Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 1282 insertions, 0 deletions

diff --git a/builtin/clone.c b/builtin/clone.c
new file mode 100644
index 0000000000..f665b28ccc
--- /dev/null
+++ b/builtin/clone.c
@@ -0,0 +1,1282 @@
+/*
+ * Builtin "git clone"
+ *
+ * Copyright (c) 2007 Kristian Høgsberg <krh@redhat.com>,
+ *		 2008 Daniel Barkalow <barkalow@iabervon.org>
+ * Based on git-commit.sh by Junio C Hamano and Linus Torvalds
+ *
+ * Clone a repository into a different directory that does not yet exist.
+ */
+
+#define USE_THE_INDEX_COMPATIBILITY_MACROS
+#include "builtin.h"
+#include "config.h"
+#include "lockfile.h"
+#include "parse-options.h"
+#include "fetch-pack.h"
+#include "refs.h"
+#include "refspec.h"
+#include "object-store.h"
+#include "tree.h"
+#include "tree-walk.h"
+#include "unpack-trees.h"
+#include "transport.h"
+#include "strbuf.h"
+#include "dir.h"
+#include "dir-iterator.h"
+#include "iterator.h"
+#include "sigchain.h"
+#include "branch.h"
+#include "remote.h"
+#include "run-command.h"
+#include "connected.h"
+#include "packfile.h"
+#include "list-objects-filter-options.h"
+#include "object-store.h"
+
+/*
+ * Overall FIXMEs:
+ *  - respect DB_ENVIRONMENT for .git/objects.
+ *
+ * Implementation notes:
+ *  - dropping use-separate-remote and no-separate-remote compatibility
+ *
+ */
+static const char * const builtin_clone_usage[] = {
+	N_("git clone [<options>] [--] <repo> [<dir>]"),
+	NULL
+};
+
+static int option_no_checkout, option_bare, option_mirror, option_single_branch = -1;
+static int option_local = -1, option_no_hardlinks, option_shared;
+static int option_no_tags;
+static int option_shallow_submodules;
+static int deepen;
+static char *option_template, *option_depth, *option_since;
+static char *option_origin = NULL;
+static char *option_branch = NULL;
+static struct string_list option_not = STRING_LIST_INIT_NODUP;
+static const char *real_git_dir;
+static char *option_upload_pack = "git-upload-pack";
+static int option_verbosity;
+static int option_progress = -1;
+static enum transport_family family;
+static struct string_list option_config = STRING_LIST_INIT_NODUP;
+static struct string_list option_required_reference = STRING_LIST_INIT_NODUP;
+static struct string_list option_optional_reference = STRING_LIST_INIT_NODUP;
+static int option_dissociate;
+static int max_jobs = -1;
+static struct string_list option_recurse_submodules = STRING_LIST_INIT_NODUP;
+static struct list_objects_filter_options filter_options;
+static struct string_list server_options = STRING_LIST_INIT_NODUP;
+static int option_remote_submodules;
+
+static int recurse_submodules_cb(const struct option *opt,
+				 const char *arg, int unset)
+{
+	if (unset)
+		string_list_clear((struct string_list *)opt->value, 0);
+	else if (arg)
+		string_list_append((struct string_list *)opt->value, arg);
+	else
+		string_list_append((struct string_list *)opt->value,
+				   (const char *)opt->defval);
+
+	return 0;
+}
+
+static struct option builtin_clone_options[] = {
+	OPT__VERBOSITY(&option_verbosity),
+	OPT_BOOL(0, "progress", &option_progress,
+		 N_("force progress reporting")),
+	OPT_BOOL('n', "no-checkout", &option_no_checkout,
+		 N_("don't create a checkout")),
+	OPT_BOOL(0, "bare", &option_bare, N_("create a bare repository")),
+	OPT_HIDDEN_BOOL(0, "naked", &option_bare,
+			N_("create a bare repository")),
+	OPT_BOOL(0, "mirror", &option_mirror,
+		 N_("create a mirror repository (implies bare)")),
+	OPT_BOOL('l', "local", &option_local,
+		N_("to clone from a local repository")),
+	OPT_BOOL(0, "no-hardlinks", &option_no_hardlinks,
+		    N_("don't use local hardlinks, always copy")),
+	OPT_BOOL('s', "shared", &option_shared,
+		    N_("setup as shared repository")),
+	OPT_ALIAS(0, "recursive", "recurse-submodules"),
+	{ OPTION_CALLBACK, 0, "recurse-submodules", &option_recurse_submodules,
+	  N_("pathspec"), N_("initialize submodules in the clone"),
+	  PARSE_OPT_OPTARG, recurse_submodules_cb, (intptr_t)"." },
+	OPT_INTEGER('j', "jobs", &max_jobs,
+		    N_("number of submodules cloned in parallel")),
+	OPT_STRING(0, "template", &option_template, N_("template-directory"),
+		   N_("directory from which templates will be used")),
+	OPT_STRING_LIST(0, "reference", &option_required_reference, N_("repo"),
+			N_("reference repository")),
+	OPT_STRING_LIST(0, "reference-if-able", &option_optional_reference,
+			N_("repo"), N_("reference repository")),
+	OPT_BOOL(0, "dissociate", &option_dissociate,
+		 N_("use --reference only while cloning")),
+	OPT_STRING('o', "origin", &option_origin, N_("name"),
+		   N_("use <name> instead of 'origin' to track upstream")),
+	OPT_STRING('b', "branch", &option_branch, N_("branch"),
+		   N_("checkout <branch> instead of the remote's HEAD")),
