config/Data: cast to std::chrono::steady_clock::duration properly

Oh no, 3413d1bf23 was broken!  Instead of passing a number as
"seconds" to the duration constructor, it just abused the duration
constructor as cast operator, which caused custom state_file_interval
settings to be extremely short.

NEWS

@@ -4,6 +4,7 @@ ver 0.22.1 (not yet released)
   - jack, pulse: reduce the delay when stopping or pausing playback
 * playlist
   - cue: fix two crash bugs
+* state_file: fix the state_file_interval setting
 
 ver 0.22 (2020/09/23)
 * protocol

src/config/Data.cxx

@@ -101,6 +101,38 @@ ConfigData::GetPositive(ConfigOption option, unsigned default_value) const
 	});
 }
 
+std::chrono::steady_clock::duration
+ConfigData::GetUnsigned(ConfigOption option,
+			std::chrono::steady_clock::duration default_value) const
+{
+	return With(option, [default_value](const char *s){
+		if (s == nullptr)
+			return default_value;
+
+		auto value = ParseDuration(s);
+		if (value < std::chrono::steady_clock::duration{})
+			throw std::runtime_error("Value must not be negative");
+
+		return value;
+	});
+}
+
+std::chrono::steady_clock::duration
+ConfigData::GetPositive(ConfigOption option,
+			std::chrono::steady_clock::duration default_value) const
+{
+	return With(option, [default_value](const char *s){
+		if (s == nullptr)
+			return default_value;
+
+		auto value = ParseDuration(s);
+		if (value <= std::chrono::steady_clock::duration{})
+			throw std::runtime_error("Value must be positive");
+
+		return value;
+	});
+}
+
 bool
 ConfigData::GetBool(ConfigOption option, bool default_value) const
 {

src/config/Data.hxx

@@ -78,22 +78,14 @@ struct ConfigData {
 
 	std::chrono::steady_clock::duration
 	GetUnsigned(ConfigOption option,
-		    std::chrono::steady_clock::duration default_value) const {
+		    std::chrono::steady_clock::duration default_value) const;
-		// TODO: allow unit suffixes
-		auto u = GetUnsigned(option, default_value.count());
-		return std::chrono::steady_clock::duration(u);
-	}
 
 	unsigned GetPositive(ConfigOption option,
 			     unsigned default_value) const;
 
 	std::chrono::steady_clock::duration
 	GetPositive(ConfigOption option,
-		    std::chrono::steady_clock::duration default_value) const {
+		    std::chrono::steady_clock::duration default_value) const;
-		// TODO: allow unit suffixes
-		auto u = GetPositive(option, default_value.count());
-		return std::chrono::steady_clock::duration(u);
-	}
 
 	bool GetBool(ConfigOption option, bool default_value) const;
 

src/config/Parser.cxx

@@ -135,3 +135,11 @@ ParseSize(const char *s, std::size_t default_factor)
 
 	return value;
 }
+
+std::chrono::steady_clock::duration
+ParseDuration(const char *s)
+{
+	// TODO: allow unit suffixes
+	const std::chrono::seconds seconds(ParseLong(s));
+	return std::chrono::duration_cast<std::chrono::steady_clock::duration>(seconds);
+}

src/config/Parser.hxx

@@ -20,6 +20,7 @@
 #ifndef MPD_CONFIG_PARSER_HXX
 #define MPD_CONFIG_PARSER_HXX
 
+#include <chrono>
 #include <cstddef>
 
 /**
@@ -54,4 +55,10 @@ ParsePositive(const char *s);
 std::size_t
 ParseSize(const char *s, std::size_t default_factor=1);
 
+/**
+ * Throws on error.
+ */
+std::chrono::steady_clock::duration
+ParseDuration(const char *s);
+
 #endif