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/*