git

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#define USE_THE_REPOSITORY_VARIABLE
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#include "git-compat-util.h"
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#include "cache-tree.h"
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#include "gettext.h"
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#include "hex.h"
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#include "lockfile.h"
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#include "object-name.h"
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#include "refs.h"
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#include "reset.h"
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#include "tree-walk.h"
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#include "tree.h"
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#include "unpack-trees.h"
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#include "hook.h"
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static int update_refs(const struct reset_head_opts *opts,
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		       const struct object_id *oid,
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		       const struct object_id *head)
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{
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	unsigned detach_head = opts->flags & RESET_HEAD_DETACH;
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	unsigned run_hook = opts->flags & RESET_HEAD_RUN_POST_CHECKOUT_HOOK;
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	unsigned update_orig_head = opts->flags & RESET_ORIG_HEAD;
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	const struct object_id *orig_head = opts->orig_head;
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	const char *switch_to_branch = opts->branch;
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	const char *reflog_branch = opts->branch_msg;
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	const char *reflog_head = opts->head_msg;
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	const char *reflog_orig_head = opts->orig_head_msg;
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	const char *default_reflog_action = opts->default_reflog_action;
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	struct object_id *old_orig = NULL, oid_old_orig;
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	struct strbuf msg = STRBUF_INIT;
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	const char *reflog_action;
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	size_t prefix_len;
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	int ret;
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	if ((update_orig_head && !reflog_orig_head) || !reflog_head) {
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		if (!default_reflog_action)
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			BUG("default_reflog_action must be given when reflog messages are omitted");
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		reflog_action = getenv(GIT_REFLOG_ACTION_ENVIRONMENT);
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		strbuf_addf(&msg, "%s: ", reflog_action ? reflog_action :
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							  default_reflog_action);
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	}
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	prefix_len = msg.len;
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	if (update_orig_head) {
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		if (!repo_get_oid(the_repository, "ORIG_HEAD", &oid_old_orig))
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			old_orig = &oid_old_orig;
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		if (head) {
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			if (!reflog_orig_head) {
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				strbuf_addstr(&msg, "updating ORIG_HEAD");
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				reflog_orig_head = msg.buf;
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			}
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			refs_update_ref(get_main_ref_store(the_repository),
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					reflog_orig_head, "ORIG_HEAD",
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					orig_head ? orig_head : head,
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					old_orig, 0, UPDATE_REFS_MSG_ON_ERR);
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		} else if (old_orig)
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			refs_delete_ref(get_main_ref_store(the_repository),
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					NULL, "ORIG_HEAD", old_orig, 0);
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	}
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	if (!reflog_head) {
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		strbuf_setlen(&msg, prefix_len);
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		strbuf_addstr(&msg, "updating HEAD");
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		reflog_head = msg.buf;
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	}
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	if (!switch_to_branch)
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		ret = refs_update_ref(get_main_ref_store(the_repository),
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				      reflog_head, "HEAD", oid, head,
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				      detach_head ? REF_NO_DEREF : 0,
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				      UPDATE_REFS_MSG_ON_ERR);
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	else {
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		ret = refs_update_ref(get_main_ref_store(the_repository),
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				      reflog_branch ? reflog_branch : reflog_head,
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				      switch_to_branch, oid, NULL, 0,
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				      UPDATE_REFS_MSG_ON_ERR);
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		if (!ret)
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			ret = refs_update_symref(get_main_ref_store(the_repository),
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						 "HEAD", switch_to_branch,
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						 reflog_head);
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	}
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	if (!ret && run_hook)
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		run_hooks_l(the_repository, "post-checkout",
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			    oid_to_hex(head ? head : null_oid()),
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			    oid_to_hex(oid), "1", NULL);
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	strbuf_release(&msg);
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	return ret;
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}
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int reset_head(struct repository *r, const struct reset_head_opts *opts)
