perf tools: Fallback to srcdir/Documentation/tips.txt

Some people don't install perf, but just use compiled version in the
source.  Fallback to lookup the source directory for those poor guys. :)
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1452334589-8782-4-git-send-email-namhyung@kernel.org
[ Make perf_tip() return NULL for ENOENT, making the fallback to really take place ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-report.c

@@ -28,6 +28,7 @@
 #include "util/tool.h"
 
 #include <subcmd/parse-options.h>
+#include <subcmd/exec-cmd.h>
 #include "util/parse-events.h"
 
 #include "util/thread.h"
@@ -433,7 +434,14 @@ static int report__browse_hists(struct report *rep)
 	int ret;
 	struct perf_session *session = rep->session;
 	struct perf_evlist *evlist = session->evlist;
-	const char *help = perf_tip(TIPDIR);
+	const char *help = perf_tip(system_path(TIPDIR));
+
+	if (help == NULL) {
+		/* fallback for people who don't install perf ;-) */
+		help = perf_tip(DOCDIR);
+		if (help == NULL)
+			help = "Cannot load tips.txt file, please install perf!";
+	}
 
 	switch (use_browser) {
 	case 1:

tools/perf/util/util.c

@@ -17,7 +17,6 @@
 #include <unistd.h>
 #include "callchain.h"
 #include "strlist.h"
-#include <subcmd/exec-cmd.h>
 
 struct callchain_param	callchain_param = {
 	.mode	= CHAIN_GRAPH_ABS,
@@ -672,14 +671,16 @@ const char *perf_tip(const char *dirpath)
 	struct str_node *node;
 	char *tip = NULL;
 	struct strlist_config conf = {
-		.dirname = system_path(dirpath) ,
+		.dirname = dirpath,
+		.file_only = true,
 	};
 
 	tips = strlist__new("tips.txt", &conf);
-	if (tips == NULL || strlist__nr_entries(tips) == 1) {
-		tip = (char *)"Cannot find tips.txt file";
+	if (tips == NULL)
+		return errno == ENOENT ? NULL : "Tip: get more memory! ;-p";
+
+	if (strlist__nr_entries(tips) == 0)
 		goto out;
-	}
 
 	node = strlist__entry(tips, random() % strlist__nr_entries(tips));
 	if (asprintf(&tip, "Tip: %s", node->s) < 0)