Tag various character arrays with NXT_NONSTRING

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

With GCC 15 this

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

will trigger a warning like

  $ gcc -Wextra -c nonstring.c
  nonstring.c: In function ‘hexit’:
  nonstring.c:9:37: warning: initializer-string for array of ‘char’ truncates NUL terminator but destination lacks ‘nonstring’ attribute (17 chars into 16 available) [-Wunterminated-string-initialization]
      9 |         static const char hex[16] = "0123456789ABCDEF";
        |                                     ^~~~~~~~~~~~~~~~~~

By adding NXT_NONSTRING like

  static const char hex[16] NXT_NONSTRING = "0123456789ABCDEF";

we no longer get the warning.

Cc: Alejandro Colomar <[email protected]>
Co-authored-by: Alejandro Colomar <[email protected]>
Signed-off-by: Alejandro Colomar <[email protected]>
Signed-off-by: Andrew Clayton <[email protected]>

Author: ac000

src/nxt_http_parse.c

@@ -516,7 +516,7 @@ nxt_http_parse_field_name(nxt_http_request_parse_t *rp, u_char **pos,
     size_t    len;
     uint32_t  hash;
 
-    static const u_char  normal[256]  nxt_aligned(64) =
+    static const u_char  normal[256]  NXT_NONSTRING nxt_aligned(64) =
         "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
     /*   \s ! " # $ % & ' ( ) * + ,        . /                 : ; < = > ?   */
         "\0\1\0\1\1\1\1\1\0\0\1\1\0" "-" "\1\0" "0123456789" "\0\0\0\0\0\0"

src/nxt_http_parse.h

@@ -21,7 +21,7 @@ typedef struct nxt_http_fields_hash_s    nxt_http_fields_hash_t;
 
 
 typedef union {
-    u_char                    str[8];
+    u_char                    str[8] NXT_NONSTRING;
     uint64_t                  ui64;
 
     struct {

src/nxt_sprintf.c

@@ -112,8 +112,8 @@ nxt_vsprintf(u_char *buf, u_char *end, const char *fmt, va_list args)
     nxt_sprintf_t        spf;
     nxt_file_name_t      *fn;
 
-    static const u_char  hexadecimal[16] = "0123456789abcdef";
-    static const u_char  HEXADECIMAL[16] = "0123456789ABCDEF";
+    static const u_char  hexadecimal[16] NXT_NONSTRING = "0123456789abcdef";
+    static const u_char  HEXADECIMAL[16] NXT_NONSTRING = "0123456789ABCDEF";
     static const u_char  nan[] = "[nan]";
     static const u_char  null[] = "[null]";
     static const u_char  infinity[] = "[infinity]";

src/nxt_string.c

@@ -598,7 +598,7 @@ nxt_encode_uri(u_char *dst, u_char *src, size_t length)
     u_char      *end;
     nxt_uint_t  n;
 
-    static const u_char  hex[16] = "0123456789ABCDEF";
+    static const u_char  hex[16] NXT_NONSTRING = "0123456789ABCDEF";
 
     end = src + length;
 
@@ -644,7 +644,7 @@ nxt_encode_complex_uri(u_char *dst, u_char *src, size_t length)
     u_char      *reserved, *end, ch;
     nxt_uint_t  n;
 
-    static const u_char  hex[16] = "0123456789ABCDEF";
+    static const u_char  hex[16] NXT_NONSTRING = "0123456789ABCDEF";
 
     reserved = (u_char *) "?#\0";