Support remote helpers implementing smart transports

Signed-off-by: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-remote-helpers.txt b/Documentation/git-remote-helpers.txt
index 20a05fe9d890e921779fa32da15edac6bc688687..4685a898f153091d2b747bfb204cf0686c6a8f82 100644 (file)
--- a/Documentation/git-remote-helpers.txt
+++ b/Documentation/git-remote-helpers.txt
@@ -93,6 +93,20 @@ Supported if the helper has the "push" capability.
 +
 Supported if the helper has the "import" capability.
 
+'connect' <service>::
+       Connects to given service. Standard input and standard output
+       of helper are connected to specified service (git prefix is
+       included in service name so e.g. fetching uses 'git-upload-pack'
+       as service) on remote side. Valid replies to this command are
+       empty line (connection established), 'fallback' (no smart
+       transport support, fall back to dumb transports) and just
+       exiting with error message printed (can't connect, don't
+       bother trying to fall back). After line feed terminating the
+       positive (empty) response, the output of service starts. After
+       the connection ends, the remote helper exits.
++
+Supported if the helper has the "connect" capability.
+
 If a fatal error occurs, the program writes the error message to
 stderr and exits. The caller should expect that a suitable error
 message has been printed if the child closes the connection without
@@ -126,6 +140,9 @@ CAPABILITIES
        all, it must cover all refs reported by the list command; if
        it is not used, it is effectively "*:*"
 
+'connect'::
+       This helper supports the 'connect' command.
+
 REF LIST ATTRIBUTES
 -------------------
 
@@ -168,9 +185,15 @@ OPTIONS
        but don't actually change any repository data.  For most
        helpers this only applies to the 'push', if supported.
 
+'option servpath <c-style-quoted-path>'::
+       Set service path (--upload-pack, --receive-pack etc.) for
+       next connect. Remote helper MAY support this option. Remote
+       helper MUST NOT rely on this option being set before
+       connect request occurs.
+
 Documentation
 -------------
-Documentation by Daniel Barkalow.
+Documentation by Daniel Barkalow and Ilari Liusvaara
 
 GIT
 ---

diff --git a/transport-helper.c b/transport-helper.c
index 97eed6cbf6bb7e076bd46f5d59cb5e66ac47ccc5..50b3bac0c45252855505f4ce019a8cec53164fad 100644 (file)
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -18,7 +18,9 @@ struct helper_data
        unsigned fetch : 1,
                import : 1,
                option : 1,
-               push : 1;
+               push : 1,
+               connect : 1,
+               no_disconnect_req : 1;
        /* These go from remote name (as in "list") to private name */
        struct refspec *refspecs;
        int refspec_nr;
@@ -37,12 +39,12 @@ static void sendline(struct helper_data *helper, struct strbuf *buffer)
                die_errno("Full write to remote helper failed");
 }
 
-static int recvline(struct helper_data *helper, struct strbuf *buffer)
+static int recvline_fh(FILE *helper, struct strbuf *buffer)
 {
        strbuf_reset(buffer);
        if (debug)
                fprintf(stderr, "Debug: Remote helper: Waiting...\n");
-       if (strbuf_getline(buffer, helper->out, '\n') == EOF) {
+       if (strbuf_getline(buffer, helper, '\n') == EOF) {
                if (debug)
                        fprintf(stderr, "Debug: Remote helper quit.\n");
                exit(128);
@@ -53,6 +55,11 @@ static int recvline(struct helper_data *helper, struct strbuf *buffer)
        return 0;
 }
 
+static int recvline(struct helper_data *helper, struct strbuf *buffer)
+{
+       return recvline_fh(helper->out, buffer);
+}
+
 static void xchgline(struct helper_data *helper, struct strbuf *buffer)
 {
        sendline(helper, buffer);
@@ -77,6 +84,15 @@ const char *remove_ext_force(const char *url)
        return url;
 }
 
+static void do_take_over(struct transport *transport)
+{
+       struct helper_data *data;
+       data = (struct helper_data *)transport->data;
+       transport_take_over(transport, data->helper);
+       fclose(data->out);
+       free(data);
+}
+
 static struct child_process *get_helper(struct transport *transport)
 {
        struct helper_data *data = transport->data;
@@ -103,12 +119,12 @@ static struct child_process *get_helper(struct transport *transport)
        if (start_command(helper))
                die("Unable to run helper: git %s", helper->argv[0]);
        data->helper = helper;
+       data->no_disconnect_req = 0;
 
