[WIP/RFC] Allow push and fetch urls to be different

[Michael J Gruber <git@drmicha.warpmail.net>]

This introduces a config setting remote.$remotename.pushurl which is
used for pushes only. If absent remote.$remotename.url is used for
pushes and fetches as before.
This is useful, for example, in order to to do passwordless fetches
(remote update) over git: but pushes over ssh.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
---
This is a working prototype, but I'd like to rfc about the approach before
coding further. Do I need to do anything in http-push.c? I don't think so.

Things that would go in a full series:
* documentation (man pages, maybe manual)
* tests
* teach builtin-remote about pushurl

 builtin-push.c |   17 +++++++++++++----
 remote.c       |   14 ++++++++++++++
 remote.h       |    4 ++++
 3 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/builtin-push.c b/builtin-push.c
index c869974..7be1239 100644
--- a/builtin-push.c
+++ b/builtin-push.c
@@ -117,6 +117,8 @@ static int do_push(const char *repo, int flags)
 {
 	int i, errs;
 	struct remote *remote = remote_get(repo);
+	const char **url;
+	int url_nr;
 
 	if (!remote) {
 		if (repo)
@@ -152,9 +154,16 @@ static int do_push(const char *repo, int flags)
 			setup_default_push_refspecs();
 	}
 	errs = 0;
-	for (i = 0; i < remote->url_nr; i++) {
+	if (remote->pushurl_nr) {
+		url = remote->pushurl;
+		url_nr = remote->pushurl_nr;
+	} else {
+		url = remote->url;
+		url_nr = remote->url_nr;
+	}
+	for (i = 0; i < url_nr; i++) {
 		struct transport *transport =
-			transport_get(remote, remote->url[i]);
+			transport_get(remote, url[i]);
 		int err;
 		if (receivepack)
 			transport_set_option(transport,
@@ -163,14 +172,14 @@ static int do_push(const char *repo, int flags)
 			transport_set_option(transport, TRANS_OPT_THIN, "yes");
 
 		if (flags & TRANSPORT_PUSH_VERBOSE)
-			fprintf(stderr, "Pushing to %s\n", remote->url[i]);
+			fprintf(stderr, "Pushing to %s\n", url[i]);
 		err = transport_push(transport, refspec_nr, refspec, flags);
 		err |= transport_disconnect(transport);
 
 		if (!err)
 			continue;
 
-		error("failed to push some refs to '%s'", remote->url[i]);
+		error("failed to push some refs to '%s'", url[i]);
 		errs++;
 	}
 	return !!errs;
diff --git a/remote.c b/remote.c
index 08a5964..9a0397e 100644
--- a/remote.c
+++ b/remote.c
@@ -106,6 +106,12 @@ static void add_url_alias(struct remote *remote, const char *url)
 	add_url(remote, alias_url(url));
 }
 
+static void add_pushurl(struct remote *remote, const char *pushurl)
+{
+	ALLOC_GROW(remote->pushurl, remote->pushurl_nr + 1, remote->pushurl_alloc);
+	remote->pushurl[remote->pushurl_nr++] = pushurl;
+}
+
 static struct remote *make_remote(const char *name, int len)
 {
 	struct remote *ret;
@@ -379,6 +385,11 @@ static int handle_config(const char *key, const char *value, void *cb)
 		if (git_config_string(&v, key, value))
 			return -1;
 		add_url(remote, v);
+	} else if (!strcmp(subkey, ".pushurl")) {
+		const char *v;
+		if (git_config_string(&v, key, value))
+			return -1;
+		add_pushurl(remote, v);
 	} else if (!strcmp(subkey, ".push")) {
 		const char *v;
 		if (git_config_string(&v, key, value))
@@ -424,6 +435,9 @@ static void alias_all_urls(void)
 		for (j = 0; j < remotes[i]->url_nr; j++) {
 			remotes[i]->url[j] = alias_url(remotes[i]->url[j]);
 		}
+		for (j = 0; j < remotes[i]->pushurl_nr; j++) {
+			remotes[i]->pushurl[j] = alias_url(remotes[i]->pushurl[j]);
+		}
 	}
 }
 
diff --git a/remote.h b/remote.h
index 257a555..5db8420 100644
--- a/remote.h
+++ b/remote.h
@@ -15,6 +15,10 @@ struct remote {
 	int url_nr;
 	int url_alloc;
 
+	const char **pushurl;
+	int pushurl_nr;
+	int pushurl_alloc;
+
 	const char **push_refspec;
 	struct refspec *push;
 	int push_refspec_nr;
-- 
1.6.3.2.277.gd10543