Property values with encodings different from the input stream's encoding not read correctly (vCard 2.1) about ez-vcard

[GoogleCodeExporter]

This is a tough one.  It would basically require the VCardReader to iterate 
over the vCard one byte at a time so that it could change the character 
encoding of the property value when it finds a "CHARSET" parameter.

Original comment by mike.angstadt on 22 Nov 2014 at 4:20

• Changed title: Property values with encodings different from the input stream's encoding not read correctly (vCard 2.1)

[GoogleCodeExporter]

One workaround is to use an iso reader and reencode it afterwards,

InputStream is = new FileInputStream("test/resources/Herr Steve Jobs.vcf");
InputStreamReader isr = new InputStreamReader(is, StandardCharsets.ISO_8859_1);
Ezvcard.parse(isr).all();

byte[] raw = 
vCards.get(0).getAddresses().get(0).getStreetAddress().getBytes(StandardCharsets
.ISO_8859_1);
String charset = vCards.get(0).getAddresses().get(0).getCharset();
return new String(raw, charset);

This way I can trick the reader (charbased, multibyte) into reading single 
bytes and encode the bytes with the given encoding.

But you are right, the proper fix would be to change the inner logic in the 
library from reading chars to streaming bytes.
The method parse(Reader reader) shouldn't exist. At the end of a line you would 
convert the read value bytes into a string using the parameter encoding or utf8 
(vcard3+) or system encoding (old vcards, no param).

I'm surprised nobody noticed this game breaking bug so far. Or no not English 
programmer has reported it and instead looked for another library. On github 
I'd probably send you a pull request if you don't want to fix it yourself.

Original comment by [email protected] on 22 Nov 2014 at 6:16

[GoogleCodeExporter]

A patch would be most welcome. :)  The code would need to be clean and easy to 
read, of course. :P

I was always under the impression that the CHARSET parameter was intended to be 
used in conjunction with quoted-printable values, so it knows that character 
encoding to use when decoding the quoted-printable string.

Are you creating this vCard yourself or is Outlook generating it?  If you are 
creating it yourself, one work-around would be to encode the property value in 
quoted-printable encoding.

Original comment by mike.angstadt on 22 Nov 2014 at 10:58

[mangstadt]

I got this to work by modifying the parser to read one byte at a time instead of one char at a time. But it only works for ASCII-compatible character sets because each byte had to be cast to a char in order to parse the vCard syntax (the property name, parameters, etc). If the vCard file as a whole is encoded in something like UTF-16 (which encodes each character in 2 bytes instead of 1), it fails.

This "cast byte to char" approach also fails for a number of more obscure character sets. I tested this by looping through all available character sets supported by the JVM and saving a vCard file in each one. I then attempted to read the file using the "cast byte to char" approach, and many failed.

String s = "BEGIN:VCARD\r\nVERSION:4.0\r\nFN:Name\r\nEND:VCARD\r\n";
for (Charset c : Charset.availableCharsets().values()) {
    File file = new File("temp.vcf");
    FileOutputStream out = new FileOutputStream(file);
    BufferedWriter w = new BufferedWriter(new OutputStreamWriter(out, c));
    w.write(s);
    w.close();

    //read the vCard file...
}

The work around described by David only works if the vCard file is encoded in an ASCII-compatible character encoding (which ISO-8859-1 is). If the file is encoded in, say, UTF-16, it fails because the parser is trying to parse the file using ISO-8859-1, which is not compatible with UTF-16.

The problem boils down to this: How do you parse a file that contains text encoded in multiple character encodings? This is not something that happens often. 99.99% of the time, a text file is encoded in a single character set, not multiple.

The Reader class does not let you switch character encodings mid-stream. _Therefore, the only way to do this is to treat the vCard file as a binary file and manually convert each byte to a character as it is read off the stream, switching character sets when the property value is reached._ How this is done, I don't know. It might be possible using the CharsetDecoder class.

I tried wrapping the raw InputStream in a new Reader object when the property value was reached, but that didn't work. For some reason, its read() method returned -1, even though the stream has not ended. This problem can be demonstrated as follows:

@Test
public void multiple_readers() throws Exception {
    String s = "Hello world!";
    byte[] b = s.getBytes("UTF-8");

    ByteArrayInputStream in = new ByteArrayInputStream(b);
    Reader r1 = new InputStreamReader(in, "UTF-8");
    Reader r2 = new InputStreamReader(in, "UTF-8");

    assertEquals('H', r1.read());
    assertEquals('e', r2.read()); //fails
}