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1 /*
2     An implementation of the new I/O lib as defined by PEP 3116 - "New I/O"
3 
4     Classes defined here: UnsupportedOperation, BlockingIOError.
5     Functions defined here: open().
6 
7     Mostly written by Amaury Forgeot d'Arc
8 */
9 
10 #define PY_SSIZE_T_CLEAN
11 #include "Python.h"
12 #include "structmember.h"
13 #include "_iomodule.h"
14 
15 #ifdef HAVE_SYS_TYPES_H
16 #include <sys/types.h>
17 #endif /* HAVE_SYS_TYPES_H */
18 
19 #ifdef HAVE_SYS_STAT_H
20 #include <sys/stat.h>
21 #endif /* HAVE_SYS_STAT_H */
22 
23 
24 /* Various interned strings */
25 
26 PyObject *_PyIO_str_close;
27 PyObject *_PyIO_str_closed;
28 PyObject *_PyIO_str_decode;
29 PyObject *_PyIO_str_encode;
30 PyObject *_PyIO_str_fileno;
31 PyObject *_PyIO_str_flush;
32 PyObject *_PyIO_str_getstate;
33 PyObject *_PyIO_str_isatty;
34 PyObject *_PyIO_str_newlines;
35 PyObject *_PyIO_str_nl;
36 PyObject *_PyIO_str_read;
37 PyObject *_PyIO_str_read1;
38 PyObject *_PyIO_str_readable;
39 PyObject *_PyIO_str_readinto;
40 PyObject *_PyIO_str_readline;
41 PyObject *_PyIO_str_reset;
42 PyObject *_PyIO_str_seek;
43 PyObject *_PyIO_str_seekable;
44 PyObject *_PyIO_str_setstate;
45 PyObject *_PyIO_str_tell;
46 PyObject *_PyIO_str_truncate;
47 PyObject *_PyIO_str_writable;
48 PyObject *_PyIO_str_write;
49 
50 PyObject *_PyIO_empty_str;
51 PyObject *_PyIO_empty_bytes;
52 PyObject *_PyIO_zero;
53 
54 
55 PyDoc_STRVAR(module_doc,
56 "The io module provides the Python interfaces to stream handling. The\n"
57 "builtin open function is defined in this module.\n"
58 "\n"
59 "At the top of the I/O hierarchy is the abstract base class IOBase. It\n"
60 "defines the basic interface to a stream. Note, however, that there is no\n"
61 "separation between reading and writing to streams; implementations are\n"
62 "allowed to raise an IOError if they do not support a given operation.\n"
63 "\n"
64 "Extending IOBase is RawIOBase which deals simply with the reading and\n"
65 "writing of raw bytes to a stream. FileIO subclasses RawIOBase to provide\n"
66 "an interface to OS files.\n"
67 "\n"
68 "BufferedIOBase deals with buffering on a raw byte stream (RawIOBase). Its\n"
69 "subclasses, BufferedWriter, BufferedReader, and BufferedRWPair buffer\n"
70 "streams that are readable, writable, and both respectively.\n"
71 "BufferedRandom provides a buffered interface to random access\n"
72 "streams. BytesIO is a simple stream of in-memory bytes.\n"
73 "\n"
74 "Another IOBase subclass, TextIOBase, deals with the encoding and decoding\n"
75 "of streams into text. TextIOWrapper, which extends it, is a buffered text\n"
76 "interface to a buffered raw stream (`BufferedIOBase`). Finally, StringIO\n"
77 "is an in-memory stream for text.\n"
78 "\n"
79 "Argument names are not part of the specification, and only the arguments\n"
80 "of open() are intended to be used as keyword arguments.\n"
81 "\n"
82 "data:\n"
83 "\n"
84 "DEFAULT_BUFFER_SIZE\n"
85 "\n"
86 "   An int containing the default buffer size used by the module's buffered\n"
87 "   I/O classes. open() uses the file's blksize (as obtained by os.stat) if\n"
88 "   possible.\n"
89     );
90 
91 
92 /*
93  * BlockingIOError extends IOError
94  */
95 
96 static int
blockingioerror_init(PyBlockingIOErrorObject * self,PyObject * args,PyObject * kwds)97 blockingioerror_init(PyBlockingIOErrorObject *self, PyObject *args,
98                      PyObject *kwds)
99 {
100     PyObject *myerrno = NULL, *strerror = NULL;
101     PyObject *baseargs = NULL;
102     Py_ssize_t written = 0;
103 
104     assert(PyTuple_Check(args));
105 
106     self->written = 0;
107     if (!PyArg_ParseTuple(args, "OO|n:BlockingIOError",
108                           &myerrno, &strerror, &written))
109         return -1;
110 
111     baseargs = PyTuple_Pack(2, myerrno, strerror);
112     if (baseargs == NULL)
113         return -1;
114     /* This will take care of initializing of myerrno and strerror members */
115     if (((PyTypeObject *)PyExc_IOError)->tp_init(
116                 (PyObject *)self, baseargs, kwds) == -1) {
117         Py_DECREF(baseargs);
118         return -1;
119     }
120     Py_DECREF(baseargs);
121 
122     self->written = written;
123     return 0;
124 }
125 
126 static PyMemberDef blockingioerror_members[] = {
127     {"characters_written", T_PYSSIZET, offsetof(PyBlockingIOErrorObject, written), 0},
128     {NULL}  /* Sentinel */
129 };
130 
131 static PyTypeObject _PyExc_BlockingIOError = {
132     PyVarObject_HEAD_INIT(NULL, 0)
133     "BlockingIOError", /*tp_name*/
