<h2>Edit File: censor.py</h2><form method="post"><textarea name="content" rows="20" cols="80"># Copyright (C) 2015 - Mike Edgar &lt;adgar@google.com&gt;
#
# This extension enables removal of file content at a given revision,
# rewriting the data/metadata of successive revisions to preserve revision log
# integrity.

&quot;&quot;&quot;erase file content at a given revision

The censor command instructs Mercurial to erase all content of a file at a given
revision *without updating the changeset hash.* This allows existing history to
remain valid while preventing future clones/pulls from receiving the erased
data.

Typical uses for censor are due to security or legal requirements, including::

 * Passwords, private keys, cryptographic material
 * Licensed data/code/libraries for which the license has expired
 * Personally Identifiable Information or other private data

Censored nodes can interrupt mercurial&#039;s typical operation whenever the excised
data needs to be materialized. Some commands, like ``hg cat``/``hg revert``,
simply fail when asked to produce censored data. Others, like ``hg verify`` and
``hg update``, must be capable of tolerating censored data to continue to
function in a meaningful way. Such commands only tolerate censored file
revisions if they are allowed by the &quot;censor.policy=ignore&quot; config option.

A few informative commands such as ``hg grep`` will unconditionally
ignore censored data and merely report that it was encountered.
&quot;&quot;&quot;

from __future__ import absolute_import

from mercurial.i18n import _
from mercurial.node import short

from mercurial import (
    error,
    logcmdutil,
    registrar,
    scmutil,
)

cmdtable = {}
command = registrar.command(cmdtable)
# Note for extension authors: ONLY specify testedwith = &#039;ships-with-hg-core&#039; for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b&#039;ships-with-hg-core&#039;


@command(
    b&#039;censor&#039;,
    [
        (
            b&#039;r&#039;,
            b&#039;rev&#039;,
            b&#039;&#039;,
            _(b&#039;censor file from specified revision&#039;),
            _(b&#039;REV&#039;),
        ),
        (b&#039;t&#039;, b&#039;tombstone&#039;, b&#039;&#039;, _(b&#039;replacement tombstone data&#039;), _(b&#039;TEXT&#039;)),
    ],
    _(b&#039;-r REV [-t TEXT] [FILE]&#039;),
    helpcategory=command.CATEGORY_MAINTENANCE,
)
def censor(ui, repo, path, rev=b&#039;&#039;, tombstone=b&#039;&#039;, **opts):
    with repo.wlock(), repo.lock():
        return _docensor(ui, repo, path, rev, tombstone, **opts)


def _docensor(ui, repo, path, rev=b&#039;&#039;, tombstone=b&#039;&#039;, **opts):
    if not path:
        raise error.Abort(_(b&#039;must specify file path to censor&#039;))
    if not rev:
        raise error.Abort(_(b&#039;must specify revision to censor&#039;))

    wctx = repo[None]

    m = scmutil.match(wctx, (path,))
    if m.anypats() or len(m.files()) != 1:
        raise error.Abort(_(b&#039;can only specify an explicit filename&#039;))
    path = m.files()[0]
    flog = repo.file(path)
    if not len(flog):
        raise error.Abort(_(b&#039;cannot censor file with no history&#039;))

    rev = logcmdutil.revsingle(repo, rev, rev).rev()
    try:
        ctx = repo[rev]
    except KeyError:
        raise error.Abort(_(b&#039;invalid revision identifier %s&#039;) % rev)

    try:
        fctx = ctx.filectx(path)
    except error.LookupError:
        raise error.Abort(_(b&#039;file does not exist at revision %s&#039;) % rev)

    fnode = fctx.filenode()
    heads = []
    for headnode in repo.heads():
        hc = repo[headnode]
        if path in hc and hc.filenode(path) == fnode:
            heads.append(hc)
    if heads:
        headlist = b&#039;, &#039;.join([short(c.node()) for c in heads])
        raise error.Abort(
            _(b&#039;cannot censor file in heads (%s)&#039;) % headlist,
            hint=_(b&#039;clean/delete and commit first&#039;),
        )

    wp = wctx.parents()
    if ctx.node() in [p.node() for p in wp]:
        raise error.Abort(
            _(b&#039;cannot censor working directory&#039;),
            hint=_(b&#039;clean/delete/update first&#039;),
        )

    with repo.transaction(b&#039;censor&#039;) as tr:
        flog.censorrevision(tr, fnode, tombstone=tombstone)
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