+finish_zstream (struct sfm_writer *w)
+{
+ struct zblock *block;
+ int error;
+
+ assert (w->zstream.total_in <= ZBLOCK_SIZE);
+
+ w->zstream.next_in = NULL;
+ w->zstream.avail_in = 0;
+ do
+ {
+ uint8_t buf[4096];
+
+ w->zstream.next_out = buf;
+ w->zstream.avail_out = sizeof buf;
+ error = deflate (&w->zstream, Z_FINISH);
+ write_bytes (w, buf, w->zstream.next_out - buf);
+ }
+ while (error == Z_OK);
+
+ if (error != Z_STREAM_END)
+ msg (ME, _("Failed to complete ZLIB stream compression (%s)."),
+ w->zstream.msg);
+
+ if (w->n_blocks >= w->allocated_blocks)
+ w->blocks = x2nrealloc (w->blocks, &w->allocated_blocks,
+ sizeof *w->blocks);
+ block = &w->blocks[w->n_blocks++];
+ block->uncompressed_size = w->zstream.total_in;
+ block->compressed_size = w->zstream.total_out;
+ deflateEnd (&w->zstream);
+}
+
+static void
+write_zlib (struct sfm_writer *w, const void *data_, unsigned int n)
+{
+ const uint8_t *data = data_;
+
+ while (n > 0)
+ {
+ unsigned int chunk;
+
+ if (w->zstream.total_in >= ZBLOCK_SIZE)
+ {
+ finish_zstream (w);
+ start_zstream (w);
+ }
+
+ chunk = MIN (n, ZBLOCK_SIZE - w->zstream.total_in);
+
+ w->zstream.next_in = CONST_CAST (uint8_t *, data);
+ w->zstream.avail_in = chunk;
+ do
+ {
+ uint8_t buf[4096];
+ int error;
+
+ w->zstream.next_out = buf;
+ w->zstream.avail_out = sizeof buf;
+ error = deflate (&w->zstream, Z_NO_FLUSH);
+ write_bytes (w, buf, w->zstream.next_out - buf);
+ if (error != Z_OK)
+ {
+ msg (ME, _("ZLIB stream compression failed (%s)."),
+ w->zstream.msg);
+ return;
+ }
+ }
+ while (w->zstream.avail_in > 0 || w->zstream.avail_out == 0);
+ data += chunk;
+ n -= chunk;
+ }
+}
+
+static void
+write_ztrailer (struct sfm_writer *w)