Re: (ITS#4566) incorrect descriptor handling

[hyc@symas.com]

That's interesting, but nss_ldap is not part of the OpenLDAP Project. 
Perhaps you should report this in PADL's bug tracker.

kazakov@gmail.com wrote:
> Full_Name: Artem Kazakov
> Version: 2.3.21
> OS: FreeBSD
> URL: ftp://ftp.openldap.org/incoming/
> Submission from: (NULL) (130.87.161.100)
>
>
> ------- Forwarded Message --------
> From: Christos Zoulas <christos@zoulas.com>
>   
>> To: Artem Kazakov <kazakov@gmail.com>, Tcsh-Bugs@mx.gw.com
>> Subject: Re: tcsh problem
>> Date: Thu, 25 May 2006 09:24:16 -0400
>>
>> On May 25,  9:33am, kazakov@gmail.com (Artem Kazakov) wrote:
>> -- Subject: tcsh problem
>>
>> | Dear All, 
>> | 
>> | The story started from this pr: 
>> | http://www.freebsd.org/cgi/query-pr.cgi?pr=ports/77574
>> | 
>> | While debugging I realized that the problem is because of the way tcsh
>> | manages descriptors. 
>> | So, the problem is: 
>> | when you use nss_ldap, and it has persistent connections enabled. 
>> | You type somthing like :
>> | $ cd ~ab[tab] 
>> | At this point a lookup through nss_ldap is made. At the moment
>> | descriptors 0,1,2 are free. So when nss_ldap makes a call to socket() it
>> | returns 1 (0 is used for logging if I get it right, and 2 is used too
>> | then). And as connection stays open the descriptor is still held and
>> | descriptor id = 1; 
>> | So then you issue a command: 
>> | $ cd ~abc[enter] 
>> | at this point, tcsh makes call to doio() - as I understand this function
>> | should set proper descriptors for pipe, io-redirection etc. 
>> | And here is the code: 
>> | 
>> | doio(t, pipein, pipeout)
>> |     struct command *t;
>> |     int    *pipein, *pipeout;
>> | {
>> | .... 
>> | 
>> |             (void) close(0);
>> |             (void) dup(OLDSTD);
>> | ....  
>> |            (void) close(1);
>> |            (void) dup(SHOUT);
>> | ....  
>> |     (void) close(2);
>> |     if (flags & F_STDERR) {
>> |         (void) dup(1);
>> |         is2atty = is1atty;
>> |     }
>> |     else {
>> |         (void) dup(SHDIAG);
>> |         is2atty = isdiagatty;
>> | ....
>> | 
>> | So, descriptors 0,1,2 were closed and dup()ed.
>> | 
>> | And after that a lookup through nss_ldap is done again (we issued a
>> | command cd ~abc) 
>> | But it thinks that connection is still alive, and when it calls write()
>> | all the data goes to terminal, instead of socket. 
>> | Later, nss_ldap tries to write to syslog, but fails, because socked id=2
>> | was reopened by  tcsh. And nss_ldap closes in then opens with socket(); 
>> | And after, when user is not found tcsh writes error message to socket
>> | id=2, and it goes to syslog.
>> | 
>> | The results are not we wanted to get. 
>> | 
>> | Current workaround exists, you just have not to use persistent
>> | connections with nss_ldap. 
>> | 
>> | But tcsh should be fixed, I suppose. 
>> | I'm not familiar with tcsh code, so can't do that. 
>>
>> YP (NIS) has the same issue, but it works properly because it tests the
>> file descriptor it opened before it uses it. LDAP should do the same.
>>
>> christos
>>     
-- 
  -- Howard Chu
  Chief Architect, Symas Corp.  http://www.symas.com
  Director, Highland Sun        http://highlandsun.com/hyc
  OpenLDAP Core Team            http://www.openldap.org/project/