Development of CVS: Macintosh

This page is aimed at people who are working on CVS for the Macintosh.

Working Directory Formats

There is some discussion, and differing implementations, of how to store working directories on the Macintosh.

CVS/Repository files: should be fine. Relative repositories (which MacCVS Pro writes) are legitimate and as far as I know, MacCVS should accept them already. The MacCVS Pro page mentioned below also mentions some (relatively obscure) cases with modules.

ckid resource: This is the only way on the Macintosh to mark a file as read-only. As far as I know both MPW and CodeWarrior respect this setting. MPW at least also looks at the version number and some of the other fields (and/or makes that information available to shell scripts). Last I heard, MacCVS Pro maintains this resource but MacCVS does not.

mcvs resource: The issue is whether to store this information in a resource or in the CVS directory (or both). Speed is probably not a huge issue one way or the other (do some benchmarking if concerned). Having resources in source files can be a pain when it comes time to copy files and such (for the ckid resource there apparently is a popular program called OrphanFiles which removes the resource, but it of course doesn't deal with mcvs, which is CVS-specific). Not all applications will preserve ckid and mcvs resources when they edit the files. Last I heard, MacCVS Pro maintains the mcvs resource but MacCVS does not.

The main data in mcvs which is not in CVS/Entries is the AppleSingle flag. This could be added to CVS/Entries (or some other file in the CVS directory), which is a win in the sense that one can just copy in a binary file, and have things work without worrying about resources. If it really wants to be in a resource, the fUnused, fUserID, fFileID, fRevisionID fields in ckid are apparently available for a version control system to use any way it wants (as far as I know it won't break development environments if CVS uses those fields in its own way, although it might be a bad idea, in terms of not knowing whether a file was written by CVS or some other version control tool).

The mcvs resource also contains the filename, and one might use this to detect renames. This is/would-be kind of a cute/useful capability (I forget whether MacCVS Pro already has it). I, Jim Kingdon, don't have a clear idea of the pros and cons, so I'm going to reserve judgment.

Line endings: According to the standard CVS working directory format (as documented in the Cederqvist), both text files under version control and the files in the CVS directory are stored using the operating system's standard convention for text files. On the macintosh this would be CR-only to end a line. As far as I know the existing implementations all implement this (but don't quote me on that :-)).

Repository Format

For the most part there is no compelling reason to add any Macintosh-specific features to the CVS server. One issue which obviously affects the repository is resource forks. The current solution, which I believe is adopted by both MacCVS and MacCVS Pro in a compatible way, is to store files with resource forks in AppleSingle format in the repository. MacCVSClient 1.4 also supports AppleSingle.

MacCVSClient also has a text-based format called RBL which is mergeable (at least in some cases) and can be used along with RCS keywords. So there are some nice things about it but also some disadvantages (most notably, it doesn't store data forks; I'm not sure why not).

AppleEvents interface

Various plug-ins and scripts may wish to drive CVS via some kind of interface. It might be useful to consider whether the various CVS clients might want to agree on an interface. The most popular such interface for the Mac is the AppleEvents interface supported by MacCVS; I'm not aware of any similar interface supported by MacCVS Pro or MacCVSClient.

Other pages at Cyclic

User-oriented Macintosh page.

There is some Rhapsody information on the Portability page.

Our user interfaces page contains information about each of the graphical CVS clients.

Here are some notes from December 1996 about the port of CVS which can be run from the MPW command line.

For more information

The MacCVS Pro people have a page about working directory formats.