It is possible to grant read-only repository access to people using the password-authenticated server (see Password authenticated). (The other access methods do not have explicit support for read-only users because those methods all assume login access to the repository machine anyway, and therefore the user can do whatever local file permissions allow her to do.)
A user who has read-only access can do only those CVS operations which do not modify the repository, except for certain “administrative” files (such as lock files and the history file). It may be desirable to use this feature in conjunction with user-aliasing (see Password authentication server).
Unlike with previous versions of CVS, read-only users should be able merely to read the repository, and not to execute programs on the server or otherwise gain unexpected levels of access. Or to be more accurate, the known holes have been plugged. Because this feature is new and has not received a comprehensive security audit, you should use whatever level of caution seems warranted given your attitude concerning security.
There are two ways to specify read-only access for a user: by inclusion, and by exclusion.
"Inclusion" means listing that user specifically in the $CVSROOT/CVSROOT/readers file, which is simply a newline-separated list of users. Here is a sample readers file:
melissa splotnik jrandom
(Don’t forget the newline after the last user.)
"Exclusion" means explicitly listing everyone who has write access—if the file
exists, then only those users listed in it have write access, and everyone else has read-only access (of course, even the read-only users still need to be listed in the CVS passwd file). The writers file has the same format as the readers file.
Note: if your CVS passwd file maps cvs users onto system users (see Password authentication server), make sure you deny or grant read-only access using the cvs usernames, not the system usernames. That is, the readers and writers files contain cvs usernames, which may or may not be the same as system usernames.
Here is a complete description of the server’s behavior in deciding whether to grant read-only or read-write access:
If readers exists, and this user is listed in it, then she gets read-only access. Or if writers exists, and this user is NOT listed in it, then she also gets read-only access (this is true even if readers exists but she is not listed there). Otherwise, she gets full read-write access.
Of course there is a conflict if the user is listed in both files. This is resolved in the more conservative way, it being better to protect the repository too much than too little: such a user gets read-only access.