Add `format` annotations

2 files changed, 11 insertions, 2 deletions

diff --git a/include/fortify-headers.h b/include/fortify-headers.h
index a9b7498..67c4792 100644
--- a/include/fortify-headers.h
+++ b/include/fortify-headers.h
@@ -59,15 +59,20 @@
 #define __bos(ptr, type) __builtin_object_size (ptr, type)
 #endif
 
-/* This needs to be two different conditions: https://gcc.gnu.org/onlinedocs/cpp/_005f_005fhas_005fattribute.html */
 #if defined __has_attribute
+
 #if __has_attribute (access)
 #define __access(...) __attribute__ ((access (__VA_ARGS__)))
 #else
 #define __access(...)
 #endif
+
+#if __has_attribute (format)
+#define __format(...) __attribute__ ((format (__VA_ARGS__)))
 #else
-#define __access(...)
+#define __format(...)
+#endif
+
 #endif
 
 #endif
diff --git a/include/stdio.h b/include/stdio.h
index 67738ed..aebe861 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -76,6 +76,7 @@ _FORTIFY_FN(fwrite) size_t fwrite(const void * _FORTIFY_POS0 __d, size_t __n,
         return __orig_fwrite(__d, __n, __m, __f);
 }
 
+__format(printf, 3, 0)
 __access(write_only, 1, 2)
 __access(read_only, 3)
 _FORTIFY_FN(vsnprintf) int vsnprintf(char * _FORTIFY_POS0 __s, size_t __n,
@@ -88,6 +89,7 @@ _FORTIFY_FN(vsnprintf) int vsnprintf(char * _FORTIFY_POS0 __s, size_t __n,
         return __orig_vsnprintf(__s, __n, __f, __v);
 }
 
+__format(printf, 2, 0)
 __access(write_only, 1)
 __access(read_only, 2)
 _FORTIFY_FN(vsprintf) int vsprintf(char * _FORTIFY_POS0 __s, const char *__f,
@@ -121,6 +123,7 @@ _FORTIFY_FN(vsprintf) int vsprintf(char * _FORTIFY_POS0 __s, const char *__f,
  * 3) not implementing these under clang, which is what we do for now
  */
 
+__format(printf, 3, 4)
 _FORTIFY_FN(snprintf) int snprintf(char *__s, size_t __n,
                                     const char *__f, ...)
 {
@@ -131,6 +134,7 @@ _FORTIFY_FN(snprintf) int snprintf(char *__s, size_t __n,
         return __orig_snprintf(__s, __n, __f, __builtin_va_arg_pack());
 }
 
+__format(printf, 2, 3)
 _FORTIFY_FN(sprintf) int sprintf(char *__s, const char *__f, ...)
 {
         size_t __b = __bos(__s, 0);