Re: [PATCH] credential.c: fix credential reading with regards to CR/LF

From: Jeff King <peff@peff.net>
Date: Feb 14, 2020, 18:32 UTC
Message-ID: <20200214183200.GP150965@coredump.intra.peff.net>
In-Reply-To: <pull.710.git.git.1581688196706.gitgitgadget@gmail.com>

On Fri, Feb 14, 2020 at 01:49:56PM +0000, Johannes Schindelin via GitGitGadget wrote:

Show 13 quoted lines

> From: Nikita Leonov <nykyta.leonov@gmail.com>
> 
> This fix makes using Git credentials more friendly to Windows users. In
> previous version it was unable to finish input correctly without
> configuration changes (tested in PowerShell, CMD, Cygwin).
> 
> We know credential filling should be finished by empty input, but the
> current implementation does not take into account CR/LF ending, and
> hence instead of the empty string we get '\r', which is interpreted as
> an incorrect string.
> 
> So this commit changes default reading function to a more Windows
> compatible reading function.

This does make it impossible to have a CR at the end of a data value. I think that should be OK (we already disallow LF with no mechanism for quoting, because who the hell puts a LF in their password?).

But we should perhaps update the section in git-credential(1) that describes the rules. I had trouble coming up with a wording that wasn't totally awkward, though:

diff --git a/Documentation/git-credential.txt b/Documentation/git-credential.txt
index 6f0c7ca80f..09e4b58321 100644
--- a/Documentation/git-credential.txt
+++ b/Documentation/git-credential.txt
@@ -112,7 +112,9 @@ specified by a key-value pair, separated by an `=` (equals) sign,
 followed by a newline. The key may contain any bytes except `=`,
 newline, or NUL. The value may contain any bytes except newline or NUL.
 In both cases, all bytes are treated as-is (i.e., there is no quoting,
-and one cannot transmit a value with newline or NUL in it). The list of
+and one cannot transmit a value with newline or NUL in it). Note that
+Git will treat a carriage return before the final newline as part of
+line ending, and not part of the data. The list of
 attributes is terminated by a blank line or end-of-file.
 Git understands the following attributes:
 

This is talking about the git-credential tool itself, but the actual
helper protocol documentation links to this. (As an aside, I notice that
the protocol documentation recently got moved into credential.h along
with the C API bits. Yuck. That probably should be in
gitcredentials(7)).

-Peff