[PATCH v2 0/3] support remote archive from stateless transport

From: Jiang Xin <zhiyou.jx@alibaba-inc.com>

Enable stateless-rpc connection in "connect_helper()", and add support for remote archive from a stateless transport.

range-diff v1...v2:

1:  4457ca910b ! 1:  6fabd4dcab transport-helper: no connection restriction in connect_helper
    @@ Metadata
      ## Commit message ##
         transport-helper: no connection restriction in connect_helper
     
    -    For protocol-v2, "stateless-connection" can be used to establish a
    -    stateless connection between the client and the server, but trying to
    -    establish http connection by calling "transport->vtable->connect" will
    -    fail. This restriction was first introduced in commit b236752a87
    -    (Support remote archive from all smart transports, 2009-12-09) by
    -    adding a limitation in the "connect_helper()" function.
    +    When commit b236752a (Support remote archive from all smart transports,
    +    2009-12-09) added "remote archive" support for "smart transports", it
    +    was for transport that supports the ".connect" method. The
    +    "connect_helper()" function protected itself from getting called for a
    +    transport without the method before calling process_connect_service(),
    +    which did not work with such a transport.
     
    -    Remove the restriction in the "connect_helper()" function and use the
    -    logic in the "process_connect_service()" function to check the protocol
    -    version and service name. By this way, we can make a connection and do
    -    something useful. E.g., in a later commit, implements remote archive
    -    for a repository over HTTP protocol.
    +    Later, commit edc9caf7 (transport-helper: introduce stateless-connect,
    +    2018-03-15) added a way for a transport without the ".connect" method
    +    to establish a "stateless" connection in protocol-v2, which
    +    process_connect_service() was taught to handle the "stateless"
    +    connection, making the old safety valve in its caller that insisted
    +    that ".connect" method must be defined too strict, and forgot to loosen
    +    it.
     
    +    Remove the restriction in the "connect_helper()" function and give the
    +    function "process_connect_service()" the opportunity to establish a
    +    connection using ".connect" or ".stateless_connect" for protocol v2. So
    +    we can connect with a stateless-rpc and do something useful. E.g., in a
    +    later commit, implements remote archive for a repository over HTTP
    +    protocol.
    +
    +    Helped-by: Junio C Hamano <gitster@pobox.com>
         Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
     
      ## transport-helper.c ##
-:  ---------- > 2:  1d687abc7e transport-helper: run do_take_over in connect_helper
2:  d4242d1f27 ! 3:  051d66f48e archive: support remote archive from stateless transport
    @@ Commit message
     
          1. Add support for "git-upload-archive" service in "http-backend".
     
    -     2. Unable to access the URL ".../info/refs?service=git-upload-archive"
    -        to detect the protocol version, use the "git-upload-pack" service
    -        instead.
    +     2. Use the URL ".../info/refs?service=git-upload-pack" to detect the
    +        protocol version, instead of use the "git-upload-archive" service.
     
    -     3. "git-archive" does not resolve the protocol version and capabilities
    -        when connecting to remote-helper, so the remote-helper should not
    -        send them.
    -
    -     4. "git-archive" may not be able to disconnect the stateless
    -        connection. Run "do_take_over()" to take_over the transfer for
    -        a graceful disconnect function.
    +     3. "git-archive" does not expect to see protocol version and
    +        capabilities when connecting to remote-helper, so do not send them
    +        in "remote-curl.c" for the "git-upload-archive" service.
     
         Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
     
    @@ transport-helper.c: static int process_connect_service(struct transport *transpo
      		strbuf_addf(&cmdbuf, "stateless-connect %s\n", name);
      		ret = run_connect(transport, &cmdbuf);
      		if (ret)
    -@@ transport-helper.c: static int connect_helper(struct transport *transport, const char *name,
    - 
    - 	fd[0] = data->helper->out;
    - 	fd[1] = data->helper->in;
    -+
    -+	do_take_over(transport);
    - 	return 0;
    - }
    - 

Jiang Xin (3):
  transport-helper: no connection restriction in connect_helper
  transport-helper: run do_take_over in connect_helper
  archive: support remote archive from stateless transport

 http-backend.c         | 15 +++++++++++++--
 remote-curl.c          | 14 +++++++++++---
 t/t5003-archive-zip.sh | 30 ++++++++++++++++++++++++++++++
 transport-helper.c     |  7 ++++---
 4 files changed, 58 insertions(+), 8 deletions(-)