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Tiny Deathstars of Foulness

In Mac OS X Lion, applications can make use of a feature to auto-save and version files. This feature locks files that are inactive for editing and when the file is unlocked then starts automatically saving versions. If you have a problem with the file you can then always step back to a previous version of the file. The feature is manifested in the title bar and the file menu of applications that make use of it. When you open a file, it can be locked. Viewing the file in the Finder also shows that it is locked. Clicking on locked provides the option to unlock. Once unlocked you can make changes as you normally would. The next time you save the file, a version is created. Hovering the mouse over the title of a file results in a disclosure triangle. clicking that results in some options otherwise located in the file menu.

Clicking on the Lock option again locks the file. Files inactive can automatically be locked as well. The Duplication option is similar to that of Save As. You are asked where you want to duplicate the file to. No versioning information is sent with the file. These same options are in the File menu as well.

The command-S will still save a file, and in fact now it does more and it saves a new version of the file (also done as part of the auto-save routine). The Revert to Saved options in the File menu and title bar menu will bring up an interface similar to that of Time Machine. You can navigate through here to find a version that you want to restore and restore your data. Versioning information is persistent across a restore. In fact, once restored, you can revert back to a more recent save than that which was restored. In my testing so far, versioning information is not always persistent across restores of files (works with Time Machine, doesn’t work with 3 other applications I’ve tested). But YMMV there as patches are introduced in (hopefully) the next few weeks. Versions data is stored in /.DocumentRevisions-V100. In the /.DocumentRevisions-V100/db-V1 directory is a sqlite database with information and pages files are stored in containers by UID of local users in the /.DocumentRevisions-V100/PerUID directory. Permissions here are owner of root, group of wheel and d–x–x–x. bash-3.2# cd /.DocumentRevisions-V100/ bash-3.2# ls -al total 0 d--x--x--x   7 root  wheel   238 Jul 18 22:39 . drwxr-xr-x  36 root  wheel  1292 Jul 28 23:24 .. drwx------   5 root  wheel   170 Jul 28 23:27 .cs drw-------   2 root  wheel    68 Jul 18 22:39 ChunkTemp d--x--x--x   3 root  wheel   102 Jul 18 22:39 PerUID drwx------   4 root  wheel   136 Jul 28 23:27 db-V1 drwx--x--x   2 root  wheel    68 Jul 18 22:39 staging Changing the permissions to 000 causes the feature to report no versions for the files but then you also cannot save changes to files. If you remove the .DocumentRevisions-V100 directory altogether it does not automatically recreate itself at the creation of a new document; however, it does not create itself initially until the first time you’re saving a document. Putting the directory structure back in place resolves any saving problems (is all this sounding a bit like how Spotlight indexes work to anyone???). Versioning is saved locally for files that are stored on network volumes. If you move a file that was versioned locally to a network volume and back then it will loose versioning information. If you open a file from a network share there is no versioning information in the file unless the local computer you are using had been used to make those versions. When you save a file stored on a network volume you are informed that the volume does not support permanent version storage. If you open the file and start editing it on another host and changes occur on both hosts (which the system will allow to happen) then at the next save you will get an alert that states that the file has been changed by another application. Clicking Save Anyway will overwrite changes from the other computer and Revert will revert to the last saved document or more likely error out with a complaint about permissions (even if those permissions are 777). Continuing to make changes on both hosts will eventually cause a “GSLibraryErrorDomain error 1” error code; however, the file will remain open so you can copy your changes off into another file. A few other points of information:
  • Initially I had read that Time Machine was required to make use of this feature. That is incorrect. It works perfectly well with Time Machine disabled. Having said this, the app does report a message about Time Machine but this can safely be disregarded.
  • Initially I had read that it saves data into the ~/Library/Saved Application State directory. That too is incorrect. The state of versions-enabled applications is saved there but not the data
  • Large (> 500 page files) will auto-save very slowly if you have made a lot of changes in them. This is due to the fact that versioning results in copy operations.
  • Root can traverse into other users version files.
  • I have found no way thus far to change the auto-save interval (will hopefully update this when I do).
  • Pasting graphics into large files is much slower than previous versions (but likely offset by the new ability to flip through versions of files).
  • Not all applications have built-in Versions options yet (e.g. Office) but I think most will at some point in the future.
You can still mv a file to a .zip, unzip it and extract images and raw index data; however the versioning information is not actually saved there. Scanning the file system for changes during a version change only nets the file itself and the temp file (nested within /tmp) as having been altered. The Apple Developer Library explains Versioning as follows:
In the applications that ship as part of Mac OS X v10.7, users no longer need to save documents explicitly or be concerned about losing unsaved changes. Document-based Cocoa applications can opt into this autosaving behavior with a simple override. With automatic saving enabled, the system automatically writes document data to disk as necessary so that data displayed in a document window is, in effect, always the same as the document data on disk. A file coordination mechanism maintains sequential access to files. (See “Mac OS X File Coordination.”) Applications that support automatic saving also support document version history browsing. To browse previous versions of a document, choose Browse All Versions from the pull-down menu at the right end of the menu bar.
For more on NSDocumentController here’s Apple’s page for that. Overall, Versions has taken me a little while to get used to. Especially in TextEdit. But I’ll take the latency in exchange for the ability to roll back changes. If you are rolling out Lion in a larger environment, you’re going to want to check out whether or not users expect this to persist across network shares, copying files to additional computers or even backups in many cases.

