Re: Is there a scriptable way to update the stat-info in the index without having git open and read those files?

[Pete Wyckoff <pw@padd.com>]

newren@gmail.com wrote on Mon, 22 Aug 2011 16:28 -0600:
> I want to do something really close to
>   git update-index -q --refresh
> However, I want it to assume the files in the working tree are
> unmodified from the index (i.e. don't waste time opening and reading
> the file) and simply update the stat information in the index to match
> the current files on disk.
> 
> Yes, I know that would be unsafe if the files don't have the
> appropriate contents; I'm promising that they do have the appropriate
> contents and don't want to pay the performance penalty for git to
> verify.  Is that possible?

I have the same issue in my workflow, and agree with Junio that this
is just too bizarre to put in the code.  Here's the script I use,
relying on dulwich, that you might find helpful.

		-- Pete


------8<------------------
#!/usr/bin/env python2.6
# git-index-clone - Update index after a volume clone
# Copyright 2010 Pete Wyckoff <pw@padd.com>

import sys
import os
from dulwich.index import Index

index_name = ".git/index"

#
# Debugging option:  show the index entry for just one file name,
# e.g. git-index-clone file/name/in/tree
#
def show_entry(name):
    idx = Index(index_name)
    if name not in idx:
	print >>sys.stderr, "No index entry", name
	return
    print "index", idx[name]
    t = update_from_stat(idx[name], name)
    print "stat ", t

#
# Stat the file, return the new tuple
#
def update_from_stat(idx, name):
    (ctime, mtime, dev, ino, mode, uid, gid, size, sha, flags) = idx

    sb = os.lstat(name)

    # times are float; dulwich converts to (sec, ns) on write
    ctime = sb.st_ctime
    mtime = sb.st_mtime
    dev = sb.st_dev
    ino = sb.st_ino
    # assume mode unchanged
    uid = sb.st_uid
    gid = sb.st_gid
    # assume size, sha, flags unchanged
    return (ctime, mtime, dev, ino, mode, uid, gid, size, sha, flags)

def convert():
    idx_in = Index(index_name)
    os.unlink(index_name)

    idx_out = Index(index_name)

    for name in idx_in:
	idx_out[name] = update_from_stat(idx_in[name], name)

    idx_out.write()
    os.chmod(index_name, 0644)  # drop exec perms

def usage():
    print >>sys.stderr, "Usage: %s [<index entry name>]\n"
    sys.exit(1)

def main():
    if len(sys.argv) == 1:
	convert()
    elif len(sys.argv) == 2:
	show_entry(sys.argv[1])
    else:
	usage()
    return 0

if __name__ == "__main__":
    sys.exit(main())