fix v2.56.0.vfs.0.0 "requires the GVFS protocol" regression when ref tip is not local

builtin/fetch.c

@@ -1401,6 +1401,7 @@ static int check_exist_and_connected(struct ref *ref_map)
 {
 	struct ref *rm = ref_map;
 	struct check_connected_options opt = CHECK_CONNECTED_INIT;
+	enum odb_has_object_flags flags = ODB_HAS_OBJECT_RECHECK_PACKED;
 	struct ref *r;
 
 	/*
@@ -1420,14 +1421,17 @@ static int check_exist_and_connected(struct ref *ref_map)
 	if (refetch)
 		return -1;
 
-
 	/*
 	 * check_connected() allows objects to merely be promised, but
-	 * we need all direct targets to exist.
+	 * we need all direct targets to exist. A virtualized object store
+	 * may need to fetch those targets through its object providers.
 	 */
+	if (gvfs_virtualize_objects(the_repository))
+		flags |= ODB_HAS_OBJECT_FETCH_PROMISOR;
+
 	for (r = rm; r; r = r->next) {
 		if (!odb_has_object(the_repository->objects, &r->old_oid,
-				    ODB_HAS_OBJECT_RECHECK_PACKED))
+				    flags))
 			return -1;
 	}
 

compat/lazyload-curl.c

@@ -175,6 +175,20 @@ static curl_easy_setopt_pointer_type curl_easy_setopt_pointer_func;
 typedef CURLcode (*curl_easy_setopt_off_t_type)(CURL *curl, CURLoption opt, curl_off_t value);
 static curl_easy_setopt_off_t_type curl_easy_setopt_off_t_func;
 
+typedef CURLU *(*curl_url_type)(void);
+static curl_url_type curl_url_func;
+
+typedef void (*curl_url_cleanup_type)(CURLU *u);
+static curl_url_cleanup_type curl_url_cleanup_func;
+
+typedef CURLUcode (*curl_url_get_type)(const CURLU *u, CURLUPart what,
+				       char **part, unsigned int flags);
+static curl_url_get_type curl_url_get_func;
+
+typedef CURLUcode (*curl_url_set_type)(CURLU *u, CURLUPart what,
+				       const char *part, unsigned int flags);
+static curl_url_set_type curl_url_set_func;
+
 static char ssl_backend[64];
 
 static void lazy_load_curl(void)
@@ -231,6 +245,11 @@ static void lazy_load_curl(void)
 	curl_easy_setopt_long_func = (curl_easy_setopt_long_type)curl_easy_setopt_func;
 	curl_easy_setopt_pointer_func = (curl_easy_setopt_pointer_type)curl_easy_setopt_func;
 	curl_easy_setopt_off_t_func = (curl_easy_setopt_off_t_type)curl_easy_setopt_func;
+
+	curl_url_func = (curl_url_type)load_function(libcurl, "curl_url");
+	curl_url_cleanup_func = (curl_url_cleanup_type)load_function(libcurl, "curl_url_cleanup");
+	curl_url_get_func = (curl_url_get_type)load_function(libcurl, "curl_url_get");
+	curl_url_set_func = (curl_url_set_type)load_function(libcurl, "curl_url_set");
 }
 
 struct curl_version_info_data *curl_version_info(CURLversion version)
@@ -426,3 +445,25 @@ CURLcode curl_easy_setopt(CURL *curl, CURLoption opt, ...)
 	va_end(ap);
 	return res;
 }
+
+CURLU *curl_url(void)
+{
+	return curl_url_func();
+}
+
+void curl_url_cleanup(CURLU *u)
+{
+	curl_url_cleanup_func(u);
+}
+
+CURLUcode curl_url_get(const CURLU *u, CURLUPart what,
+		       char **part, unsigned int flags)
+{
+	return curl_url_get_func(u, what, part, flags);
+}
+
+CURLUcode curl_url_set(CURLU *u, CURLUPart what,
+		       const char *part, unsigned int flags)
+{
+	return curl_url_set_func(u, what, part, flags);
+}

git-curl-compat.h

@@ -28,6 +28,13 @@
  * introduced, oldest first, in the official version of cURL library.
  */
 
