static VALUE
strio_read(int argc, VALUE *argv, VALUE self)
{
struct StringIO *ptr = readable(StringIO(self));
VALUE str = Qnil;
long len;
int binary = 0;
switch (argc) {
case 2:
str = argv[1];
if (!NIL_P(str)) {
StringValue(str);
rb_str_modify(str);
}
case 1:
if (!NIL_P(argv[0])) {
len = NUM2LONG(argv[0]);
if (len < 0) {
rb_raise(rb_eArgError, "negative length %ld given", len);
}
if (len > 0 && ptr->pos >= RSTRING_LEN(ptr->string)) {
if (!NIL_P(str)) rb_str_resize(str, 0);
return Qnil;
}
binary = 1;
break;
}
/* fall through */
case 0:
len = RSTRING_LEN(ptr->string);
if (len <= ptr->pos) {
if (NIL_P(str)) {
str = rb_str_new(0, 0);
}
else {
rb_str_resize(str, 0);
}
return str;
}
else {
len -= ptr->pos;
}
break;
default:
rb_raise(rb_eArgError, "wrong number of arguments (%d for 0)", argc);
}
if (NIL_P(str)) {
str = strio_substr(ptr, ptr->pos, len);
if (binary) rb_enc_associate(str, rb_ascii8bit_encoding());
}
else {
long rest = RSTRING_LEN(ptr->string) - ptr->pos;
if (len > rest) len = rest;
rb_str_resize(str, len);
MEMCPY(RSTRING_PTR(str), RSTRING_PTR(ptr->string) + ptr->pos, char, len);
if (binary)
rb_enc_associate(str, rb_ascii8bit_encoding());
else
rb_enc_copy(str, ptr->string);
}
ptr->pos += RSTRING_LEN(str);
return str;
}