Merge branch 'pk/rebase-in-c'

Rewrite of the "rebase" machinery in C.

* pk/rebase-in-c:
  builtin/rebase: support running "git rebase <upstream>"
  rebase: refactor common shell functions into their own file
  rebase: start implementing it as a builtin

.gitignore

@@ -81,6 +81,7 @@
 /git-init-db
 /git-interpret-trailers
 /git-instaweb
+/git-legacy-rebase
 /git-log
 /git-ls-files
 /git-ls-remote
@@ -121,6 +122,7 @@
 /git-read-tree
 /git-rebase
 /git-rebase--am
+/git-rebase--common
 /git-rebase--helper
 /git-rebase--interactive
 /git-rebase--merge

Makefile

@@ -616,7 +616,7 @@ SCRIPT_SH += git-merge-one-file.sh
 SCRIPT_SH += git-merge-resolve.sh
 SCRIPT_SH += git-mergetool.sh
 SCRIPT_SH += git-quiltimport.sh
-SCRIPT_SH += git-rebase.sh
+SCRIPT_SH += git-legacy-rebase.sh
 SCRIPT_SH += git-remote-testgit.sh
 SCRIPT_SH += git-request-pull.sh
 SCRIPT_SH += git-stash.sh
@@ -626,6 +626,7 @@ SCRIPT_SH += git-web--browse.sh
 SCRIPT_LIB += git-mergetool--lib
 SCRIPT_LIB += git-parse-remote
 SCRIPT_LIB += git-rebase--am
+SCRIPT_LIB += git-rebase--common
 SCRIPT_LIB += git-rebase--interactive
 SCRIPT_LIB += git-rebase--preserve-merges
 SCRIPT_LIB += git-rebase--merge
@@ -1093,6 +1094,7 @@ BUILTIN_OBJS += builtin/pull.o
 BUILTIN_OBJS += builtin/push.o
 BUILTIN_OBJS += builtin/range-diff.o
 BUILTIN_OBJS += builtin/read-tree.o
+BUILTIN_OBJS += builtin/rebase.o
 BUILTIN_OBJS += builtin/rebase--helper.o
 BUILTIN_OBJS += builtin/receive-pack.o
 BUILTIN_OBJS += builtin/reflog.o

builtin.h

@@ -204,6 +204,7 @@ extern int cmd_pull(int argc, const char **argv, const char *prefix);
 extern int cmd_push(int argc, const char **argv, const char *prefix);
 extern int cmd_range_diff(int argc, const char **argv, const char *prefix);
 extern int cmd_read_tree(int argc, const char **argv, const char *prefix);
+extern int cmd_rebase(int argc, const char **argv, const char *prefix);
 extern int cmd_rebase__helper(int argc, const char **argv, const char *prefix);
 extern int cmd_receive_pack(int argc, const char **argv, const char *prefix);
 extern int cmd_reflog(int argc, const char **argv, const char *prefix);

