contrib/dumprevlog

histedit: add description about basic histedit function to command help

Before this patch, there is no explicit description that histedit
edits changesets between specified ancestor and the parent of the
working directory: users may notice it by error message "REV is not an
ancestor of working directory".

This patch adds description about basic histedit function to command
help of it.

This patch uses term "ancestor" instead of "parent", because it seems
to be more suitable, and almost all (error) messages already use it.

#!/usr/bin/env python
# Dump revlogs as raw data stream
# $ find .hg/store/ -name "*.i" | xargs dumprevlog > repo.dump

import sys
from mercurial import revlog, node, util

for fp in (sys.stdin, sys.stdout, sys.stderr):
    util.setbinary(fp)

for f in sys.argv[1:]:
    binopen = lambda fn: open(fn, 'rb')
    r = revlog.revlog(binopen, f)
    print "file:", f
    for i in r:
        n = r.node(i)
        p = r.parents(n)
        d = r.revision(n)
        print "node:", node.hex(n)
        print "linkrev:", r.linkrev(i)
        print "parents:", node.hex(p[0]), node.hex(p[1])
        print "length:", len(d)
        print "-start-"
        print d
        print "-end-"