[PATCH 2/2] fetch/push: readd rsync support

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

We lost rsync support when transitioning from shell to C.  Support it
again (even if the transport is technically deprecated, some people just
do not have any chance to use anything else).

Also, add a test to t5510.  Since rsync transport is not configured by
default on most machines, and especially not such that you can
write to rsync://127.0.0.1$(pwd)/, it is disabled by default; you can
enable it by setting the environment variable TEST_RSYNC.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 t/t5510-fetch.sh |   35 ++++++
 transport.c      |  328 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 362 insertions(+), 1 deletions(-)

diff --git a/t/t5510-fetch.sh b/t/t5510-fetch.sh
index 439430f..73a4e3c 100755
--- a/t/t5510-fetch.sh
+++ b/t/t5510-fetch.sh
@@ -153,4 +153,39 @@ test_expect_success 'bundle should be able to create a full history' '
 
 '
 
+test "$TEST_RSYNC" && {
+test_expect_success 'fetch via rsync' '
+	git pack-refs &&
+	mkdir rsynced &&
+	cd rsynced &&
+	git init &&
+	git fetch rsync://127.0.0.1$(pwd)/../.git master:refs/heads/master &&
+	git gc --prune &&
+	test $(git rev-parse master) = $(cd .. && git rev-parse master) &&
+	git fsck --full
+'
+
+test_expect_success 'push via rsync' '
+	mkdir ../rsynced2 &&
+	(cd ../rsynced2 &&
+	 git init) &&
+	git push rsync://127.0.0.1$(pwd)/../rsynced2/.git master &&
+	cd ../rsynced2 &&
+	git gc --prune &&
+	test $(git rev-parse master) = $(cd .. && git rev-parse master) &&
+	git fsck --full
+'
+
+test_expect_success 'push via rsync' '
+	cd .. &&
+	mkdir rsynced3 &&
+	(cd rsynced3 &&
+	 git init) &&
+	git push --all rsync://127.0.0.1$(pwd)/rsynced3/.git &&
+	cd rsynced3 &&
+	test $(git rev-parse master) = $(cd .. && git rev-parse master) &&
+	git fsck --full
+'
+}
+
 test_done
diff --git a/transport.c b/transport.c
index 4f9cddc..c8eed95 100644
--- a/transport.c
+++ b/transport.c
@@ -6,6 +6,330 @@
 #include "fetch-pack.h"
 #include "walker.h"
 #include "bundle.h"
+#include "dir.h"
+#include "refs.h"
+
+/* rsync support */
+
+/*
+ * We copy packed-refs and refs/ into a temporary file, then read the
+ * loose refs recursively (sorting whenever possible), and then inserting
+ * those packed refs that are not yet in the list (not validating, but
+ * assuming that the file is sorted).
+ *
+ * Appears refactoring this from refs.c is too cumbersome.
+ */
+
+static int direntry_cmp(const void *a, const void *b)
+{
+	const struct dirent *d1 = a;
+	const struct dirent *d2 = b;
+
+	return strcmp(d1->d_name, d2->d_name);
+}
+
+/*
+ * path is assumed to point to a buffer of PATH_MAX bytes, and
+ * path + name_offset is expected to point to "refs/".
+ */
+
+static int read_loose_refs(struct strbuf *path, int name_offset,
+		struct ref **tail)
+{
+	DIR *dir = opendir(path->buf);
+	struct dirent *de;
+	struct {
+		char **entries;
+		int nr, alloc;
+	} list;
+	int i, pathlen;
+
+	if (!dir)
+		return -1;
+
+	memset (&list, 0, sizeof(list));
+
+	while ((de = readdir(dir))) {
+		if (de->d_name[0] == '.' && (de->d_name[1] == '\0' ||
+				(de->d_name[1] == '.' &&
+				 de->d_name[2] == '\0')))
+			continue;
+		ALLOC_GROW(list.entries, list.nr + 1, list.alloc);
+		list.entries[list.nr++] = xstrdup(de->d_name);
+	}
+	closedir(dir);
+
+	/* sort the list */
+
+	qsort(list.entries, list.nr, sizeof(*de), direntry_cmp);
+
+	pathlen = path->len;
+	strbuf_addch(path, '/');
+
+	for (i = 0; i < list.nr; i++, strbuf_setlen(path, pathlen + 1)) {
