Re: [PATCH] Improve error reporting when serializing non-Unicode strings to JSON

[Philipp Stephani]

Eli Zaretskii <address@hidden> schrieb am Sa., 23. Dez. 2017 um 16:34 Uhr:

> From: Philipp Stephani <address@hidden>
> Date: Sat, 23 Dec 2017 15:19:17 +0000
> Cc: address@hidden, address@hidden
>
>  So let's use check_utf_8, as its downsides don't sound serious to me,
>
> Well it needs to be rewritten significantly to take a char*, length argument instead of the coding_system
> struct.

But creating a coding_system struct requires a single call to
setup_coding_system, which doesn't sound too bad.

Unfortunately it's not that easy. coding_system has many fields that setup_coding_system doesn't initialize.

I've tried using check_utf_8, but it doesn't seem to work:

static void

json_check_utf8 (Lisp_Object string)

{

  eassert (!STRING_MULTIBYTE (string));

  struct coding_system coding;

  setup_coding_system (Qutf_8_unix, &coding);

  /* We initialize only the fields that check_utf_8 accesses.  */

  coding.src_pos = 0;

  coding.src_pos_byte = 0;

  coding.src_chars = SCHARS (string);

  coding.src_bytes = SBYTES (string);

  coding.src_object = string;

  coding.eol_seen = EOL_SEEN_NONE;

  CHECK_TYPE (check_utf_8 (&coding) >= 0, Qutf_8_string_p, string);

}

This apparently fails to detect the unibyte string "u\xFFv" as invalid UTF-8.