From dc9d161607137f00c1747477c7de7406dc97f5fa Mon Sep 17 00:00:00 2001
From: Michael Maroszek <maroszek@gmx.net>
Date: Sun, 21 May 2023 00:24:32 +0200
Subject: [PATCH] detect current zone on OpenWRT systems

---
 src/tz.cpp | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/src/tz.cpp b/src/tz.cpp
index aa6b7bd..dcadf40 100644
--- a/src/tz.cpp
+++ b/src/tz.cpp
@@ -4170,6 +4170,25 @@ tzdb::current_zone() const
         }
         // Fall through to try other means.
     }
+    // On OpenWRT we need to check /etc/config/system
+    // It will have a line with the following structure
+    //   ...
+    //   option zoneName 'Europe/Berlin'
+    //   ...
+    {
+        std::ifstream timezone_file("/etc/config/system");
+        if (timezone_file.is_open())
+        {
+            for(std::string result; std::getline(timezone_file, result);) {
+                std::string findStr = "option zoneName '";
+                size_t startPos = result.find(findStr);
+                if (startPos != std::string::npos) {
+                    size_t endPos = result.find("'", startPos + findStr.size());
+                    return locate_zone(result.substr(startPos + findStr.size(), endPos - startPos - findStr.size()));
+                }
+            }
+        }
+    }
     throw std::runtime_error("Could not get current timezone");
 }