Function _tarWriteHeader

src/backend/replication/basebackup.c:2031–2068

static int64
_tarWriteHeader(const char *filename, const char *linktarget,
				struct stat *statbuf, bool sizeonly)
{
	char		h[TAR_BLOCK_SIZE];
	enum tarError rc;

	if (!sizeonly)
	{
		rc = tarCreateHeader(h, filename, linktarget, statbuf->st_size,
							 statbuf->st_mode, statbuf->st_uid, statbuf->st_gid,
							 statbuf->st_mtime);

		switch (rc)
		{
			case TAR_OK:
				break;
			case TAR_NAME_TOO_LONG:
				ereport(ERROR,
						(errmsg("file name too long for tar format: \"%s\"",
								filename)));
				break;
			case TAR_SYMLINK_TOO_LONG:
				ereport(ERROR,
						(errmsg("symbolic link target too long for tar format: "
								"file name \"%s\", target \"%s\"",
								filename, linktarget)));
				break;
			default:
				elog(ERROR, "unrecognized tar error: %d", rc);
		}

		pq_putmessage('d', h, sizeof(h));
		update_basebackup_progress(sizeof(h));
	}

	return sizeof(h);
}

/*
 * Write tar header for a directory.  If the entry in statbuf is a link then