showmount issues

showmount issues

[Leisner, Martin]

I have a system (which is using the legacy SUN derived rpcbind).

For some reason, showmount wasn't "always" working.   It reported
nothing when running from the command line, but worked under strace
(ugh!)

I was running fedora8 (showmount 1.1.0).
I built nfs-utils 1.1.2 -- same problems.

(I just tried a 1.0.6 on a RedHat Enterprise Linux 3 -- it worked fine)

Running the code under gdb, I found some "interesting" problems...

I changed:
bash2 :2 mleisner@mleisner-linux 05:59:55; rcsdiff -u showmount.c
===================================================================
RCS file: showmount.c,v
retrieving revision 1.1
diff -u -r1.1 showmount.c
--- showmount.c 2008/07/17 21:28:59     1.1
+++ showmount.c 2008/07/17 21:45:45
@@ -82,6 +82,8 @@
  *
  *  tout contains the timeout.  It will be modified to contain the time
  *  remaining (i.e. time provided - time elasped).
+ *
+ *    Returns 0 if it works
  */
 static int connect_nb(int fd, struct sockaddr_in *addr, struct timeval
*tout)
 {
@@ -177,7 +179,7 @@
                tout.tv_sec = TIMEOUT_TCP;

                ret = connect_nb(sock, &saddr, &tout);
-               if (ret == -1) {
+               if (ret < 0) {
                        close(sock);
                        rpc_createerr.cf_stat = RPC_SYSTEMERROR;
                        rpc_createerr.cf_error.re_errno = errno;
@@ -350,7 +352,7 @@
                                         MOUNTPROG, MOUNTVERS,
IPPROTO_TCP);
                if (server_addr.sin_port) {
                        ret = connect_nb(msock, &server_addr, 0);
-                       if (ret != -1)
+                       if (ret == 0)
                                mclient = clnttcp_create(&server_addr,
                                                MOUNTPROG, MOUNTVERS,
&msock,
                                                0, 0);


and now it works....

marty

Re: showmount issues

[Chuck Lever]

Hi Martin-

On Jul 17, 2008, at 6:01 PM, Leisner, Martin wrote:
> I have a system (which is using the legacy SUN derived rpcbind).
>
> For some reason, showmount wasn't "always" working.   It reported
> nothing when running from the command line, but worked under strace
> (ugh!)
>
> I was running fedora8 (showmount 1.1.0).
> I built nfs-utils 1.1.2 -- same problems.
>
> (I just tried a 1.0.6 on a RedHat Enterprise Linux 3 -- it worked  
> fine)
>
> Running the code under gdb, I found some "interesting" problems...
>
> I changed:
> bash2 :2 mleisner@mleisner-linux 05:59:55; rcsdiff -u showmount.c
> ===================================================================
> RCS file: showmount.c,v
> retrieving revision 1.1
> diff -u -r1.1 showmount.c
> --- showmount.c 2008/07/17 21:28:59     1.1
> +++ showmount.c 2008/07/17 21:45:45
> @@ -82,6 +82,8 @@
>  *
>  *  tout contains the timeout.  It will be modified to contain the  
> time
>  *  remaining (i.e. time provided - time elasped).
> + *
> + *    Returns 0 if it works
>  */
> static int connect_nb(int fd, struct sockaddr_in *addr, struct timeval
> *tout)
> {
> @@ -177,7 +179,7 @@
>                tout.tv_sec = TIMEOUT_TCP;
>
>                ret = connect_nb(sock, &saddr, &tout);
> -               if (ret == -1) {
> +               if (ret < 0) {
>                        close(sock);
>                        rpc_createerr.cf_stat = RPC_SYSTEMERROR;
>                        rpc_createerr.cf_error.re_errno = errno;
> @@ -350,7 +352,7 @@
>                                         MOUNTPROG, MOUNTVERS,
> IPPROTO_TCP);
>                if (server_addr.sin_port) {
>                        ret = connect_nb(msock, &server_addr, 0);
> -                       if (ret != -1)
> +                       if (ret == 0)
>                                mclient = clnttcp_create(&server_addr,
>                                                MOUNTPROG, MOUNTVERS,
> &msock,
>                                                0, 0);
>
>
> and now it works....

I think the underlying problem is that sometimes connect_nb() returns  
"-1" to signal an error, and sometimes it returns a negative errno  
type code.

It would be a slightly nicer fix if connect_nb() were changed to  
always return 0 on success and -1 on error.  connect_nb()'s callers do  
not appear to care why it failed, so returning an errno is unnecessary.

Documenting connect_nb()'s return codes (as you did in your patch) is  
a nice finishing touch.

When posting patches, can you also include a patch description and a  
Signed-off-by: line?  Some basic instructions for submitting Linux  
kernel patches can be found here:

http://lxr.linux.no/linux/Documentation/SubmittingPatches

but most of these also apply to submitting to user space packages like  
nfs-utils.

Steve, perhaps this should be included in 1.1.3?

--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com

Re: showmount issues

[Steve Dickson]

Leisner, Martin wrote:
> I have a system (which is using the legacy SUN derived rpcbind).
> 
> For some reason, showmount wasn't "always" working.   It reported
> nothing when running from the command line, but worked under strace
> (ugh!)
> 
> I was running fedora8 (showmount 1.1.0).
> I built nfs-utils 1.1.2 -- same problems.
> 
> (I just tried a 1.0.6 on a RedHat Enterprise Linux 3 -- it worked fine)
> 
> Running the code under gdb, I found some "interesting" problems...
Committed...

steved.