Re: warning about closing an already closed file descriptor

[Kamil Dudka <kdudka@xxxxxxxxxx>]

On Monday 19 January 2015 17:28:50 Peter Stephenson wrote:
> On Mon, 19 Jan 2015 14:59:35 +0000
> 
> Peter Stephenson <p.stephenson@xxxxxxxxxxx> wrote:
> > The problem that change fixed wasn't really intended to have a visible
> > effect, apart from closing f.d.s the shell didn't know about.  If it's
> > more useful without the message than with it, it can be removed.
> >
> >...
> >
> > We can special case the {varid}<&- syntax --- that might be useful since
> > it implies the user was previously in direct control of the f.d. so is
> > ikely to be interested in an error if closing it failed.
> 
> This easy patch does that.  Is anyone other than Kamil interested enough
> to comment?
> 
> pws
> 
> diff --git a/Src/exec.c b/Src/exec.c
> index f42fb2b..3b0e936 100644
> --- a/Src/exec.c
> +++ b/Src/exec.c
> @@ -3203,7 +3203,12 @@ execcmd(Estate state, int input, int output, int how,
> int last1) }
>  		if (fn->fd1 < 10)
>  		    closemn(mfds, fn->fd1, REDIR_CLOSE);
> -		if (!closed && zclose(fn->fd1) < 0) {
> +		/*
> +		 * Only report failures to close file descriptors
> +		 * if they're under user control as we don't know
> +		 * what the previous status of others was.
> +		 */
> +		if (!closed && zclose(fn->fd1) < 0 && fn->varid) {
>  		    zwarn("failed to close file descriptor %d: %e",
>  			  fn->fd1, errno);
>  		}

Looks reasonable and fixes the problem for me.  Thanks for the patch!

Kamil

> diff --git a/Test/A04redirect.ztst b/Test/A04redirect.ztst
> index a39ce46..cb67788 100644
> --- a/Test/A04redirect.ztst
> +++ b/Test/A04redirect.ztst
> @@ -152,11 +152,13 @@
> 
>  >hello
>  >goodbye
> 
> -  ({ exec 3<&- } 2>/dev/null
> -  exec 3<&-
> -  read foo <&-)
> +  (exec {varid}<&0
> +  exec {varid}<&-
> +  print About to close a second time >&2
> +  read {varid}<&-)
>  1:'<&-' redirection
> -*?\(eval\):*: failed to close file descriptor 3:*
> +?About to close a second time
> +*?\(eval\):*: failed to close file descriptor *
> 
>    print foo >&-
>  0:'>&-' redirection