Function get_oid_basic

object-name.c:668–826

static int interpret_nth_prior_checkout(struct repository *r, const char *name, int namelen, struct strbuf *buf);

static int get_oid_basic(struct repository *r, const char *str, int len,
			 struct object_id *oid, unsigned int flags)
{
	static const char *warn_msg = "refname '%.*s' is ambiguous.";
	static const char *object_name_msg = N_(
	"Git normally never creates a ref that ends with 40 hex characters\n"
	"because it will be ignored when you just specify 40-hex. These refs\n"
	"may be created by mistake. For example,\n"
	"\n"
	"  git switch -c $br $(git rev-parse ...)\n"
	"\n"
	"where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
	"examine these refs and maybe delete them. Turn this message off by\n"
	"running \"git config set advice.objectNameWarning false\"");
	struct object_id tmp_oid;
	char *real_ref = NULL;
	int refs_found = 0;
	int at, reflog_len, nth_prior = 0;
	int fatal = !(flags & GET_OID_QUIETLY);
	struct repo_config_values *cfg = repo_config_values(the_repository);

	if (len == r->hash_algo->hexsz && !get_oid_hex(str, oid)) {
		if (!(flags & GET_OID_SKIP_AMBIGUITY_CHECK) &&
		    repo_settings_get_warn_ambiguous_refs(r) &&
		    cfg->warn_on_object_refname_ambiguity) {
			refs_found = repo_dwim_ref(r, str, len, &tmp_oid, &real_ref, 0);
			if (refs_found > 0) {
				warning(warn_msg, len, str);
				if (advice_enabled(ADVICE_OBJECT_NAME_WARNING))
					fprintf(stderr, "%s\n", _(object_name_msg));
			}
			free(real_ref);
		}
		return 0;
	}

	/* basic@{time or number or -number} format to query ref-log */
	reflog_len = at = 0;
	if (len && str[len-1] == '}') {
		for (at = len-4; at >= 0; at--) {
			if (str[at] == '@' && str[at+1] == '{') {
				if (str[at+2] == '-') {
					if (at != 0)
						/* @{-N} not at start */
						return -1;
					nth_prior = 1;
					continue;
				}
				if (!upstream_mark(str + at, len - at) &&
				    !push_mark(str + at, len - at)) {
					reflog_len = (len-1) - (at+2);
					len = at;
				}
				break;
			}
		}
	}