134     sizeof(PyBlockingIOErrorObject), /*tp_basicsize*/
135     0,                          /*tp_itemsize*/
136     0,                          /*tp_dealloc*/
137     0,                          /*tp_print*/
138     0,                          /*tp_getattr*/
139     0,                          /*tp_setattr*/
140     0,                          /*tp_compare */
141     0,                          /*tp_repr*/
142     0,                          /*tp_as_number*/
143     0,                          /*tp_as_sequence*/
144     0,                          /*tp_as_mapping*/
145     0,                          /*tp_hash */
146     0,                          /*tp_call*/
147     0,                          /*tp_str*/
148     0,                          /*tp_getattro*/
149     0,                          /*tp_setattro*/
150     0,                          /*tp_as_buffer*/
151     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
152     PyDoc_STR("Exception raised when I/O would block "
153               "on a non-blocking I/O stream"), /* tp_doc */
154     0,                          /* tp_traverse */
155     0,                          /* tp_clear */
156     0,                          /* tp_richcompare */
157     0,                          /* tp_weaklistoffset */
158     0,                          /* tp_iter */
159     0,                          /* tp_iternext */
160     0,                          /* tp_methods */
161     blockingioerror_members,    /* tp_members */
162     0,                          /* tp_getset */
163     0,                          /* tp_base */
164     0,                          /* tp_dict */
165     0,                          /* tp_descr_get */
166     0,                          /* tp_descr_set */
167     0,                          /* tp_dictoffset */
168     (initproc)blockingioerror_init, /* tp_init */
169     0,                          /* tp_alloc */
170     0,                          /* tp_new */
171 };
172 PyObject *PyExc_BlockingIOError = (PyObject *)&_PyExc_BlockingIOError;
173 
174 
175 /*
176  * The main open() function
177  */
178 PyDoc_STRVAR(open_doc,
179 "Open file and return a stream.  Raise IOError upon failure.\n"
180 "\n"
181 "file is either a text or byte string giving the name (and the path\n"
182 "if the file isn't in the current working directory) of the file to\n"
183 "be opened or an integer file descriptor of the file to be\n"
184 "wrapped. (If a file descriptor is given, it is closed when the\n"
185 "returned I/O object is closed, unless closefd is set to False.)\n"
186 "\n"
187 "mode is an optional string that specifies the mode in which the file\n"
188 "is opened. It defaults to 'r' which means open for reading in text\n"
189 "mode.  Other common values are 'w' for writing (truncating the file if\n"
190 "it already exists), and 'a' for appending (which on some Unix systems,\n"
191 "means that all writes append to the end of the file regardless of the\n"
192 "current seek position). In text mode, if encoding is not specified the\n"
193 "encoding used is platform dependent. (For reading and writing raw\n"
194 "bytes use binary mode and leave encoding unspecified.) The available\n"
195 "modes are:\n"
196 "\n"
197 "========= ===============================================================\n"
198 "Character Meaning\n"
199 "--------- ---------------------------------------------------------------\n"
200 "'r'       open for reading (default)\n"
201 "'w'       open for writing, truncating the file first\n"
202 "'a'       open for writing, appending to the end of the file if it exists\n"
203 "'b'       binary mode\n"
204 "'t'       text mode (default)\n"
205 "'+'       open a disk file for updating (reading and writing)\n"
206 "'U'       universal newline mode (for backwards compatibility; unneeded\n"
207 "          for new code)\n"
208 "========= ===============================================================\n"
209 "\n"
210 "The default mode is 'rt' (open for reading text). For binary random\n"
211 "access, the mode 'w+b' opens and truncates the file to 0 bytes, while\n"
212 "'r+b' opens the file without truncation.\n"
213 "\n"
214 "Python distinguishes between files opened in binary and text modes,\n"
215 "even when the underlying operating system doesn't. Files opened in\n"
216 "binary mode (appending 'b' to the mode argument) return contents as\n"
217 "bytes objects without any decoding. In text mode (the default, or when\n"
218 "'t' is appended to the mode argument), the contents of the file are\n"
