Need help with iconv() usage

I keep getting errors popup whenever my source input is not UTF-8 so I'm clearly using it wrong somehow, this is how I've been using it so far:

Code:

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        U8.used = utflen(u8) + 1;
        if ( (ret = vecsize( &CB, U8.size * 4 )) != EXIT_SUCCESS )
                goto literalc_cleanup;
        cb = CB.buff;
        iconvSrcBuff = U8.buff;
        iconvSrcSize = U8.used * sizeof(char8_t);
        iconvDstBuff = CB.buff;
        iconvDstSize = CB.size;
        if ( encoding != std_encoding_utf ) {
                while ( iconvSrcSize && iconvDstSize ) {
                        bytes = iconv( utf_to_iconv[encoding],
                                &iconvSrcBuff, &iconvSrcSize,
                                &iconvDstBuff, &iconvDstSize );
                        if ( !bytes ) break;
                        if ( errno != EXIT_SUCCESS ) break;
                }
                if ( errno != EXIT_SUCCESS ) {
// Should not reach here in unit tests but does
                        ret = errno;
                        errno = 0;
                        FAIL( stderr, ret, "" );
                }
        }
        else (void)utfcpy( cb, U8.used, u8, U8.used );

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And this is the section of unit tests that it fails at:

Code:

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...
u8"abcd\u2ea2wxyz" =  64636261, 'abcd\u2ea2wxyz'
u'cd' =  00FFFE63, '
u'\u2ea2' =  0000A22E, '
u'a\u2ea2' =  2E6100A2, '
u'\u2ea2a' =  00A22E61, '
u"\u2ea2" =  00002EA2, '
Last character was '        '
Character hex: 00 00 00 00 00 00
rm libtsc.so libbase62.so char.elf libnext.so
char.c:692:literalc(): Error: 0x00000054, 84, Invalid or incomplete multibyte or wide character, Info:
char.c:692:literalc(): Error: 0x00000054, 84, Invalid or incomplete multibyte or wide character, Info:
make: *** [makefile:36: char.run] Error 1
Compilation failed.

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Edit 1: Just thought to clear errno before starting the loop so something else must be setting it instead, or it's setting it elsewhere, give me a few minutes
Edit 2: Turned out printf was setting it, despite supporting %ls it doesn't actually support doing it, resolved it with a switch statement which was need anyway

Code:

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switch ( encoding ) {
        case std_encoding_wcs:
                for ( i = 0; (c = ((wchar_t*)cb)[i]); ++i )
                        putwchar( c );
                putchar('\'');
                break;
        case std_encoding_u16:
                for ( i = 0; (c = ((char16_t*)cb)[i]); ++i )
                        putwchar( c );
                putchar('\'');
                break;
        case std_encoding_u32:
                for ( i = 0; (c = ((char32_t*)cb)[i]); ++i )
                        putwchar( c );
                putchar('\'');
                break;
        default:
                printf( "%s'", cb );
        }

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