+	OPT_STRING('u', "upload-pack", &option_upload_pack, N_("path"),
+		   N_("path to git-upload-pack on the remote")),
+	OPT_STRING(0, "depth", &option_depth, N_("depth"),
+		    N_("create a shallow clone of that depth")),
+	OPT_STRING(0, "shallow-since", &option_since, N_("time"),
+		    N_("create a shallow clone since a specific time")),
+	OPT_STRING_LIST(0, "shallow-exclude", &option_not, N_("revision"),
+			N_("deepen history of shallow clone, excluding rev")),
+	OPT_BOOL(0, "single-branch", &option_single_branch,
+		    N_("clone only one branch, HEAD or --branch")),
+	OPT_BOOL(0, "no-tags", &option_no_tags,
+		 N_("don't clone any tags, and make later fetches not to follow them")),
+	OPT_BOOL(0, "shallow-submodules", &option_shallow_submodules,
+		    N_("any cloned submodules will be shallow")),
+	OPT_STRING(0, "separate-git-dir", &real_git_dir, N_("gitdir"),
+		   N_("separate git dir from working tree")),
+	OPT_STRING_LIST('c', "config", &option_config, N_("key=value"),
+			N_("set config inside the new repository")),
+	OPT_STRING_LIST(0, "server-option", &server_options,
+			N_("server-specific"), N_("option to transmit")),
+	OPT_SET_INT('4', "ipv4", &family, N_("use IPv4 addresses only"),
+			TRANSPORT_FAMILY_IPV4),
+	OPT_SET_INT('6', "ipv6", &family, N_("use IPv6 addresses only"),
+			TRANSPORT_FAMILY_IPV6),
+	OPT_PARSE_LIST_OBJECTS_FILTER(&filter_options),
+	OPT_BOOL(0, "remote-submodules", &option_remote_submodules,
+		    N_("any cloned submodules will use their remote-tracking branch")),
+	OPT_END()
+};
+
+static const char *get_repo_path_1(struct strbuf *path, int *is_bundle)
+{
+	static char *suffix[] = { "/.git", "", ".git/.git", ".git" };
+	static char *bundle_suffix[] = { ".bundle", "" };
+	size_t baselen = path->len;
+	struct stat st;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(suffix); i++) {
+		strbuf_setlen(path, baselen);
+		strbuf_addstr(path, suffix[i]);
+		if (stat(path->buf, &st))
+			continue;
+		if (S_ISDIR(st.st_mode) && is_git_directory(path->buf)) {
+			*is_bundle = 0;
+			return path->buf;
+		} else if (S_ISREG(st.st_mode) && st.st_size > 8) {
+			/* Is it a "gitfile"? */
+			char signature[8];
+			const char *dst;
+			int len, fd = open(path->buf, O_RDONLY);
+			if (fd < 0)
+				continue;
+			len = read_in_full(fd, signature, 8);
+			close(fd);
+			if (len != 8 || strncmp(signature, "gitdir: ", 8))
+				continue;
+			dst = read_gitfile(path->buf);
+			if (dst) {
+				*is_bundle = 0;
+				return dst;
+			}
+		}
+	}
+
+	for (i = 0; i < ARRAY_SIZE(bundle_suffix); i++) {
+		strbuf_setlen(path, baselen);
+		strbuf_addstr(path, bundle_suffix[i]);
+		if (!stat(path->buf, &st) && S_ISREG(st.st_mode)) {
+			*is_bundle = 1;
+			return path->buf;
+		}
+	}
+
+	return NULL;
+}
+
+static char *get_repo_path(const char *repo, int *is_bundle)
+{
+	struct strbuf path = STRBUF_INIT;
+	const char *raw;
+	char *canon;
+
+	strbuf_addstr(&path, repo);
+	raw = get_repo_path_1(&path, is_bundle);
+	canon = raw ? absolute_pathdup(raw) : NULL;
+	strbuf_release(&path);
+	return canon;
+}
+
+static char *guess_dir_name(const char *repo, int is_bundle, int is_bare)
+{
+	const char *end = repo + strlen(repo), *start, *ptr;
+	size_t len;
+	char *dir;
+
+	/*
+	 * Skip scheme.
+	 */
+	start = strstr(repo, "://");
+	if (start == NULL)
+		start = repo;
+	else
+		start += 3;
+
+	/*
+	 * Skip authentication data. The stripping does happen
+	 * greedily, such that we strip up to the last '@' inside
+	 * the host part.
+	 */
+	for (ptr = start; ptr < end && !is_dir_sep(*ptr); ptr++) {
+		if (*ptr == '@')
+			start = ptr + 1;
+	}
+
+	/*
+	 * Strip trailing spaces, slashes and /.git
+	 */
+	while (start < end && (is_dir_sep(end[-1]) || isspace(end[-1])))
+		end--;
+	if (end - start > 5 && is_dir_sep(end[-5]) &&
+	    !strncmp(end - 4, ".git", 4)) {
+		end -= 5;
+		while (start < end && is_dir_sep(end[-1]))
+			end--;
+	}
+
+	/*
+	 * Strip trailing port number if we've got only a
+	 * hostname (that is, there is no dir separator but a
+	 * colon). This check is required such that we do not
+	 * strip URI's like '/foo/bar:2222.git', which should
+	 * result in a dir '2222' being guessed due to backwards
+	 * compatibility.
+	 */
+	if (memchr(start, '/', end - start) == NULL
+	    && memchr(start, ':', end - start) != NULL) {
+		ptr = end;
+		while (start < ptr && isdigit(ptr[-1]) && ptr[-1] != ':')
+			ptr--;
+		if (start < ptr && ptr[-1] == ':')
+			end = ptr - 1;
+	}
+
+	/*
+	 * Find last component. To remain backwards compatible we
+	 * also regard colons as path separators, such that
+	 * cloning a repository 'foo:bar.git' would result in a
+	 * directory 'bar' being guessed.
+	 */
+	ptr = end;
+	while (start < ptr && !is_dir_sep(ptr[-1]) && ptr[-1] != ':')
+		ptr--;
+	start = ptr;
+
+	/*
+	 * Strip .{bundle,git}.
