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git/contrib/svn-fe/svn-fe.txt
David Barr 7a75e661c5 vcs-svn: implement text-delta handling
Handle input in Subversion's dumpfile format, version 3.  This is the
format produced by "svnrdump dump" and "svnadmin dump --deltas", and
the main difference between v3 dumpfiles and the dumpfiles already
handled is that these can include nodes whose properties and text are
expressed relative to some other node.

To handle such nodes, we find which node the text and properties are
based on, handle its property changes, use the cat-blob command to
request the basis blob from the fast-import backend, use the
svndiff0_apply() helper to apply the text delta on the fly, writing
output to a temporary file, and then measure that postimage file's
length and write its content to the fast-import stream.

The temporary postimage file is shared between delta-using nodes to
avoid some file system overhead.

The svn-fe interface needs to be more complicated to accomodate the
backward flow of information from the fast-import backend to svn-fe.
The backflow fd is not needed when parsing streams without deltas,
though, so existing scripts using svn-fe on v2 dumps should
continue to work.

NEEDSWORK: generalize interface so caller sets the backflow fd, close
temporary file before exiting

Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
2011-05-26 02:28:04 -05:00

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svn-fe(1)
=========
NAME
----
svn-fe - convert an SVN "dumpfile" to a fast-import stream
SYNOPSIS
--------
[verse]
mkfifo backchannel &&
svnadmin dump --deltas REPO |
svn-fe [url] 3<backchannel |
git fast-import --cat-blob-fd=3 3>backchannel
DESCRIPTION
-----------
Converts a Subversion dumpfile into input suitable for
git-fast-import(1) and similar importers. REPO is a path to a
Subversion repository mirrored on the local disk. Remote Subversion
repositories can be mirrored on local disk using the `svnsync`
command.
Note: this tool is very young. The details of its commandline
interface may change in backward incompatible ways.
INPUT FORMAT
------------
Subversion's repository dump format is documented in full in
`notes/dump-load-format.txt` from the Subversion source tree.
Files in this format can be generated using the 'svnadmin dump' or
'svk admin dump' command.
OUTPUT FORMAT
-------------
The fast-import format is documented by the git-fast-import(1)
manual page.
NOTES
-----
Subversion dumps do not record a separate author and committer for
each revision, nor a separate display name and email address for
each author. Like git-svn(1), 'svn-fe' will use the name
---------
user <user@UUID>
---------
as committer, where 'user' is the value of the `svn:author` property
and 'UUID' the repository's identifier.
To support incremental imports, 'svn-fe' puts a `git-svn-id` line at
the end of each commit log message if passed an url on the command
line. This line has the form `git-svn-id: URL@REVNO UUID`.
The resulting repository will generally require further processing
to put each project in its own repository and to separate the history
of each branch. The 'git filter-branch --subdirectory-filter' command
may be useful for this purpose.
BUGS
----
Empty directories and unknown properties are silently discarded.
The exit status does not reflect whether an error was detected.
SEE ALSO
--------
git-svn(1), svn2git(1), svk(1), git-filter-branch(1), git-fast-import(1),
https://svn.apache.org/repos/asf/subversion/trunk/notes/dump-load-format.txt