I don't disagree with you, but I'd prefer to see bug #529866 fixed first so that the API only need be changed once, to this:

public static bool get_contents (string filename,
  [CCode (array_length_type = "size_t")] out char[] contents) throws FileError;
public static bool set_contents (string filename,
  [CCode (array_length_type = "ssize_t")] char[] contents) throws FileError;

Meanwhile, recent versions of valac have a string.to_utf8() method (see http://git.gnome.org/cgit/vala/commit/?id=6f4c7dec8d16ede148824da2203b447d77db5763) which should help... it still makes a copy, but at least it's easy.

Thanks for response. Yep, that one needs to be fixed first.
By the way, there is another problem with file's content not necessarily being UTF-8 encoded text. It can be a different encoding or some arbitrary binary data (with NUL characters), in which case to_utf8() can't be used.

The receive, receive_from, send and send_to methods on GIO's Socket class also have string arguments for what are really byte arrays. Should a separate bug be opened for each discovered case of this same problem?

Sam, no, I'll make sure to include them. Thanks for reporting them, though.

FWIW, I think I'm going to have to go through all everything that comes up in `grep -P 'string [^,]+\, [a-z0-9_]+ (len|size)' *.vapi` (~200 methods).

commit d51a3caec9bda0536b066aef066b744d494d92c1
Author: Luca Bruno <lucabru@src.gnome.org>
Date:   Wed May 11 22:23:13 2011 +0200

    gio-2.0: Use out uint8[] for File.load_* methods
    
    Fixes bug 594376.

This problem has been fixed in the development version. The fix will be available in the next major software release. Thank you for your bug report.