perf tools: Default to cpu// for events v5

When an event fails to parse and it's not in a new style format,
try to parse it again as a cpu event.

This allows to use sysfs exported events directly without //, so you can use

perf record -e mem-loads ...

instead of

perf record -e cpu/mem-loads/

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1366480949-32292-1-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/string.c b/tools/perf/util/string.c
index 29c7b2c..f0b0c00 100644
--- a/tools/perf/util/string.c
+++ b/tools/perf/util/string.c
@@ -387,3 +387,27 @@
 
 	return p;
 }
+
+/**
+ * str_append - reallocate string and append another
+ * @s: pointer to string pointer
+ * @len: pointer to len (initialized)
+ * @a: string to append.
+ */
+int str_append(char **s, int *len, const char *a)
+{
+	int olen = *s ? strlen(*s) : 0;
+	int nlen = olen + strlen(a) + 1;
+	if (*len < nlen) {
+		*len = *len * 2;
+		if (*len < nlen)
+			*len = nlen;
+		*s = realloc(*s, *len);
+		if (!*s)
+			return -ENOMEM;
+		if (olen == 0)
+			**s = 0;
+	}
+	strcat(*s, a);
+	return 0;
+}