+		strbuf_addstr(path, list.entries[i]);
+		if (read_loose_refs(path, name_offset, tail)) {
+			int fd = open(path->buf, O_RDONLY);
+			char buffer[40];
+			struct ref *next;
+
+			if (fd < 0)
+				continue;
+			next = alloc_ref(path->len - name_offset + 1);
+			if (read_in_full(fd, buffer, 40) != 40 ||
+					get_sha1_hex(buffer, next->old_sha1)) {
+				free(next);
+				continue;
+			}
+			close(fd);
+			strcpy(next->name, path->buf + name_offset);
+			(*tail)->next = next;
+			*tail = next;
+		}
+	}
+
+	for (i = 0; i < list.nr; i++)
+		free(list.entries[i]);
+	free(list.entries);
+
+	return 0;
+}
+
+/* insert the packed refs for which no loose refs were found */
+
+static void insert_packed_refs(const char *packed_refs, struct ref **list)
+{
+	FILE *f = fopen(packed_refs, "r");
+	static char buffer[PATH_MAX];
+
+	if (!f)
+		return;
+
+	for (;;) {
+		int cmp, len;
+
+		if (!fgets(buffer, sizeof(buffer), f)) {
+			fclose(f);
+			return;
+		}
+
+		if (hexval(buffer[0]) & 0x10)
+			continue;
+		len = strlen(buffer);
+		if (buffer[len - 1] == '\n')
+			buffer[--len] = '\0';
+		if (len < 41)
+			continue;
+		while ((*list)->next &&
+				(cmp = strcmp(buffer + 41,
+				      (*list)->next->name)) > 0)
+			list = &(*list)->next;
+		if (!(*list)->next || cmp < 0) {
+			struct ref *next = alloc_ref(len - 40);
+			buffer[40] = '\0';
+			if (get_sha1_hex(buffer, next->old_sha1)) {
+				warning ("invalid SHA-1: %s", buffer);
+				free(next);
+				continue;
+			}
+			strcpy(next->name, buffer + 41);
+			next->next = (*list)->next;
+			(*list)->next = next;
+			list = &(*list)->next;
+		}
+	}
+}
+
+static struct ref *get_refs_via_rsync(const struct transport *transport)
+{
+	struct strbuf buf = STRBUF_INIT, temp_dir = STRBUF_INIT;
+	struct ref dummy, *result = &dummy;
+	struct child_process rsync;
+	const char *args[5];
+	int temp_dir_len;
+
+	/* copy the refs to the temporary directory */
+
+	strbuf_addstr(&temp_dir, git_path("rsync-refs-XXXXXX"));
+	if (!mkdtemp(temp_dir.buf))
+		die ("Could not make temporary directory");
+	temp_dir_len = temp_dir.len;
+
+	strbuf_addstr(&buf, transport->url);
+	strbuf_addstr(&buf, "/refs");
+
+	memset(&rsync, 0, sizeof(rsync));
+	rsync.argv = args;
+	rsync.stdout_to_stderr = 1;
+	args[0] = "rsync";
+	args[1] = transport->verbose ? "-rv" : "-r";
+	args[2] = buf.buf;
+	args[3] = temp_dir.buf;
+	args[4] = NULL;
+
+	if (run_command(&rsync))
+		die ("Could not run rsync to get refs");
+
+	strbuf_reset(&buf);
+	strbuf_addstr(&buf, transport->url);
+	strbuf_addstr(&buf, "/packed-refs");
+
+	args[2] = buf.buf;
+
+	if (run_command(&rsync))
+		die ("Could not run rsync to get refs");
+
+	/* read the copied refs */
+
+	strbuf_addstr(&temp_dir, "/refs");
+	read_loose_refs(&temp_dir, temp_dir_len + 1, &result);
+	strbuf_setlen(&temp_dir, temp_dir_len);
+
+	result = &dummy;
+	strbuf_addstr(&temp_dir, "/packed-refs");
+	insert_packed_refs(temp_dir.buf, &result);
+	strbuf_setlen(&temp_dir, temp_dir_len);
+
+	if (remove_dir_recursively(&temp_dir, 0))
+		warning ("Error removing temporary directory %s.",
+				temp_dir.buf);
+
+	strbuf_release(&buf);
+	strbuf_release(&temp_dir);
+
+	return dummy.next;
+}
+
+static int fetch_objs_via_rsync(struct transport *transport,
+				 int nr_objs, struct ref **to_fetch)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct child_process rsync;
+	const char *args[8];
+	int result;
+
+	strbuf_addstr(&buf, transport->url);
+	strbuf_addstr(&buf, "/objects/");
+