builtin/rebase.c

@@ -0,0 +1,421 @@
+/*
+ * "git rebase" builtin command
+ *
+ * Copyright (c) 2018 Pratik Karki
+ */
+
+#include "builtin.h"
+#include "run-command.h"
+#include "exec-cmd.h"
+#include "argv-array.h"
+#include "dir.h"
+#include "packfile.h"
+#include "refs.h"
+#include "quote.h"
+#include "config.h"
+#include "cache-tree.h"
+#include "unpack-trees.h"
+#include "lockfile.h"
+
+static GIT_PATH_FUNC(apply_dir, "rebase-apply")
+static GIT_PATH_FUNC(merge_dir, "rebase-merge")
+
+enum rebase_type {
+	REBASE_UNSPECIFIED = -1,
+	REBASE_AM,
+	REBASE_MERGE,
+	REBASE_INTERACTIVE,
+	REBASE_PRESERVE_MERGES
+};
+
+static int use_builtin_rebase(void)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	struct strbuf out = STRBUF_INIT;
+	int ret;
+
+	argv_array_pushl(&cp.args,
+			 "config", "--bool", "rebase.usebuiltin", NULL);
+	cp.git_cmd = 1;
+	if (capture_command(&cp, &out, 6)) {
+		strbuf_release(&out);
+		return 0;
+	}
+
+	strbuf_trim(&out);
+	ret = !strcmp("true", out.buf);
+	strbuf_release(&out);
+	return ret;
+}
+
+static int apply_autostash(void)
+{
+	warning("TODO");
+	return 0;
+}
+
+struct rebase_options {
+	enum rebase_type type;
+	const char *state_dir;
+	struct commit *upstream;
+	const char *upstream_name;
+	char *head_name;
+	struct object_id orig_head;
+	struct commit *onto;
+	const char *onto_name;
+	const char *revisions;
+	int root;
+	struct commit *restrict_revision;
+	int dont_finish_rebase;
+};
+
+/* Returns the filename prefixed by the state_dir */
+static const char *state_dir_path(const char *filename, struct rebase_options *opts)
+{
+	static struct strbuf path = STRBUF_INIT;
+	static size_t prefix_len;
+
+	if (!prefix_len) {
+		strbuf_addf(&path, "%s/", opts->state_dir);
+		prefix_len = path.len;
+	}
+
+	strbuf_setlen(&path, prefix_len);
+	strbuf_addstr(&path, filename);
+	return path.buf;
+}
+
+static int finish_rebase(struct rebase_options *opts)
+{
+	struct strbuf dir = STRBUF_INIT;
+	const char *argv_gc_auto[] = { "gc", "--auto", NULL };
+
+	delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
+	apply_autostash();
+	close_all_packs(the_repository->objects);
+	/*
+	 * We ignore errors in 'gc --auto', since the
+	 * user should see them.
+	 */
+	run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
+	strbuf_addstr(&dir, opts->state_dir);
+	remove_dir_recursively(&dir, 0);
+	strbuf_release(&dir);
+
+	return 0;
+}
+
+static struct commit *peel_committish(const char *name)
+{
+	struct object *obj;
+	struct object_id oid;
+
+	if (get_oid(name, &oid))
+		return NULL;
+	obj = parse_object(the_repository, &oid);
+	return (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
+}
+
+static void add_var(struct strbuf *buf, const char *name, const char *value)
+{
+	if (!value)
+		strbuf_addf(buf, "unset %s; ", name);
+	else {
+		strbuf_addf(buf, "%s=", name);
+		sq_quote_buf(buf, value);
+		strbuf_addstr(buf, "; ");
+	}
+}
+
+static int run_specific_rebase(struct rebase_options *opts)
+{
+	const char *argv[] = { NULL, NULL };
+	struct strbuf script_snippet = STRBUF_INIT;
+	int status;
+	const char *backend, *backend_func;
+
+	add_var(&script_snippet, "GIT_DIR", absolute_path(get_git_dir()));
+	add_var(&script_snippet, "state_dir", opts->state_dir);
+
+	add_var(&script_snippet, "upstream_name", opts->upstream_name);
+	add_var(&script_snippet, "upstream",
+				 oid_to_hex(&opts->upstream->object.oid));
+	add_var(&script_snippet, "head_name", opts->head_name);
+	add_var(&script_snippet, "orig_head", oid_to_hex(&opts->orig_head));
+	add_var(&script_snippet, "onto", oid_to_hex(&opts->onto->object.oid));
+	add_var(&script_snippet, "onto_name", opts->onto_name);
+	add_var(&script_snippet, "revisions", opts->revisions);
+	add_var(&script_snippet, "restrict_revision", opts->restrict_revision ?