+	 */
+	len = end - start;
+	strip_suffix_mem(start, &len, is_bundle ? ".bundle" : ".git");
+
+	if (!len || (len == 1 && *start == '/'))
+		die(_("No directory name could be guessed.\n"
+		      "Please specify a directory on the command line"));
+
+	if (is_bare)
+		dir = xstrfmt("%.*s.git", (int)len, start);
+	else
+		dir = xstrndup(start, len);
+	/*
+	 * Replace sequences of 'control' characters and whitespace
+	 * with one ascii space, remove leading and trailing spaces.
+	 */
+	if (*dir) {
+		char *out = dir;
+		int prev_space = 1 /* strip leading whitespace */;
+		for (end = dir; *end; ++end) {
+			char ch = *end;
+			if ((unsigned char)ch < '\x20')
+				ch = '\x20';
+			if (isspace(ch)) {
+				if (prev_space)
+					continue;
+				prev_space = 1;
+			} else
+				prev_space = 0;
+			*out++ = ch;
+		}
+		*out = '\0';
+		if (out > dir && prev_space)
+			out[-1] = '\0';
+	}
+	return dir;
+}
+
+static void strip_trailing_slashes(char *dir)
+{
+	char *end = dir + strlen(dir);
+
+	while (dir < end - 1 && is_dir_sep(end[-1]))
+		end--;
+	*end = '\0';
+}
+
+static int add_one_reference(struct string_list_item *item, void *cb_data)
+{
+	struct strbuf err = STRBUF_INIT;
+	int *required = cb_data;
+	char *ref_git = compute_alternate_path(item->string, &err);
+
+	if (!ref_git) {
+		if (*required)
+			die("%s", err.buf);
+		else
+			fprintf(stderr,
+				_("info: Could not add alternate for '%s': %s\n"),
+				item->string, err.buf);
+	} else {
+		struct strbuf sb = STRBUF_INIT;
+		strbuf_addf(&sb, "%s/objects", ref_git);
+		add_to_alternates_file(sb.buf);
+		strbuf_release(&sb);
+	}
+
+	strbuf_release(&err);
+	free(ref_git);
+	return 0;
+}
+
+static void setup_reference(void)
+{
+	int required = 1;
+	for_each_string_list(&option_required_reference,
+			     add_one_reference, &required);
+	required = 0;
+	for_each_string_list(&option_optional_reference,
+			     add_one_reference, &required);
+}
+
+static void copy_alternates(struct strbuf *src, const char *src_repo)
+{
+	/*
+	 * Read from the source objects/info/alternates file
+	 * and copy the entries to corresponding file in the
+	 * destination repository with add_to_alternates_file().
+	 * Both src and dst have "$path/objects/info/alternates".
+	 *
+	 * Instead of copying bit-for-bit from the original,
+	 * we need to append to existing one so that the already
+	 * created entry via "clone -s" is not lost, and also
+	 * to turn entries with paths relative to the original
+	 * absolute, so that they can be used in the new repository.
+	 */
+	FILE *in = xfopen(src->buf, "r");
+	struct strbuf line = STRBUF_INIT;
+
+	while (strbuf_getline(&line, in) != EOF) {
+		char *abs_path;
+		if (!line.len || line.buf[0] == '#')
+			continue;
+		if (is_absolute_path(line.buf)) {
+			add_to_alternates_file(line.buf);
+			continue;
+		}
+		abs_path = mkpathdup("%s/objects/%s", src_repo, line.buf);
+		if (!normalize_path_copy(abs_path, abs_path))
+			add_to_alternates_file(abs_path);
+		else
+			warning("skipping invalid relative alternate: %s/%s",
+				src_repo, line.buf);
+		free(abs_path);
+	}
+	strbuf_release(&line);
+	fclose(in);
+}
+
+static void mkdir_if_missing(const char *pathname, mode_t mode)
+{
+	struct stat st;
+
+	if (!mkdir(pathname, mode))
+		return;
+
+	if (errno != EEXIST)
+		die_errno(_("failed to create directory '%s'"), pathname);
+	else if (stat(pathname, &st))
+		die_errno(_("failed to stat '%s'"), pathname);
+	else if (!S_ISDIR(st.st_mode))
+		die(_("%s exists and is not a directory"), pathname);
+}
+
+static void copy_or_link_directory(struct strbuf *src, struct strbuf *dest,
+				   const char *src_repo)
+{
+	int src_len, dest_len;
+	struct dir_iterator *iter;
+	int iter_status;
+	unsigned int flags;
+
+	mkdir_if_missing(dest->buf, 0777);
+
+	flags = DIR_ITERATOR_PEDANTIC | DIR_ITERATOR_FOLLOW_SYMLINKS;
+	iter = dir_iterator_begin(src->buf, flags);
+
+	if (!iter)
+		die_errno(_("failed to start iterator over '%s'"), src->buf);
+
+	strbuf_addch(src, '/');
+	src_len = src->len;
+	strbuf_addch(dest, '/');
+	dest_len = dest->len;
+
+	while ((iter_status = dir_iterator_advance(iter)) == ITER_OK) {
+		strbuf_setlen(src, src_len);
+		strbuf_addstr(src, iter->relative_path);
+		strbuf_setlen(dest, dest_len);
+		strbuf_addstr(dest, iter->relative_path);
+
+		if (S_ISDIR(iter->st.st_mode)) {
+			mkdir_if_missing(dest->buf, 0777);
+			continue;
+		}
+
+		/* Files that cannot be copied bit-for-bit... */
+		if (!fspathcmp(iter->relative_path, "info/alternates")) {
+			copy_alternates(src, src_repo);
+			continue;
+		}
+
+		if (unlink(dest->buf) && errno != ENOENT)
+			die_errno(_("failed to unlink '%s'"), dest->buf);
+		if (!option_no_hardlinks) {
+			if (!link(real_path(src->buf), dest->buf))
+				continue;
+			if (option_local > 0)
+				die_errno(_("failed to create link '%s'"), dest->buf);
+			option_no_hardlinks = 1;
