lib/util: add spdk_str_trim()

Function to trim leading and trailing whitespace from a string.

Originally based on code imported from istgt.

Change-Id: I87abe584130bdf4930098fadb8e57291f18eda7f
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>

include/spdk/string.h

@@ -67,6 +67,13 @@ char *spdk_strlwr(char *s);
  */
 char *spdk_strsepq(char **stringp, const char *delim);
 
+/**
+ * Trim whitespace from a string in place.
+ *
+ * \param s String to trim.
+ */
+char *spdk_str_trim(char *s);
+
 #ifdef __cplusplus
 }
 #endif

lib/util/string.c

@@ -166,3 +166,37 @@ spdk_strsepq(char **stringp, const char *delim)
 
 	return p;
 }
+
+char *
+spdk_str_trim(char *s)
+{
+	char *p, *q;
+
+	if (s == NULL) {
+		return NULL;
+	}
+
+	/* remove header */
+	p = s;
+	while (*p != '\0' && isspace(*p)) {
+		p++;
+	}
+
+	/* remove tailer */
+	q = p + strlen(p);
+	while (q - 1 >= p && isspace(*(q - 1))) {
+		q--;
+		*q = '\0';
+	}
+
+	/* if remove header, move */
+	if (p != s) {
+		q = s;
+		while (*p != '\0') {
+			*q++ = *p++;
+		}
+		*q = '\0';
+	}
+
+	return s;
+}