|
|
|
|
Git-send-pack internals
|
|
|
|
|
=======================
|
|
|
|
|
|
|
|
|
|
Overall operation
|
|
|
|
|
-----------------
|
|
|
|
|
|
|
|
|
|
. Connects to the remote side and invokes git-receive-pack.
|
|
|
|
|
|
|
|
|
|
. Learns what refs the remote has and what commit they point at.
|
|
|
|
|
Matches them to the refspecs we are pushing.
|
|
|
|
|
|
|
|
|
|
. Checks if there are non-fast-forwards. Unlike fetch-pack,
|
|
|
|
|
the repository send-pack runs in is supposed to be a superset
|
|
|
|
|
of the recipient in fast-forward cases, so there is no need
|
|
|
|
|
for want/have exchanges, and fast-forward check can be done
|
|
|
|
|
locally. Tell the result to the other end.
|
|
|
|
|
|
|
|
|
|
. Calls pack_objects() which generates a packfile and sends it
|
|
|
|
|
over to the other end.
|
|
|
|
|
|
|
|
|
|
. If the remote side is new enough (v1.1.0 or later), wait for
|
|
|
|
|
the unpack and hook status from the other end.
|
|
|
|
|
|
|
|
|
|
. Exit with appropriate error codes.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Pack_objects pipeline
|
|
|
|
|
---------------------
|
|
|
|
|
|
|
|
|
|
This function gets one file descriptor (`fd`) which is either a
|
|
|
|
|
socket (over the network) or a pipe (local). What's written to
|
|
|
|
|
this fd goes to git-receive-pack to be unpacked.
|
|
|
|
|
|
|
|
|
|
send-pack ---> fd ---> receive-pack
|
|
|
|
|
|
|
|
|
|
The function pack_objects creates a pipe and then forks. The
|
|
|
|
|
forked child execs pack-objects with --revs to receive revision
|
|
|
|
|
parameters from its standard input. This process will write the
|
|
|
|
|
packfile to the other end.
|
|
|
|
|
|
|
|
|
|
send-pack
|
|
|
|
|
|
|
|
|
|
|
pack_objects() ---> fd ---> receive-pack
|
|
|
|
|
| ^ (pipe)
|
|
|
|
|
v |
|
|
|
|
|
(child)
|
|
|
|
|
|
|
|
|
|
The child dup2's to arrange its standard output to go back to
|
|
|
|
|
the other end, and read its standard input to come from the
|
|
|
|
|
pipe. After that it exec's pack-objects. On the other hand,
|
|
|
|
|
the parent process, before starting to feed the child pipeline,
|
|
|
|
|
closes the reading side of the pipe and fd to receive-pack.
|
|
|
|
|
|
|
|
|
|
send-pack
|
|
|
|
|
|
|
|
|
|
|
pack_objects(parent)
|
|
|
|
|
|
|
|
|
|
|
v [0]
|
|
|
|
|
pack-objects [0] ---> receive-pack
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
[jc: the pipeline was much more complex and needed documentation before
|
|
|
|
|
I understood an earlier bug, but now it is trivial and straightforward.]
|
