_iobase.c 25.8 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902
/*
    An implementation of the I/O abstract base classes hierarchy
    as defined by PEP 3116 - "New I/O"
    
    Classes defined here: IOBase, RawIOBase.
    
    Written by Amaury Forgeot d'Arc and Antoine Pitrou
*/


#define PY_SSIZE_T_CLEAN
#include "Python.h"
#include "structmember.h"
#include "_iomodule.h"

/*
 * IOBase class, an abstract class
 */

typedef struct {
    PyObject_HEAD
    
    PyObject *dict;
    PyObject *weakreflist;
} IOBaseObject;

PyDoc_STRVAR(IOBase_doc,
    "The abstract base class for all I/O classes, acting on streams of\n"
    "bytes. There is no public constructor.\n"
    "\n"
    "This class provides dummy implementations for many methods that\n"
    "derived classes can override selectively; the default implementations\n"
    "represent a file that cannot be read, written or seeked.\n"
    "\n"
    "Even though IOBase does not declare read, readinto, or write because\n"
    "their signatures will vary, implementations and clients should\n"
    "consider those methods part of the interface. Also, implementations\n"
    "may raise a IOError when operations they do not support are called.\n"
    "\n"
    "The basic type used for binary data read from or written to a file is\n"
    "bytes. bytearrays are accepted too, and in some cases (such as\n"
    "readinto) needed. Text I/O classes work with str data.\n"
    "\n"
    "Note that calling any method (even inquiries) on a closed stream is\n"
    "undefined. Implementations may raise IOError in this case.\n"
    "\n"
    "IOBase (and its subclasses) support the iterator protocol, meaning\n"
    "that an IOBase object can be iterated over yielding the lines in a\n"
    "stream.\n"
    "\n"
    "IOBase also supports the :keyword:`with` statement. In this example,\n"
    "fp is closed after the suite of the with statment is complete:\n"
    "\n"
    "with open('spam.txt', 'r') as fp:\n"
    "    fp.write('Spam and eggs!')\n");

/* Use this macro whenever you want to check the internal `closed` status
   of the IOBase object rather than the virtual `closed` attribute as returned
   by whatever subclass. */

#define IS_CLOSED(self) \
    PyObject_HasAttrString(self, "__IOBase_closed")

/* Internal methods */
static PyObject *
IOBase_unsupported(const char *message)
{
    PyErr_SetString(IO_STATE->unsupported_operation, message);
    return NULL;
}

/* Positionning */

PyDoc_STRVAR(IOBase_seek_doc,
    "Change stream position.\n"
    "\n"
    "Change the stream position to byte offset offset. offset is\n"
    "interpreted relative to the position indicated by whence.  Values\n"
    "for whence are:\n"
    "\n"
    "* 0 -- start of stream (the default); offset should be zero or positive\n"
    "* 1 -- current stream position; offset may be negative\n"
    "* 2 -- end of stream; offset is usually negative\n"
    "\n"
    "Return the new absolute position.");

static PyObject *
IOBase_seek(PyObject *self, PyObject *args)
{
    return IOBase_unsupported("seek");
}

PyDoc_STRVAR(IOBase_tell_doc,
             "Return current stream position.");

static PyObject *
IOBase_tell(PyObject *self, PyObject *args)
{
    return PyObject_CallMethod(self, "seek", "ii", 0, 1);
}

PyDoc_STRVAR(IOBase_truncate_doc,
    "Truncate file to size bytes.\n"
    "\n"
    "Size defaults to the current IO position as reported by tell().  Return\n"
    "the new size.");

static PyObject *
IOBase_truncate(PyObject *self, PyObject *args)
{
    return IOBase_unsupported("truncate");
}

/* Flush and close methods */

PyDoc_STRVAR(IOBase_flush_doc,
    "Flush write buffers, if applicable.\n"
    "\n"
    "This is not implemented for read-only and non-blocking streams.\n");

static PyObject *
IOBase_flush(PyObject *self, PyObject *args)
{
    /* XXX Should this return the number of bytes written??? */
    if (IS_CLOSED(self)) {
        PyErr_SetString(PyExc_ValueError, "I/O operation on closed file.");
        return NULL;
    }
    Py_RETURN_NONE;
}

