crucible: add cleanup class

Store a function (or closure) in an instance and invoke the function
from the destructor.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

include/crucible/cleanup.h

@@ -0,0 +1,18 @@
+#ifndef CRUCIBLE_CLEANUP_H
+#define CRUCIBLE_CLEANUP_H
+
+#include <functional>
+
+namespace crucible {
+	using namespace std;
+
+	class Cleanup {
+		function<void()> m_cleaner;
+	public:
+		Cleanup(function<void()> func);
+		~Cleanup();
+	};
+
+}
+
+#endif // CRUCIBLE_CLEANUP_H

lib/Makefile

@@ -3,8 +3,9 @@ TAG := $(shell git describe --always --dirty || echo UNKNOWN)
 default: libcrucible.so
 
 OBJS = \
-	crc64.o \
 	chatter.o \
+	cleanup.o \
+	crc64.o \
 	error.o \
 	extentwalker.o \
 	fd.o \

lib/cleanup.cc

@@ -0,0 +1,17 @@
+#include <crucible/cleanup.h>
+
+namespace crucible {
+
+	Cleanup::Cleanup(function<void()> func) :
+		m_cleaner(func)
+	{
+	}
+
+	Cleanup::~Cleanup()
+	{
+		if (m_cleaner) {
+			m_cleaner();
+		}
+	}
+
+}