Function should_exclude_current_ref

refs/reftable-backend.c:543–604

* Handle exclude patterns. Returns either `1`, which tells the caller that the * current reference shall not be shown. Or `0`, which indicates that it should * be shown. */

 * be shown.
 */
static int should_exclude_current_ref(struct reftable_ref_iterator *iter)
{
	while (iter->exclude_patterns[iter->exclude_patterns_index]) {
		const char *pattern = iter->exclude_patterns[iter->exclude_patterns_index];
		char *ref_after_pattern;
		int cmp;

		/*
		 * Lazily cache the pattern length so that we don't have to
		 * recompute it every time this function is called.
		 */
		if (!iter->exclude_patterns_strlen)
			iter->exclude_patterns_strlen = strlen(pattern);

		/*
		 * When the reference name is lexicographically bigger than the
		 * current exclude pattern we know that it won't ever match any
		 * of the following references, either. We thus advance to the
		 * next pattern and re-check whether it matches.
		 *
		 * Otherwise, if it's smaller, then we do not have a match and
		 * thus want to show the current reference.
		 */
		cmp = strncmp(iter->ref.refname, pattern,
			      iter->exclude_patterns_strlen);
		if (cmp > 0) {
			iter->exclude_patterns_index++;
			iter->exclude_patterns_strlen = 0;
			continue;
		}
		if (cmp < 0)
			return 0;

		/*
		 * The reference shares a prefix with the exclude pattern and
		 * shall thus be omitted. We skip all references that match the
		 * pattern by seeking to the first reference after the block of
		 * matches.
		 *
		 * This is done by appending the highest possible character to
		 * the pattern. Consequently, all references that have the
		 * pattern as prefix and whose suffix starts with anything in
		 * the range [0x00, 0xfe] are skipped. And given that 0xff is a
		 * non-printable character that shouldn't ever be in a ref name,
		 * we'd not yield any such record, either.
		 *
		 * Note that the seeked-to reference may also be excluded. This
		 * is not handled here though, but the caller is expected to
		 * loop and re-verify the next reference for us.
		 */
		ref_after_pattern = xstrfmt("%s%c", pattern, 0xff);
		iter->err = reftable_iterator_seek_ref(&iter->iter, ref_after_pattern);
		iter->exclude_patterns_index++;
		iter->exclude_patterns_strlen = 0;
		trace2_counter_add(TRACE2_COUNTER_ID_REFTABLE_RESEEKS, 1);

		free(ref_after_pattern);
		return 1;