+/**
+ * curl_url() interface added in 7.62.0 (October 2018)
+ */
+#if LIBCURL_VERSION_NUM >= 0x073e00
+#define GIT_CURL_HAVE_CURL_URL
+#endif
+
 /**
  * Versions before curl 7.66.0 (September 2019) required manually setting the
  * transfer-encoding for a streaming POST; after that this is handled

http.c

@@ -2401,6 +2401,45 @@ static int http_request(const char *url,
 	return ret;
 }
 
+#ifndef GIT_CURL_HAVE_CURL_URL
+#define strip_url_credential(in) NULL
+#else
+static char *strip_url_credential(const char *in)
+{
+	char *ret = NULL;
+	CURLU *url;
+
+	url = curl_url();
+	if (!url)
+		goto out;
+
+	if (curl_url_set(url, CURLUPART_URL, in, 0))
+		goto out;
+
+	curl_url_set(url, CURLUPART_USER, NULL, 0);
+	curl_url_set(url, CURLUPART_PASSWORD, NULL, 0);
+	curl_url_get(url, CURLUPART_URL, &ret, 0);
+
+out:
+	curl_url_cleanup(url);
+	return ret;
+}
+#endif
+
+static int match_effective_url(const char *asked, const char *got)
+{
+	char *stripped;
+	int ret;
+
+	if (!strcmp(asked, got))
+		return 1;
+
+	stripped = strip_url_credential(asked);
+	ret = stripped && !strcmp(stripped, got);
+	curl_free(stripped);
+	return ret;
+}
+
 /*
  * Update the "base" url to a more appropriate value, as deduced by
  * redirects seen when requesting a URL starting with "url".
@@ -2433,7 +2472,7 @@ static int update_url_from_redirect(struct strbuf *base,
 	const char *tail;
 	size_t new_len;
 
-	if (!strcmp(asked, got->buf))
+	if (match_effective_url(asked, got->buf))
 		return 0;
 
 	if (!skip_prefix(asked, base->buf, &tail))

t/t0410/read-object-all

@@ -0,0 +1,114 @@
+#!/usr/bin/perl
+#
+# Example implementation of the Git read-object protocol version 1 that
+# serves objects of any type (not just blobs) from a host repository.
+# See Documentation/technical/read-object-protocol.txt
+#
+# The host repository is taken from the READ_OBJECT_DIR environment
+# variable so the same hook can be reused by different tests. It must
+# point at the ".git" directory (or bare repository) that holds the
+# objects to be served.
+#
+
+use strict;
+use warnings;
+
+my $DIR = $ENV{"READ_OBJECT_DIR"} || "../.git/";
+
+sub packet_bin_read {
+	my $buffer;
+	my $bytes_read = read STDIN, $buffer, 4;
+	if ( $bytes_read == 0 ) {
+
+		# EOF - Git stopped talking to us!
+		exit();
+	}
+	elsif ( $bytes_read != 4 ) {
+		die "invalid packet: '$buffer'";
+	}
+	my $pkt_size = hex($buffer);
+	if ( $pkt_size == 0 ) {
+		return ( 1, "" );
+	}
+	elsif ( $pkt_size > 4 ) {
+		my $content_size = $pkt_size - 4;
+		$bytes_read = read STDIN, $buffer, $content_size;
+		if ( $bytes_read != $content_size ) {
+			die "invalid packet ($content_size bytes expected; " .
+				"$bytes_read bytes read)";
+		}
+		return ( 0, $buffer );
+	}
+	else {
+		die "invalid packet size: $pkt_size";
+	}
+}
+
+sub packet_txt_read {
+	my ( $res, $buf ) = packet_bin_read();
+	unless ( $buf =~ s/\n$// ) {
+		die "A non-binary line MUST be terminated by an LF.";
+	}
+	return ( $res, $buf );
+}
+
+sub packet_bin_write {
+	my $buf = shift;
+	print STDOUT sprintf( "%04x", length($buf) + 4 );
+	print STDOUT $buf;
+	STDOUT->flush();
+}
+
+sub packet_txt_write {
+	packet_bin_write( $_[0] . "\n" );
+}
+
+sub packet_flush {
+	print STDOUT sprintf( "%04x", 0 );
+	STDOUT->flush();
+}
+
+( packet_txt_read() eq ( 0, "git-read-object-client" ) ) ||
+	die "bad initialize";
+( packet_txt_read() eq ( 0, "version=1" ) ) || die "bad version";
+( packet_bin_read() eq ( 1, "" ) ) || die "bad version end";
+
+packet_txt_write("git-read-object-server");
+packet_txt_write("version=1");
+packet_flush();
+
+( packet_txt_read() eq ( 0, "capability=get" ) )    || die "bad capability";
+( packet_bin_read() eq ( 1, "" ) )                  || die "bad capability end";
+
+packet_txt_write("capability=get");
+packet_flush();
+
+while (1) {
+	my ($command) = packet_txt_read() =~ /^command=([^=]+)$/;
+
+	if ( $command eq "get" ) {
+		my ($sha1) = packet_txt_read() =~ /^sha1=([0-9a-f]{40,64})$/;
+		packet_bin_read();
+
+		my $type = `git --git-dir="$DIR" cat-file -t $sha1 2>/dev/null`;
+		chomp $type;
+		if ( $type eq "" ) {
+			packet_txt_write("status=error");
+			packet_flush();
+			next;
+		}
+
+		system ('git --git-dir="' . $DIR . '" cat-file ' .
+			$type . ' ' . $sha1 .
+			' | git -c core.virtualizeobjects=false hash-object ' .
+			'-t ' . $type . ' -w --stdin >/dev/null 2>&1');
+		packet_txt_write(($?) ? "status=error" : "status=success");
+		packet_flush();
+
+		open my $log, '>>.git/read-object-hook.log';
+		print $log "Read object $sha1, exit code $?\n";
+		close $log;
+	} else {
+		die "bad command '$command'";
+	}
+}

