util/TimeConvert: new utility library

src/util/TimeConvert.cxx

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2007-2017 Content Management AG
+ * All rights reserved.
+ *
+ * author: Max Kellermann <mk@cm4all.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "TimeConvert.hxx"
+
+#include <stdexcept>
+
+#include <time.h>
+
+struct tm
+GmTime(std::chrono::system_clock::time_point tp)
+{
+	const time_t t = std::chrono::system_clock::to_time_t(tp);
+#ifdef _WIN32
+	const struct tm *tm = gmtime(&t);
+#else
+	struct tm buffer, *tm = gmtime_r(&t, &buffer);
+#endif
+	if (tm == nullptr)
+		throw std::runtime_error("gmtime_r() failed");
+
+	return *tm;
+}
+
+struct tm
+LocalTime(std::chrono::system_clock::time_point tp)
+{
+	const time_t t = std::chrono::system_clock::to_time_t(tp);
+#ifdef _WIN32
+	const struct tm *tm = localtime(&t);
+#else
+	struct tm buffer, *tm = localtime_r(&t, &buffer);
+#endif
+	if (tm == nullptr)
+		throw std::runtime_error("localtime_r() failed");
+
+	return *tm;
+}
+
+#ifdef __GLIBC__
+
+std::chrono::system_clock::time_point
+TimeGm(struct tm &tm)
+{
+	return std::chrono::system_clock::from_time_t(timegm(&tm));
+}
+
+#endif
+
+std::chrono::system_clock::time_point
+MakeTime(struct tm &tm)
+{
+	return std::chrono::system_clock::from_time_t(mktime(&tm));
+}

src/util/TimeConvert.hxx

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2007-2017 Content Management AG
+ * All rights reserved.
+ *
+ * author: Max Kellermann <mk@cm4all.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef TIME_CONVERT_HXX
+#define TIME_CONVERT_HXX
+
+#include <chrono>
+
+/**
+ * Convert a UTC-based time point to a UTC-based "struct tm".
+ */
+struct tm
+GmTime(std::chrono::system_clock::time_point tp);
+
+/**
+ * Convert a UTC-based time point to a local "struct tm".
+ */
+struct tm
+LocalTime(std::chrono::system_clock::time_point tp);
+
+#ifdef __GLIBC__
+
+/**
+ * Convert a UTC-based "struct tm" to a UTC-based time point.
+ */
+std::chrono::system_clock::time_point
+TimeGm(struct tm &tm);
+
+#endif
+
+/**
+ * Convert a local "struct tm" to a UTC-based time point.
+ */
+std::chrono::system_clock::time_point
+MakeTime(struct tm &tm);
+
+#endif