libperf: Add debug output support

Add the perf_set_print() function to allow setting an output function
for warn/info/debug messages.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190721112506.12306-28-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/tools/perf/lib/core.c b/tools/perf/lib/core.c
index e69de29bb2d1..29d5e3348718 100644
--- a/tools/perf/lib/core.c
+++ b/tools/perf/lib/core.c
@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define __printf(a, b)  __attribute__((format(printf, a, b)))
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <perf/core.h>
+#include "internal.h"
+
+static int __base_pr(enum libperf_print_level level, const char *format,
+		     va_list args)
+{
+	return vfprintf(stderr, format, args);
+}
+
+static libperf_print_fn_t __libperf_pr = __base_pr;
+
+void libperf_set_print(libperf_print_fn_t fn)
+{
+	__libperf_pr = fn;
+}
+
+__printf(2, 3)
+void libperf_print(enum libperf_print_level level, const char *format, ...)
+{
+	va_list args;
+
+	if (!__libperf_pr)
+		return;
+
+	va_start(args, format);
+	__libperf_pr(level, format, args);
+	va_end(args);
+}