Split into multiple files

For multiple reasons the program is now split:
- Make future porting to OpenBSD easier
- Assign header includes to individiual functions
- Make future program extensions easier
- Recompile only changed parts

disk.c

@@ -0,0 +1,60 @@
+#include <err.h>
+#include <stdio.h>
+#include <sys/statvfs.h>
+
+#include "util.h"
+
+const char *
+disk_free(const char *mnt)
+{
+	struct statvfs fs;
+
+	if (statvfs(mnt, &fs) < 0) {
+		warn("Failed to get filesystem info");
+		return NULL;
+	}
+
+	return bprintf("%f", (float)fs.f_bsize * (float)fs.f_bfree / 1024 / 1024 / 1024);
+}
+
+const char *
+disk_perc(const char *mnt)
+{
+	int perc;
+	struct statvfs fs;
+
+	if (statvfs(mnt, &fs) < 0) {
+		warn("Failed to get filesystem info");
+		return NULL;
+	}
+
+	perc = 100 * (1.0f - ((float)fs.f_bfree / (float)fs.f_blocks));
+
+	return bprintf("%d", perc);
+}
+
+const char *
+disk_total(const char *mnt)
+{
+	struct statvfs fs;
+
+	if (statvfs(mnt, &fs) < 0) {
+		warn("Failed to get filesystem info");
+		return NULL;
+	}
+
+	return bprintf("%f", (float)fs.f_bsize * (float)fs.f_blocks / 1024 / 1024 / 1024);
+}
+
+const char *
+disk_used(const char *mnt)
+{
+	struct statvfs fs;
+
+	if (statvfs(mnt, &fs) < 0) {
+		warn("Failed to get filesystem info");
+		return NULL;
+	}
+
+	return bprintf("%f", (float)fs.f_bsize * ((float)fs.f_blocks - (float)fs.f_bfree) / 1024 / 1024 / 1024);
+}