Merge branch 'dt/smart-http-detect-server-going-away'

When the http server gives an incomplete response to a smart-http
rpc call, it could lead to client waiting for a full response that
will never come.  Teach the client side to notice this condition
and abort the transfer.

An improvement counterproposal has failed.
cf. <20161114194049.mktpsvgdhex2f4zv@sigill.intra.peff.net>

* dt/smart-http-detect-server-going-away:
  upload-pack: optionally allow fetching any sha1
  remote-curl: don't hang when a server dies before any output

Documentation/config.txt

@@ -3030,6 +3030,11 @@ uploadpack.allowReachableSHA1InWant::
 	section of the linkgit:gitnamespaces[7] man page; it's best to
 	keep private data in a separate repository.
 
+uploadpack.allowAnySHA1InWant::
+	Allow `upload-pack` to accept a fetch request that asks for any
+	object at all.
+	Defaults to `false`.
+
 uploadpack.keepAlive::
 	When `upload-pack` has started `pack-objects`, there may be a
 	quiet period while `pack-objects` prepares the pack. Normally

Documentation/git-fetch-pack.txt

@@ -119,9 +119,9 @@ be in a separate packet, and the list must end with a flush packet.
 	$GIT_DIR (e.g. "HEAD", "refs/heads/master").  When
 	unspecified, update from all heads the remote side has.
 +
-If the remote has enabled the options `uploadpack.allowTipSHA1InWant` or
+If the remote has enabled the options `uploadpack.allowTipSHA1InWant`,
-`uploadpack.allowReachableSHA1InWant`, they may alternatively be 40-hex
+`uploadpack.allowReachableSHA1InWant`, or `uploadpack.allowAnySHA1InWant`,
-sha1s present on the remote.
+they may alternatively be 40-hex sha1s present on the remote.
 
 SEE ALSO
 --------

remote-curl.c

@@ -404,6 +404,7 @@ struct rpc_state {
 	size_t pos;
 	int in;
 	int out;
+	int any_written;
 	struct strbuf result;
 	unsigned gzip_request : 1;
 	unsigned initial_buffer : 1;
@@ -460,6 +461,8 @@ static size_t rpc_in(char *ptr, size_t eltsize,
 {
 	size_t size = eltsize * nmemb;
 	struct rpc_state *rpc = buffer_;
+	if (size)
+		rpc->any_written = 1;
 	write_or_die(rpc->in, ptr, size);
 	return size;
 }
@@ -663,6 +666,8 @@ retry:
 	curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, rpc_in);
 	curl_easy_setopt(slot->curl, CURLOPT_FILE, rpc);
 
+
+	rpc->any_written = 0;
 	err = run_slot(slot, NULL);
 	if (err == HTTP_REAUTH && !large_request) {
 		credential_fill(&http_auth);
@@ -671,6 +676,9 @@ retry:
 	if (err != HTTP_OK)
 		err = -1;
 
+	if (!rpc->any_written)
+		err = -1;
+
 	curl_slist_free_all(headers);
 	free(gzip_body);
 	return err;

t/t5551-http-fetch-smart.sh

@@ -280,6 +280,58 @@ test_expect_success 'large fetch-pack requests can be split across POSTs' '
 	test_line_count = 2 posts
 '
 
+test_expect_success 'test allowreachablesha1inwant' '
+	test_when_finished "rm -rf test_reachable.git" &&
+	server="$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
+	master_sha=$(git -C "$server" rev-parse refs/heads/master) &&
+	git -C "$server" config uploadpack.allowreachablesha1inwant 1 &&
+
+	git init --bare test_reachable.git &&
+	git -C test_reachable.git remote add origin "$HTTPD_URL/smart/repo.git" &&
+	git -C test_reachable.git fetch origin "$master_sha"
+'
+
+test_expect_success 'test allowreachablesha1inwant with unreachable' '
+	test_when_finished "rm -rf test_reachable.git; git reset --hard $(git rev-parse HEAD)" &&
+
+	#create unreachable sha
+	echo content >file2 &&
+	git add file2 &&
+	git commit -m two &&
+	git push public HEAD:refs/heads/doomed &&
+	git push public :refs/heads/doomed &&
+
+	server="$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
+	master_sha=$(git -C "$server" rev-parse refs/heads/master) &&
+	git -C "$server" config uploadpack.allowreachablesha1inwant 1 &&
+
+	git init --bare test_reachable.git &&
+	git -C test_reachable.git remote add origin "$HTTPD_URL/smart/repo.git" &&
+	test_must_fail git -C test_reachable.git fetch origin "$(git rev-parse HEAD)"
+'
+
+test_expect_success 'test allowanysha1inwant with unreachable' '
+	test_when_finished "rm -rf test_reachable.git; git reset --hard $(git rev-parse HEAD)" &&
+
+	#create unreachable sha
+	echo content >file2 &&
+	git add file2 &&
+	git commit -m two &&
+	git push public HEAD:refs/heads/doomed &&
+	git push public :refs/heads/doomed &&
+
+	server="$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
+	master_sha=$(git -C "$server" rev-parse refs/heads/master) &&
+	git -C "$server" config uploadpack.allowreachablesha1inwant 1 &&
+
+	git init --bare test_reachable.git &&
+	git -C test_reachable.git remote add origin "$HTTPD_URL/smart/repo.git" &&
+	test_must_fail git -C test_reachable.git fetch origin "$(git rev-parse HEAD)" &&
+
+	git -C "$server" config uploadpack.allowanysha1inwant 1 &&
+	git -C test_reachable.git fetch origin "$(git rev-parse HEAD)"
+'
+
 test_expect_success EXPENSIVE 'http can handle enormous ref negotiation' '
 	(
 		cd "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&

upload-pack.c

@@ -46,6 +46,8 @@ static int no_progress, daemon_mode;
 #define ALLOW_TIP_SHA1	01
 /* Allow request of a sha1 if it is reachable from a ref (possibly hidden ref). */
 #define ALLOW_REACHABLE_SHA1	02
+/* Allow request of any sha1. Implies ALLOW_TIP_SHA1 and ALLOW_REACHABLE_SHA1. */
+#define ALLOW_ANY_SHA1	07
 static unsigned int allow_unadvertised_object_request;
 static int shallow_nr;
 static struct object_array have_obj;
@@ -825,7 +827,8 @@ static void receive_needs(void)
 			    sha1_to_hex(sha1_buf));
 		if (!(o->flags & WANTED)) {
 			o->flags |= WANTED;
-			if (!is_our_ref(o))
+			if (!((allow_unadvertised_object_request & ALLOW_ANY_SHA1) == ALLOW_ANY_SHA1
+			      || is_our_ref(o)))
 				has_non_tip = 1;
 			add_object_array(o, NULL, &want_obj);
 		}
@@ -1008,6 +1011,11 @@ static int upload_pack_config(const char *var, const char *value, void *unused)
 			allow_unadvertised_object_request |= ALLOW_REACHABLE_SHA1;
 		else
 			allow_unadvertised_object_request &= ~ALLOW_REACHABLE_SHA1;
+	} else if (!strcmp("uploadpack.allowanysha1inwant", var)) {
+		if (git_config_bool(var, value))
+			allow_unadvertised_object_request |= ALLOW_ANY_SHA1;
+		else
+			allow_unadvertised_object_request &= ~ALLOW_ANY_SHA1;
 	} else if (!strcmp("uploadpack.keepalive", var)) {
 		keepalive = git_config_int(var, value);
 		if (!keepalive)