PyDoc_STRVAR(IOBase_close_doc,
    "Flush and close the IO object.\n"
    "\n"
    "This method has no effect if the file is already closed.\n");

static int
IOBase_closed(PyObject *self)
{
    PyObject *res;
    int closed;
    /* This gets the derived attribute, which is *not* __IOBase_closed
       in most cases! */
    res = PyObject_GetAttr(self, _PyIO_str_closed);
    if (res == NULL)
        return 0;
    closed = PyObject_IsTrue(res);
    Py_DECREF(res);
    return closed;
}

static PyObject *
IOBase_closed_get(PyObject *self, void *context)
{
    return PyBool_FromLong(IS_CLOSED(self));
}

PyObject *
_PyIOBase_checkClosed(PyObject *self, PyObject *args)
{
    if (IOBase_closed(self)) {
        PyErr_SetString(PyExc_ValueError, "I/O operation on closed file.");
        return NULL;
    }
    if (args == Py_True)
        return Py_None;
    else
        Py_RETURN_NONE;
}

/* XXX: IOBase thinks it has to maintain its own internal state in
   `__IOBase_closed` and call flush() by itself, but it is redundant with
   whatever behaviour a non-trivial derived class will implement. */

static PyObject *
IOBase_close(PyObject *self, PyObject *args)
{
    PyObject *res;

    if (IS_CLOSED(self))
        Py_RETURN_NONE;

    res = PyObject_CallMethodObjArgs(self, _PyIO_str_flush, NULL);
    PyObject_SetAttrString(self, "__IOBase_closed", Py_True);
    if (res == NULL) {
        /* If flush() fails, just give up */
        if (PyErr_ExceptionMatches(PyExc_IOError))
            PyErr_Clear();
        else
            return NULL;
    }
    Py_XDECREF(res);
    Py_RETURN_NONE;
}

/* Finalization and garbage collection support */

int
_PyIOBase_finalize(PyObject *self)
{
    PyObject *res;
    PyObject *tp, *v, *tb;
    int closed = 1;
    int is_zombie;

    /* If _PyIOBase_finalize() is called from a destructor, we need to
       resurrect the object as calling close() can invoke arbitrary code. */
    is_zombie = (Py_REFCNT(self) == 0);
    if (is_zombie) {
        ++Py_REFCNT(self);
    }
    PyErr_Fetch(&tp, &v, &tb);
    /* If `closed` doesn't exist or can't be evaluated as bool, then the
       object is probably in an unusable state, so ignore. */
    res = PyObject_GetAttr(self, _PyIO_str_closed);
    if (res == NULL)
        PyErr_Clear();
    else {
        closed = PyObject_IsTrue(res);
        Py_DECREF(res);
        if (closed == -1)
            PyErr_Clear();
    }
    if (closed == 0) {
        res = PyObject_CallMethodObjArgs((PyObject *) self, _PyIO_str_close,
                                          NULL);
        /* Silencing I/O errors is bad, but printing spurious tracebacks is
           equally as bad, and potentially more frequent (because of
           shutdown issues). */
        if (res == NULL)
            PyErr_Clear();
        else
            Py_DECREF(res);
    }
    PyErr_Restore(tp, v, tb);
    if (is_zombie) {
        if (--Py_REFCNT(self) != 0) {
            /* The object lives again. The following code is taken from
               slot_tp_del in typeobject.c. */
            Py_ssize_t refcnt = Py_REFCNT(self);
            _Py_NewReference(self);
            Py_REFCNT(self) = refcnt;
            /* If Py_REF_DEBUG, _Py_NewReference bumped _Py_RefTotal, so
             * we need to undo that. */
            _Py_DEC_REFTOTAL;
            /* If Py_TRACE_REFS, _Py_NewReference re-added self to the object
             * chain, so no more to do there.
             * If COUNT_ALLOCS, the original decref bumped tp_frees, and
             * _Py_NewReference bumped tp_allocs:  both of those need to be
             * undone.
             */
#ifdef COUNT_ALLOCS
            --Py_TYPE(self)->tp_frees;
            --Py_TYPE(self)->tp_allocs;
#endif
            return -1;
        }
    }
    return 0;
}

static int
IOBase_traverse(IOBaseObject *self, visitproc visit, void *arg)
{
    Py_VISIT(self->dict);
    return 0;
}

static int
IOBase_clear(IOBaseObject *self)
{
    if (_PyIOBase_finalize((PyObject *) self) < 0)
        return -1;
    Py_CLEAR(self->dict);
    return 0;
}

