[Libvir] [patch 9/9] Implement better error reporting

[Richard W.M. Jones]

oneMark McLoughlin wrote:
> Add a qemudLog() function which uses syslog() if we're in
> daemon mode, doesn't output INFO/DEBUG messages unless
> the verbose flag is set and doesn't output DEBUG messages
> unless compiled with --enable-debug.

You're all gonna hate this I know, but libvirtd handles syslog by 
forking an external logger(1) process.  Messages sent to stderr go to 
syslog.  This is partly necessary because the SunRPC code within glibc 
is a bit too happy to send debug messages to stderr & nowhere else.

The brief code snippet to enable this is below (and note my original 
patch which you can also find on this list enables a test for LOGGER in 
autoconf):

#ifdef LOGGER
         /* Send stderr to syslog using logger.  It's a lot simpler
          * to do this.  Note that SunRPC in glibc prints lots of
          * gumf to stderr and it'd be a load of work to change that.
          */
         int fd[2];
         if (pipe (fd) == -1) {
             perror ("pipe");
             exit (2);
         }
         int pid = fork ();
         if (pid == -1) {
             perror ("fork");
             exit (2);
         }
         if (pid == 0) {         /* Child - logger. */
             const char *args[] = {
                 "logger", "-tlibvirtd", "-p", "daemon.notice", NULL
             };
             close (fd[1]);
             dup2 (fd[0], 0);
             close (fd[0]);
             execv (LOGGER, (char *const *) args);
             perror ("execv");
             _exit (1);
         }
         close (fd[0]);
         dup2 (fd[1], 2);
         close (fd[1]);
#endif

Rich.

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