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 <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/include/linux/string.h

···
 #include <string.h>
 
 void *memdup(const void *src, size_t len);
+int str_append(char **s, int *len, const char *a);

tools/perf/util/parse-events.c

···
 #include "parse-options.h"
 #include "parse-events.h"
 #include "exec_cmd.h"
-#include "string.h"
+#include "linux/string.h"
 #include "symbol.h"
 #include "cache.h"
 #include "header.h"
···
 	return 0;
 }
 
+static int parse_events__scanner(const char *str, void *data, int start_token);
+
+static int parse_events_fixup(int ret, const char *str, void *data,
+			      int start_token)
+{
+	char *o = strdup(str);
+	char *s = NULL;
+	char *t = o;
+	char *p;
+	int len = 0;
+
+	if (!o)
+		return ret;
+	while ((p = strsep(&t, ",")) != NULL) {
+		if (s)
+			str_append(&s, &len, ",");
+		str_append(&s, &len, "cpu/");
+		str_append(&s, &len, p);
+		str_append(&s, &len, "/");
+	}
+	free(o);
+	if (!s)
+		return -ENOMEM;
+	return parse_events__scanner(s, data, start_token);
+}
+
 static int parse_events__scanner(const char *str, void *data, int start_token)
 {
 	YY_BUFFER_STATE buffer;
···
 	parse_events__flush_buffer(buffer, scanner);
 	parse_events__delete_buffer(buffer, scanner);
 	parse_events_lex_destroy(scanner);
+	if (ret && !strchr(str, '/'))
+		ret = parse_events_fixup(ret, str, data, start_token);
 	return ret;
 }
 

tools/perf/util/string.c

···
 
 	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;
+}