[PATCH 0/7] config.c may fail to notice some write() failures

[Jeff King <peff@peff.net>]

On Wed, Sep 13, 2017 at 01:59:17PM +0200, demerphq wrote:

> After being away for a while I saw the following message in one of my git repos:
> 
> $ git status
> On branch yves/xxx
> Your branch is based on 'origin/yves/xxx', but the upstream is gone.
>   (use "git branch --unset-upstream" to fixup)
> 
> nothing to commit, working tree clean
> $ git branch --unset-upstream
> fatal: could not unset 'branch.yves/simple_projection.merge'
> 
> At this point my .git/config file was empty, and all of my config was lost.

Here's the fix, along with some related cleanups. The actual bugfix is
in the first patch, which I think should go to "maint". The rest are not
as important, so could go to master (but would also be fine for maint,
as there should be no user-visible changes).

  [1/7]: config: avoid "write_in_full(fd, buf, len) < len" pattern
  [2/7]: get-tar-commit-id: check write_in_full() return against 0
  [3/7]: avoid "write_in_full(fd, buf, len) != len" pattern
  [4/7]: convert less-trivial versions of "write_in_full() != len"
  [5/7]: pkt-line: check write_in_full() errors against "< 0"
  [6/7]: notes-merge: use ssize_t for write_in_full() return value
  [7/7]: config: flip return value of store_write_*()

 builtin/get-tar-commit-id.c |  3 +--
 builtin/receive-pack.c      |  2 +-
 builtin/rerere.c            |  2 +-
 builtin/unpack-file.c       |  2 +-
 config.c                    | 38 +++++++++++++++++++-------------------
 diff.c                      |  2 +-
 entry.c                     |  5 +++--
 fast-import.c               |  2 +-
 http-backend.c              |  4 ++--
 ll-merge.c                  |  2 +-
 notes-merge.c               |  2 +-
 pkt-line.c                  | 29 ++++++++++++++---------------
 read-cache.c                |  6 +++---
 refs.c                      |  2 +-
 refs/files-backend.c        | 10 +++++-----
 rerere.c                    |  2 +-
 shallow.c                   |  6 +++---
 streaming.c                 |  2 +-
 t/helper/test-delta.c       |  2 +-
 transport-helper.c          |  5 ++---
 wrapper.c                   |  2 +-
 21 files changed, 64 insertions(+), 66 deletions(-)

-Peff