Bug#305831: mbrtowc() fails for vi_VN.tcvn

[Ross Paterson <ross@soi.city.ac.uk>]

Package: locales
Version: 2.3.2.ds1-20
Severity: normal

According to the spec, mbrtowc(&wc, buf, 1, &st) should either return 1
and set wc, or return 0, (size_t)-1 or (size_t)-2.  In this locale it
returns either 0 or 1, but doesn't always set wc in the latter case,
as the following test program shows.  I believe it should be returning
(size_t)-2 (incomplete encoding) for (most) letters, and setting wc in
all the other cases (except \0).

(In iconvdata/tcvn5712-1.c, this decoding is treated as stateful, but
I don't think it should be.)

This behaviour sends readline into an infinite loop in this locale.
------------------------------ cut here ------------------------------
#include <stdio.h>
#include <wchar.h>
#include <locale.h>
#include <sys/types.h>

main() {
	int c;
	mbstate_t st;
	char buf[1];
	size_t size;
	wchar_t wc;

	setlocale(LC_CTYPE, "vi_VN.tcvn");
	for (c = 0; c <= 0xff; c++) {
		wc = 0xbaad;
		buf[0] = c;
		memset(&st, 0, sizeof(st));
		size = mbrtowc(&wc, buf, 1, &st);
		printf("c = 0x%02x, size = %u, wc = U+%04X\n", c, size, wc);
	}
	return 0;
}