Ubuntu Manpage: repocutter - surgical and filtering operations on Subversion dump files

NAME

       repocutter - surgical and filtering operations on Subversion dump files

SYNOPSIS

       repocutter [-q] [-d n] [-i 'filename'] [-r 'selection'] 'subcommand'

DESCRIPTION

This program does surgical and filtering operations on Subversion dump files. While it is
is not as flexible as reposurgeon(1), it can perform Subversion-specific transformations
that reposurgeon cannot, and can be useful for processing Subversion repositories into a
form suitable for conversion. Also, it supports the version 3 dumpfile format, which
reposurgeon does not.

In all commands, the -r (or --range) option limits the selection of revisions over which
an operation will be performed. Usually other revisions will be passed through unaltered,
except in the select and deselect commands for which the option controls which revisions
will be passed through. A selection consists of one or more comma-separated ranges. A
range may consist of an integer revision number or the special name HEAD for the head
revision. Or it may be a colon-separated pair of integers, or an integer followed by a
colon followed by HEAD.

(Older versions of this tool, before 4.30, treated -r as an implied selection filter
rather than passing through unselected revisions unaltered. If you have old scripts using
repocutter they may need modification.)

Normally, each subcommand produces a progress spinner on standard error; each turn means
another revision has been filtered. The -q (or --quiet) option suppresses this.

The -d option enables debug messages on standard error. It takes an integer debug level.
These messages are probably only of interest to repocutter developers.

The -i option sets the input source to a specified filename. This is primarily useful when
running the program under a debugger. When this option is not present the program expects
to read a stream from standard input.

Generally, if you need to use this program at all, you will find that you need to pipe
your dump file through multiple instances of it doing one kind of operation each. This is
not as expensive as it sounds; with the exception of the reduce subcommand, the working
set of this program is bounded by the size of the the largest single blob plus its
metadata. It does not need to hold the entire repo metadata in memory.

The -t option sets a tag to be included in error message. This will be useful for
determining which stage of a multistage repocutter pipeline failed.

The following subcommands are available:

select
The 'select' subcommand selects a range and permits only revisions and nodes in that
range to pass to standard output. A range beginning with 0 includes the dumpfile
header.

deselect
The 'deselect' subcommand selects a range and permits only revisions and nodes NOT in
that range to pass to standard output.

see
Render a very condensed report on the repository node structure, mainly useful for
examining strange and pathological repositories. File content is ignored. You get one
line per repository operation, reporting the revision, operation type, file path, and
the copy source (if any). Directory paths are distinguished by a trailing slash. The
'copy' operation is really an 'add' with a directory source and target; the display
name is changed to make them easier to see. This report can be restricted by a
selection set.

renumber
Renumber all revisions, patching Node-copyfrom headers as required. Any selection
option is ignored. Takes no arguments. The -b option can be used to set the base to
renumber from, defaulting to 0.

log
Generate a log report, same format as the output of svn log on a repository, to
standard output.

setlog
Replace the log entries in the input dumpfile with the corresponding entries in the
LOGFILE, which should be in the format of an svn log output. Replacements may be
restricted to a specified range.

propdel
Delete the property PROPNAME. May be restricted by a revision selection. You may
specify multiple properties to be deleted.

proprename
Rename the property OLDNAME to NEWNAME. May be restricted by a revision selection. You
may specify multiple properties to be renamed.

propset
Set the property PROPNAME to PROPVAL. May be restricted by a revision selection. You
may specify multiple property settings.

ppropclean
Every path with a suffix matching one of SUFFIXES gets a property turned off. The
default prperty is svn::Another prperty may be set with the -p option.

expunge
Delete all operations with Node-path or Node-copyfrom-path headers matching specified
Golang regular expressions (opposite of 'sift'). Any revision left with no Node
records after this filtering has its Revision

Matches are constrained so that each match must be a path segment or a sequence of
path segments; that is, the left end must be either at the start of path or
immediately following a /, and the right end must precede a / or be at end of string.
With a leading ^ the match is constrained to be a leading sequence of the pathname;
with a trailing $, a trailing one. record is removed as well.