t/t0499-read-object.sh

@@ -85,4 +85,44 @@ test_expect_success 'no-fetch commit lookups still report corruption' '
 	done
 '
 
+test_expect_success PERL_TEST_HELPERS 'setup fetch with a virtualized ref tip' '
+	git init -b main fetch-server &&
+	git -C fetch-server commit --allow-empty -m only &&
+	server_tip=$(git -C fetch-server rev-parse HEAD) &&
+	server_odb="$(pwd)/fetch-server/.git" &&
+
+	git init -b main fetch-client &&
+	mkdir -p fetch-client/.git/hooks &&
+	sed "1s|/usr/bin/perl|$PERL_PATH|" \
+	   <$TEST_DIRECTORY/t0410/read-object-all \
+	   >fetch-client/.git/hooks/read-object &&
+	chmod +x fetch-client/.git/hooks/read-object &&
+	git -C fetch-client config core.virtualizeobjects true
+'
+
+# The ref tip is not in the client object store and is newer than any
+# pack a GVFS cache server has published. The fetch existence check must
+# allow object acquisition in a virtualized repository so that the
+# read-object hook supplies the tip without a fetch-pack exchange.
+test_expect_success PERL_TEST_HELPERS 'read-object hook runs for missing tip' '
+	test_path_is_missing fetch-client/.git/read-object-hook.log &&
+
+	READ_OBJECT_DIR="$server_odb" \
+	GIT_TRACE2_EVENT="$PWD/fetch.trace" \
+		git -C fetch-client fetch "$(pwd)/fetch-server" \
+		+refs/heads/main:refs/remotes/server/main &&
+
+	echo "$server_tip" >expect &&
+	git -C fetch-client rev-parse refs/remotes/server/main >actual &&
+	test_cmp expect actual &&
+
+	test_grep ! "\"label\":\"fetch_refs\"" fetch.trace &&
+
+	find fetch-client/.git/objects/pack -name "*.pack" >packs &&
+	test_must_be_empty packs &&
+
+	test_path_is_file fetch-client/.git/read-object-hook.log &&
+	test_grep "$server_tip" fetch-client/.git/read-object-hook.log
+'
+
 test_done