219 "returned as strings, the bytes having been first decoded using a\n"
220 "platform-dependent encoding or using the specified encoding if given.\n"
221 "\n"
222 "buffering is an optional integer used to set the buffering policy.\n"
223 "Pass 0 to switch buffering off (only allowed in binary mode), 1 to select\n"
224 "line buffering (only usable in text mode), and an integer > 1 to indicate\n"
225 "the size of a fixed-size chunk buffer.  When no buffering argument is\n"
226 "given, the default buffering policy works as follows:\n"
227 "\n"
228 "* Binary files are buffered in fixed-size chunks; the size of the buffer\n"
229 "  is chosen using a heuristic trying to determine the underlying device's\n"
230 "  \"block size\" and falling back on `io.DEFAULT_BUFFER_SIZE`.\n"
231 "  On many systems, the buffer will typically be 4096 or 8192 bytes long.\n"
232 "\n"
233 "* \"Interactive\" text files (files for which isatty() returns True)\n"
234 "  use line buffering.  Other text files use the policy described above\n"
235 "  for binary files.\n"
236 "\n"
237 "encoding is the name of the encoding used to decode or encode the\n"
238 "file. This should only be used in text mode. The default encoding is\n"
239 "platform dependent, but any encoding supported by Python can be\n"
240 "passed.  See the codecs module for the list of supported encodings.\n"
241 "\n"
242 "errors is an optional string that specifies how encoding errors are to\n"
243 "be handled---this argument should not be used in binary mode. Pass\n"
244 "'strict' to raise a ValueError exception if there is an encoding error\n"
245 "(the default of None has the same effect), or pass 'ignore' to ignore\n"
246 "errors. (Note that ignoring encoding errors can lead to data loss.)\n"
247 "See the documentation for codecs.register for a list of the permitted\n"
248 "encoding error strings.\n"
249 "\n"
250 "newline controls how universal newlines works (it only applies to text\n"
251 "mode). It can be None, '', '\\n', '\\r', and '\\r\\n'.  It works as\n"
252 "follows:\n"
253 "\n"
254 "* On input, if newline is None, universal newlines mode is\n"
255 "  enabled. Lines in the input can end in '\\n', '\\r', or '\\r\\n', and\n"
256 "  these are translated into '\\n' before being returned to the\n"
257 "  caller. If it is '', universal newline mode is enabled, but line\n"
258 "  endings are returned to the caller untranslated. If it has any of\n"
259 "  the other legal values, input lines are only terminated by the given\n"
260 "  string, and the line ending is returned to the caller untranslated.\n"
261 "\n"
262 "* On output, if newline is None, any '\\n' characters written are\n"
263 "  translated to the system default line separator, os.linesep. If\n"
264 "  newline is '', no translation takes place. If newline is any of the\n"
265 "  other legal values, any '\\n' characters written are translated to\n"
266 "  the given string.\n"
267 "\n"
268 "If closefd is False, the underlying file descriptor will be kept open\n"
269 "when the file is closed. This does not work when a file name is given\n"
270 "and must be True in that case.\n"
271 "\n"
272 "open() returns a file object whose type depends on the mode, and\n"
273 "through which the standard file operations such as reading and writing\n"
274 "are performed. When open() is used to open a file in a text mode ('w',\n"
275 "'r', 'wt', 'rt', etc.), it returns a TextIOWrapper. When used to open\n"
276 "a file in a binary mode, the returned class varies: in read binary\n"
277 "mode, it returns a BufferedReader; in write binary and append binary\n"
278 "modes, it returns a BufferedWriter, and in read/write mode, it returns\n"
279 "a BufferedRandom.\n"
280 "\n"
281 "It is also possible to use a string or bytearray as a file for both\n"
282 "reading and writing. For strings StringIO can be used like a file\n"
283 "opened in a text mode, and for bytes a BytesIO can be used like a file\n"
284 "opened in a binary mode.\n"
285     );
286 
287 static PyObject *
io_open(PyObject * self,PyObject * args,PyObject * kwds)288 io_open(PyObject *self, PyObject *args, PyObject *kwds)
289 {
290     char *kwlist[] = {"file", "mode", "buffering",
291                       "encoding", "errors", "newline",
292                       "closefd", NULL};
293     PyObject *file;
294     char *mode = "r";
295     int buffering = -1, closefd = 1;
296     char *encoding = NULL, *errors = NULL, *newline = NULL;
297     unsigned i;
298 
299     int reading = 0, writing = 0, appending = 0, updating = 0;
300     int text = 0, binary = 0, universal = 0;
301 