The -f/-fixed option disables regexp compilation of the patterns, treating them as
fixed strings.

sift
Delete all operations with Node-path or Node-copyfrom-path headers not matching
specified Golang regular expressions (opposite of 'expunge'). Any revision left with
no Node records after this filtering has its Revision record removed as well. This
transform can be restricted by a selection set.

The -f/-fixed option disables regexp compilation of the patterns, treating them as
fixed strings.

closure
The 'closure' subcommand computes the transitive closure of a path set under the
relation 'copies from' - that is, with the smallest set of additional paths such that
every copy-from source is in the set.

pathlist
List all distinct node-paths in the stream, once each, in the order first encountered.

pathrename
Modify Node-path headers, Node-copyfrom-path headers, and svn::expression FROM;
replace with TO. TO may contain Golang-style backreferences (${1}, ${2} etc - curly
brackets not optional) to parenthesized portions of FROM.

Multiple FROM/TO pairs may be specified and are applied in order. This transform can
be restricted by a selection set.

pop
Pop initial segment off each path. May be useful after a sift command to turn a dump
from a subproject stripped from a dump for a multiple-project repository into the
normal form with trunk/tags/branches at the top level. This transform can be
restricted by a selection set.

push
Push an initial segment onto each path. Normally used to add a "trunk" prefix to every
path ion a flat repository. This transform can be restricted by a selection set.

skipcopy
Replace the source revision and path of a copy at the upper end of the selection with
the source revisions and path of a copy at the lower end. Fails unless both revisions
are copies. Used to remove an unwanted intermediate copy or copies - fails noisily if
there is a change operating on the target path between these revisions.

swap
Swap the top two elements of each pathname in every revision in the selection set.
Useful following a sift operation for straightening out a common form of multi-project
repository. If a PATTERN argument is given, only paths matching the pattern are
swapped. This transform can be restricted by a selection set.

swapsvn
Like swap, but is aware of Subversion structure. Used for transforming multiproject
repositories into a standard layout with trunk, tags, and branches at the top level.

Fires when the second component of a matching path is "trunk", "branches", or "tags",
or the path consists of a single segment that is a top-level project directory; passes
through all paths for this is not so unaltered.

Top-level project directories with properties or comments make this command die
(return status 1) with an error message on stderr; otherwise these directories are
silently discarded.

Otherwise, swaps "trunk" and the top-level (project) directory straight up. For tags
and branches, the following two components are swapped to the top. thus,
"foo/branches/release23" becomes "branches/release23/foo", putting the project
directory beneath the branch.

Also fires when an entire project directory is copied; this is transformed into a copy
of trunk and copies of each subbranch and tag that exists.

After the swap, there are attempts to recognize spans of copies into branch
directories, and copies into tag subdirectories that are parallel in all top-level
(project) directories. These are coalesced into single copies in the inverted
structure. No attempts is made to coalesce deletes; the user must manually trim
unneeded branches.

Accordingly, copies with three-segment sources and three-segment targets are
transformed; for tags/ and branches/ paths the last segment (the subdirectory below
the branch name) is dropped, Following copies are skipped.

This has two minor negative consequences. One is that metadata belonging to all
deletes or copies after the first one in a coalesced span is lost. The other is that
branches and tags local to individual project directories are promoted to global
branches and tags across the entire transformed repository; no content is lost this
way.

Parallel rename sequences are also coalesced.

If a PATTERN argument is given, only paths matching the pattern are swapped.

Note that the result of swapping does not have initial trunk/branches/tags directory
creations and can thus not be fed directly to svnload. reposurgeon copes with this,
but Subversion will not.

