Merge branch 'pk/rebase-in-c' into pu

Piecemeal rewrite of the "rebase" machinery in C.

* pk/rebase-in-c:
  builtin/rebase: support running "git rebase <upstream>"
  sequencer: refactor the code to detach HEAD to checkout.c
  rebase: refactor common shell functions into their own file
  rebase: start implementing it as a builtin

Author: gitster

.gitignore

@@ -78,6 +78,7 @@
 /git-init-db
 /git-interpret-trailers
 /git-instaweb
+/git-legacy-rebase
 /git-log
 /git-ls-files
 /git-ls-remote
@@ -117,6 +118,7 @@
 /git-read-tree
 /git-rebase
 /git-rebase--am
+/git-rebase--common
 /git-rebase--helper
 /git-rebase--interactive
 /git-rebase--merge

Makefile

@@ -609,7 +609,7 @@ 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
@@ -619,6 +619,7 @@ 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
@@ -1071,6 +1072,7 @@ 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

@@ -203,6 +203,7 @@ 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 +1,292 @@
+/*
+ * "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 "checkout.h"
+#include "refs.h"
+#include "quote.h"
+
+static GIT_PATH_FUNC(apply_dir, "rebase-apply");
+static GIT_PATH_FUNC(merge_dir, "rebase-merge");
+
+enum rebase_type {
+	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))
+		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;
+	const char *root;
+};
+
+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)
+{
+	strbuf_addstr(buf, name);
+	strbuf_addstr(buf, "=");
+	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, "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);
+
+	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-rebase--common && . %s && %s",
+		    backend, backend_func);
+	argv[0] = script_snippet.buf;
+
+	status = run_command_v_opt(argv, RUN_USING_SHELL);
+	if (status == 0)
+		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;
+}
+
+int cmd_rebase(int argc, const char **argv, const char *prefix)
+{
+	struct rebase_options options = { -1 };
+	const char *branch_name;
+	int ret, flags, quiet = 0;
+	struct strbuf msg = STRBUF_INIT;
+	struct strbuf revisions = STRBUF_INIT;
+	const char *restrict_revision = NULL;
+
+	/*
+	 * 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
+			die("sane_execvp() returned???");
+	}
+
+	if (argc != 2)
+		die("Usage: %s <base>", argv[0]);
+	prefix = setup_git_directory();
+	trace_repo_setup(prefix);
+	setup_work_tree();
+
+	options.type = REBASE_AM;
+
+	switch (options.type) {
+	case REBASE_AM:
+		options.state_dir = apply_dir();
+		break;
+	case REBASE_MERGE:
+	case REBASE_INTERACTIVE:
+	case REBASE_PRESERVE_MERGES:
+		options.state_dir = merge_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"));
+	}
+
+	/* Detach HEAD and reset the tree */
+	if (!quiet)
+		printf("First, rewinding head to replay your work on top of it...");
+
+	strbuf_addf(&msg, "rebase: checkout %s", options.onto_name);
+	if (detach_head_to(&options.onto->object.oid, "checkout", msg.buf))
+		die(_("Could not detach HEAD"));
+	strbuf_release(&msg);
+	if (update_ref("rebase", "ORIG_HEAD", &options.orig_head, NULL, 0,
+		       UPDATE_REFS_MSG_ON_ERR) < 0)
+		die(_("Could not update ORIG_HEAD to '%s'"),
+		    oid_to_hex(&options.orig_head));
+
+	strbuf_addf(&revisions, "%s..%s",
+		!options.root ? oid_to_hex(&options.onto->object.oid) :
+		    (restrict_revision ? restrict_revision :
+			    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;
+}