[Skiboot] [PATCH 15/15] external/trace: Add 'follow' option to dump_trace

[Jordan Niethe]

When monitoring traces, an option like the tail command's '-f' (follow)
is very useful. This option continues to append to the output as more
data arrives. Add an option to allow dump_trace to operate similarly.
---
 external/trace/dump_trace.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/external/trace/dump_trace.c b/external/trace/dump_trace.c
index f29da62fbabc..05cdab99846a 100644
--- a/external/trace/dump_trace.c
+++ b/external/trace/dump_trace.c
@@ -40,6 +40,8 @@ struct trace_entry {
 	struct list_node link;
 };
 
+static int follow;
+
 static void *ezalloc(size_t size)
 {
 	void *p;
@@ -248,14 +250,23 @@ int main(int argc, char *argv[])
 {
 	struct trace_reader *trs;
 	struct trace_info *ti;
-	int fd, i;
+	int fd, opt, i;
 
+	while ((opt = getopt(argc, argv, "f")) != -1) {
+		switch (opt) {
+		case 'f':
+			follow++;
+			break;
+		default:
+			errx(1, "Unknown option: %c", optopt);
+		}
+	}
+	argc -= optind;
+	argv += optind;
 
-	if (argc < 2)
-		errx(1, "Usage: dump_trace file...");
+	if (argc < 1)
+		errx(1, "Usage: dump_trace [-f] file...");
 
-	argc--;
-	argv++;
 	trs = ezalloc(sizeof(struct trace_reader) * argc);
 
 	for (i =  0; i < argc; i++) {
@@ -272,8 +283,12 @@ int main(int argc, char *argv[])
 		list_head_init(&trs[i].traces);
 	}
 
-	load_traces(trs, argc);
-	display_traces(trs, argc);
+	do {
+		load_traces(trs, argc);
+		display_traces(trs, argc);
+		if (follow)
+			sleep(1);
+	} while (follow);
 
 	return 0;
 }
-- 
2.20.1