Tag various character arrays with NJS_NONSTRING.

In njs we have a number of character arrays which are intentionally not
NUL terminated.

With GCC 15 this

  static const u_char  hex[16] = "0123456789ABCDEF";

will trigger a warning (which we treat as an error) like

  src/njs_string.h: In function ‘njs_string_encode’:
  src/njs_string.h:212:36: error: initializer-string for array of ‘unsigned char’ truncates NUL terminator but destination lacks ‘nonstring’ attribute (17 chars into 16 available) [-Werror=unterminated-string-initialization]
    212 |     static const u_char  hex[16] = "0123456789ABCDEF";
        |                                    ^~~~~~~~~~~~~~~~~~

By adding NJS_NONSTRING like

  static const u_char  hex[16] NJS_NONSTRING = "0123456789ABCDEF";

we no longer get the warning.

Closes: #857
Signed-off-by: Andrew Clayton <[email protected]>

Author: ac000

src/njs_sprintf.c

@@ -95,8 +95,8 @@ njs_vsprintf(u_char *buf, u_char *end, const char *fmt, va_list args)
     njs_bool_t     sign;
     njs_sprintf_t  spf;
 
-    static const u_char  hexadecimal[16] = "0123456789abcdef";
-    static const u_char  HEXADECIMAL[16] = "0123456789ABCDEF";
+    static const u_char  hexadecimal[16] NJS_NONSTRING = "0123456789abcdef";
+    static const u_char  HEXADECIMAL[16] NJS_NONSTRING = "0123456789ABCDEF";
     static const u_char  nan[] = "[nan]";
     static const u_char  infinity[] = "[infinity]";
 

src/njs_string.c

@@ -309,7 +309,7 @@ njs_encode_hex(njs_str_t *dst, const njs_str_t *src)
     size_t        i, len;
     const u_char  *start;
 
-    static const u_char  hex[16] = "0123456789abcdef";
+    static const u_char  hex[16] NJS_NONSTRING = "0123456789abcdef";
 
     len = src->length;
     start = src->start;

src/njs_string.h

@@ -209,7 +209,7 @@ njs_string_encode(const uint32_t *escape, size_t size, const u_char *src,
     u_char *dst)
 {
     uint8_t              byte;
-    static const u_char  hex[16] = "0123456789ABCDEF";
+    static const u_char  hex[16] NJS_NONSTRING = "0123456789ABCDEF";
 
     do {
         byte = *src++;