on a failure, but if we're checking a corrupt map we could also get back
a zero from ypserv without really encountering any actual error. Flag this
condition and generate an meaningful error message.
- Fix transmission of ypxfr_clear to ypserv: error checking was wrong
and we sending YPXFR_YPERR as an error status instead of YPXFR_CLEAR.
- To help avoid a race condition (or at least reduce the likelyhood of
it occuring), use rename() to move a newly transfered map into place
instead of unlink()ing the old one first and then renaming. Da man page
sez that rename should do the unlink() for us. This prevents ypserv
from returning 'no such map in domain' when asked to query a map which
ypxfr has just unlink()ed but not yet replaced.
- Fix a SEGV condition in ypxfr_main.c that reared its ugly head while I
was working on the 'parallel jobs' feature of the new yppush. After we've
completed the map transfer and created a local temporary copy, we check
the order number of the map on ypserv again to make sure it didn't change
while the transfer was in progress (map skew). If for some reason we flat
out fail to get the order number from the server, we flag this as an
error and bail, telling ypxfr_exit() to clean up our temporary files
for us. However, ypxfr_exit() tries to close the database before unkining
it, not realizing that it has already been closed prior to the skew check.
The second attempt to close the database causes a SEGV somewhere inside
the DB code.
(Well, it does on my 2.0.5 machine anyway. I haven't seen anyone modify
the DB library code in ages, so the condition is probably still there.)
To work around this, we deliberately set dbp to NULL after closing the
database and check for the condition in ypxfr_exit(), being careful to
avoid the second close if we see the NULL.
- In yp_dbwrite.c, make yp_open_db_rw() open the database with O_EXLOCK
flag set. This probably won't affect much of anything, but I feel better
having it there.
