[PATCH v5 3/3] builtin/rebase: support running "git rebase <upstream>"

From

Pratik Karki <predatoramigo@gmail.com>

Date

Jul 30, 2018, 16:29 UTC

Message-ID

<20180730162920.20318-4-predatoramigo@gmail.com>

In-Reply-To

<20180730162920.20318-1-predatoramigo@gmail.com>

It can be tested thusly by:

git -c rebase.usebuiltin=true rebase HEAD~2

Note: We take an alternative approach here which is *not* to set the
environment variables via `run_command_v_opt_cd_env()` because those
variables would then be visible by processes spawned from the rebase
backends. Instead, we work hard to set them in the shell script snippet.
On Windows, some of the tests fail merely due to core.fileMode not
being heeded that's why the core.*config variables is parsed here.

Signed-off-by: Pratik Karki <predatoramigo@gmail.com>
---
 builtin/rebase.c | 350 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 349 insertions(+), 1 deletion(-)

diff --git a/builtin/rebase.c b/builtin/rebase.c
index c44addb2a4..5863139204 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -9,6 +9,24 @@
 #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)
 {
@@ -30,8 +48,243 @@ static int use_builtin_rebase(void)
 	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;
+	const char *restrict_revision;
+};
+
+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(&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);
+	if (value) {
+		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, "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);
+	if (opts->restrict_revision == NULL)
+		add_var(&script_snippet, "restrict_revision", "");
+	else
+		add_var(&script_snippet, "restrict_revision",
+			opts->restrict_revision);
+
+	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 (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;
+}
+
+#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;
+	if (!detach_head)
+		unpack_tree_opts.reset = 1;
+	else
+		unpack_tree_opts.merge = 1;
+
+	if (read_index(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, orig, 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, quiet = 0;
+	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
@@ -54,5 +307,100 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 	trace_repo_setup(prefix);
 	setup_work_tree();
 
-	die("TODO");
+	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:
+		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"));
+	}
+
+	/* 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 (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 ? options.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;
 }

-- 
2.18.0