From a2bc1d8572c62442b8a26bb15ee5e6db9bf61850 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Beat=20K=C3=BCng?= <beat-kueng@gmx.net>
Date: Mon, 29 Mar 2021 10:41:34 +0200
Subject: [PATCH] QGCLZMA: init crc table only once

---
 src/Compression/QGCLZMA.cc | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/Compression/QGCLZMA.cc b/src/Compression/QGCLZMA.cc
index 7ac69a4..d7e08b7 100644
--- a/src/Compression/QGCLZMA.cc
+++ b/src/Compression/QGCLZMA.cc
@@ -13,8 +13,13 @@
 #include <QDir>
 #include <QtDebug>
 
+#include <mutex>
+
 #include "xz.h"
 
+
+static std::once_flag crc_init;
+
 bool QGCLZMA::inflateLZMAFile(const QString& lzmaFilename, const QString& decompressedFilename)
 {
     QFile inputFile(lzmaFilename);
@@ -30,9 +35,10 @@ bool QGCLZMA::inflateLZMAFile(const QString& lzmaFilename, const QString& decomp
     }
 
 
-    // TODO: call once during startup
-    xz_crc32_init();
-    xz_crc64_init();
+    std::call_once(crc_init, []() {
+        xz_crc32_init();
+        xz_crc64_init();
+    });
 
 
     xz_dec *s = xz_dec_init(XZ_DYNALLOC, (uint32_t)-1);