each_byte

/*
 *  call-seq:
 *     ios.each_byte {|byte| block }  => nil
 *  
 *  Calls the given block once for each byte (0..255) in <em>ios</em>,
 *  passing the byte as an argument. The stream must be opened for
 *  reading or an <code>IOError</code> will be raised.
 *     
 *     f = File.new("testfile")
 *     checksum = 0
 *     f.each_byte {|x| checksum ^= x }   #=> #<File:testfile>
 *     checksum                           #=> 12
 */

static VALUE
rb_io_each_byte(io)
    VALUE io;
{
    OpenFile *fptr;
    FILE *f;
    int c;

    GetOpenFile(io, fptr);

    for (;;) {
        rb_io_check_readable(fptr);
        f = fptr->f;
        READ_CHECK(f);
        clearerr(f);
        TRAP_BEG;
        c = getc(f);
        TRAP_END;
        if (c == EOF) {
            if (ferror(f)) {
                clearerr(f);
                if (!rb_io_wait_readable(fileno(f)))
                    rb_sys_fail(fptr->path);
                continue;
            }
            break;
        }
        rb_yield(INT2FIX(c & 0xff));
    }
    if (ferror(f)) rb_sys_fail(fptr->path);
    return io;
}