[0/3] Auditing use of xwrite()

Message

Junio C Hamano March 2, 2024, 7:03 p.m. UTC

The xwrite() helper relieves us from having to worry about an
interrupted write(2) system call that returns an EINTR error without
writing any, in which case we need to retry the system call.  It,
just as the underlying write(2) system call, however can return
without writing the bytes requested to be written fully.  A code
that uses xwrite() and wants to write the full contents of the
buffer needs to take care of such a "short write" situation,
typically by calling xwrite() in a loop.

We recently audited all the calls to xwrite(), and have found two
classes of potential "problems".  This miniseries is about fixing them.

 * There are such loops around xwrite() as described above, which
   were written long time ago.  The write_in_full() helper does
   implement such a loop in a reusable way, and we should just call
   it instead.

 * There are xwrite() calls whose return value is ignored.  We would
   not be able to detect (and complete) "short write" in such callers,
   of course, but more importantly, we would not notice I/O failures.
   Again, use write_in_full() to deal with short writes, and check
   the return value from it to detect errors.

Junio C Hamano (3):
  unpack: rewrite hand-rolled loop of xwrite()s with write_in_full()
  sideband: avoid short write(2)
  repack: check error writing to pack-objects subprocess

 builtin/index-pack.c     | 17 +++--------------
 builtin/repack.c         |  5 +++--
 builtin/unpack-objects.c |  8 +-------
 sideband.c               |  4 ++--
 4 files changed, 9 insertions(+), 25 deletions(-)