This transform can be restricted by a selection set.

replace
Perform a regular expression search/replace on blob content. The first character of
the argument (normally /) is treated as the end delimiter for the regular-expression
and replacement parts. This transform can be restricted by a selection set.

strip
Replace content with unique generated cookies on all node paths matching the specified
regular expressions; if no expressions are given, match all paths. Useful when you
need to examine a particularly complex node structure. This transform can be
restricted by a selection set.

obscure
Replace path segments and committer IDs with arbitrary but consistent names in order
to obscure them. The replacement algorithm is tuned to make the replacements readily
distinguishable by eyeball. This transform can be restricted by a selection set.

reduce
Strip revisions out of a dump so the only parts left those likely to be relevant to a
conversion problem. This is done by dropping every node that consists of a change on a
file and has no property settings.

testify
Replace commit timestamps with a monotonically increasing clock tick starting at the
Unix epoch and advancing by 10 seconds per commit. Replace all attributions with
'fred'. Discard the repository UUID. Use this to neutralize procedurally-generated
streams so they can be compared. This transform can be restricted by a selection set.

version
Report major and minor repocutter version.

HISTORY

       Under the name "svncutter", an ancestor of this program traveled in the 'contrib/'
       director of the Subversion distribution. It had functional overlap with reposurgeon(1)
       because it was directly ancestral to that code. It was moved to the reposurgeon(1)
       distribution in January 2016. This program was ported from Python to Go in August 2018, at
       which time the obsolete "squash" command was retired. The syntax of regular expressions in
       the pathrename command changed at that time.

       The reason for the partial functional overlap between repocutter and reposurgeon is that
       repocutter was first written earlier and became a testbed for some of the design concepts
       in reposurgeon. After reposurgeon was written, the author learned that it could not
       naturally support some useful operations very specific to Subversion, and enhanced
       repocutter to do those.

BUGS

       There is one regression since the Python version: repocutter no longer recognizes
       Macintosh-style line endings consisting of a carriage return only. This may be addressed
       in a future version.

EXAMPLE

       Suppose you have a Subversion repository with the following semi-pathological structure:

           Directory1/ (with unrelated content)
           Directory2/ (with unrelated content)
           TheDirIWantToMigrate/
                           branches/
                                          crazy-feature/
                                                          UnrelatedApp1/
                                                          TheAppIWantToMigrate/
                           tags/
                                          v1.001/
                                                          UnrelatedApp1/
                                                          UnrelatedApp2/
                                                          TheAppIWantToMigrate/
                           trunk/
                                          UnrelatedApp1/
                                          UnrelatedApp2/
                                          TheAppIWantToMigrate/

       You want to transform the dump file so that TheAppIWantToMigrate can be subject to a
       regular branchy lift. A way to dissect out the code of interest would be with the
       following series of filters applied:

           repocutter expunge '^Directory1' '^Directory2'
           repocutter pathrename '^TheDirIWantToMigrate/' ''
           repocutter expunge '^branches/crazy-feature/UnrelatedApp1/
           repocutter pathrename 'branches/crazy-feature/TheAppIWantToMigrate/' 'branches/crazy-feature/'
           repocutter expunge '^tags/v1.001/UnrelatedApp1/'
           repocutter expunge '^tags/v1.001/UnrelatedApp2/'
           repocutter pathrename '^tags/v1.001/TheAppIWantToMigrate/' 'tags/v1.001/'
           repocutter expunge '^trunk/UnrelatedApp1/'
           repocutter expunge '^trunk/UnrelatedApp2/'
           repocutter pathrename '^trunk/TheAppIWantToMigrate/' 'trunk/'

LIMITATIONS

       The sift and expunge operations can produce output dumps that are invalid. The problem is
       copyfrom operations (Subversion branch and tag creations). If an included revision
       includes a copyfrom reference to an excluded one, the reference target won’t be in the
       emitted dump; it won’t load correctly in Subversion, and while reposurgeon has fallback
       logic that backs down to the latest existing revision before the kissing one this
       expedient is fragile. The revision number in a copyfrom header pointing to a missing
       revision will be zero. Attempts to be clever about this won’t work; the problem is
       inherent in the data model of Subversion.

AUTHOR

       Eric S. Raymond esr@thyrsus.com. This tool is distributed with reposurgeon; see the
       project page <http://www.catb.org/~esr/reposurgeon>.

                                            2022-01-12                              REPOCUTTER(1)