July 28th, 2011

Posted In: Mac OS X

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Mac OS X Server comes with a number of DHCP options available; most notably the options available in the GUI. But what about options that aren’t available in the GUI, such as NTP. Well, using /etc/bootpd.plist, the same file we used to define servers allowed to relay, you can also define other options. These begin with the following keys that can be added into your property list:
  • dhcp_time_offset (option 2)
  • dhcp_router (option 3)
  • dhcp_domain_name_server (option 6)
  • dhcp_domain_name (option 15)
  • dhcp_network_time_protocol_servers (option 42)
  • dhcp_nb_over_tcpip_name_server (option 44)
  • dhcp_nb__over_tcpip_dgram_dist_server (option 45)
  • dhcp_nb_over_tcpip_node_type (option 46)
  • dhcp_nb_over_tcpip_scope (option 47)
  • dhcp_smtp_server (option 69)
  • dhcp_pop3_server (option 70)
  • dhcp_nntp_server (option 71)
  • dhcp_ldap_url (option 95)
  • dhcp_netinfo_server_address (option 112)
  • dhcp_netinfo_server_tag (option 113)
  • dhcp_url (option 114)
  • dhcp_domain_search (option 119)
  • dhcp_proxy_auto_discovery_url (option 252)
But you can also add options by their numerical identifier. To add them, add the following into your /etc/bootpd.plist file and then restart the DHCP service: <string>dhcp_option_120</string> <data> 192.168.210.7 </data>
In the above, you’d replace the option 120 (SIP) with the option you wish to use. Numbers correspond to options as follows:
0 – Pad
1 – Subnet Mask
3 – Router
4 – Time Server
5 – Name Server
6 – Domain Name Server
7 – Log Server
8 Quote Server
9 – LPR Server
10 – Impress Server
11 – Resource Location Server
12 – Host Name
13 – Boot File Size
14 – Merit Dump File
15 – Domain Name
16 – Swap Server
17 – Root Path
18 – Extensions Path
19 – IP Forwarding
20 – WAN Source Routing
21 – Policy Filter
22 – Maximum Datagram Reassembly Size
23 – Default IP Time-to-live
24 – Path MTU Aging Timeout
25 – Path MTU Plateau Table
26 – Interface MTU
27 – All Subnets are Local
28 – Broadcast Address
29 – Perform Mask Discovery
30 – Mask supplier
31 – Perform router discovery
32 – Router solicitation address
33 – Static routing table
34 – Trailer encapsulation.
35 – ARP cache timeout
36 – Ethernet encapsulation
37 – Default TCP TTL
38 – TCP keep alive interval
39 – TCP keep alive garbage
40 – Network Information Service Domain
41 – Network Information Servers
42 – NTP servers
43 – Vendor specific information
44 – NetBIOS over TCP/IP name server
45 – NetBIOS over TCP/IP Datagram Distribution Server
46 – NetBIOS over TCP/IP Node Type
47 – NetBIOS over TCP/IP Scope
48 – X Window System Font Server
49 – X Window System Display Manager
50 – Requested IP Address
51 – IP address lease time
52 – Option overload
53 – DHCP message type
54 – Server identifier
55 – Parameter request list
56 – Message
57 – Maximum DHCP message size
58 – Renew time value
59 – Rebinding time value
60 – Class-identifier
61 – Client-identifier
62 – NetWare over IP Domain Name
63 – NetWare over IP information
64 – Network Information Service Domain
65 – Network Information Service Servers
66 – TFTP server name
67 – Bootfile name
68 – Mobile IP Home Agent
69 – Simple Mail Transport Protocol Server
70 – Post Office Protocol Server
71 – Network News Transport Protocol Server
72 – Default World Wide Web Server
73 – Default Finger Server
74 – Default Internet Relay Chat Server
77 – User Class Information
78 – SLP Directory Agent
79 – SLP Service Scope
80 – Rapid Commit
81 – Fully Qualified Domain Name
82 – Relay Agent Information
83 – Internet Storage Name Service
85 – NDS servers
86 – NDS tree name
87 – NDS context
88 – BCMCS Controller Domain Name list
89 – BCMCS Controller IPv4 address list
90 – Authentication
91 – Client Last Transaction Time
92 – Associated IP
93 – Client System Architecture Type
94 – Client Network Interface Identifier
95 – LDAP, Lightweight Directory Access Protocol
97 – Client Machine Identifier
98 – Open Group User Authentication
100 – IEEE 1003.1 TZ String
101 – Reference to the TZ Database
112 – NetInfo Parent Server Address
113 – NetInfo Parent Server Tag
114- URL
116 – Auto-Configure
117 – Name Service Search
118 – Subnet Selection
119 – DNS domain search list
120 – SIP Servers DHCP Option
121 – Classless Static Route Option
123 – GeoConfiguration
124 – Vendor-Identifying Vendor Class
125 – Vendor-Identifying Vendor Specific
128 – TFPT Server IP address
129 – Call Server IP address
130 – Discrimination string
131 – Remote statistics server IP address
132 – 802.1P VLAN ID
133 – 802.1Q L2 Priority
134 – Diffserv Code Point
135 – HTTP Proxy for phone-specific applications
136 – PANA Authentication Agent
139 – IPv4 MoS
140 – IPv4 Fully Qualified Domain Name MoS
150 – TFTP server address
176 – IP Telephone
220 – Subnet Allocation
221 – Virtual Subnet Selection
252 – Proxy auto-discovery
254 – Private use
255 – End

October 6th, 2009

Posted In: Mac OS X Server, Mass Deployment, Network Infrastructure

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