FILE CONDITIONS

Read configuring-access before you read this.

mercurial-server supports file and branch conditions, which restrict an
operation depending on what files it modifies and what branch the work is
on. However, the way these conditions work is subtle and can be
counterintuitive - if you want to keep things simple, stick to user and
repo conditions, and then things are likely to work the way you would
expect.

File and branch conditions are added to the conditions against which a rule
matches, just like user and repo conditions; they have this form:

    file=<globpattern> - file in the repo
    branch=<globpattern> - name of the branch

However, in order to understand what effect adding these conditions will
have, it helps to understand how and when these rules are applied.

The rules file is used to make four decisions:

- Whether to allow a repository to be created
- Whether to allow access to a repository
- Whether to allow a changeset on a particular branch at all
- Whether to allow a changeset to change a particular file

When the first two of these decisions are being made, nothing is known
about what files might be changed, and so all file conditions automatically
succeed for the purpose of such decisions. This means that doing tricky
things with file conditions can have counterintuitive consequences:

- You cannot limit read access to a subset of a repository with a "read"
rule and a file condition: any user who has access to a repository can read
all of it and its full history. Such a rule can only have the effect of
masking a later "write" rule, as in this example:

   read repo=specialrepo file=dontwritethis
   write repo=specialrepo

allows all users to read specialrepo, and to write to all files *except*
that any changeset which writes to "dontwritethis" will be rejected.

- For similar reasons, don't give "init" rules file conditions.

- Don't try to deny write access to a particular file on a particular
branch - a developer can write to the file on another branch and then merge
it in. Either deny all writes to the branch from that user, or allow them
to write to all the files they can write to on any branch. In other words,
something like this will have the intended effect:

  write user=docs/* branch=docs file=docs/*

But something like this will not have the intended effect; it will
effectively allow these users to write to any file on any branch, by
writing it to "docs" first:

  write user=docs/* branch=docs
  write user=docs/* file=docs/*
  read user=docs/*