proper helper function to get utc time

crash_printer/linux.cpp

@@ -52,11 +52,7 @@ static void exception_handler(int signal, siginfo_t *info, void *context, struct
     
     std::ofstream file(logs_filepath, std::ios::app);
 
-    auto now = std::chrono::system_clock::now();
+    std::string time(common_helpers::get_utc_time());
-    auto t_now = std::chrono::system_clock::to_time_t(now);
-    auto gm_time = std::gmtime(&t_now);
-    auto time = std::string(std::asctime(gm_time));
-    time.pop_back(); // remove the trailing '\n' added by asctime
     common_helpers::write(file, "[" + time + "]");
     {
         std::stringstream ss{};

crash_printer/win.cpp

@@ -106,12 +106,7 @@ static void log_exception(LPEXCEPTION_POINTERS ex_pointers)
     
     std::ofstream file(std::filesystem::path(logs_filepath), std::ios::app);
 
-    auto now = std::chrono::system_clock::now();
+    std::string time(common_helpers::get_utc_time());
-    auto t_now = std::chrono::system_clock::to_time_t(now);
-    auto gm_time = std::gmtime(&t_now);
-    auto asc_time = std::asctime(gm_time);
-    auto time = std::string(asc_time ? asc_time : "");
-    time.pop_back(); // remove the trailing '\n' added by asctime
     common_helpers::write(file, "[" + time + "]");
     {
         std::stringstream ss{};

helpers/common_helpers.cpp

@@ -5,6 +5,11 @@
 #include <cctype>
 #include <random>
 
+// for gmtime_s()
+#define __STDC_WANT_LIB_EXT1__ 1
+#include <time.h>
+
+
 namespace common_helpers {
 
 KillableWorker::KillableWorker(
@@ -407,3 +412,24 @@ size_t common_helpers::rand_number(size_t max)
 
     return distrib(gen);
 }
+
+std::string common_helpers::get_utc_time()
+{
+    // https://en.cppreference.com/w/cpp/chrono/c/strftime
+    std::time_t time = std::time({});
+    std::tm utc_time{};
+
+    bool is_ok{};
+#if defined(__GNUC__) || defined(POSIX)
+    is_ok = !!gmtime_s(&time, &utc_time);
+#else
+    is_ok = !gmtime_s(&utc_time, &time);
+#endif
+    std::string time_str(4 +1 +2 +1 +2 +3 +2 +1 +2 +1 +2 +1, '\0');
+    if (is_ok) {
+        constexpr const static char fmt[] = "%Y/%m/%d - %H:%M:%S";
+        size_t chars = std::strftime(&time_str[0], time_str.size(), fmt, &utc_time);
+        time_str.resize(chars);
+    }
+    return time_str;
+}

helpers/common_helpers/common_helpers.hpp

@@ -101,4 +101,6 @@ bool dir_exist(const std::wstring &dirpath);
 // between 0 and max, 0 and max are included
 size_t rand_number(size_t max);
 
+std::string get_utc_time();
+
 }