This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
Also generallize the yp_dbwrite functions a little: allow the caller
to specify certain flags. I need this mostly for some changes to
rpc.yppasswdd to allow in-place updates.
Also change Makefile a little to use the same format as ypserv.
R_NOOVERWRITE flag and process return codes so that we can tell the
difference between a failure due to a duplicate database entry and
failure due to some other error.
- 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.
