From 4f2c9703a128d21db7d0bf2ea14c5fe50d0dfe7e Mon Sep 17 00:00:00 2001 From: Alviro Iskandar Setiawan Date: Fri, 20 May 2022 00:21:16 +0700 Subject: tools/nolibc/stdio: Add format attribute to enable printf warnings When we use printf and fprintf functions from the nolibc, we don't get any warning from the compiler if we have the wrong arguments. For example, the following calls will compile silently: ``` printf("%s %s\n", "aaa"); fprintf(stdout, "%s %s\n", "xxx", 1); ``` (Note the wrong arguments). Those calls are undefined behavior. The compiler can help us warn about the above mistakes by adding a `printf` format attribute to those functions declaration. This patch adds it, and now it yields these warnings for those mistakes: ``` warning: format `%s` expects a matching `char *` argument [-Wformat=] warning: format `%s` expects argument of type `char *`, but argument 4 has type `int` [-Wformat=] ``` [ ammarfaizi2: Simplify the attribute placement. ] Signed-off-by: Alviro Iskandar Setiawan Signed-off-by: Ammar Faizi Acked-by: Willy Tarreau Signed-off-by: Paul E. McKenney --- tools/include/nolibc/stdio.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'tools/include') diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h index 15dedf8d0902..a3cebc4bc3ac 100644 --- a/tools/include/nolibc/stdio.h +++ b/tools/include/nolibc/stdio.h @@ -273,7 +273,7 @@ int vfprintf(FILE *stream, const char *fmt, va_list args) return written; } -static __attribute__((unused)) +static __attribute__((unused, format(printf, 2, 3))) int fprintf(FILE *stream, const char *fmt, ...) { va_list args; @@ -285,7 +285,7 @@ int fprintf(FILE *stream, const char *fmt, ...) return ret; } -static __attribute__((unused)) +static __attribute__((unused, format(printf, 1, 2))) int printf(const char *fmt, ...) { va_list args; -- cgit v1.2.3