+	memset(&rsync, 0, sizeof(rsync));
+	rsync.argv = args;
+	rsync.stdout_to_stderr = 1;
+	args[0] = "rsync";
+	args[1] = transport->verbose ? "-rv" : "-r";
+	args[2] = "--ignore-existing";
+	args[3] = "--exclude";
+	args[4] = "info";
+	args[5] = buf.buf;
+	args[6] = get_object_directory();
+	args[7] = NULL;
+
+	/* NEEDSWORK: handle one level of alternates */
+	result = run_command(&rsync);
+
+	strbuf_release(&buf);
+
+	return result;
+}
+
+static int write_one_ref(const char *name, const unsigned char *sha1,
+		int flags, void *data)
+{
+	struct strbuf *buf = data;
+	int len = buf->len;
+	FILE *f;
+
+	if (flags && prefixcmp(name, "refs/heads/") &&
+			prefixcmp(name, "refs/tags/"))
+		return 0;
+
+	strbuf_addstr(buf, name);
+	if (safe_create_leading_directories(buf->buf) ||
+			!(f = fopen(buf->buf, "w")) ||
+			!fwrite(sha1_to_hex(sha1), 40, 1, f) ||
+			fputc('\n', f) == EOF ||
+			fclose(f))
+		return error("problems writing temporary file %s", buf->buf);
+	strbuf_setlen(buf, len);
+	return 0;
+}
+
+static int write_refs_to_temp_dir(struct strbuf *temp_dir,
+		int refspec_nr, const char **refspec)
+{
+	int i;
+
+	for (i = 0; i < refspec_nr; i++) {
+		unsigned char sha1[20];
+		char *ref;
+
+		if (dwim_ref(refspec[i], strlen(refspec[i]), sha1, &ref) != 1)
+			return error("Could not get ref %s", refspec[i]);
+
+		if (write_one_ref(ref, sha1, 0, temp_dir)) {
+			free(ref);
+			return -1;
+		}
+		free(ref);
+	}
+	return 0;
+}
+
+static int rsync_transport_push(struct transport *transport,
+		int refspec_nr, const char **refspec, int flags) {
+	struct strbuf buf = STRBUF_INIT, temp_dir = STRBUF_INIT;
+	int result = 0, i;
+	struct child_process rsync;
+	const char *args[8];
+
+	/* first push the objects */
+
+	strbuf_addstr(&buf, transport->url);
+	strbuf_addch(&buf, '/');
+
+	memset(&rsync, 0, sizeof(rsync));
+	rsync.argv = args;
+	rsync.stdout_to_stderr = 1;
+	args[0] = "rsync";
+	args[1] = transport->verbose ? "-av" : "-a";
+	args[2] = "--ignore-existing";
+	args[3] = "--exclude";
+	args[4] = "info";
+	args[5] = get_object_directory();;
+	args[6] = buf.buf;
+	args[7] = NULL;
+
+	if (run_command(&rsync))
+		return error("Could not push objects to %s", transport->url);
+
+	/* copy the refs to the temporary directory; they could be packed. */
+
+	strbuf_addstr(&temp_dir, git_path("rsync-refs-XXXXXX"));
+	if (!mkdtemp(temp_dir.buf))
+		die ("Could not make temporary directory");
+	strbuf_addch(&temp_dir, '/');
+
+	if (flags & TRANSPORT_PUSH_ALL) {
+		if (for_each_ref(write_one_ref, &temp_dir))
+			return -1;
+	} else if (write_refs_to_temp_dir(&temp_dir, refspec_nr, refspec))
+		return -1;
+
+	i = (flags & TRANSPORT_PUSH_FORCE) ? 2 : 3;
+	args[i++] = temp_dir.buf;
+	args[i++] = transport->url;
+	args[i++] = NULL;
+	if (run_command(&rsync))
+		result = error("Could not push to %s", transport->url);
+
+	if (remove_dir_recursively(&temp_dir, 0))
+		warning ("Could not remove temporary directory %s.",
+				temp_dir.buf);
+
+	strbuf_release(&buf);
+	strbuf_release(&temp_dir);
+
+	return result;
+}
 
 /* Generic functions for using commit walkers */
 
@@ -402,7 +726,9 @@ struct transport *transport_get(struct remote *remote, const char *url)
 	ret->url = url;
 
 	if (!prefixcmp(url, "rsync://")) {
-		/* not supported; don't populate any ops */
+		ret->get_refs_list = get_refs_via_rsync;
+		ret->fetch = fetch_objs_via_rsync;
+		ret->push = rsync_transport_push;
 
 	} else if (!prefixcmp(url, "http://")
 	        || !prefixcmp(url, "https://")
-- 
1.5.3.2.1102.g9487