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{
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	const struct object_id *oid = opts->oid;
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	const char *switch_to_branch = opts->branch;
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	unsigned reset_hard = opts->flags & RESET_HEAD_HARD;
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	unsigned refs_only = opts->flags & RESET_HEAD_REFS_ONLY;
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	unsigned update_orig_head = opts->flags & RESET_ORIG_HEAD;
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	struct object_id *head = NULL, head_oid;
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	struct tree_desc desc[2] = { { NULL }, { NULL } };
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	struct lock_file lock = LOCK_INIT;
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	struct unpack_trees_options unpack_tree_opts = { 0 };
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	struct tree *tree;
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	const char *action;
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	int ret = 0, nr = 0;
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	if (switch_to_branch && !starts_with(switch_to_branch, "refs/"))
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		BUG("Not a fully qualified branch: '%s'", switch_to_branch);
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	if (opts->orig_head_msg && !update_orig_head)
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		BUG("ORIG_HEAD reflog message given without updating ORIG_HEAD");
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	if (opts->branch_msg && !opts->branch)
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		BUG("branch reflog message given without a branch");
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	if (!refs_only && repo_hold_locked_index(r, &lock, LOCK_REPORT_ON_ERROR) < 0) {
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		ret = -1;
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		goto leave_reset_head;
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	}
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	if (!repo_get_oid(r, "HEAD", &head_oid)) {
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		head = &head_oid;
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	} else if (!oid || !reset_hard) {
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		ret = error(_("could not determine HEAD revision"));
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		goto leave_reset_head;
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	}
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	if (!oid)
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		oid = &head_oid;
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	if (refs_only)
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		return update_refs(opts, oid, head);
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	action = reset_hard ? "reset" : "checkout";
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	setup_unpack_trees_porcelain(&unpack_tree_opts, action);
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	unpack_tree_opts.head_idx = 1;
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	unpack_tree_opts.src_index = r->index;
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	unpack_tree_opts.dst_index = r->index;
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	unpack_tree_opts.fn = reset_hard ? oneway_merge : twoway_merge;
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	unpack_tree_opts.update = 1;
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	unpack_tree_opts.merge = 1;
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	unpack_tree_opts.preserve_ignored = 0; /* FIXME: !overwrite_ignore */
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	unpack_tree_opts.skip_cache_tree_update = 1;
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	init_checkout_metadata(&unpack_tree_opts.meta, switch_to_branch, oid, NULL);
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	if (reset_hard)
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		unpack_tree_opts.reset = UNPACK_RESET_PROTECT_UNTRACKED;
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	if (repo_read_index_unmerged(r) < 0) {
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		ret = error(_("could not read index"));
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		goto leave_reset_head;
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	}
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	if (!reset_hard && !fill_tree_descriptor(r, &desc[nr++], &head_oid)) {
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		ret = error(_("failed to find tree of %s"),
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			    oid_to_hex(&head_oid));
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		goto leave_reset_head;
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	}
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	if (!fill_tree_descriptor(r, &desc[nr++], oid)) {
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		ret = error(_("failed to find tree of %s"), oid_to_hex(oid));
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		goto leave_reset_head;
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	}
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	if (unpack_trees(nr, desc, &unpack_tree_opts)) {
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		ret = -1;
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		goto leave_reset_head;
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	}
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	tree = parse_tree_indirect(oid);
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	if (!tree) {
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		ret = error(_("unable to read tree (%s)"), oid_to_hex(oid));
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		goto leave_reset_head;
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	}
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	prime_cache_tree(r, r->index, tree);
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	if (write_locked_index(r->index, &lock, COMMIT_LOCK) < 0) {
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		ret = error(_("could not write index"));
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		goto leave_reset_head;
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	}
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	if (oid != &head_oid || update_orig_head || switch_to_branch)
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		ret = update_refs(opts, oid, head);
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leave_reset_head:
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	rollback_lock_file(&lock);
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	clear_unpack_trees_porcelain(&unpack_tree_opts);
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	while (nr)
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		free((void *)desc[--nr].buffer);
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	return ret;
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}
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