*Save, *State: use the OutputStream API instead of FILE*

src/mixer/Volume.cxx

@@ -24,6 +24,7 @@
 #include "util/StringUtil.hxx"
 #include "util/Domain.hxx"
 #include "system/PeriodClock.hxx"
+#include "fs/output/BufferedOutputStream.hxx"
 #include "Log.hxx"
 
 #include <assert.h>
@@ -110,9 +111,10 @@ read_sw_volume_state(const char *line, MultipleOutputs &outputs)
 	return true;
 }
 
-void save_sw_volume_state(FILE *fp)
+void
+save_sw_volume_state(BufferedOutputStream &os)
 {
-	fprintf(fp, SW_VOLUME_STATE "%u\n", volume_software_set);
+	os.Format(SW_VOLUME_STATE "%u\n", volume_software_set);
 }
 
 unsigned

src/mixer/Volume.hxx

@@ -22,9 +22,8 @@
 
 #include "Compiler.h"
 
-#include <stdio.h>
-
 class MultipleOutputs;
+class BufferedOutputStream;
 
 void
 InvalidateHardwareVolume();
@@ -39,7 +38,8 @@ volume_level_change(MultipleOutputs &outputs, unsigned volume);
 bool
 read_sw_volume_state(const char *line, MultipleOutputs &outputs);
 
-void save_sw_volume_state(FILE *fp);
+void
+save_sw_volume_state(BufferedOutputStream &os);
 
 /**
  * Generates a hash number for the current state of the software