Merge branch 'bc/smart-http-atomic-push'

The atomic push over smart HTTP transport did not work, which has
been corrected.

* bc/smart-http-atomic-push:
  remote-curl: pass on atomic capability to remote side

Documentation/gitremote-helpers.txt

@@ -509,6 +509,11 @@ set by Git if the remote helper has the 'option' capability.
 	Indicate that only the objects wanted need to be fetched, not
 	their dependents.
 
+'option atomic' {'true'|'false'}::
+	When pushing, request the remote server to update refs in a single atomic
+	transaction.  If successful, all refs will be updated, or none will.  If the
+	remote side does not support this capability, the push will fail.
+
 SEE ALSO
 --------
 linkgit:git-remote[1]

remote-curl.c

@@ -40,7 +40,8 @@ struct options {
 		push_cert : 2,
 		deepen_relative : 1,
 		from_promisor : 1,
-		no_dependents : 1;
+		no_dependents : 1,
+		atomic : 1;
 };
 static struct options options;
 static struct string_list cas_options = STRING_LIST_INIT_DUP;
@@ -148,6 +149,14 @@ static int set_option(const char *name, const char *value)
 		else
 			return -1;
 		return 0;
+	} else if (!strcmp(name, "atomic")) {
+		if (!strcmp(value, "true"))
+			options.atomic = 1;
+		else if (!strcmp(value, "false"))
+			options.atomic = 0;
+		else
+			return -1;
+		return 0;
 	} else if (!strcmp(name, "push-option")) {
 		if (*value != '"')
 			string_list_append(&options.push_options, value);
@@ -1196,6 +1205,8 @@ static int push_git(struct discovery *heads, int nr_spec, const char **specs)
 		argv_array_push(&args, "--signed=yes");
 	else if (options.push_cert == SEND_PACK_PUSH_CERT_IF_ASKED)
 		argv_array_push(&args, "--signed=if-asked");
+	if (options.atomic)
+		argv_array_push(&args, "--atomic");
 	if (options.verbosity == 0)
 		argv_array_push(&args, "--quiet");
 	else if (options.verbosity > 1)

t/t5541-http-push-smart.sh

@@ -184,11 +184,12 @@ test_expect_success 'push --atomic also prevents branch creation, reports collat
 	test_config -C "$d" http.receivepack true &&
 	up="$HTTPD_URL"/smart/atomic-branches.git &&
 
-	# Tell "$up" about two branches for now
+	# Tell "$up" about three branches for now
 	test_commit atomic1 &&
 	test_commit atomic2 &&
 	git branch collateral &&
-	git push "$up" master collateral &&
+	git branch other &&
+	git push "$up" master collateral other &&
 
 	# collateral is a valid push, but should be failed by atomic push
 	git checkout collateral &&
@@ -226,6 +227,41 @@ test_expect_success 'push --atomic also prevents branch creation, reports collat
 	grep "^ ! .*rejected.* collateral -> collateral .*atomic push failed" output
 '
 
+test_expect_success 'push --atomic fails on server-side errors' '
+	# Use previously set up repository
+	d=$HTTPD_DOCUMENT_ROOT_PATH/atomic-branches.git &&
+	test_config -C "$d" http.receivepack true &&
+	up="$HTTPD_URL"/smart/atomic-branches.git &&
+
+	# break ref updates for other on the remote site
+	mkdir "$d/refs/heads/other.lock" &&
+
+	# add the new commit to other
+	git branch -f other collateral &&
+
+	# --atomic should cause entire push to be rejected
+	test_must_fail git push --atomic "$up" atomic other 2>output  &&
+
+	# the new branch should not have been created upstream
+	test_must_fail git -C "$d" show-ref --verify refs/heads/atomic &&
+
+	# upstream should still reflect atomic2, the last thing we pushed
+	# successfully
+	git rev-parse atomic2 >expected &&
+	# ...to other.
+	git -C "$d" rev-parse refs/heads/other >actual &&
+	test_cmp expected actual &&
+
+	# the new branch should not have been created upstream
+	test_must_fail git -C "$d" show-ref --verify refs/heads/atomic &&
+
+	# the failed refs should be indicated to the user
+	grep "^ ! .*rejected.* other -> other .*atomic transaction failed" output &&
+
+	# the collateral failure refs should be indicated to the user
+	grep "^ ! .*rejected.* atomic -> atomic .*atomic transaction failed" output
+'
+
 test_expect_success 'push --all can push to empty repo' '
 	d=$HTTPD_DOCUMENT_ROOT_PATH/empty-all.git &&
 	git init --bare "$d" &&

transport-helper.c

@@ -854,6 +854,10 @@ static void set_common_push_options(struct transport *transport,
 			die(_("helper %s does not support --signed=if-asked"), name);
 	}
 
+	if (flags & TRANSPORT_PUSH_ATOMIC)
+		if (set_helper_option(transport, TRANS_OPT_ATOMIC, "true") != 0)
+			die(_("helper %s does not support --atomic"), name);
+
 	if (flags & TRANSPORT_PUSH_OPTIONS) {
 		struct string_list_item *item;
 		for_each_string_list_item(item, transport->push_options)

transport.h

@@ -208,6 +208,9 @@ void transport_check_allowed(const char *type);
 /* Filter objects for partial clone and fetch */
 #define TRANS_OPT_LIST_OBJECTS_FILTER "filter"
 
+/* Request atomic (all-or-nothing) updates when pushing */
+#define TRANS_OPT_ATOMIC "atomic"
+
 /**
  * Returns 0 if the option was used, non-zero otherwise. Prints a
  * message to stderr if the option is not used.