s390-tools: Add function util_strstrip

Function strstrip strips leading and trailung
spaces from a given string.
During review it was decided to move this function
to the libutil library to make it available for other tools.

Signed-off-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

include/lib/util_str.h

@@ -0,0 +1,25 @@
+/**
+ * @defgroup util_str
+ * @{
+ * @brief Strip leading and trailing blanks
+ *
+ * Copyright IBM Corp. 2018
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#ifndef LIB_UTIL_STR_H
+#define LIB_UTIL_STR_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+char *util_strstrip(char *s);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /** LIB_UTIL_STRSTRIP_H @} */

libutil/Makefile

@@ -26,7 +26,8 @@ objects =	util_base.o \
 		util_part.o \
 		util_prg.o \
 		util_proc.o \
-		util_rec.o
+		util_rec.o \
+		util_str.o
 
 util_base_example: util_base_example.o $(lib)
 util_panic_example: util_panic_example.o $(lib)

libutil/util_str.c

@@ -0,0 +1,39 @@
+/*
+ * util - Utility function library
+ *
+ * Strip leading and trailing blanks.
+ *
+ * Copyright IBM Corp. 2018
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#include <string.h>
+#include <ctype.h>
+
+#include "lib/util_str.h"
+
+/*
+ * strip leading and trailing blanks
+ */
+char *util_strstrip(char *s)
+{
+	size_t size;
+	char *end;
+
+	size = strlen(s);
+
+	if (!size)
+		return s;
+
+	end = s + size - 1;
+	while (end >= s && isspace(*end))
+		end--;
+	*(end + 1) = '\0';
+
+	while (*s && isspace(*s))
+		s++;
+
+	return s;
+}