+		}
+		if (copy_file_with_time(dest->buf, src->buf, 0666))
+			die_errno(_("failed to copy file to '%s'"), dest->buf);
+	}
+
+	if (iter_status != ITER_DONE) {
+		strbuf_setlen(src, src_len);
+		die(_("failed to iterate over '%s'"), src->buf);
+	}
+}
+
+static void clone_local(const char *src_repo, const char *dest_repo)
+{
+	if (option_shared) {
+		struct strbuf alt = STRBUF_INIT;
+		get_common_dir(&alt, src_repo);
+		strbuf_addstr(&alt, "/objects");
+		add_to_alternates_file(alt.buf);
+		strbuf_release(&alt);
+	} else {
+		struct strbuf src = STRBUF_INIT;
+		struct strbuf dest = STRBUF_INIT;
+		get_common_dir(&src, src_repo);
+		get_common_dir(&dest, dest_repo);
+		strbuf_addstr(&src, "/objects");
+		strbuf_addstr(&dest, "/objects");
+		copy_or_link_directory(&src, &dest, src_repo);
+		strbuf_release(&src);
+		strbuf_release(&dest);
+	}
+
+	if (0 <= option_verbosity)
+		fprintf(stderr, _("done.\n"));
+}
+
+static const char *junk_work_tree;
+static int junk_work_tree_flags;
+static const char *junk_git_dir;
+static int junk_git_dir_flags;
+static enum {
+	JUNK_LEAVE_NONE,
+	JUNK_LEAVE_REPO,
+	JUNK_LEAVE_ALL
+} junk_mode = JUNK_LEAVE_NONE;
+
+static const char junk_leave_repo_msg[] =
+N_("Clone succeeded, but checkout failed.\n"
+   "You can inspect what was checked out with 'git status'\n"
+   "and retry with 'git restore --source=HEAD :/'\n");
+
+static void remove_junk(void)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	switch (junk_mode) {
+	case JUNK_LEAVE_REPO:
+		warning("%s", _(junk_leave_repo_msg));
+		/* fall-through */
+	case JUNK_LEAVE_ALL:
+		return;
+	default:
+		/* proceed to removal */
+		break;
+	}
+
+	if (junk_git_dir) {
+		strbuf_addstr(&sb, junk_git_dir);
+		remove_dir_recursively(&sb, junk_git_dir_flags);
+		strbuf_reset(&sb);
+	}
+	if (junk_work_tree) {
+		strbuf_addstr(&sb, junk_work_tree);
+		remove_dir_recursively(&sb, junk_work_tree_flags);
+	}
+	strbuf_release(&sb);
+}
+
+static void remove_junk_on_signal(int signo)
+{
+	remove_junk();
+	sigchain_pop(signo);
+	raise(signo);
+}
+
+static struct ref *find_remote_branch(const struct ref *refs, const char *branch)
+{
+	struct ref *ref;
+	struct strbuf head = STRBUF_INIT;
+	strbuf_addstr(&head, "refs/heads/");
+	strbuf_addstr(&head, branch);
+	ref = find_ref_by_name(refs, head.buf);
+	strbuf_release(&head);
+
+	if (ref)
+		return ref;
+
+	strbuf_addstr(&head, "refs/tags/");
+	strbuf_addstr(&head, branch);
+	ref = find_ref_by_name(refs, head.buf);
+	strbuf_release(&head);
+
+	return ref;
+}
+
+static struct ref *wanted_peer_refs(const struct ref *refs,
+		struct refspec *refspec)
+{
+	struct ref *head = copy_ref(find_ref_by_name(refs, "HEAD"));
+	struct ref *local_refs = head;
+	struct ref **tail = head ? &head->next : &local_refs;
+
+	if (option_single_branch) {
+		struct ref *remote_head = NULL;
+
+		if (!option_branch)
+			remote_head = guess_remote_head(head, refs, 0);
+		else {
+			local_refs = NULL;
+			tail = &local_refs;
+			remote_head = copy_ref(find_remote_branch(refs, option_branch));
+		}
+
+		if (!remote_head && option_branch)
+			warning(_("Could not find remote branch %s to clone."),
+				option_branch);
+		else {
+			int i;
+			for (i = 0; i < refspec->nr; i++)
+				get_fetch_map(remote_head, &refspec->items[i],
+					      &tail, 0);
+
+			/* if --branch=tag, pull the requested tag explicitly */
+			get_fetch_map(remote_head, tag_refspec, &tail, 0);
+		}
+	} else {
+		int i;
+		for (i = 0; i < refspec->nr; i++)
+			get_fetch_map(refs, &refspec->items[i], &tail, 0);
+	}
+
+	if (!option_mirror && !option_single_branch && !option_no_tags)
+		get_fetch_map(refs, tag_refspec, &tail, 0);
+
+	return local_refs;
+}
+
+static void write_remote_refs(const struct ref *local_refs)
+{
+	const struct ref *r;
+
+	struct ref_transaction *t;
+	struct strbuf err = STRBUF_INIT;
+
+	t = ref_transaction_begin(&err);
+	if (!t)
+		die("%s", err.buf);
+
+	for (r = local_refs; r; r = r->next) {
+		if (!r->peer_ref)
+			continue;
+		if (ref_transaction_create(t, r->peer_ref->name, &r->old_oid,
+					   0, NULL, &err))
+			die("%s", err.buf);
+	}
+
+	if (initial_ref_transaction_commit(t, &err))
+		die("%s", err.buf);
+
+	strbuf_release(&err);
+	ref_transaction_free(t);
+}
+
+static void write_followtags(const struct ref *refs, const char *msg)
+{
+	const struct ref *ref;
+	for (ref = refs; ref; ref = ref->next) {
+		if (!starts_with(ref->name, "refs/tags/"))
+			continue;
+		if (ends_with(ref->name, "^{}"))
+			continue;
+		if (!has_object_file(&ref->old_oid))
+			continue;
+		update_ref(msg, ref->name, &ref->old_oid, NULL, 0,
+			   UPDATE_REFS_DIE_ON_ERR);
+	}
+}
+
+static int iterate_ref_map(void *cb_data, struct object_id *oid)
+{
+	struct ref **rm = cb_data;
+	struct ref *ref = *rm;
+
+	/*
+	 * Skip anything missing a peer_ref, which we are not
+	 * actually going to write a ref for.