/* Destructor */

static void
IOBase_dealloc(IOBaseObject *self)
{
    /* NOTE: since IOBaseObject has its own dict, Python-defined attributes
       are still available here for close() to use.
       However, if the derived class declares a __slots__, those slots are
       already gone.
    */
    if (_PyIOBase_finalize((PyObject *) self) < 0) {
        /* When called from a heap type's dealloc, the type will be
           decref'ed on return (see e.g. subtype_dealloc in typeobject.c). */
        if (PyType_HasFeature(Py_TYPE(self), Py_TPFLAGS_HEAPTYPE))
            Py_INCREF(Py_TYPE(self));
        return;
    }
    _PyObject_GC_UNTRACK(self);
    if (self->weakreflist != NULL)
        PyObject_ClearWeakRefs((PyObject *) self);
    Py_CLEAR(self->dict);
    Py_TYPE(self)->tp_free((PyObject *) self);
}

/* Inquiry methods */

PyDoc_STRVAR(IOBase_seekable_doc,
    "Return whether object supports random access.\n"
    "\n"
    "If False, seek(), tell() and truncate() will raise IOError.\n"
    "This method may need to do a test seek().");

static PyObject *
IOBase_seekable(PyObject *self, PyObject *args)
{
    Py_RETURN_FALSE;
}

PyObject *
_PyIOBase_checkSeekable(PyObject *self, PyObject *args)
{
    PyObject *res  = PyObject_CallMethodObjArgs(self, _PyIO_str_seekable, NULL);
    if (res == NULL)
        return NULL;
    if (res != Py_True) {
        Py_CLEAR(res);
        PyErr_SetString(PyExc_IOError, "File or stream is not seekable.");
        return NULL;
    }
    if (args == Py_True) {
        Py_DECREF(res);
    }
    return res;
}

PyDoc_STRVAR(IOBase_readable_doc,
    "Return whether object was opened for reading.\n"
    "\n"
    "If False, read() will raise IOError.");

static PyObject *
IOBase_readable(PyObject *self, PyObject *args)
{
    Py_RETURN_FALSE;
}

/* May be called with any object */
PyObject *
_PyIOBase_checkReadable(PyObject *self, PyObject *args)
{
    PyObject *res  = PyObject_CallMethodObjArgs(self, _PyIO_str_readable, NULL);
    if (res == NULL)
        return NULL;
    if (res != Py_True) {
        Py_CLEAR(res);
        PyErr_SetString(PyExc_IOError, "File or stream is not readable.");
        return NULL;
    }
    if (args == Py_True) {
        Py_DECREF(res);
    }
    return res;
}

PyDoc_STRVAR(IOBase_writable_doc,
    "Return whether object was opened for writing.\n"
    "\n"
    "If False, read() will raise IOError.");

static PyObject *
IOBase_writable(PyObject *self, PyObject *args)
{
    Py_RETURN_FALSE;
}

/* May be called with any object */
PyObject *
_PyIOBase_checkWritable(PyObject *self, PyObject *args)
{
    PyObject *res  = PyObject_CallMethodObjArgs(self, _PyIO_str_writable, NULL);
    if (res == NULL)
        return NULL;
    if (res != Py_True) {
        Py_CLEAR(res);
        PyErr_SetString(PyExc_IOError, "File or stream is not writable.");
        return NULL;
    }
    if (args == Py_True) {
        Py_DECREF(res);
    }
    return res;
}

