Reorg of two aspects of node update.
* install-rpm, install-tarfile, spewrpmtar.php3, spewrpmtar.in: Pumped up even more! The db file we store in /var/db now records both the timestamp (of the file, or if remote the install time) and the MD5 of the file that was installed. Locally, we can get this info when accessing the file via NFS (copymode on or off). Remote, we use wget to get the file, and so pass the timestamp along in the URL request, and let spewrpmtar.in determine if the file has changed. If the timestamp it gets is >= to the timestamp of the file, an error code of 304 (Not Modifed) is returned. Otherwise the file is returned. If the timestamps are different (remote, server sends back an actual file), the MD5 of the file is compared against the value stored. If they are equal, update the timestamp in the db file to avoid repeated MD5s (or server downloads) in the future. If the MD5 is different, then reinstall the tarball or rpm, and update the db file with the new timestamp and MD5. Presto, we have auto update capability! Caveat: I pass along the old MD5 in the URL, but it is currently ignored. I do not know if doing the MD5 on the server is a good idea, but obviously it is easy to add later. At the moment it happens on the node, which means wasted bandwidth when the timestamp has changed, but the file has not (probably not something that will happen in typical usage). Caveat: The timestamp used on remote nodes is the time the tarfile is installed (GM time of course). We could arrange to return the timestamp of the local file back to the node, but that would mean complicating the protocol (or using an http header) and I was not in the mood for that. In typical usage, I do not think that people will be changing tarfiles and rpms so rapidly that this will make a difference, but if it does, we can change it. * node_update.in, client side watchdog, and various web pages: Deflated node_update, removing all of the older ssh code. We now assume that all nodes will auto update on a periodic basis, via the watchdog that runs on all client nodes, including plab nodes. Changed the permission check to look for new UPDATE permission (used to be UPDATEACCOUNT). As before, it requires local_root or better. The reason for this is that node_update now implies more than just updating the accounts/mounts. The web pages have been changed to explain that in addition to mounts/accounts, rpms and tarfiles will also be updated. At the moment, this is still tied to a single variable (update_accounts) in the nodes table, but as Kirk requested at the meeting, it will probably be nice to split these out in the future. Added the ability to node_update a single node in an experiment (in addition to all nodes option on the showexp page). This has been added to the shownode webpage menu options. Changed locking code to use the newer wrapper states, and to move the experiment to RUNNING_LOCKED until the update completes. This is to prevent mayhem in the rest of the system (which could be dealt with, but is not worth the trouble; people have to wait until their initiated update is complete, before they can swap out the experiment). Added "short" mode to shownode routine, equiv to the recently added short mode for showexp. I use this on the confirmation page for updating a single node, giving the user a couple of pertinent (feel good) facts before they comfirm.