perf lib: Introduce rtrim

Remove the trailing whitespaces.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-8bxozh5lyixgjmziqaxo9675@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/string.c

@@ -313,3 +313,25 @@ int strtailcmp(const char *s1, const char *s2)
 	return 0;
 }
 
+/**
+ * rtrim - Removes trailing whitespace from @s.
+ * @s: The string to be stripped.
+ *
+ * Note that the first trailing whitespace is replaced with a %NUL-terminator
+ * in the given string @s. Returns @s.
+ */
+char *rtrim(char *s)
+{
+	size_t size = strlen(s);
+	char *end;
+
+	if (!size)
+		return s;
+
+	end = s + size - 1;
+	while (end >= s && isspace(*end))
+		end--;
+	*(end + 1) = '\0';
+
+	return s;
+}

tools/perf/util/util.h

@@ -264,4 +264,6 @@ bool is_power_of_2(unsigned long n)
 
 size_t hex_width(u64 v);
 
+char *rtrim(char *s);
+
 #endif