[PATCH 3/3] protocol docs: explain receive-pack push options

[Jonathan Tan <jonathantanmy@google.com>]

Support for push options in the receive-pack protocol (and all Git
components that speak it) have been added over a few commits, but not
fully documented (especially its interaction with signed pushes). Update
the protocol documentation to include the relevant details.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
---
 Documentation/technical/pack-protocol.txt | 32 +++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/Documentation/technical/pack-protocol.txt b/Documentation/technical/pack-protocol.txt
index 5b0ba3ef2..cf7cb48c3 100644
--- a/Documentation/technical/pack-protocol.txt
+++ b/Documentation/technical/pack-protocol.txt
@@ -473,13 +473,10 @@ that it wants to update, it sends a line listing the obj-id currently on
 the server, the obj-id the client would like to update it to and the name
 of the reference.
 
-This list is followed by a flush-pkt. Then the push options are transmitted
-one per packet followed by another flush-pkt. After that the packfile that
-should contain all the objects that the server will need to complete the new
-references will be sent.
+This list is followed by a flush-pkt.
 
 ----
-  update-request    =  *shallow ( command-list | push-cert ) [packfile]
+  update-request    =  *shallow ( command-list | push-cert )
 
   shallow           =  PKT-LINE("shallow" SP obj-id)
 
@@ -500,12 +497,35 @@ references will be sent.
 		      PKT-LINE("pusher" SP ident LF)
 		      PKT-LINE("pushee" SP url LF)
 		      PKT-LINE("nonce" SP nonce LF)
+		      *PKT-LINE("push-option" SP push-option LF)
 		      PKT-LINE(LF)
 		      *PKT-LINE(command LF)
 		      *PKT-LINE(gpg-signature-lines LF)
 		      PKT-LINE("push-cert-end" LF)
 
-  packfile          = "PACK" 28*(OCTET)
+  push-option       =  1*CHAR
+----
+
+If the server has advertised the 'push-options' capability and the client has
+specified 'push-options' as part of the capability list above, the client then
+sends its push options followed by a flush-pkt.
+
+----
+  push-options      =  *PKT-LINE(push-option) flush-pkt
+----
+
+For backwards compatibility with older Git servers, if the client sends a push
+cert and push options, it SHOULD send its push options both embedded within the
+push cert and after the push cert. (Note that the push options within the cert
+are prefixed, but the push options after the cert are not.) Both these lists
+SHOULD be consistent.
+
+After that the packfile that
+should contain all the objects that the server will need to complete the new
+references will be sent.
+
+----
+  packfile          =  "PACK" 28*(OCTET)
 ----
 
 If the receiving end does not support delete-refs, the sending end MUST
-- 
2.13.0.rc1.294.g07d810a77f-goog