fortify(stdio): emit diagnostics regardless of API level

Bug: 141267932
Test: m checkbuild on internal-master

Change-Id: I875a072c74f578d4404576c5bb42fd8ea30ff68d
diff --git a/libc/include/bits/fortify/stdio.h b/libc/include/bits/fortify/stdio.h
index 8bb5b68..528d5fb 100644
--- a/libc/include/bits/fortify/stdio.h
+++ b/libc/include/bits/fortify/stdio.h
@@ -50,7 +50,23 @@
 }
 #endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
 
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int sprintf(char* dest, const char* format)
+    __overloadable
+    __enable_if(__bos_unevaluated_lt(__bos(dest), __builtin_strlen(format)),
+                "format string will always overflow destination buffer")
+    __errorattr("format string will always overflow destination buffer");
+
 #if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+__BIONIC_FORTIFY_VARIADIC __printflike(2, 3)
+int sprintf(char* const __pass_object_size dest, const char* format, ...) __overloadable {
+    va_list va;
+    va_start(va, format);
+    int result = __builtin___vsprintf_chk(dest, 0, __bos(dest), format, va);
+    va_end(va);
+    return result;
+}
+
 /* No diag -- clang diagnoses misuses of this on its own.  */
 __BIONIC_FORTIFY_VARIADIC __printflike(3, 4)
 int snprintf(char* const __pass_object_size dest, size_t size, const char* format, ...)
@@ -61,26 +77,9 @@
     va_end(va);
     return result;
 }
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-int sprintf(char* dest, const char* format)
-    __overloadable
-    __enable_if(__bos_unevaluated_lt(__bos(dest), __builtin_strlen(format)),
-                "format string will always overflow destination buffer")
-    __errorattr("format string will always overflow destination buffer");
-
-__BIONIC_FORTIFY_VARIADIC __printflike(2, 3)
-int sprintf(char* const __pass_object_size dest, const char* format, ...) __overloadable {
-    va_list va;
-    va_start(va, format);
-    int result = __builtin___vsprintf_chk(dest, 0, __bos(dest), format, va);
-    va_end(va);
-    return result;
-}
 #endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
 
-#if __ANDROID_API__ >= __ANDROID_API_N__
-#define __bos_trivially_not_lt_mul(bos_val, size, count) \
+#define __bos_trivially_ge_mul(bos_val, size, count) \
   __bos_dynamic_check_impl_and(bos_val, >=, (size) * (count), \
                                !__unsafe_check_mul_overflow(size, count))
 
@@ -91,12 +90,14 @@
                          "in call to 'fread', size * count overflows")
         __clang_error_if(__bos_unevaluated_lt(__bos0(buf), size * count),
                          "in call to 'fread', size * count is too large for the given buffer") {
+#if __ANDROID_API__ >= __ANDROID_API_N__
     size_t bos = __bos0(buf);
 
-    if (__bos_trivially_not_lt_mul(bos, size, count)) {
-        return __call_bypassing_fortify(fread)(buf, size, count, stream);
+    if (!__bos_trivially_ge_mul(bos, size, count)) {
+        return __fread_chk(buf, size, count, stream, bos);
     }
-    return __fread_chk(buf, size, count, stream, bos);
+#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
+    return __call_bypassing_fortify(fread)(buf, size, count, stream);
 }
 
 __BIONIC_FORTIFY_INLINE
@@ -106,32 +107,31 @@
                          "in call to 'fwrite', size * count overflows")
         __clang_error_if(__bos_unevaluated_lt(__bos0(buf), size * count),
                          "in call to 'fwrite', size * count is too large for the given buffer") {
+#if __ANDROID_API__ >= __ANDROID_API_N__
     size_t bos = __bos0(buf);
 
-    if (__bos_trivially_not_lt_mul(bos, size, count)) {
-        return __call_bypassing_fortify(fwrite)(buf, size, count, stream);
+    if (!__bos_trivially_ge_mul(bos, size, count)) {
+        return __fwrite_chk(buf, size, count, stream, bos);
     }
-
-    return __fwrite_chk(buf, size, count, stream, bos);
-}
-#undef __bos_trivially_not_lt_mul
 #endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
+    return __call_bypassing_fortify(fwrite)(buf, size, count, stream);
+}
+#undef __bos_trivially_ge_mul
 
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
 __BIONIC_FORTIFY_INLINE
 char* fgets(char* const __pass_object_size dest, int size, FILE* stream)
         __overloadable
         __clang_error_if(size < 0, "in call to 'fgets', size should not be negative")
         __clang_error_if(__bos_unevaluated_lt(__bos(dest), size),
                          "in call to 'fgets', size is larger than the destination buffer") {
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
     size_t bos = __bos(dest);
 
-    if (__bos_dynamic_check_impl_and(bos, >=, (size_t)size, size >= 0)) {
-        return __call_bypassing_fortify(fgets)(dest, size, stream);
+    if (!__bos_dynamic_check_impl_and(bos, >=, (size_t)size, size >= 0)) {
+        return __fgets_chk(dest, size, stream, bos);
     }
-
-    return __fgets_chk(dest, size, stream, bos);
-}
 #endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+    return __call_bypassing_fortify(fgets)(dest, size, stream);
+}
 
 #endif /* defined(__BIONIC_FORTIFY) */