[PATCH v2 3/5] perf evlist: Refactor evlist__scnprintf_evsels

[Ian Rogers <irogers@google.com>]

Switch output to using a strbuf so the storage can be resized. Add a
maximum size argument to avoid too much output that may happen for
uncore events. Rename as scnprintf is no longer used.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-record.c |  9 ++++++---
 tools/perf/util/evlist.c    | 21 ++++++++++++---------
 tools/perf/util/evlist.h    |  3 ++-
 3 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index ba20bf7c011d..9a3f7d9f881d 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -51,6 +51,7 @@
 #include "util/clockid.h"
 #include "util/off_cpu.h"
 #include "util/bpf-filter.h"
+#include "util/strbuf.h"
 #include "asm/bug.h"
 #include "perf.h"
 #include "cputopo.h"
@@ -2784,13 +2785,15 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 		record__auxtrace_snapshot_exit(rec);
 
 	if (forks && workload_exec_errno) {
-		char msg[STRERR_BUFSIZE], strevsels[2048];
+		char msg[STRERR_BUFSIZE];
 		const char *emsg = str_error_r(workload_exec_errno, msg, sizeof(msg));
+		struct strbuf sb = STRBUF_INIT;
 
-		evlist__scnprintf_evsels(rec->evlist, sizeof(strevsels), strevsels);
+		evlist__format_evsels(rec->evlist, &sb, 2048);
 
 		pr_err("Failed to collect '%s' for the '%s' workload: %s\n",
-			strevsels, argv[0], emsg);
+			sb.buf, argv[0], emsg);
+		strbuf_release(&sb);
 		err = -1;
 		goto out_child;
 	}
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index c1a04141aed0..ffb5be41a465 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -35,6 +35,7 @@
 #include "util/util.h"
 #include "util/env.h"
 #include "util/intel-tpebs.h"
+#include "util/strbuf.h"
 #include <signal.h>
 #include <unistd.h>
 #include <sched.h>
@@ -2468,23 +2469,25 @@ struct evsel *evlist__find_evsel(struct evlist *evlist, int idx)
 	return NULL;
 }
 
-int evlist__scnprintf_evsels(struct evlist *evlist, size_t size, char *bf)
+void evlist__format_evsels(struct evlist *evlist, struct strbuf *sb, size_t max_length)
 {
 	struct evsel *evsel;
-	int printed = 0;
+	bool first = true;
 
 	evlist__for_each_entry(evlist, evsel) {
 		if (evsel__is_dummy_event(evsel))
 			continue;
-		if (size > (strlen(evsel__name(evsel)) + (printed ? 2 : 1))) {
-			printed += scnprintf(bf + printed, size - printed, "%s%s", printed ? "," : "", evsel__name(evsel));
-		} else {
-			printed += scnprintf(bf + printed, size - printed, "%s...", printed ? "," : "");
-			break;
+
+		if (!first)
+			strbuf_addch(sb, ',');
+
+		if (sb->len > max_length) {
+			strbuf_addstr(sb, "...");
+			return;
 		}
+		strbuf_addstr(sb, evsel__name(evsel));
+		first = false;
 	}
-
-	return printed;
 }
 
 void evlist__check_mem_load_aux(struct evlist *evlist)
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index edcbf1c10e92..21f6bff319fd 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -20,6 +20,7 @@ struct pollfd;
 struct thread_map;
 struct perf_cpu_map;
 struct record_opts;
+struct strbuf;
 struct target;
 
 /*
@@ -430,7 +431,7 @@ int event_enable_timer__process(struct event_enable_timer *eet);
 
 struct evsel *evlist__find_evsel(struct evlist *evlist, int idx);
 
-int evlist__scnprintf_evsels(struct evlist *evlist, size_t size, char *bf);
+void evlist__format_evsels(struct evlist *evlist, struct strbuf *sb, size_t max_length);
 void evlist__check_mem_load_aux(struct evlist *evlist);
 void evlist__warn_user_requested_cpus(struct evlist *evlist, const char *cpu_list);
 void evlist__uniquify_name(struct evlist *evlist);
-- 
2.49.0.504.g3bcea36a83-goog