Re: [RFC] embedded TAB and LF in pathnames

Alex Riesen <raa.lkml@gmail.com> writes:

          Quote  nongraphic  characters in file names using alphabetic and
          octal backslash sequences like those used in C. This  option  is
          the  same as -Q except that filenames are not surrounded by dou-
          ble-quotes.

If you have a file whose name is 'foo' + LF + 'bar', and if you
use backslash convention, your diff would start like this:

    diff --git a/foo\nbar b/foo\nbar
    @@ 1,2 3,4 @@
     context
    -deleted
    ...

which looks quite natural.

I would, however, prefer this kind of funny pathnames to *stand*
*out* more than usual, to make it really obvious that there is
something really funky going on.  In that sense, the above is a
bit too innocuous-looking to my taste.

But this "embedded LF and TAB" is a corner case.  I would not be
using such paths that would trigger the quoting myself anyway,
and I do not particularly care as long as the tools do the right
thing -- any quoting rule would do, as long as the generating
side (git-diff) is consistent with accepting side (git-apply),
and as long as there is no new ambiguity introduced.

The backslash proposal is introducing a small ambiguity.  You
cannot tell if the file had an embedded LF between 'foo' and
'bar' (and generated with your git-diff) or had an embedded
backslash between 'foo' and 'nbar' (and generated with existing
git-diff).  Since we never had a version of git-diff that
outputs double-slashes '//' in paths, there is no ambiguity if
we use it as a quoting mechanism.

Just as a concrete demonstration, here is how the git-status
output and git-diff output would look like for a file 'pqr' in a
directory whose name is 'def' + LF + 'ghi' that uses the version
of git-diff from the proposed updates branch:

        # Changed but not updated:
        #   (use git-update-index to mark for commit)
        #
        #	modified: def//{LF}//ghi/pqr

        diff --git a/def//{LF}//ghi/pqr b/def//{LF}//ghi/pqr
        index 9ee055c..47dbc3f 100644
        --- a/def//{LF}//ghi/pqr
        +++ b/def//{LF}//ghi/pqr
        @@ -1 +1,2 @@
         Fri Oct  7 23:19:04 PDT 2005
        +foo

I am not married to this quoting syntax -- I think it *is* ugly,
but as I said before, I'd prefer to have something ugly here.

I would easily be persuaded otherwise, though.  A working patch
would probably be the most effective way of persuasion, but a
mock output without the code to produce and/or parse it would
also be fine as a starting point for discussion.


-
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html