Re: [leafnode-list] Reproducibly truncate groupinfo

[krasel@xxxxxxxxxxxxxxxxxxxxxxxxxxxx (Cornelius Krasel)]

Matthias Andree wrote:

> I slightly modified writeactive and caught these:
> 
> Jun 13 11:16:47 emma1 leafnode[15058]: cannot open new groupinfo file: \
>   file already exists

Yuck. This should have caught by the locking mechanism.

Would it be a good idea to modify your additional code as follows to
avoid the problem of concurrent processes writing to the groupinfo file?

>         int fd;
> 
>     strcpy(s, spooldir);
>     strcat(s, "/leaf.node/groupinfo.new");
          while ((fd = open(s, O_WRONLY | O_CREAT | O_EXCL, 0600)) < 0) {
	      if (errno != EEXIST) {
>                 syslog(LOG_ERR, "cannot open new groupinfo file: %m");
>                 return;
	      }
	      sleep(1);
>         }
>         
>     a = fdopen( fd, "w" );
>     if ( !a ) {
>         syslog( LOG_ERR, "cannot fdopen new groupinfo file: %m" );
>         return;
>     }

(Obviously, this does not tackle the source of the problem, i.e. the
buggy file locking.)

--Cornelius.

-- 
/* Cornelius Krasel, U Wuerzburg, Dept. of Pharmacology, Versbacher Str. 9 */
/* D-97078 Wuerzburg, Germany   email: krasel@xxxxxxxxxxxxxxxxxxxxxxxxxxxx */
/* "Science is the game we play with God to find out what His rules are."  */

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