git-set-file-times

#!/usr/bin/perl
use strict;
use warnings;

# Sets mtime and atime of files to the latest commit time in git.
#
# This is useful after the first clone of the rsync repository BEFORE you
# do any building.  It is also safe if you have done a "make distclean".

my %ls;
my $commit_time;
my $prefix = @ARGV && $ARGV[0] =~ s/^--prefix=// ? shift : '';

$/ = "\0";
open FH, 'git ls-files -z|' or die $!;
while (<FH>) {
    chomp;
    $ls{$_} = $_;
}
close FH;

$/ = "\n";
open FH, "git log -r --name-only --no-color --pretty=raw -z @ARGV |" or die $!;
while (<FH>) {
    chomp;
    if (/^committer .*? (\d+) (?:[\-\+]\d+)$/) {
	$commit_time = $1;
    } elsif (s/\0\0commit [a-f0-9]{40}$// or s/\0$//) {
	my @files = delete @ls{split(/\0/, $_)};
	@files = grep { defined $_ } @files;
	next unless @files;
	map { s/^/$prefix/ } @files;
	utime $commit_time, $commit_time, @files;
    }
    last unless %ls;
}
close FH;