+		oid_to_hex(&opts->restrict_revision->object.oid) : NULL);
+
+	switch (opts->type) {
+	case REBASE_AM:
+		backend = "git-rebase--am";
+		backend_func = "git_rebase__am";
+		break;
+	case REBASE_INTERACTIVE:
+		backend = "git-rebase--interactive";
+		backend_func = "git_rebase__interactive";
+		break;
+	case REBASE_MERGE:
+		backend = "git-rebase--merge";
+		backend_func = "git_rebase__merge";
+		break;
+	case REBASE_PRESERVE_MERGES:
+		backend = "git-rebase--preserve-merges";
+		backend_func = "git_rebase__preserve_merges";
+		break;
+	default:
+		BUG("Unhandled rebase type %d", opts->type);
+		break;
+	}
+
+	strbuf_addf(&script_snippet,
+		    ". git-sh-setup && . git-rebase--common &&"
+		    " . %s && %s", backend, backend_func);
+	argv[0] = script_snippet.buf;
+
+	status = run_command_v_opt(argv, RUN_USING_SHELL);
+	if (opts->dont_finish_rebase)
+		; /* do nothing */
+	else if (status == 0) {
+		if (!file_exists(state_dir_path("stopped-sha", opts)))
+			finish_rebase(opts);
+	} else if (status == 2) {
+		struct strbuf dir = STRBUF_INIT;
+
+		apply_autostash();
+		strbuf_addstr(&dir, opts->state_dir);
+		remove_dir_recursively(&dir, 0);
+		strbuf_release(&dir);
+		die("Nothing to do");
+	}
+
+	strbuf_release(&script_snippet);
+
+	return status ? -1 : 0;
+}
+
+#define GIT_REFLOG_ACTION_ENVIRONMENT "GIT_REFLOG_ACTION"
+
+static int reset_head(struct object_id *oid, const char *action,
+		      const char *switch_to_branch, int detach_head)
+{
+	struct object_id head_oid;
+	struct tree_desc desc;
+	struct lock_file lock = LOCK_INIT;
+	struct unpack_trees_options unpack_tree_opts;
+	struct tree *tree;
+	const char *reflog_action;
+	struct strbuf msg = STRBUF_INIT;
+	size_t prefix_len;
+	struct object_id *orig = NULL, oid_orig,
+		*old_orig = NULL, oid_old_orig;
+	int ret = 0;
+
+	if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0)
+		return -1;
+
+	if (!oid) {
+		if (get_oid("HEAD", &head_oid)) {
+			rollback_lock_file(&lock);
+			return error(_("could not determine HEAD revision"));
+		}
+		oid = &head_oid;
+	}
+
+	memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
+	setup_unpack_trees_porcelain(&unpack_tree_opts, action);
+	unpack_tree_opts.head_idx = 1;
+	unpack_tree_opts.src_index = the_repository->index;
+	unpack_tree_opts.dst_index = the_repository->index;
+	unpack_tree_opts.fn = oneway_merge;
+	unpack_tree_opts.update = 1;
+	unpack_tree_opts.merge = 1;
+	if (!detach_head)
+		unpack_tree_opts.reset = 1;
+
+	if (read_index_unmerged(the_repository->index) < 0) {
+		rollback_lock_file(&lock);
+		return error(_("could not read index"));
+	}
+
+	if (!fill_tree_descriptor(&desc, oid)) {
+		error(_("failed to find tree of %s"), oid_to_hex(oid));
+		rollback_lock_file(&lock);
+		free((void *)desc.buffer);
+		return -1;
+	}
+
+	if (unpack_trees(1, &desc, &unpack_tree_opts)) {
+		rollback_lock_file(&lock);
+		free((void *)desc.buffer);
+		return -1;
+	}
+
+	tree = parse_tree_indirect(oid);
+	prime_cache_tree(the_repository->index, tree);
+
+	if (write_locked_index(the_repository->index, &lock, COMMIT_LOCK) < 0)
+		ret = error(_("could not write index"));
+	free((void *)desc.buffer);
+
+	if (ret)
+		return ret;
+
+	reflog_action = getenv(GIT_REFLOG_ACTION_ENVIRONMENT);
+	strbuf_addf(&msg, "%s: ", reflog_action ? reflog_action : "rebase");
+	prefix_len = msg.len;
+
+	if (!get_oid("ORIG_HEAD", &oid_old_orig))
+		old_orig = &oid_old_orig;
+	if (!get_oid("HEAD", &oid_orig)) {
+		orig = &oid_orig;
+		strbuf_addstr(&msg, "updating ORIG_HEAD");
+		update_ref(msg.buf, "ORIG_HEAD", orig, old_orig, 0,
+			   UPDATE_REFS_MSG_ON_ERR);
+	} else if (old_orig)
+		delete_ref(NULL, "ORIG_HEAD", old_orig, 0);
+	strbuf_setlen(&msg, prefix_len);
+	strbuf_addstr(&msg, "updating HEAD");
+	if (!switch_to_branch)
+		ret = update_ref(msg.buf, "HEAD", oid, orig, REF_NO_DEREF,