+	 */
+	while (ref && !ref->peer_ref)
+		ref = ref->next;
+	/* Returning -1 notes "end of list" to the caller. */
+	if (!ref)
+		return -1;
+
+	oidcpy(oid, &ref->old_oid);
+	*rm = ref->next;
+	return 0;
+}
+
+static void update_remote_refs(const struct ref *refs,
+			       const struct ref *mapped_refs,
+			       const struct ref *remote_head_points_at,
+			       const char *branch_top,
+			       const char *msg,
+			       struct transport *transport,
+			       int check_connectivity,
+			       int check_refs_only)
+{
+	const struct ref *rm = mapped_refs;
+
+	if (check_connectivity) {
+		struct check_connected_options opt = CHECK_CONNECTED_INIT;
+
+		opt.transport = transport;
+		opt.progress = transport->progress;
+		opt.check_refs_only = !!check_refs_only;
+
+		if (check_connected(iterate_ref_map, &rm, &opt))
+			die(_("remote did not send all necessary objects"));
+	}
+
+	if (refs) {
+		write_remote_refs(mapped_refs);
+		if (option_single_branch && !option_no_tags)
+			write_followtags(refs, msg);
+	}
+
+	if (remote_head_points_at && !option_bare) {
+		struct strbuf head_ref = STRBUF_INIT;
+		strbuf_addstr(&head_ref, branch_top);
+		strbuf_addstr(&head_ref, "HEAD");
+		if (create_symref(head_ref.buf,
+				  remote_head_points_at->peer_ref->name,
+				  msg) < 0)
+			die(_("unable to update %s"), head_ref.buf);
+		strbuf_release(&head_ref);
+	}
+}
+
+static void update_head(const struct ref *our, const struct ref *remote,
+			const char *msg)
+{
+	const char *head;
+	if (our && skip_prefix(our->name, "refs/heads/", &head)) {
+		/* Local default branch link */
+		if (create_symref("HEAD", our->name, NULL) < 0)
+			die(_("unable to update HEAD"));
+		if (!option_bare) {
+			update_ref(msg, "HEAD", &our->old_oid, NULL, 0,
+				   UPDATE_REFS_DIE_ON_ERR);
+			install_branch_config(0, head, option_origin, our->name);
+		}
+	} else if (our) {
+		struct commit *c = lookup_commit_reference(the_repository,
+							   &our->old_oid);
+		/* --branch specifies a non-branch (i.e. tags), detach HEAD */
+		update_ref(msg, "HEAD", &c->object.oid, NULL, REF_NO_DEREF,
+			   UPDATE_REFS_DIE_ON_ERR);
+	} else if (remote) {
+		/*
+		 * We know remote HEAD points to a non-branch, or
+		 * HEAD points to a branch but we don't know which one.
+		 * Detach HEAD in all these cases.
+		 */
+		update_ref(msg, "HEAD", &remote->old_oid, NULL, REF_NO_DEREF,
+			   UPDATE_REFS_DIE_ON_ERR);
+	}
+}
+
+static int checkout(int submodule_progress)
+{
+	struct object_id oid;
+	char *head;
+	struct lock_file lock_file = LOCK_INIT;
+	struct unpack_trees_options opts;
+	struct tree *tree;
+	struct tree_desc t;
+	int err = 0;
+
+	if (option_no_checkout)
+		return 0;
+
+	head = resolve_refdup("HEAD", RESOLVE_REF_READING, &oid, NULL);
+	if (!head) {
+		warning(_("remote HEAD refers to nonexistent ref, "
+			  "unable to checkout.\n"));
+		return 0;
+	}
+	if (!strcmp(head, "HEAD")) {
+		if (advice_detached_head)
+			detach_advice(oid_to_hex(&oid));
+	} else {
+		if (!starts_with(head, "refs/heads/"))
+			die(_("HEAD not found below refs/heads!"));
+	}
+	free(head);
+
+	/* We need to be in the new work tree for the checkout */
+	setup_work_tree();
+
+	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
+
+	memset(&opts, 0, sizeof opts);
+	opts.update = 1;
+	opts.merge = 1;
+	opts.clone = 1;
+	opts.fn = oneway_merge;
+	opts.verbose_update = (option_verbosity >= 0);
+	opts.src_index = &the_index;
+	opts.dst_index = &the_index;
+
+	tree = parse_tree_indirect(&oid);
+	parse_tree(tree);
+	init_tree_desc(&t, tree->buffer, tree->size);
+	if (unpack_trees(1, &t, &opts) < 0)
+		die(_("unable to checkout working tree"));
+
+	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
+		die(_("unable to write new index file"));
+
+	err |= run_hook_le(NULL, "post-checkout", sha1_to_hex(null_sha1),
+			   oid_to_hex(&oid), "1", NULL);
+
+	if (!err && (option_recurse_submodules.nr > 0)) {
+		struct argv_array args = ARGV_ARRAY_INIT;
+		argv_array_pushl(&args, "submodule", "update", "--init", "--recursive", NULL);
+
+		if (option_shallow_submodules == 1)
+			argv_array_push(&args, "--depth=1");
+
+		if (max_jobs != -1)
+			argv_array_pushf(&args, "--jobs=%d", max_jobs);
+
+		if (submodule_progress)
+			argv_array_push(&args, "--progress");
+
+		if (option_verbosity < 0)
+			argv_array_push(&args, "--quiet");
+
+		if (option_remote_submodules) {
+			argv_array_push(&args, "--remote");
+			argv_array_push(&args, "--no-fetch");
+		}
+
+		err = run_command_v_opt(args.argv, RUN_GIT_CMD);
+		argv_array_clear(&args);
+	}
+
+	return err;
+}
+
+static int write_one_config(const char *key, const char *value, void *data)
+{
