By returning previously set print callback from libbpf_set_print, it's
possible to restore it, eventually. This is useful when running many
independent test with one default print function, but overriding log
verbosity for particular subset of tests.
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
---
tools/lib/bpf/libbpf.c | 5 ++++-
tools/lib/bpf/libbpf.h | 2 +-
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 8741c39adb1c..ead915aec349 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -74,9 +74,12 @@ static int __base_pr(enum libbpf_print_level level, const char *format,
static libbpf_print_fn_t __libbpf_pr = __base_pr;
-void libbpf_set_print(libbpf_print_fn_t fn)
+libbpf_print_fn_t libbpf_set_print(libbpf_print_fn_t fn)
{
+ libbpf_print_fn_t old_print_fn = __libbpf_pr;
+
__libbpf_pr = fn;
+ return old_print_fn;
}
__printf(2, 3)
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 5cbf459ece0b..8a9d462a6f6d 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -57,7 +57,7 @@ enum libbpf_print_level {
typedef int (*libbpf_print_fn_t)(enum libbpf_print_level level,
const char *, va_list ap);
-LIBBPF_API void libbpf_set_print(libbpf_print_fn_t fn);
+LIBBPF_API libbpf_print_fn_t libbpf_set_print(libbpf_print_fn_t fn);
/* Hide internal to user */
struct bpf_object;
--
2.17.1
