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

util.c

@@ -0,0 +1,42 @@
+#include <err.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "util.h"
+
+const char *
+bprintf(const char *fmt, ...)
+{
+	va_list ap;
+	size_t len;
+
+	va_start(ap, fmt);
+	len = vsnprintf(buf, sizeof(buf) - 1, fmt, ap);
+	va_end(ap);
+
+	if (len >= sizeof(buf))
+		buf[sizeof(buf)-1] = '\0';
+
+	return buf;
+}
+
+int
+pscanf(const char *path, const char *fmt, ...)
+{
+	FILE *fp;
+	va_list ap;
+	int n;
+
+	if (!(fp = fopen(path, "r"))) {
+		warn("fopen %s: %s\n", path, strerror(errno));
+		return -1;
+	}
+	va_start(ap, fmt);
+	n = vfscanf(fp, fmt, ap);
+	va_end(ap);
+	fclose(fp);
+
+	return (n == EOF) ? -1 : n;
+}