The client side codepaths in "git push" have been cleaned up
and the user can request to perform an optional "signed push",
i.e. sign only when the other end accepts signed push.

* db/push-sign-if-asked:
  push: add a config option push.gpgSign for default signed pushes
  push: support signing pushes iff the server supports it
  builtin/send-pack.c: use parse_options API
  config.c: rename git_config_maybe_bool_text and export it as git_parse_maybe_bool
  transport: remove git_transport_options.push_cert
  gitremote-helpers.txt: document pushcert option
  Documentation/git-send-pack.txt: document --signed
  Documentation/git-send-pack.txt: wrap long synopsis line
  Documentation/git-push.txt: document when --signed may fail

Add a new flag --sign=true (or --sign=false), which means the same
thing as the original --signed (or --no-signed).  Give it a third
value --sign=if-asked to tell push and send-pack to send a push
certificate if and only if the server advertised a push cert nonce.

If not, warn the user that their push may not be as secure as they
thought.

Signed-off-by: Dave Borowitz <dborowitz@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Identify parts of the code that knows that we use SHA-1 hash to
name our objects too much, and use (1) symbolic constants instead
of hardcoded 20 as byte count and/or (2) use struct object_id
instead of unsigned char [20] for object names.

* bc/object-id:
  apply: convert threeway_stage to object_id
  patch-id: convert to use struct object_id
  commit: convert parts to struct object_id
  diff: convert struct combine_diff_path to object_id
  bulk-checkin.c: convert to use struct object_id
  zip: use GIT_SHA1_HEXSZ for trailers
  archive.c: convert to use struct object_id
  bisect.c: convert leaf functions to use struct object_id
  define utility functions for object IDs
  define a structure for object IDs

The "git push --signed" protocol extension did not limit what the
"nonce" that is a server-chosen string can contain or how long it
can be, which was unnecessarily lax.  Limit both the length and the
alphabet to a reasonably small space that can still have enough
entropy.

* jc/push-cert:
  push --signed: tighten what the receiving end can ask to sign

* sb/atomic-push:
  send-pack: unify error messages for unsupported capabilities

Instead of blindly trusting the receiving side to give us a sensible
nonce to sign, limit the length (max 256 bytes) and the alphabet
(alnum and a few selected punctuations, enough to encode in base64)
that can be used in nonce.

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

If --signed is not supported, the error message names the remote
"receiving end". If --atomic is not supported, the error message
names the remote "server". Unify the naming to "receiving end"
as we're in the context of "push".

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Convert struct commit_graft and necessary local parts of commit.c.
Also, convert several constants based on the hex length of an SHA-1 to
use GIT_SHA1_HEXSZ, and move several magic constants into variables for
readability.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

"git push" has been taught a "--atomic" option that makes push to
update more than one ref an "all-or-none" affair.

* sb/atomic-push:
  Document receive.advertiseatomic
  t5543-atomic-push.sh: add basic tests for atomic pushes
  push.c: add an --atomic argument
  send-pack.c: add --atomic command line argument
  send-pack: rename ref_update_to_be_sent to check_to_send_update
  receive-pack.c: negotiate atomic push support
  receive-pack.c: add execute_commands_atomic function
  receive-pack.c: move transaction handling in a central place
  receive-pack.c: move iterating over all commands outside execute_commands
  receive-pack.c: die instead of error in case of possible future bug
  receive-pack.c: shorten the execute_commands loop over all commands

This adds support to send-pack to negotiate and use atomic pushes
iff the server supports it. Atomic pushes are activated by a new command
line flag --atomic.

In order to do this we also need to change the semantics for send_pack()
slightly. The existing send_pack() function actually doesn't send all the
refs back to the server when multiple refs are involved, for example
when using --all. Several of the failure modes for pushes can already be
detected locally in the send_pack client based on the information from the
initial server side list of all the refs as generated by receive-pack.
Any such refs that we thus know would fail to push are thus pruned from
the list of refs we send to the server to update.

For atomic pushes, we have to deal thus with both failures that are detected
locally as well as failures that are reported back from the server. In order
to do so we treat all local failures as push failures too.

We introduce a new status code REF_STATUS_ATOMIC_PUSH_FAILED so we can
flag all refs that we would normally have tried to push to the server
but we did not due to local failures. This is to improve the error message
back to the end user to flag that "these refs failed to update since the
atomic push operation failed."

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