+				 UPDATE_REFS_MSG_ON_ERR);
+	else {
+		ret = create_symref("HEAD", switch_to_branch, msg.buf);
+		if (!ret)
+			ret = update_ref(msg.buf, "HEAD", oid, NULL, 0,
+					 UPDATE_REFS_MSG_ON_ERR);
+	}
+
+	strbuf_release(&msg);
+	return ret;
+}
+
+int cmd_rebase(int argc, const char **argv, const char *prefix)
+{
+	struct rebase_options options = {
+		.type = REBASE_UNSPECIFIED,
+	};
+	const char *branch_name;
+	int ret, flags;
+	struct strbuf msg = STRBUF_INIT;
+	struct strbuf revisions = STRBUF_INIT;
+
+	/*
+	 * NEEDSWORK: Once the builtin rebase has been tested enough
+	 * and git-legacy-rebase.sh is retired to contrib/, this preamble
+	 * can be removed.
+	 */
+
+	if (!use_builtin_rebase()) {
+		const char *path = mkpath("%s/git-legacy-rebase",
+					  git_exec_path());
+
+		if (sane_execvp(path, (char **)argv) < 0)
+			die_errno(_("could not exec %s"), path);
+		else
+			BUG("sane_execvp() returned???");
+	}
+
+	if (argc != 2)
+		die(_("Usage: %s <base>"), argv[0]);
+	prefix = setup_git_directory();
+	trace_repo_setup(prefix);
+	setup_work_tree();
+
+	git_config(git_default_config, NULL);
+
+	switch (options.type) {
+	case REBASE_MERGE:
+	case REBASE_INTERACTIVE:
+	case REBASE_PRESERVE_MERGES:
+		options.state_dir = merge_dir();
+		break;
+	case REBASE_AM:
+		options.state_dir = apply_dir();
+		break;
+	default:
+		/* the default rebase backend is `--am` */
+		options.type = REBASE_AM;
+		options.state_dir = apply_dir();
+		break;
+	}
+
+	if (!options.root) {
+		if (argc < 2)
+			die("TODO: handle @{upstream}");
+		else {
+			options.upstream_name = argv[1];
+			argc--;
+			argv++;
+			if (!strcmp(options.upstream_name, "-"))
+				options.upstream_name = "@{-1}";
+		}
+		options.upstream = peel_committish(options.upstream_name);
+		if (!options.upstream)
+			die(_("invalid upstream '%s'"), options.upstream_name);
+	} else
+		die("TODO: upstream for --root");
+
+	/* Make sure the branch to rebase onto is valid. */
+	if (!options.onto_name)
+		options.onto_name = options.upstream_name;
+	if (strstr(options.onto_name, "...")) {
+		die("TODO");
+	} else {
+		options.onto = peel_committish(options.onto_name);
+		if (!options.onto)
+			die(_("Does not point to a valid commit '%s'"),
+				options.onto_name);
+	}
+
+	/*
+	 * If the branch to rebase is given, that is the branch we will rebase
+	 * branch_name -- branch/commit being rebased, or
+	 * 		  HEAD (already detached)
+	 * orig_head -- commit object name of tip of the branch before rebasing
+	 * head_name -- refs/heads/<that-branch> or "detached HEAD"
+	 */
+	if (argc > 1)
+		 die("TODO: handle switch_to");
+	else {
+		/* Do not need to switch branches, we are already on it. */
+		options.head_name =
+			xstrdup_or_null(resolve_ref_unsafe("HEAD", 0, NULL,
+					 &flags));
+		if (!options.head_name)
+			die(_("No such ref: %s"), "HEAD");
+		if (flags & REF_ISSYMREF) {
+			if (!skip_prefix(options.head_name,
+					 "refs/heads/", &branch_name))
+				branch_name = options.head_name;
+
+		} else {
+			options.head_name = xstrdup("detached HEAD");
+			branch_name = "HEAD";
+		}
+		if (get_oid("HEAD", &options.orig_head))
+			die(_("Could not resolve HEAD to a revision"));
+	}
+
+	strbuf_addf(&msg, "rebase: checkout %s", options.onto_name);
+	if (reset_head(&options.onto->object.oid, "checkout", NULL, 1))
+		die(_("Could not detach HEAD"));
+	strbuf_release(&msg);
+
+	strbuf_addf(&revisions, "%s..%s",
+		    options.root ? oid_to_hex(&options.onto->object.oid) :
+		    (options.restrict_revision ?
+		     oid_to_hex(&options.restrict_revision->object.oid) :
+		     oid_to_hex(&options.upstream->object.oid)),
+		    oid_to_hex(&options.orig_head));
+
+	options.revisions = revisions.buf;
+
+	ret = !!run_specific_rebase(&options);
+
+	strbuf_release(&revisions);
+	free(options.head_name);
+	return ret;
+}

