Re: [RFC] Applying a graft to a tree and "rippling" the changes through the history

Hi, Junio C Hamano wrote:

You're not the only one. My tool is different, however, in that it accepts a list of old=>new commits. I have used it successfully to re-graft my changes from a CVS->GIT tree to the corresponding CVS->SVN->GIT tree (which cannot be identical, because (a) SVN's timestamps are not accurate enough and (b) SVN's CVS import is more accurate in reproducing CVS archives than cvsps can be).

I'd suggest adding the capability of grafting something onto a tag...

#!/usr/bin/python

# This is a simple script which clones a git subtree to another.

import sys,re,optparse,os,subprocess

parser = optparse.OptionParser("corresponding_file [ old_commit ]", conflict_handler="resolve", description="""\ Transfer a list of commits from one repository to another.

The first argument is a list of SHA1 entries of the form
	old new
It lists which commits are "the same".

old_commit and those of its parents which are not listed in the corresponding_file are copied, i.e. new commit objects are created. Their SHA1s are added to the file so that you may repeat the process with other commits, or run it incrementally.

""")
parser.add_option("-h","--help","-?", action="help",
                    help="Print this help message and exit")
parser.add_option("-v", "--verbose", dest="verbose", action="store_true",
                    help="Report progress")

(options, args) = parser.parse_args()

if len(args) < 1 or len(args) > 3:
	parser.error("requires one to three arguments")

def end(p):
	try:
		retcode = p.wait()
	except OSError,e:
		print >>sys.stderr, "git-rev-list failed:", e
	else:
		if retcode < 0:
			print >>sys.stderr, "git-rev-list was terminated by signal", -retcode
			sys.exit(1)
		elif retcode > 0:
			print >>sys.stderr, "git-rev-list exited with non-zero exit code", retcode
			sys.exit(1)

re_cmt = re.compile(r'\s*#.*')
corr = {}
for l in open(args[0]):
	l = re_cmt.sub("",l).strip()
	if l == "": continue
	try:
		a,b = l.split()
	except ValueError:
		continue
	if len(a) != 40: continue
	if len(b) != 40: continue
	corr[a]=b

corrf=open(args[0],"a")

if len(args) >= 2:
	srctag = args[1]
else:
	srctag = "HEAD"

srcrepo = os.path.curdir

commits=[]
cmd = ["git-rev-list",srctag]
for k in corr.iterkeys():
	cmd.append("^"+k)
if options.verbose:
	print cmd

p=subprocess.Popen(cmd, stdout=subprocess.PIPE)
for l in p.stdout:
	l = l.strip()
	commits.append(l)
end(p)

while len(commits):
	c = commits.pop()
	if c in corr: continue
	if options.verbose:
		print "Processing:",c

	p=subprocess.Popen(["git-cat-file","commit",c], stdout=subprocess.PIPE)
	qf=os.tempnam()
	try:
		q=open(qf,"w")
		nx=False
		for l in p.stdout:
			if nx:
				q.write(l)
				continue
			l = l.strip()
			if l == "":
				nx=True
				q.write("\n")
				continue
			a,b = l.split(" ",1)
			if a == "parent":
				b = corr[b]
			print >>q,a,b
		q.close()
		q=subprocess.Popen(["git-hash-object","-w","-t","commit",qf], stdout=subprocess.PIPE)
		d = q.stdout.read().strip()
		end(q)
	finally:
		os.unlink(qf)
	end(p)
	corr[c] = d
	print >>corrf, c,d
	if options.verbose:
		print c,d,l

# OK, everything is done. corrf.close() print d