smart: importing common.{h,c} from munin-c

The compilation is very easy, a simple `make` should work, as I provided
a convenient `Makefile`

plugins/disk/smart-c/common.h

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2008 Helmut Grohne <helmut@subdivi.de> - All rights reserved.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU General Public License v.2 or v.3.
+ */
+#ifndef COMMON_H
+#define COMMON_H
+
+#define PROC_STAT "/proc/stat"
+
+/** Write yes to stdout and return 0. The intended use is give an autoconf
+ * response like "return writeyes();".
+ * @returns a success state to be passed on as the return value from main */
+int writeyes(void);
+
+/** Answer an autoconf request by checking the readability of the given file.
+ */
+int autoconf_check_readable(const char *);
+
+/** Obtain an integer value from the environment. In the absence of the
+ * variable the given defaultvalue is returned.  */
+int getenvint(const char *, int defaultvalue);
+
+/** Print a name.warning line using the "name_warning" or "warning" environment
+ * variables. */
+void print_warning(const char *name);
+
+/** Print a name.critical line using the "name_critical" or "critical"
+ * environment variables. */
+void print_critical(const char *name);
+
+/** Print both name.warning and name.critical lines using environment
+ * variables. */
+void print_warncrit(const char *name);
+
+/** Fail by printing the given message and a newline to stderr.
+ * @returns a failure state to be passed on as the return value from main */
+int fail(const char *message);
+
+#define xisspace(x) isspace((int)(unsigned char) x)
+#define xisdigit(x) isdigit((int)(unsigned char) x)
+
+#endif