view mercurial/help/internals/censor.txt @ 36681:340e4b711df7

bdiff: avoid pointer arithmetic on void* MSVC 2008 complains: mercurial/cext/bdiff.c(106) : error C2036: 'void *' : unknown size mercurial/cext/bdiff.c(107) : error C2036: 'void *' : unknown size Maybe it's a gcc extension? https://stackoverflow.com/questions/37460579/error-c2036-void-unknown-size
author Matt Harbison <matt_harbison@yahoo.com>
date Sat, 03 Mar 2018 23:29:40 -0500
parents 1b699a208cee
children
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The censor system allows retroactively removing content from
files. Actually censoring a node requires using the censor extension,
but the functionality for handling censored nodes is partially in core.

Censored nodes in a filelog have the flag ``REVIDX_ISCENSORED`` set,
and the contents of the censored node are replaced with a censor
tombstone. For historical reasons, the tombstone is packed in the
filelog metadata field ``censored``. This allows censored nodes to be
(mostly) safely transmitted through old formats like changegroup
versions 1 and 2. When using changegroup formats older than 3, the
receiver is required to re-add the ``REVIDX_ISCENSORED`` flag when
storing the revision. This depends on the ``censored`` metadata key
never being used for anything other than censoring revisions, which is
true as of January 2017. Note that the revlog flag is the
authoritative marker of a censored node: the tombstone should only be
consulted when looking for a reason a node was censored or when revlog
flags are unavailable as mentioned above.

The tombstone data is a free-form string. It's expected that users of
censor will want to record the reason for censoring a node in the
tombstone. Censored nodes must be able to fit in the size of the
content being censored.