+	return git_config_set_multivar_gently(key,
+					      value ? value : "true",
+					      CONFIG_REGEX_NONE, 0);
+}
+
+static void write_config(struct string_list *config)
+{
+	int i;
+
+	for (i = 0; i < config->nr; i++) {
+		if (git_config_parse_parameter(config->items[i].string,
+					       write_one_config, NULL) < 0)
+			die(_("unable to write parameters to config file"));
+	}
+}
+
+static void write_refspec_config(const char *src_ref_prefix,
+		const struct ref *our_head_points_at,
+		const struct ref *remote_head_points_at,
+		struct strbuf *branch_top)
+{
+	struct strbuf key = STRBUF_INIT;
+	struct strbuf value = STRBUF_INIT;
+
+	if (option_mirror || !option_bare) {
+		if (option_single_branch && !option_mirror) {
+			if (option_branch) {
+				if (starts_with(our_head_points_at->name, "refs/tags/"))
+					strbuf_addf(&value, "+%s:%s", our_head_points_at->name,
+						our_head_points_at->name);
+				else
+					strbuf_addf(&value, "+%s:%s%s", our_head_points_at->name,
+						branch_top->buf, option_branch);
+			} else if (remote_head_points_at) {
+				const char *head = remote_head_points_at->name;
+				if (!skip_prefix(head, "refs/heads/", &head))
+					BUG("remote HEAD points at non-head?");
+
+				strbuf_addf(&value, "+%s:%s%s", remote_head_points_at->name,
+						branch_top->buf, head);
+			}
+			/*
+			 * otherwise, the next "git fetch" will
+			 * simply fetch from HEAD without updating
+			 * any remote-tracking branch, which is what
+			 * we want.
+			 */
+		} else {
+			strbuf_addf(&value, "+%s*:%s*", src_ref_prefix, branch_top->buf);
+		}
+		/* Configure the remote */
+		if (value.len) {
+			strbuf_addf(&key, "remote.%s.fetch", option_origin);
+			git_config_set_multivar(key.buf, value.buf, "^$", 0);
+			strbuf_reset(&key);
+
+			if (option_mirror) {
+				strbuf_addf(&key, "remote.%s.mirror", option_origin);
+				git_config_set(key.buf, "true");
+				strbuf_reset(&key);
+			}
+		}
+	}
+
+	strbuf_release(&key);
+	strbuf_release(&value);
+}
+
+static void dissociate_from_references(void)
+{
+	static const char* argv[] = { "repack", "-a", "-d", NULL };
+	char *alternates = git_pathdup("objects/info/alternates");
+
+	if (!access(alternates, F_OK)) {
+		if (run_command_v_opt(argv, RUN_GIT_CMD|RUN_COMMAND_NO_STDIN))
+			die(_("cannot repack to clean up"));
+		if (unlink(alternates) && errno != ENOENT)
+			die_errno(_("cannot unlink temporary alternates file"));
+	}
+	free(alternates);
+}
+
+static int dir_exists(const char *path)
+{
+	struct stat sb;
+	return !stat(path, &sb);
+}
+
+int cmd_clone(int argc, const char **argv, const char *prefix)
+{
+	int is_bundle = 0, is_local;
+	const char *repo_name, *repo, *work_tree, *git_dir;
+	char *path, *dir;
+	int dest_exists;
+	const struct ref *refs, *remote_head;
+	const struct ref *remote_head_points_at;
+	const struct ref *our_head_points_at;
+	struct ref *mapped_refs;
+	const struct ref *ref;
+	struct strbuf key = STRBUF_INIT;
+	struct strbuf default_refspec = STRBUF_INIT;
+	struct strbuf branch_top = STRBUF_INIT, reflog_msg = STRBUF_INIT;
+	struct transport *transport = NULL;
+	const char *src_ref_prefix = "refs/heads/";
+	struct remote *remote;
+	int err = 0, complete_refs_before_fetch = 1;
+	int submodule_progress;
+
+	struct argv_array ref_prefixes = ARGV_ARRAY_INIT;
+
+	fetch_if_missing = 0;
+
+	packet_trace_identity("clone");
+	argc = parse_options(argc, argv, prefix, builtin_clone_options,
+			     builtin_clone_usage, 0);
+
+	if (argc > 2)
+		usage_msg_opt(_("Too many arguments."),
+			builtin_clone_usage, builtin_clone_options);
+
+	if (argc == 0)
+		usage_msg_opt(_("You must specify a repository to clone."),
+			builtin_clone_usage, builtin_clone_options);
+
+	if (option_depth || option_since || option_not.nr)
+		deepen = 1;
+	if (option_single_branch == -1)
+		option_single_branch = deepen ? 1 : 0;
+
+	if (option_mirror)
+		option_bare = 1;
+
+	if (option_bare) {
+		if (option_origin)
+			die(_("--bare and --origin %s options are incompatible."),
+			    option_origin);
+		if (real_git_dir)
+			die(_("--bare and --separate-git-dir are incompatible."));
+		option_no_checkout = 1;
+	}
+
+	if (!option_origin)
+		option_origin = "origin";
+
+	repo_name = argv[0];
+
+	path = get_repo_path(repo_name, &is_bundle);
+	if (path)
+		repo = absolute_pathdup(repo_name);
+	else if (!strchr(repo_name, ':'))
+		die(_("repository '%s' does not exist"), repo_name);
+	else
+		repo = repo_name;
+
+	/* no need to be strict, transport_set_option() will validate it again */
+	if (option_depth && atoi(option_depth) < 1)
+		die(_("depth %s is not a positive number"), option_depth);
+
+	if (argc == 2)
+		dir = xstrdup(argv[1]);
