Re: Consider escaping special characters like 'less' does

From: Jeff King <peff@peff.net>
Date: Oct 23, 2017, 00:45 UTC
Message-ID: <20171023004523.temglxnlpuns2ejy@sigill.intra.peff.net>
In-Reply-To: <37013BB09DFE493BB7E11E66A34657CE@blackfat>

On Sun, Oct 22, 2017 at 08:27:20AM -0400, Jason Pyeron wrote:

> > ESC (for color)
> > +			if ($line =~ s/[\000-\011\013-\032\034-\037]/?/g) {
> 
> What about CR [0x0D] ?

I assumed that CR was one of the things we'd want to avoid (and it was in fact what I used to test this). E.g., try:

  echo base >file
  git add file
  printf 'foo\r+bar\n' >file

Running through "less" shows something like:

  diff --git a/file b/file
  index df967b9..5b6ee80 100644
  --- a/file
  +++ b/file
  @@ -1 +1 @@
  -base
  +foo^M+bar

but "git add -p" shows:

  $ git add -p
  diff --git a/file b/file
  index df967b9..5b6ee80 100644
  --- a/file
  +++ b/file
  @@ -1 +1 @@
  -base
  +bar
  Stage this hunk [y,n,q,a,d,/,e,?]?

For systems where CRLF is the native line ending, we'd still expect to see only LFs here when line-ending conversion is on (since the diff shows the canonical in-repo form).

For files where the CRs must remain for some reason, they'd show as a "?" at the end. The "^M" shown by "less" is a bit more informative. If we really do want to pursue this direction, it might make sense to use more descriptive placeholders.

-Peff