[PATCH] error, warn, warnx: Use __fxprintf for wide printing [BZ #23519]

[Gabriel F. T. Gomes]

On Tue, 14 Aug 2018, Florian Weimer wrote:

> void
> vwarnx (const char *format, __gnuc_va_list ap)
> {
>   flockfile (stderr);
>-  if (_IO_fwide (stderr, 0) > 0)
>-    {
>-      __fwprintf (stderr, L"%s: ", __progname);
>-      convert_and_print (format, ap);
>-      putwc_unlocked (L'\n', stderr);
>-    }
>-  else
>-    {
>-      fprintf (stderr, "%s: ", __progname);
>-      if (format)
>-	vfprintf (stderr, format, ap);
>-      putc_unlocked ('\n', stderr);
>-    }
>+  __fxprintf (stderr, "%s: ", __progname);
>+  if (format)
>+    __vfxprintf (stderr, format, ap);
>+  __fxprintf (stderr, "\n");

Is it true that you can remove the call to 'convert_and_print' because
__fxprintf and __vfxprintf already check the wideness of the output and
convert (indirectly via locked_vfxprintf)?

It appears so, and your patch looks good to me.

>--- a/misc/error.c
>+++ b/misc/error.c
>@@ -203,72 +203,14 @@ static void _GL_ATTRIBUTE_FORMAT_PRINTF (3, 0) _GL_ARG_NONNULL ((3))
> error_tail (int status, int errnum, const char *message, va_list args)
> {
> #if _LIBC
>+  int ret = __vfxprintf (stderr, message, args);
>+  if (ret < 0 && errno == ENOMEM && _IO_fwide (stderr, 0) > 0)
>+    /* Leave a trace in case the heap allocation of the message string
>+       failed.  */
>+    fputws_unlocked (L"out of memory\n", stderr);
>+#else
>+  vfprintf (stderr, message, args);
> #endif

Just out of curiosity, how do we know that other programs use this code
outside of glibc?  (assuming this is the reason for the _LIBC check).