Implement strbuf_addbuf() as a normal function in order to avoid calling
strbuf_grow() twice, with the second callinside strbud_add() being a
no-op.  This is slightly faster and also reduces the text size a bit.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Use strbuf_addbuf() where possible; it's shorter and more efficient.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Signed-off-by: Junio C Hamano <gitster@pobox.com>

* maint-2.5:
  Git 2.5.5
  Git 2.4.11
  list-objects: pass full pathname to callbacks
  list-objects: drop name_path entirely
  list-objects: convert name_path to a strbuf
  show_object_with_name: simplify by using path_name()
  http-push: stop using name_path
  tree-diff: catch integer overflow in combine_diff_path allocation
  add helpers for detecting size_t overflow

Signed-off-by: Junio C Hamano <gitster@pobox.com>

* maint-2.4:
  Git 2.4.11
  list-objects: pass full pathname to callbacks
  list-objects: drop name_path entirely
  list-objects: convert name_path to a strbuf
  show_object_with_name: simplify by using path_name()
  http-push: stop using name_path
  tree-diff: catch integer overflow in combine_diff_path allocation
  add helpers for detecting size_t overflow

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Bugfix patches were backported from the 'master' front to plug heap
corruption holes, to catch integer overflow in the computation of
pathname lengths, and to get rid of the name_path API.  Both of
these would have resulted in writing over an under-allocated buffer
when formulating pathnames while tree traversal.

* jk/path-name-safety-2.4:
  list-objects: pass full pathname to callbacks
  list-objects: drop name_path entirely
  list-objects: convert name_path to a strbuf
  show_object_with_name: simplify by using path_name()
  http-push: stop using name_path
  tree-diff: catch integer overflow in combine_diff_path allocation
  add helpers for detecting size_t overflow

When we find a blob at "a/b/c", we currently pass this to
our show_object_fn callbacks as two components: "a/b/" and
"c". Callbacks which want the full value then call
path_name(), which concatenates the two. But this is an
inefficient interface; the path is a strbuf, and we could
simply append "c" to it temporarily, then roll back the
length, without creating a new copy.

So we could improve this by teaching the callsites of
path_name() this trick (and there are only 3). But we can
also notice that no callback actually cares about the
broken-down representation, and simply pass each callback
the full path "a/b/c" as a string. The callback code becomes
even simpler, then, as we do not have to worry about freeing
an allocated buffer, nor rolling back our modification to
the strbuf.

This is theoretically less efficient, as some callbacks
would not bother to format the final path component. But in
practice this is not measurable. Since we use the same
strbuf over and over, our work to grow it is amortized, and
we really only pay to memcpy a few bytes.

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

In the previous commit, we left name_path as a thin wrapper
around a strbuf. This patch drops it entirely. As a result,
every show_object_fn callback needs to be adjusted. However,
none of their code needs to be changed at all, because the
only use was to pass it to path_name(), which now handles
the bare strbuf.

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