Re: SHA1 collisions found

["René Scharfe" <l.s.r@web.de>]

Am 25.02.2017 um 20:04 schrieb brian m. carlson:
>>> So I think that the current scope left is best estimated by the
>>> following command:
>>>
>>>   git grep -P 'unsigned char\s+(\*|.*20)' | grep -v '^Documentation'
>>>
>>> So there are approximately 1200 call sites left, which is quite a bit of
>>> work.  I estimate between the work I've done and other people's
>>> refactoring work (such as the refs backend refactor), we're about 40%
>>> done.
> 
> As a note, I've been working on this pretty much nonstop since the
> collision announcement was made.  After another 27 commits, I've got it
> down from 1244 to 1119.
> 
> I plan to send another series out sometime after the existing series has
> hit next.  People who are interested can follow the object-id-part*
> branches at https://github.com/bk2204/git.

Perhaps the following script can help a bit; it converts local and static
variables in specified files.  It's just a simplistic parser which can get
at least shadowing variables, strings and comments wrong, so its results
need to be reviewed carefully.

I failed to come up with an equivalent Coccinelle patch so far. :-/

René


#!/bin/sh
while test $# -gt 0
do
	file="$1"
	tmp="$file.new"
	test -f "$file" &&
	perl -e '
		use strict;
		my %indent;
		my %old;
		my %new;
		my $in_struct = 0;
		while (<>) {
			if (/^(\s*)}/) {
				my $len = length $1;
				foreach my $key (keys %indent) {
					if ($len < length($indent{$key})) {
						delete $indent{$key};
						delete $old{$key};
						delete $new{$key};
					}
				}
				$in_struct = 0;
			}
			if (!$in_struct and /^(\s*)(static )?unsigned char (\w+)\[20\];$/) {
				my $prefix = "$1$2";
				my $name = $3;
				$indent{$.} = $1;
				$old{$.} = qr/(?<!->)(?<!\.)(?<!-)\b$name\b/;
				$name =~ s/sha1/oid/;
				print $prefix . "struct object_id " . $name . ";\n";
				$new{$.} = $name . ".hash";
				next;
			}
			if (/^(\s*)(static )?struct (\w+ )?\{$/) {
				$in_struct = 1;
			}
			if (!$in_struct and ! /\/\*/) {
				foreach my $key (keys %indent) {
					s/$old{$key}/$new{$key}/g;
				}
			}
			print;
		}
	' "$file" >"$tmp" &&
	mv "$tmp" "$file" ||
	exit 1
	shift
done