util/ChronoUtil: new utility library for std::chrono

Makefile.am

@@ -405,6 +405,7 @@ libutil_a_SOURCES = \
 	src/util/Macros.hxx \
 	src/util/BindMethod.hxx \
 	src/util/Cast.hxx \
+	src/util/Chrono.hxx \
 	src/util/Clamp.hxx \
 	src/util/DeleteDisposer.hxx \
 	src/util/Alloc.cxx src/util/Alloc.hxx \

src/storage/plugins/CurlStorage.cxx

@@ -33,6 +33,7 @@
 #include "event/DeferredMonitor.hxx"
 #include "thread/Mutex.hxx"
 #include "thread/Cond.hxx"
+#include "util/ChronoUtil.hxx"
 #include "util/RuntimeError.hxx"
 #include "util/StringCompare.hxx"
 #include "util/TimeParser.hxx"
@@ -420,7 +421,7 @@ protected:
 			? StorageFileInfo::Type::DIRECTORY
 			: StorageFileInfo::Type::REGULAR;
 		info.size = r.length;
-		info.mtime = r.mtime > std::chrono::system_clock::time_point()
+		info.mtime = !IsNegative(r.mtime)
 			? std::chrono::system_clock::to_time_t(r.mtime)
 			: 0;
 		info.device = info.inode = 0;
@@ -517,7 +518,7 @@ protected:
 			? StorageFileInfo::Type::DIRECTORY
 			: StorageFileInfo::Type::REGULAR;
 		info.size = r.length;
-		info.mtime = r.mtime > std::chrono::system_clock::time_point()
+		info.mtime = !IsNegative(r.mtime)
 			? std::chrono::system_clock::to_time_t(r.mtime)
 			: 0;
 		info.device = info.inode = 0;

src/util/ChronoUtil.hxx

@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2017 Max Kellermann <max.kellermann@gmail.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 CHRONO_UTIL_HXX
+#define CHRONO_UTIL_HXX
+
+#include <chrono>
+
+template<typename Clock, typename Duration>
+constexpr bool
+IsNegative(const std::chrono::time_point<Clock, Duration> p)
+{
+	return p < std::chrono::time_point<Clock, Duration>();
+}
+
+#endif