tools: bpftool: fix -Wmissing declaration warnings

Help compiler check arguments for several utility functions used to
print items to the console by adding the "printf" attribute when
declaring those functions.

Also, declare as "static" two functions that are only used in prog.c.

All of them discovered by compiling bpftool with
-Wmissing-format-attribute -Wmissing-declarations.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/tools/bpf/bpftool/json_writer.c b/tools/bpf/bpftool/json_writer.c
index a07d17918725..bff7ee026680 100644
--- a/tools/bpf/bpftool/json_writer.c
+++ b/tools/bpf/bpftool/json_writer.c
@@ -20,6 +20,7 @@
 #include <malloc.h>
 #include <inttypes.h>
 #include <stdint.h>
+#include <linux/compiler.h>
 
 #include "json_writer.h"
 
@@ -157,7 +158,8 @@ void jsonw_name(json_writer_t *self, const char *name)
                 putc(' ', self->out);
 }
 
-void jsonw_vprintf_enquote(json_writer_t *self, const char *fmt, va_list ap)
+void __printf(2, 0)
+jsonw_vprintf_enquote(json_writer_t *self, const char *fmt, va_list ap)
 {
         jsonw_eor(self);
         putc('"', self->out);
@@ -165,7 +167,7 @@ void jsonw_vprintf_enquote(json_writer_t *self, const char *fmt, va_list ap)
         putc('"', self->out);
 }
 
-void jsonw_printf(json_writer_t *self, const char *fmt, ...)
+void __printf(2, 3) jsonw_printf(json_writer_t *self, const char *fmt, ...)
 {
         va_list ap;