/* Context manager */

static PyObject *
IOBase_enter(PyObject *self, PyObject *args)
{
    if (_PyIOBase_checkClosed(self, Py_True) == NULL)
        return NULL;

    Py_INCREF(self);
    return self;
}

static PyObject *
IOBase_exit(PyObject *self, PyObject *args)
{
    return PyObject_CallMethodObjArgs(self, _PyIO_str_close, NULL);
}

/* Lower-level APIs */

/* XXX Should these be present even if unimplemented? */

PyDoc_STRVAR(IOBase_fileno_doc,
    "Returns underlying file descriptor if one exists.\n"
    "\n"
    "An IOError is raised if the IO object does not use a file descriptor.\n");

static PyObject *
IOBase_fileno(PyObject *self, PyObject *args)
{
    return IOBase_unsupported("fileno");
}

PyDoc_STRVAR(IOBase_isatty_doc,
    "Return whether this is an 'interactive' stream.\n"
    "\n"
    "Return False if it can't be determined.\n");

static PyObject *
IOBase_isatty(PyObject *self, PyObject *args)
{
    if (_PyIOBase_checkClosed(self, Py_True) == NULL)
        return NULL;
    Py_RETURN_FALSE;
}

/* Readline(s) and writelines */

PyDoc_STRVAR(IOBase_readline_doc,
    "Read and return a line from the stream.\n"
    "\n"
    "If limit is specified, at most limit bytes will be read.\n"
    "\n"
    "The line terminator is always b'\n' for binary files; for text\n"
    "files, the newlines argument to open can be used to select the line\n"
    "terminator(s) recognized.\n");

static PyObject *
IOBase_readline(PyObject *self, PyObject *args)
{
    /* For backwards compatibility, a (slowish) readline(). */

    Py_ssize_t limit = -1;
    int has_peek = 0;
    PyObject *buffer, *result;
    Py_ssize_t old_size = -1;

    if (!PyArg_ParseTuple(args, "|n:readline", &limit)) {
        return NULL;
    }

    if (PyObject_HasAttrString(self, "peek"))
        has_peek = 1;

    buffer = PyByteArray_FromStringAndSize(NULL, 0);
    if (buffer == NULL)
        return NULL;

    while (limit < 0 || Py_SIZE(buffer) < limit) {
        Py_ssize_t nreadahead = 1;
        PyObject *b;

        if (has_peek) {
            PyObject *readahead = PyObject_CallMethod(self, "peek", "i", 1);
            if (readahead == NULL)
                goto fail;
            if (!PyBytes_Check(readahead)) {
                PyErr_Format(PyExc_IOError,
                             "peek() should have returned a bytes object, "
                             "not '%.200s'", Py_TYPE(readahead)->tp_name);
                Py_DECREF(readahead);
                goto fail;
            }
            if (PyBytes_GET_SIZE(readahead) > 0) {
                Py_ssize_t n = 0;
                const char *buf = PyBytes_AS_STRING(readahead);
                if (limit >= 0) {
                    do {
                        if (n >= PyBytes_GET_SIZE(readahead) || n >= limit)
                            break;
                        if (buf[n++] == '\n')
                            break;
                    } while (1);
                }
                else {
                    do {
                        if (n >= PyBytes_GET_SIZE(readahead))
                            break;
                        if (buf[n++] == '\n')
                            break;
                    } while (1);
                }
                nreadahead = n;
            }
            Py_DECREF(readahead);
        }

        b = PyObject_CallMethod(self, "read", "n", nreadahead);
        if (b == NULL)
            goto fail;
        if (!PyBytes_Check(b)) {
            PyErr_Format(PyExc_IOError,
                         "read() should have returned a bytes object, "
                         "not '%.200s'", Py_TYPE(b)->tp_name);
            Py_DECREF(b);
            goto fail;
        }
        if (PyBytes_GET_SIZE(b) == 0) {
            Py_DECREF(b);
            break;
        }

        old_size = PyByteArray_GET_SIZE(buffer);
        PyByteArray_Resize(buffer, old_size + PyBytes_GET_SIZE(b));
        memcpy(PyByteArray_AS_STRING(buffer) + old_size,
               PyBytes_AS_STRING(b), PyBytes_GET_SIZE(b));