+	else
+		dir = guess_dir_name(repo_name, is_bundle, option_bare);
+	strip_trailing_slashes(dir);
+
+	dest_exists = dir_exists(dir);
+	if (dest_exists && !is_empty_dir(dir))
+		die(_("destination path '%s' already exists and is not "
+			"an empty directory."), dir);
+
+	strbuf_addf(&reflog_msg, "clone: from %s", repo);
+
+	if (option_bare)
+		work_tree = NULL;
+	else {
+		work_tree = getenv("GIT_WORK_TREE");
+		if (work_tree && dir_exists(work_tree))
+			die(_("working tree '%s' already exists."), work_tree);
+	}
+
+	if (option_bare || work_tree)
+		git_dir = xstrdup(dir);
+	else {
+		work_tree = dir;
+		git_dir = mkpathdup("%s/.git", dir);
+	}
+
+	atexit(remove_junk);
+	sigchain_push_common(remove_junk_on_signal);
+
+	if (!option_bare) {
+		if (safe_create_leading_directories_const(work_tree) < 0)
+			die_errno(_("could not create leading directories of '%s'"),
+				  work_tree);
+		if (dest_exists)
+			junk_work_tree_flags |= REMOVE_DIR_KEEP_TOPLEVEL;
+		else if (mkdir(work_tree, 0777))
+			die_errno(_("could not create work tree dir '%s'"),
+				  work_tree);
+		junk_work_tree = work_tree;
+		set_git_work_tree(work_tree);
+	}
+
+	if (real_git_dir) {
+		if (dir_exists(real_git_dir))
+			junk_git_dir_flags |= REMOVE_DIR_KEEP_TOPLEVEL;
+		junk_git_dir = real_git_dir;
+	} else {
+		if (dest_exists)
+			junk_git_dir_flags |= REMOVE_DIR_KEEP_TOPLEVEL;
+		junk_git_dir = git_dir;
+	}
+	if (safe_create_leading_directories_const(git_dir) < 0)
+		die(_("could not create leading directories of '%s'"), git_dir);
+
+	if (0 <= option_verbosity) {
+		if (option_bare)
+			fprintf(stderr, _("Cloning into bare repository '%s'...\n"), dir);
+		else
+			fprintf(stderr, _("Cloning into '%s'...\n"), dir);
+	}
+
+	if (option_recurse_submodules.nr > 0) {
+		struct string_list_item *item;
+		struct strbuf sb = STRBUF_INIT;
+
+		/* remove duplicates */
+		string_list_sort(&option_recurse_submodules);
+		string_list_remove_duplicates(&option_recurse_submodules, 0);
+
+		/*
+		 * NEEDSWORK: In a multi-working-tree world, this needs to be
+		 * set in the per-worktree config.
+		 */
+		for_each_string_list_item(item, &option_recurse_submodules) {
+			strbuf_addf(&sb, "submodule.active=%s",
+				    item->string);
+			string_list_append(&option_config,
+					   strbuf_detach(&sb, NULL));
+		}
+
+		if (option_required_reference.nr &&
+		    option_optional_reference.nr)
+			die(_("clone --recursive is not compatible with "
+			      "both --reference and --reference-if-able"));
+		else if (option_required_reference.nr) {
+			string_list_append(&option_config,
+				"submodule.alternateLocation=superproject");
+			string_list_append(&option_config,
+				"submodule.alternateErrorStrategy=die");
+		} else if (option_optional_reference.nr) {
+			string_list_append(&option_config,
+				"submodule.alternateLocation=superproject");
+			string_list_append(&option_config,
+				"submodule.alternateErrorStrategy=info");
+		}
+	}
+
+	init_db(git_dir, real_git_dir, option_template, INIT_DB_QUIET);
+
+	if (real_git_dir)
+		git_dir = real_git_dir;
+
+	write_config(&option_config);
+
+	git_config(git_default_config, NULL);
+
+	if (option_bare) {
+		if (option_mirror)
+			src_ref_prefix = "refs/";
+		strbuf_addstr(&branch_top, src_ref_prefix);
+
+		git_config_set("core.bare", "true");
+	} else {
+		strbuf_addf(&branch_top, "refs/remotes/%s/", option_origin);
+	}
+
+	strbuf_addf(&key, "remote.%s.url", option_origin);
+	git_config_set(key.buf, repo);
+	strbuf_reset(&key);
+
+	if (option_no_tags) {
+		strbuf_addf(&key, "remote.%s.tagOpt", option_origin);
+		git_config_set(key.buf, "--no-tags");
+		strbuf_reset(&key);
+	}
+
+	if (option_required_reference.nr || option_optional_reference.nr)
+		setup_reference();
+
+	remote = remote_get(option_origin);
+
+	strbuf_addf(&default_refspec, "+%s*:%s*", src_ref_prefix,
+		    branch_top.buf);
+	refspec_append(&remote->fetch, default_refspec.buf);
+
+	transport = transport_get(remote, remote->url[0]);
+	transport_set_verbosity(transport, option_verbosity, option_progress);
+	transport->family = family;
+
+	path = get_repo_path(remote->url[0], &is_bundle);
+	is_local = option_local != 0 && path && !is_bundle;
+	if (is_local) {
+		if (option_depth)
+			warning(_("--depth is ignored in local clones; use file:// instead."));
+		if (option_since)
+			warning(_("--shallow-since is ignored in local clones; use file:// instead."));
+		if (option_not.nr)
+			warning(_("--shallow-exclude is ignored in local clones; use file:// instead."));
+		if (filter_options.choice)
+			warning(_("--filter is ignored in local clones; use file:// instead."));
+		if (!access(mkpath("%s/shallow", path), F_OK)) {
