Move bionic over to GCC's 'warning' attribute.

This is a better solution than the old __warn_references because it's
a compile-time rather than link-time warning, it doesn't rely on something
that doesn't appear to be supported by gold (which is why you only used
to see these warnings on mips builds), and the errors refer to the exact
call site(s) rather than just telling you which object file contains a
reference to the bad function.

This is primarily so we can build bionic for aarch64; building libc.so
caused these warnings to fire (because link time is the wrong time) and
warnings are errors.

Change-Id: I5df9281b2a9d98b164a9b11807ea9472c6faa9e3

1 files changed, 12 insertions, 12 deletions

diff --git a/libc/include/stdio.h b/libc/include/stdio.h
index 409afeaf8..260a4e706 100644
--- a/libc/include/stdio.h
+++ b/libc/include/stdio.h
@@ -222,13 +222,13 @@ int	 getchar(void);
 ssize_t	 getdelim(char ** __restrict, size_t * __restrict, int,
 	    FILE * __restrict);
 ssize_t	 getline(char ** __restrict, size_t * __restrict, FILE * __restrict);
-char	*gets(char *);
+
 #if __BSD_VISIBLE && !defined(__SYS_ERRLIST)
 #define __SYS_ERRLIST
-
 extern int sys_nerr;			/* perror(3) external variables */
 extern char *sys_errlist[];
 #endif
+
 void	 perror(const char *);
 int	 printf(const char * __restrict, ...)
 		__printflike(1, 2);
@@ -251,13 +251,16 @@ int	 vprintf(const char * __restrict, __va_list)
 		__printflike(1, 0);
 
 #ifndef __AUDIT__
-char	*gets(char *);
-int	 sprintf(char * __restrict, const char * __restrict, ...)
-		__printflike(2, 3);
-char	*tmpnam(char *);
-int	 vsprintf(char * __restrict, const char * __restrict,
-    __va_list)
-		__printflike(2, 0);
+char* gets(char*) __warnattr("gets is very unsafe; consider using fgets");
+int sprintf(char* __restrict, const char* __restrict, ...)
+    __printflike(2, 3) __warnattr("sprintf is often misused; please use snprintf");
+char* tmpnam(char*) __warnattr("tmpnam possibly used unsafely; consider using mkstemp");
+int vsprintf(char* __restrict, const char* __restrict, __va_list)
+    __printflike(2, 0) __warnattr("vsprintf is often misused; please use vsnprintf");
+#if __XPG_VISIBLE
+char* tempnam(const char*, const char*)
+    __warnattr("tempnam possibly used unsafely; consider using mkstemp");
+#endif
 #endif
 
 extern int rename(const char*, const char*);
@@ -320,9 +323,6 @@ int	 putc_unlocked(int, FILE *);
 int	 putchar_unlocked(int);
 #endif /* __POSIX_VISIBLE >= 199506 */
 
-#if __XPG_VISIBLE
-char	*tempnam(const char *, const char *);
-#endif
 __END_DECLS
 
 #endif /* __BSD_VISIBLE || __POSIX_VISIBLE || __XPG_VISIBLE */