        Py_DECREF(b);

        if (PyByteArray_AS_STRING(buffer)[PyByteArray_GET_SIZE(buffer) - 1] == '\n')
            break;
    }

    result = PyBytes_FromStringAndSize(PyByteArray_AS_STRING(buffer),
                                       PyByteArray_GET_SIZE(buffer));
    Py_DECREF(buffer);
    return result;
  fail:
    Py_DECREF(buffer);
    return NULL;
}

static PyObject *
IOBase_iter(PyObject *self)
{
    if (_PyIOBase_checkClosed(self, Py_True) == NULL)
        return NULL;

    Py_INCREF(self);
    return self;
}

static PyObject *
IOBase_iternext(PyObject *self)
{
    PyObject *line = PyObject_CallMethodObjArgs(self, _PyIO_str_readline, NULL);

    if (line == NULL)
        return NULL;

    if (PyObject_Size(line) == 0) {
        Py_DECREF(line);
        return NULL;
    }

    return line;
}

PyDoc_STRVAR(IOBase_readlines_doc,
    "Return a list of lines from the stream.\n"
    "\n"
    "hint can be specified to control the number of lines read: no more\n"
    "lines will be read if the total size (in bytes/characters) of all\n"
    "lines so far exceeds hint.");

static PyObject *
IOBase_readlines(PyObject *self, PyObject *args)
{
    Py_ssize_t hint = -1, length = 0;
    PyObject *hintobj = Py_None, *result;

    if (!PyArg_ParseTuple(args, "|O:readlines", &hintobj)) {
        return NULL;
    }
    if (hintobj != Py_None) {
        hint = PyNumber_AsSsize_t(hintobj, PyExc_ValueError);
        if (hint == -1 && PyErr_Occurred())
            return NULL;
    }

    result = PyList_New(0);
    if (result == NULL)
        return NULL;

    if (hint <= 0) {
        /* XXX special-casing this made sense in the Python version in order
           to remove the bytecode interpretation overhead, but it could
           probably be removed here. */
        PyObject *ret = PyObject_CallMethod(result, "extend", "O", self);
        if (ret == NULL) {
            Py_DECREF(result);
            return NULL;
        }
        Py_DECREF(ret);
        return result;
    }

    while (1) {
        PyObject *line = PyIter_Next(self);
        if (line == NULL) {
            if (PyErr_Occurred()) {
                Py_DECREF(result);
                return NULL;
            }
            else
                break; /* StopIteration raised */
        }

        if (PyList_Append(result, line) < 0) {
            Py_DECREF(line);
            Py_DECREF(result);
            return NULL;
        }
        length += PyObject_Size(line);
        Py_DECREF(line);

        if (length > hint)
            break;
    }
    return result;
}

static PyObject *
IOBase_writelines(PyObject *self, PyObject *args)
{
    PyObject *lines, *iter, *res;

    if (!PyArg_ParseTuple(args, "O:writelines", &lines)) {
        return NULL;
    }

    if (_PyIOBase_checkClosed(self, Py_True) == NULL)
        return NULL;

    iter = PyObject_GetIter(lines);
    if (iter == NULL)
        return NULL;

    while (1) {
        PyObject *line = PyIter_Next(iter);
        if (line == NULL) {
            if (PyErr_Occurred()) {
                Py_DECREF(iter);
                return NULL;
            }
            else
                break; /* Stop Iteration */
        }

        res = PyObject_CallMethodObjArgs(self, _PyIO_str_write, line, NULL);
        Py_DECREF(line);
        if (res == NULL) {
            Py_DECREF(iter);
            return NULL;
        }
        Py_DECREF(res);
    }
    Py_DECREF(iter);
    Py_RETURN_NONE;
}

static PyMethodDef IOBase_methods[] = {
    {"seek", IOBase_seek, METH_VARARGS, IOBase_seek_doc},
    {"tell", IOBase_tell, METH_NOARGS, IOBase_tell_doc},
    {"truncate", IOBase_truncate, METH_VARARGS, IOBase_truncate_doc},
    {"flush", IOBase_flush, METH_NOARGS, IOBase_flush_doc},
    {"close", IOBase_close, METH_NOARGS, IOBase_close_doc},

