec flag on pipe file descriptors

[Miklos S. <mi...@sz...>]

On Wed, Feb 6, 2013 at 10:51 AM, Eric Wong <nor...@yh...> wrote:
> The FUSE library may be used from any number of programs which
> may also fork() + execve(), so set the close-on-exec flag to
> avoid inadvertant leakage of pipe file descriptors.
>
> While we're at it, attempt to use pipe2() since this is within a
> (currently) Linux-only code path and pipe2() offers thread-safety.

Thanks, applied.

Miklos

> ---
>  configure.ac        |  2 +-
>  lib/fuse_lowlevel.c | 35 ++++++++++++++++++++++++++---------
>  2 files changed, 27 insertions(+), 10 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index 274ac70..7bf6553 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -52,7 +52,7 @@ if test "$enable_mtab" = "no"; then
>         AC_DEFINE(IGNORE_MTAB, 1, [Don't update /etc/mtab])
>  fi
>
> -AC_CHECK_FUNCS([fork setxattr fdatasync splice vmsplice utimensat])
> +AC_CHECK_FUNCS([fork setxattr fdatasync splice vmsplice utimensat pipe2])
>  AC_CHECK_FUNCS([posix_fallocate])
>  AC_CHECK_MEMBERS([struct stat.st_atim])
>  AC_CHECK_MEMBERS([struct stat.st_atimespec])
> diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
> index b4ea0e3..e28cce3 100644
> --- a/lib/fuse_lowlevel.c
> +++ b/lib/fuse_lowlevel.c
> @@ -483,6 +483,31 @@ static void fuse_ll_pipe_free(struct fuse_ll_pipe *llp)
>  }
>
>  #ifdef HAVE_SPLICE
> +#if !defined(HAVE_PIPE2) || !defined(O_CLOEXEC)
> +static int fuse_pipe(int fds[2])
> +{
> +       int rv = pipe(fds);
> +
> +       if (rv == -1)
> +               return rv;
> +
> +       if (fcntl(fds[0], F_SETFL, O_NONBLOCK) == -1 ||
> +           fcntl(fds[1], F_SETFL, O_NONBLOCK) == -1 ||
> +           fcntl(fds[0], F_SETFD, FD_CLOEXEC) == -1 ||
> +           fcntl(fds[1], F_SETFD, FD_CLOEXEC) == -1) {
> +               close(fds[0]);
> +               close(fds[1]);
> +               rv = -1;
> +       }
> +       return rv;
> +}
> +#else
> +static int fuse_pipe(int fds[2])
> +{
> +       return pipe2(fds, O_CLOEXEC | O_NONBLOCK);
> +}
> +#endif
> +
>  static struct fuse_ll_pipe *fuse_ll_get_pipe(struct fuse_ll *f)
>  {
>         struct fuse_ll_pipe *llp = pthread_getspecific(f->pipe_key);
> @@ -493,20 +518,12 @@ static struct fuse_ll_pipe *fuse_ll_get_pipe(struct fuse_ll *f)
>                 if (llp == NULL)
>                         return NULL;
>
> -               res = pipe(llp->pipe);
> +               res = fuse_pipe(llp->pipe);
>                 if (res == -1) {
>                         free(llp);
>                         return NULL;
>                 }
>
> -               if (fcntl(llp->pipe[0], F_SETFL, O_NONBLOCK) == -1 ||
> -                   fcntl(llp->pipe[1], F_SETFL, O_NONBLOCK) == -1) {
> -                       close(llp->pipe[0]);
> -                       close(llp->pipe[1]);
> -                       free(llp);
> -                       return NULL;
> -               }
> -
>                 /*
>                  *the default size is 16 pages on linux
>                  */
> --
> 1.8.1.2.434.g9a6c84e
>