Re: (Some?) control codes not escaped when using `git add -p`

[Jeff King <peff@peff.net>]

On Thu, Oct 12, 2017 at 12:59:06PM -0500, Mahmoud Al-Qudsi wrote:

> Hello list,
> 
> Running git 2.7.4, I’ve run into an issue where control codes that would
> normally be escaped when using `git diff` are not similarly escaped when using
> `git add -p`.
> 
> As a concrete example, I have a text file including the following "text":
> 
> :map ^[[H <Home>
> :map ^[[5~ ^B "page up
> :map ^[[6~ ^F "page down

The diffs generated for "git diff" and "git add -p" are done by the
exact same code. And that code doesn't do any escaping or cleverness; it
will output the raw bytes of the difference.

What is likely causing the different in what you see is that "git diff".
outputs through a pager, and the snippets of "add -p" do not. The
default pager, "less", does escape some control codes (but with the -R
option, which git uses by default, it passes through colors).

Try:

  git --no-pager diff

or:

  GIT_PAGER=cat git diff

and you'll likely see output similar to what you get with "add -p".

The reason that "add -p" doesn't go through a pager by default is simply
that it would be annoying, since we show snippets and then ask for user
input.

However, since Git v2.9.0, "add -p" (and all of the interactive commands
like "checkout -p", etc) know about the interactive.diffFilter config
option. You could use that to munge the results however you like. E.g.:

  # we can't use [:cntrl:] here because we want to keep newlines.
  # likewise, we want to keep ESC for color codes
  git config interactive.diffFilter "tr '\000-\011\013-\032\034-\037' '?'"

-Peff