    {"seekable", IOBase_seekable, METH_NOARGS, IOBase_seekable_doc},
    {"readable", IOBase_readable, METH_NOARGS, IOBase_readable_doc},
    {"writable", IOBase_writable, METH_NOARGS, IOBase_writable_doc},

    {"_checkClosed",   _PyIOBase_checkClosed, METH_NOARGS},
    {"_checkSeekable", _PyIOBase_checkSeekable, METH_NOARGS},
    {"_checkReadable", _PyIOBase_checkReadable, METH_NOARGS},
    {"_checkWritable", _PyIOBase_checkWritable, METH_NOARGS},

    {"fileno", IOBase_fileno, METH_NOARGS, IOBase_fileno_doc},
    {"isatty", IOBase_isatty, METH_NOARGS, IOBase_isatty_doc},

    {"__enter__", IOBase_enter, METH_NOARGS},
    {"__exit__", IOBase_exit, METH_VARARGS},

    {"readline", IOBase_readline, METH_VARARGS, IOBase_readline_doc},
    {"readlines", IOBase_readlines, METH_VARARGS, IOBase_readlines_doc},
    {"writelines", IOBase_writelines, METH_VARARGS},

    {NULL, NULL}
};

static PyGetSetDef IOBase_getset[] = {
    {"closed", (getter)IOBase_closed_get, NULL, NULL},
    {0}
};


PyTypeObject PyIOBase_Type = {
    PyVarObject_HEAD_INIT(NULL, 0)
    "_io._IOBase",              /*tp_name*/
    sizeof(IOBaseObject),       /*tp_basicsize*/
    0,                          /*tp_itemsize*/
    (destructor)IOBase_dealloc, /*tp_dealloc*/
    0,                          /*tp_print*/
    0,                          /*tp_getattr*/
    0,                          /*tp_setattr*/
    0,                          /*tp_compare */
    0,                          /*tp_repr*/
    0,                          /*tp_as_number*/
    0,                          /*tp_as_sequence*/
    0,                          /*tp_as_mapping*/
    0,                          /*tp_hash */
    0,                          /*tp_call*/
    0,                          /*tp_str*/
    0,                          /*tp_getattro*/
    0,                          /*tp_setattro*/
    0,                          /*tp_as_buffer*/
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
        | Py_TPFLAGS_HAVE_GC,   /*tp_flags*/
    IOBase_doc,                 /* tp_doc */
    (traverseproc)IOBase_traverse, /* tp_traverse */
    (inquiry)IOBase_clear,      /* tp_clear */
    0,                          /* tp_richcompare */
    offsetof(IOBaseObject, weakreflist), /* tp_weaklistoffset */
    IOBase_iter,                /* tp_iter */
    IOBase_iternext,            /* tp_iternext */
    IOBase_methods,             /* tp_methods */
    0,                          /* tp_members */
    IOBase_getset,              /* tp_getset */
    0,                          /* tp_base */
    0,                          /* tp_dict */
    0,                          /* tp_descr_get */
    0,                          /* tp_descr_set */
    offsetof(IOBaseObject, dict), /* tp_dictoffset */
    0,                          /* tp_init */
    0,                          /* tp_alloc */
    PyType_GenericNew,          /* tp_new */
};


/*
 * RawIOBase class, Inherits from IOBase.
 */
PyDoc_STRVAR(RawIOBase_doc,
             "Base class for raw binary I/O.");

/*
 * The read() method is implemented by calling readinto(); derived classes
 * that want to support read() only need to implement readinto() as a
 * primitive operation.  In general, readinto() can be more efficient than
 * read().
 *
 * (It would be tempting to also provide an implementation of readinto() in
 * terms of read(), in case the latter is a more suitable primitive operation,
 * but that would lead to nasty recursion in case a subclass doesn't implement
 * either.)
*/

static PyObject *
RawIOBase_read(PyObject *self, PyObject *args)
{
    Py_ssize_t n = -1;
    PyObject *b, *res;

    if (!PyArg_ParseTuple(args, "|n:read", &n)) {
        return NULL;
    }

    if (n < 0)
        return PyObject_CallMethod(self, "readall", NULL);

