From: Jeff King <peff@peff.net>
Date: Wed, 27 Sep 2017 06:01:07 +0000 (-0400)
Subject: avoid looking at errno for short read_in_full() returns
X-Git-Tag: v2.15.0-rc0~19^2~3
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/90dca6710e6e5aad5d78d0cd006c3adadb65524d?hp=90dca6710e6e5aad5d78d0cd006c3adadb65524d

avoid looking at errno for short read_in_full() returns

When a caller tries to read a particular set of bytes via
read_in_full(), there are three possible outcomes:

1. An error, in which case -1 is returned and errno is
set.

2. A short read, in which fewer bytes are returned and
errno is unspecified (we never saw a read error, so we
may have some random value from whatever syscall failed
last).

3. The full read completed successfully.

Many callers handle cases 1 and 2 together by just checking
the result against the requested size. If their combined
error path looks at errno (e.g., by calling die_errno), they
may report a nonsense value.

Let's fix these sites by having them distinguish between the
two error cases. That avoids the random errno confusion, and
lets us give more detailed error messages.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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