Are compression errors because zs.avail_in isn't intialized?

compression.cpp

@@ -20,6 +20,9 @@ void decompressor::begin() {
 		fprintf(stderr, "initialize decompression: %d %s\n", d, zs.msg);
 		exit(EXIT_IMPOSSIBLE);
 	}
+
+	zs.avail_out = 0;
+	zs.avail_in = 0;
 }
 
 int decompressor::fread(void *p, size_t size, size_t nmemb, std::atomic<long long> *geompos) {