        /*
         * Open the output as FILE* so strbuf_getline() can be used.
         * Do this with duped fd because fclose() will close the fd,
         * and stuff like taking over will require the fd to remain.
-        *
         */
        duped = dup(helper->out);
        if (duped < 0)
@@ -146,6 +162,8 @@ static struct child_process *get_helper(struct transport *transport)
                                   refspec_nr + 1,
                                   refspec_alloc);
                        refspecs[refspec_nr++] = strdup(buf.buf + strlen("refspec "));
+               } else if (!strcmp(capname, "connect")) {
+                       data->connect = 1;
                } else if (mandatory) {
                        die("Unknown madatory capability %s. This remote "
                            "helper probably needs newer version of Git.\n",
@@ -175,8 +193,10 @@ static int disconnect_helper(struct transport *transport)
        if (data->helper) {
                if (debug)
                        fprintf(stderr, "Debug: Disconnecting.\n");
-               strbuf_addf(&buf, "\n");
-               sendline(data, &buf);
+               if (!data->no_disconnect_req) {
+                       strbuf_addf(&buf, "\n");
+                       sendline(data, &buf);
+               }
                close(data->helper->in);
                close(data->helper->out);
                fclose(data->out);
@@ -370,12 +390,94 @@ static int fetch_with_import(struct transport *transport,
        return 0;
 }
 
+static int process_connect_service(struct transport *transport,
+                                  const char *name, const char *exec)
+{
+       struct helper_data *data = transport->data;
+       struct strbuf cmdbuf = STRBUF_INIT;
+       struct child_process *helper;
+       int r, duped, ret = 0;
+       FILE *input;
+
+       helper = get_helper(transport);
+
+       /*
+        * Yes, dup the pipe another time, as we need unbuffered version
+        * of input pipe as FILE*. fclose() closes the underlying fd and
+        * stream buffering only can be changed before first I/O operation
+        * on it.
+        */
+       duped = dup(helper->out);
+       if (duped < 0)
+               die_errno("Can't dup helper output fd");
+       input = xfdopen(duped, "r");
+       setvbuf(input, NULL, _IONBF, 0);
+
+       /*
+        * Handle --upload-pack and friends. This is fire and forget...
+        * just warn if it fails.
+        */
+       if (strcmp(name, exec)) {
+               r = set_helper_option(transport, "servpath", exec);
+               if (r > 0)
+                       warning("Setting remote service path not supported by protocol.");
+               else if (r < 0)
+                       warning("Invalid remote service path.");
+       }
+
+       if (data->connect)
+               strbuf_addf(&cmdbuf, "connect %s\n", name);
+       else
+               goto exit;
+
+       sendline(data, &cmdbuf);
+       recvline_fh(input, &cmdbuf);
+       if (!strcmp(cmdbuf.buf, "")) {
+               data->no_disconnect_req = 1;
+               if (debug)
+                       fprintf(stderr, "Debug: Smart transport connection "
+                               "ready.\n");
+               ret = 1;
+       } else if (!strcmp(cmdbuf.buf, "fallback")) {
+               if (debug)
+                       fprintf(stderr, "Debug: Falling back to dumb "
+                               "transport.\n");
+       } else
+               die("Unknown response to connect: %s",
+                       cmdbuf.buf);
+
+exit:
+       fclose(input);
+       return ret;
+}
+
+static int process_connect(struct transport *transport,
+                                    int for_push)
+{
+       struct helper_data *data = transport->data;
+       const char *name;
+       const char *exec;
+
+       name = for_push ? "git-receive-pack" : "git-upload-pack";
+       if (for_push)
+               exec = data->transport_options.receivepack;
+       else
+               exec = data->transport_options.uploadpack;
+
+       return process_connect_service(transport, name, exec);
+}
+
 static int fetch(struct transport *transport,
                 int nr_heads, struct ref **to_fetch)
 {
        struct helper_data *data = transport->data;
        int i, count;
 
+       if (process_connect(transport, 0)) {
+               do_take_over(transport);
+               return transport->fetch(transport, nr_heads, to_fetch);
+       }
+
        count = 0;
        for (i = 0; i < nr_heads; i++)
                if (!(to_fetch[i]->status & REF_STATUS_UPTODATE))
@@ -403,6 +505,11 @@ static int push_refs(struct transport *transport,
        struct child_process *helper;
        struct ref *ref;
 
+       if (process_connect(transport, 1)) {
+               do_take_over(transport);
+               return transport->push_refs(transport, remote_refs, flags);
+       }
+
        if (!remote_refs)
                return 0;
 
@@ -543,6 +650,11 @@ static struct ref *get_refs_list(struct transport *transport, int for_push)
 
        helper = get_helper(transport);
 
+       if (process_connect(transport, for_push)) {
+               do_take_over(transport);
+               return transport->get_refs_list(transport, for_push);
+       }
+
        if (data->push && for_push)
                write_str_in_full(helper->in, "list for-push\n");
        else