    /* TODO: allocate a bytes object directly instead and manually construct
       a writable memoryview pointing to it. */
    b = PyByteArray_FromStringAndSize(NULL, n);
    if (b == NULL)
        return NULL;

    res = PyObject_CallMethodObjArgs(self, _PyIO_str_readinto, b, NULL);
    if (res == NULL) {
        Py_DECREF(b);
        return NULL;
    }

    n = PyNumber_AsSsize_t(res, PyExc_ValueError);
    Py_DECREF(res);
    if (n == -1 && PyErr_Occurred()) {
        Py_DECREF(b);
        return NULL;
    }

    res = PyBytes_FromStringAndSize(PyByteArray_AsString(b), n);
    Py_DECREF(b);
    return res;
}


PyDoc_STRVAR(RawIOBase_readall_doc,
             "Read until EOF, using multiple read() call.");

static PyObject *
RawIOBase_readall(PyObject *self, PyObject *args)
{
    PyObject *b = NULL;
    Py_ssize_t cursize = 0;

    while (1) {
        Py_ssize_t length;
        PyObject *data = PyObject_CallMethod(self, "read",
                                             "i", DEFAULT_BUFFER_SIZE);

        if (!data) {
            Py_XDECREF(b);
            return NULL;
        }

        if (!PyBytes_Check(data)) {
            Py_XDECREF(b);
            Py_DECREF(data);
            PyErr_SetString(PyExc_TypeError, "read() should return bytes");
            return NULL;
        }

        length = Py_SIZE(data);

        if (b == NULL)
            b = data;
        else if (length != 0) {

            _PyBytes_Resize(&b, cursize + length);
            if (b == NULL) {
                Py_DECREF(data);
                return NULL;
            }

            memcpy(PyBytes_AS_STRING(b) + cursize,
                   PyBytes_AS_STRING(data), length);
            Py_DECREF(data);
        }

        if (length == 0)
            break;
    }

    return b;

}

static PyMethodDef RawIOBase_methods[] = {
    {"read", RawIOBase_read, METH_VARARGS},
    {"readall", RawIOBase_readall, METH_NOARGS, RawIOBase_readall_doc},
    {NULL, NULL}
};

PyTypeObject PyRawIOBase_Type = {
    PyVarObject_HEAD_INIT(NULL, 0)
    "_io._RawIOBase",                /*tp_name*/
    0,                          /*tp_basicsize*/
    0,                          /*tp_itemsize*/
    0,                          /*tp_dealloc*/
    0,                          /*tp_print*/
    0,                          /*tp_getattr*/
    0,                          /*tp_setattr*/
    0,                          /*tp_compare */
    0,                          /*tp_repr*/
    0,                          /*tp_as_number*/
    0,                          /*tp_as_sequence*/
    0,                          /*tp_as_mapping*/
    0,                          /*tp_hash */
    0,                          /*tp_call*/
    0,                          /*tp_str*/
    0,                          /*tp_getattro*/
    0,                          /*tp_setattro*/
    0,                          /*tp_as_buffer*/
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,  /*tp_flags*/
    RawIOBase_doc,              /* tp_doc */
    0,                          /* tp_traverse */
    0,                          /* tp_clear */
    0,                          /* tp_richcompare */
    0,                          /* tp_weaklistoffset */
    0,                          /* tp_iter */
    0,                          /* tp_iternext */
    RawIOBase_methods,          /* tp_methods */
    0,                          /* tp_members */
    0,                          /* tp_getset */
    &PyIOBase_Type,             /* tp_base */
    0,                          /* tp_dict */
    0,                          /* tp_descr_get */
    0,                          /* tp_descr_set */
    0,                          /* tp_dictoffset */
    0,                          /* tp_init */
    0,                          /* tp_alloc */
    0,                          /* tp_new */
};