Clarify in the Makefile a guideline to decide use of USE_NSEC.

* kb/use-nsec-doc:
  Makefile / racy-git.txt: clarify USE_NSEC prerequisites

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Doc updates.

* sb/pack-protocol-mention-smart-http:
  Documentation/technical/pack-protocol: mention http as possible protocol

for_each_ref() callback functions were taught to name the objects
not with "unsigned char sha1[20]" but with "struct object_id".

* bc/object-id: (56 commits)
  struct ref_lock: convert old_sha1 member to object_id
  warn_if_dangling_symref(): convert local variable "junk" to object_id
  each_ref_fn_adapter(): remove adapter
  rev_list_insert_ref(): remove unneeded arguments
  rev_list_insert_ref_oid(): new function, taking an object_oid
  mark_complete(): remove unneeded arguments
  mark_complete_oid(): new function, taking an object_oid
  clear_marks(): rewrite to take an object_id argument
  mark_complete(): rewrite to take an object_id argument
  send_ref(): convert local variable "peeled" to object_id
  upload-pack: rewrite functions to take object_id arguments
  find_symref(): convert local variable "unused" to object_id
  find_symref(): rewrite to take an object_id argument
  write_one_ref(): rewrite to take an object_id argument
  write_refs_to_temp_dir(): convert local variable sha1 to object_id
  submodule: rewrite to take an object_id argument
  shallow: rewrite functions to take object_id arguments
  handle_one_ref(): rewrite to take an object_id argument
  add_info_ref(): rewrite to take an object_id argument
  handle_one_reflog(): rewrite to take an object_id argument
  ...

Introduce <branch>@{push} short-hand to denote the remote-tracking
branch that tracks the branch at the remote the <branch> would be
pushed to.

* jk/at-push-sha1:
  for-each-ref: accept "%(push)" format
  for-each-ref: use skip_prefix instead of starts_with
  sha1_name: implement @{push} shorthand
  sha1_name: refactor interpret_upstream_mark
  sha1_name: refactor upstream_mark
  remote.c: add branch_get_push
  remote.c: return upstream name from stat_tracking_info
  remote.c: untangle error logic in branch_get_upstream
  remote.c: report specific errors from branch_get_upstream
  remote.c: introduce branch_get_upstream helper
  remote.c: hoist read_config into remote_get_1
  remote.c: provide per-branch pushremote name
  remote.c: hoist branch.*.remote lookup out of remote_get_1
  remote.c: drop "remote" pointer from "struct branch"
  remote.c: refactor setup of branch->merge list
  remote.c: drop default_remote_name variable

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

"git upload-pack" that serves "git fetch" can be told to serve
commits that are not at the tip of any ref, as long as they are
reachable from a ref, with uploadpack.allowReachableSHA1InWant
configuration variable.

* fm/fetch-raw-sha1:
  upload-pack: optionally allow fetching reachable sha1
  upload-pack: prepare to extend allow-tip-sha1-in-want
  config.txt: clarify allowTipSHA1InWant with camelCase

Teach the index to optionally remember already seen untracked files
to speed up "git status" in a working tree with tons of cruft.

* nd/untracked-cache: (24 commits)
  git-status.txt: advertisement for untracked cache
  untracked cache: guard and disable on system changes
  mingw32: add uname()
  t7063: tests for untracked cache
  update-index: test the system before enabling untracked cache
  update-index: manually enable or disable untracked cache
  status: enable untracked cache
  untracked-cache: temporarily disable with $GIT_DISABLE_UNTRACKED_CACHE
  untracked cache: mark index dirty if untracked cache is updated
  untracked cache: print stats with $GIT_TRACE_UNTRACKED_STATS
  untracked cache: avoid racy timestamps
  read-cache.c: split racy stat test to a separate function
  untracked cache: invalidate at index addition or removal
  untracked cache: load from UNTR index extension
  untracked cache: save to an index extension
  ewah: add convenient wrapper ewah_serialize_strbuf()
  untracked cache: don't open non-existent .gitignore
  untracked cache: mark what dirs should be recursed/saved
  untracked cache: record/validate dir mtime and reuse cached output
  untracked cache: make a wrapper around {open,read,close}dir()
  ...

Change typedef each_ref_fn to take a "const struct object_id *oid"
parameter instead of "const unsigned char *sha1".

To aid this transition, implement an adapter that can be used to wrap
old-style functions matching the old typedef, which is now called
"each_ref_sha1_fn"), and make such functions callable via the new
interface. This requires the old function and its cb_data to be
wrapped in a "struct each_ref_fn_sha1_adapter", and that object to be
used as the cb_data for an adapter function, each_ref_fn_adapter().

This is an enormous diff, but most of it consists of simple,
mechanical changes to the sites that call any of the "for_each_ref"
family of functions. Subsequent to this change, the call sites can be
rewritten one by one to use the new interface.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

With uploadpack.allowReachableSHA1InWant configuration option set on the
server side, "git fetch" can make a request with a "want" line that names
an object that has not been advertised (likely to have been obtained out
of band or from a submodule pointer). Only objects reachable from the
branch tips, i.e. the union of advertised branches and branches hidden by
transfer.hideRefs, will be processed. Note that there is an associated
cost of having to walk back the history to check the reachability.

This feature can be used when obtaining the content of a certain commit,
for which the sha1 is known, without the need of cloning the whole
repository, especially if a shallow fetch is used. Useful cases are e.g.
repositories containing large files in the history, fetching only the
needed data for a submodule checkout, when sharing a sha1 without telling
which exact branch it belongs to and in Gerrit, if you think in terms of
commits instead of change numbers. (The Gerrit case has already been
solved through allowTipSHA1InWant as every Gerrit change has a ref.)

Signed-off-by: Fredrik Medley <fredrik.medley@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>