Re: warning about closing an already closed file descriptor

[Peter Stephenson <p.stephenson@xxxxxxxxxxx>]

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);
 		}
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