git-legacy-rebase.sh

@@ -57,12 +57,7 @@ cd_to_toplevel
 LF='
 '
 ok_to_skip_pre_rebase=
-resolvemsg="
-$(gettext 'Resolve all conflicts manually, mark them as resolved with
-"git add/rm <conflicted_files>", then run "git rebase --continue".
-You can instead skip this commit: run "git rebase --skip".
-To abort and get back to the state before "git rebase", run "git rebase --abort".')
-"
+
 squash_onto=
 unset onto
 unset restrict_revision
@@ -102,6 +97,7 @@ case "$(git config --bool commit.gpgsign)" in
 true)	gpg_sign_opt=-S ;;
 *)	gpg_sign_opt= ;;
 esac
+. git-rebase--common
 
 read_basic_state () {
 	test -f "$state_dir/head-name" &&
@@ -132,67 +128,6 @@ read_basic_state () {
 	}
 }
 
-write_basic_state () {
-	echo "$head_name" > "$state_dir"/head-name &&
-	echo "$onto" > "$state_dir"/onto &&
-	echo "$orig_head" > "$state_dir"/orig-head &&
-	echo "$GIT_QUIET" > "$state_dir"/quiet &&
-	test t = "$verbose" && : > "$state_dir"/verbose
-	test -n "$strategy" && echo "$strategy" > "$state_dir"/strategy
-	test -n "$strategy_opts" && echo "$strategy_opts" > \
-		"$state_dir"/strategy_opts
-	test -n "$allow_rerere_autoupdate" && echo "$allow_rerere_autoupdate" > \
-		"$state_dir"/allow_rerere_autoupdate
-	test -n "$gpg_sign_opt" && echo "$gpg_sign_opt" > "$state_dir"/gpg_sign_opt
-	test -n "$signoff" && echo "$signoff" >"$state_dir"/signoff
-}
-
-output () {
-	case "$verbose" in
-	'')
-		output=$("$@" 2>&1 )
-		status=$?
-		test $status != 0 && printf "%s\n" "$output"
-		return $status
-		;;
-	*)
-		"$@"
-		;;
-	esac
-}
-
-move_to_original_branch () {
-	case "$head_name" in
-	refs/*)
-		message="rebase finished: $head_name onto $onto"
-		git update-ref -m "$message" \
-			$head_name $(git rev-parse HEAD) $orig_head &&
-		git symbolic-ref \
-			-m "rebase finished: returning to $head_name" \
-			HEAD $head_name ||
-		die "$(eval_gettext "Could not move back to \$head_name")"
-		;;
-	esac
-}
-
-apply_autostash () {
-	if test -f "$state_dir/autostash"
-	then
-		stash_sha1=$(cat "$state_dir/autostash")
-		if git stash apply $stash_sha1 >/dev/null 2>&1
-		then
-			echo "$(gettext 'Applied autostash.')" >&2
-		else
-			git stash store -m "autostash" -q $stash_sha1 ||
-			die "$(eval_gettext "Cannot store \$stash_sha1")"
-			gettext 'Applying autostash resulted in conflicts.
-Your changes are safe in the stash.
-You can run "git stash pop" or "git stash drop" at any time.
-' >&2
-		fi
-	fi
-}
-
 finish_rebase () {
 	rm -f "$(git rev-parse --git-path REBASE_HEAD)"
 	apply_autostash &&

