+ if (!(greedy_realloc(buffer, buffer_size, *buffer_size * 2, 1)))
+ return false;
+
+ s.next_out = *buffer + *buffer_size - s.avail_out;
+ }
+}
+
+int compress_stream(int fdf, int fdt, uint32_t preset, off_t max_bytes) {
+ _cleanup_(lzma_end) lzma_stream s = LZMA_STREAM_INIT;
+ lzma_ret ret;
+
+ uint8_t buf[BUFSIZ], out[BUFSIZ];
+ lzma_action action = LZMA_RUN;
+
+ assert(fdf >= 0);
+ assert(fdt >= 0);
+
+ ret = lzma_easy_encoder(&s, preset, LZMA_CHECK_CRC64);
+ if (ret != LZMA_OK) {
+ log_error("Failed to initialize XZ encoder: code %d", ret);
+ return -EINVAL;
+ }
+
+ for (;;) {
+ if (s.avail_in == 0 && action == LZMA_RUN) {
+ size_t m = sizeof(buf);
+ ssize_t n;
+
+ if (max_bytes != -1 && m > (size_t) max_bytes)
+ m = max_bytes;
+
+ n = read(fdf, buf, m);
+ if (n < 0)
+ return -errno;
+ if (n == 0)
+ action = LZMA_FINISH;
+ else {
+ s.next_in = buf;
+ s.avail_in = n;
+
+ if (max_bytes != -1) {
+ assert(max_bytes >= n);
+ max_bytes -= n;
+ }
+ }
+ }
+
+ if (s.avail_out == 0) {
+ s.next_out = out;
+ s.avail_out = sizeof(out);
+ }
+
+ ret = lzma_code(&s, action);
+ if (ret != LZMA_OK && ret != LZMA_STREAM_END) {
+ log_error("Compression failed: code %d", ret);
+ return -EBADMSG;
+ }
+
+ if (s.avail_out == 0 || ret == LZMA_STREAM_END) {
+ ssize_t n, k;
+
+ n = sizeof(out) - s.avail_out;
+
+ errno = 0;
+ k = loop_write(fdt, out, n, false);
+ if (k < 0)
+ return k;
+ if (k != n)
+ return errno ? -errno : -EIO;
+
+ if (ret == LZMA_STREAM_END) {
+ log_debug("Compression finished (%zu -> %zu bytes, %.1f%%)",
+ s.total_in, s.total_out,
+ (double) s.total_out / s.total_in * 100);
+
+ return 0;
+ }
+ }