Function tar_write_compressed_data

src/bin/pg_basebackup/walmethods.c:508–556

#ifdef HAVE_LIBZ
static bool
tar_write_compressed_data(void *buf, size_t count, bool flush)
{
	tar_data->zp->next_in = buf;
	tar_data->zp->avail_in = count;

	while (tar_data->zp->avail_in || flush)
	{
		int			r;

		r = deflate(tar_data->zp, flush ? Z_FINISH : Z_NO_FLUSH);
		if (r == Z_STREAM_ERROR)
		{
			tar_set_error("could not compress data");
			return false;
		}

		if (tar_data->zp->avail_out < ZLIB_OUT_SIZE)
		{
			size_t		len = ZLIB_OUT_SIZE - tar_data->zp->avail_out;

			errno = 0;
			if (write(tar_data->fd, tar_data->zlibOut, len) != len)
			{
				/* If write didn't set errno, assume problem is no disk space */
				tar_data->lasterrno = errno ? errno : ENOSPC;
				return false;
			}

			tar_data->zp->next_out = tar_data->zlibOut;
			tar_data->zp->avail_out = ZLIB_OUT_SIZE;
		}

		if (r == Z_STREAM_END)
			break;
	}

	if (flush)
	{
		/* Reset the stream for writing */
		if (deflateReset(tar_data->zp) != Z_OK)
		{
			tar_set_error("could not reset compression stream");
			return false;
		}
	}

	return true;
}
#endif

static ssize_t