git-rebase--common.sh

@@ -0,0 +1,68 @@
+
+resolvemsg="
+$(gettext 'Resolve all conflicts manually, mark them as resolved with
+"git add/rm <conflicted_files>", then run "git rebase --continue".
+You can instead skip this commit: run "git rebase --skip".
+To abort and get back to the state before "git rebase", run "git rebase --abort".')
+"
+
+write_basic_state () {
+	echo "$head_name" > "$state_dir"/head-name &&
+	echo "$onto" > "$state_dir"/onto &&
+	echo "$orig_head" > "$state_dir"/orig-head &&
+	echo "$GIT_QUIET" > "$state_dir"/quiet &&
+	test t = "$verbose" && : > "$state_dir"/verbose
+	test -n "$strategy" && echo "$strategy" > "$state_dir"/strategy
+	test -n "$strategy_opts" && echo "$strategy_opts" > \
+		"$state_dir"/strategy_opts
+	test -n "$allow_rerere_autoupdate" && echo "$allow_rerere_autoupdate" > \
+		"$state_dir"/allow_rerere_autoupdate
+	test -n "$gpg_sign_opt" && echo "$gpg_sign_opt" > "$state_dir"/gpg_sign_opt
+	test -n "$signoff" && echo "$signoff" >"$state_dir"/signoff
+}
+
+apply_autostash () {
+	if test -f "$state_dir/autostash"
+	then
+		stash_sha1=$(cat "$state_dir/autostash")
+		if git stash apply $stash_sha1 >/dev/null 2>&1
+		then
+			echo "$(gettext 'Applied autostash.')" >&2
+		else
+			git stash store -m "autostash" -q $stash_sha1 ||
+			die "$(eval_gettext "Cannot store \$stash_sha1")"
+			gettext 'Applying autostash resulted in conflicts.
+Your changes are safe in the stash.
+You can run "git stash pop" or "git stash drop" at any time.
+' >&2
+		fi
+	fi
+}
+
+move_to_original_branch () {
+	case "$head_name" in
+	refs/*)
+		message="rebase finished: $head_name onto $onto"
+		git update-ref -m "$message" \
+			$head_name $(git rev-parse HEAD) $orig_head &&
+		git symbolic-ref \
+			-m "rebase finished: returning to $head_name" \
+			HEAD $head_name ||
+		die "$(eval_gettext "Could not move back to \$head_name")"
+		;;
+	esac
+}
+
+output () {
+	case "$verbose" in
+	'')
+		output=$("$@" 2>&1 )
+		status=$?
+		test $status != 0 && printf "%s\n" "$output"
+		return $status
+		;;
+	*)
+		"$@"
+		;;
+	esac
+}

git.c

@@ -526,6 +526,12 @@ static struct cmd_struct commands[] = {
 	{ "push", cmd_push, RUN_SETUP },
 	{ "range-diff", cmd_range_diff, RUN_SETUP | USE_PAGER },
 	{ "read-tree", cmd_read_tree, RUN_SETUP | SUPPORT_SUPER_PREFIX},
+	/*
+	 * NEEDSWORK: Until the rebase is independent and needs no redirection
+	 * to rebase shell script this is kept as is, then should be changed to
+	 * RUN_SETUP | NEED_WORK_TREE
+	 */
+	{ "rebase", cmd_rebase },
 	{ "rebase--helper", cmd_rebase__helper, RUN_SETUP | NEED_WORK_TREE },
 	{ "receive-pack", cmd_receive_pack },
 	{ "reflog", cmd_reflog, RUN_SETUP },