+			if (option_local > 0)
+				warning(_("source repository is shallow, ignoring --local"));
+			is_local = 0;
+		}
+	}
+	if (option_local > 0 && !is_local)
+		warning(_("--local is ignored"));
+	transport->cloning = 1;
+
+	transport_set_option(transport, TRANS_OPT_KEEP, "yes");
+
+	if (option_depth)
+		transport_set_option(transport, TRANS_OPT_DEPTH,
+				     option_depth);
+	if (option_since)
+		transport_set_option(transport, TRANS_OPT_DEEPEN_SINCE,
+				     option_since);
+	if (option_not.nr)
+		transport_set_option(transport, TRANS_OPT_DEEPEN_NOT,
+				     (const char *)&option_not);
+	if (option_single_branch)
+		transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, "1");
+
+	if (option_upload_pack)
+		transport_set_option(transport, TRANS_OPT_UPLOADPACK,
+				     option_upload_pack);
+
+	if (server_options.nr)
+		transport->server_options = &server_options;
+
+	if (filter_options.choice) {
+		struct strbuf expanded_filter_spec = STRBUF_INIT;
+		expand_list_objects_filter_spec(&filter_options,
+						&expanded_filter_spec);
+		transport_set_option(transport, TRANS_OPT_LIST_OBJECTS_FILTER,
+				     expanded_filter_spec.buf);
+		transport_set_option(transport, TRANS_OPT_FROM_PROMISOR, "1");
+		strbuf_release(&expanded_filter_spec);
+	}
+
+	if (transport->smart_options && !deepen && !filter_options.choice)
+		transport->smart_options->check_self_contained_and_connected = 1;
+
+
+	argv_array_push(&ref_prefixes, "HEAD");
+	refspec_ref_prefixes(&remote->fetch, &ref_prefixes);
+	if (option_branch)
+		expand_ref_prefix(&ref_prefixes, option_branch);
+	if (!option_no_tags)
+		argv_array_push(&ref_prefixes, "refs/tags/");
+
+	refs = transport_get_remote_refs(transport, &ref_prefixes);
+
+	if (refs) {
+		mapped_refs = wanted_peer_refs(refs, &remote->fetch);
+		/*
+		 * transport_get_remote_refs() may return refs with null sha-1
+		 * in mapped_refs (see struct transport->get_refs_list
+		 * comment). In that case we need fetch it early because
+		 * remote_head code below relies on it.
+		 *
+		 * for normal clones, transport_get_remote_refs() should
+		 * return reliable ref set, we can delay cloning until after
+		 * remote HEAD check.
+		 */
+		for (ref = refs; ref; ref = ref->next)
+			if (is_null_oid(&ref->old_oid)) {
+				complete_refs_before_fetch = 0;
+				break;
+			}
+
+		if (!is_local && !complete_refs_before_fetch)
+			transport_fetch_refs(transport, mapped_refs);
+
+		remote_head = find_ref_by_name(refs, "HEAD");
+		remote_head_points_at =
+			guess_remote_head(remote_head, mapped_refs, 0);
+
+		if (option_branch) {
+			our_head_points_at =
+				find_remote_branch(mapped_refs, option_branch);
+
+			if (!our_head_points_at)
+				die(_("Remote branch %s not found in upstream %s"),
+				    option_branch, option_origin);
+		}
+		else
+			our_head_points_at = remote_head_points_at;
+	}
+	else {
+		if (option_branch)
+			die(_("Remote branch %s not found in upstream %s"),
+					option_branch, option_origin);
+
+		warning(_("You appear to have cloned an empty repository."));
+		mapped_refs = NULL;
+		our_head_points_at = NULL;
+		remote_head_points_at = NULL;
+		remote_head = NULL;
+		option_no_checkout = 1;
+		if (!option_bare)
+			install_branch_config(0, "master", option_origin,
+					      "refs/heads/master");
+	}
+
+	write_refspec_config(src_ref_prefix, our_head_points_at,
+			remote_head_points_at, &branch_top);
+
+	if (filter_options.choice)
+		partial_clone_register(option_origin, &filter_options);
+
+	if (is_local)
+		clone_local(path, git_dir);
+	else if (refs && complete_refs_before_fetch)
+		transport_fetch_refs(transport, mapped_refs);
+
+	update_remote_refs(refs, mapped_refs, remote_head_points_at,
+			   branch_top.buf, reflog_msg.buf, transport,
+			   !is_local, filter_options.choice);
+
+	update_head(our_head_points_at, remote_head, reflog_msg.buf);
+
+	/*
+	 * We want to show progress for recursive submodule clones iff
+	 * we did so for the main clone. But only the transport knows
+	 * the final decision for this flag, so we need to rescue the value
+	 * before we free the transport.
+	 */
+	submodule_progress = transport->progress;
+
+	transport_unlock_pack(transport);
+	transport_disconnect(transport);
+
+	if (option_dissociate) {
+		close_object_store(the_repository->objects);
+		dissociate_from_references();
+	}
+
+	junk_mode = JUNK_LEAVE_REPO;
+	fetch_if_missing = 1;
+	err = checkout(submodule_progress);
+
+	strbuf_release(&reflog_msg);
+	strbuf_release(&branch_top);
+	strbuf_release(&key);
+	strbuf_release(&default_refspec);
+	junk_mode = JUNK_LEAVE_ALL;
+
+	argv_array_clear(&ref_prefixes);
+	return err;
+}