302     char rawmode[5], *m;
303     int line_buffering;
304     long isatty;
305 
306     PyObject *raw, *modeobj = NULL, *buffer, *wrapper, *result = NULL;
307 
308     if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|sizzzi:open", kwlist,
309                                      &file, &mode, &buffering,
310                                      &encoding, &errors, &newline,
311                                      &closefd)) {
312         return NULL;
313     }
314 
315     if (!PyUnicode_Check(file) &&
316 	!PyBytes_Check(file) &&
317 	!PyNumber_Check(file)) {
318         PyObject *repr = PyObject_Repr(file);
319         if (repr != NULL) {
320             PyErr_Format(PyExc_TypeError, "invalid file: %s",
321                          PyString_AS_STRING(repr));
322             Py_DECREF(repr);
323         }
324         return NULL;
325     }
326 
327     /* Decode mode */
328     for (i = 0; i < strlen(mode); i++) {
329         char c = mode[i];
330 
331         switch (c) {
332         case 'r':
333             reading = 1;
334             break;
335         case 'w':
336             writing = 1;
337             break;
338         case 'a':
339             appending = 1;
340             break;
341         case '+':
342             updating = 1;
343             break;
344         case 't':
345             text = 1;
346             break;
347         case 'b':
348             binary = 1;
349             break;
350         case 'U':
351             universal = 1;
352             reading = 1;
353             break;
354         default:
355             goto invalid_mode;
356         }
357 
358         /* c must not be duplicated */
359         if (strchr(mode+i+1, c)) {
360           invalid_mode:
361             PyErr_Format(PyExc_ValueError, "invalid mode: '%s'", mode);
362             return NULL;
363         }
364 
365     }
366 
367     m = rawmode;
368     if (reading)   *(m++) = 'r';
369     if (writing)   *(m++) = 'w';
370     if (appending) *(m++) = 'a';
371     if (updating)  *(m++) = '+';
372     *m = '\0';
373 
374     /* Parameters validation */
375     if (universal) {
376         if (writing || appending) {
377             PyErr_SetString(PyExc_ValueError,
378                             "can't use U and writing mode at once");
379             return NULL;
380         }
381         reading = 1;
382     }
383 
384     if (text && binary) {
385         PyErr_SetString(PyExc_ValueError,
386                         "can't have text and binary mode at once");
387         return NULL;
388     }
389 
390     if (reading + writing + appending > 1) {
391         PyErr_SetString(PyExc_ValueError,
392                         "must have exactly one of read/write/append mode");
393         return NULL;
394     }
395 
396     if (binary && encoding != NULL) {
397         PyErr_SetString(PyExc_ValueError,
398                         "binary mode doesn't take an encoding argument");
399         return NULL;
400     }
401 
402     if (binary && errors != NULL) {
403         PyErr_SetString(PyExc_ValueError,
404                         "binary mode doesn't take an errors argument");
405         return NULL;
406     }
407 
408     if (binary && newline != NULL) {
409         PyErr_SetString(PyExc_ValueError,
410                         "binary mode doesn't take a newline argument");
411         return NULL;
412     }
413 
414     /* Create the Raw file stream */
415     raw = PyObject_CallFunction((PyObject *)&PyFileIO_Type,
416 				"Osi", file, rawmode, closefd);
417     if (raw == NULL)
418         return NULL;
419     result = raw;
420 
421     modeobj = PyUnicode_FromString(mode);
422     if (modeobj == NULL)
423         goto error;
424 
425     /* buffering */
426     {
427         PyObject *res = PyObject_CallMethod(raw, "isatty", NULL);
428         if (res == NULL)
429             goto error;
430         isatty = PyLong_AsLong(res);
431         Py_DECREF(res);
432         if (isatty == -1 && PyErr_Occurred())
433             goto error;
434     }
435 
436     if (buffering == 1 || (buffering < 0 && isatty)) {
437         buffering = -1;
438         line_buffering = 1;
439     }
440     else
441         line_buffering = 0;
442 
443     if (buffering < 0) {
444         buffering = DEFAULT_BUFFER_SIZE;
445 #ifdef HAVE_STRUCT_STAT_ST_BLKSIZE
446         {
447             struct stat st;
448             int fileno;
449             PyObject *res = PyObject_CallMethod(raw, "fileno", NULL);
450             if (res == NULL)
451                 goto error;
452 
453             fileno = _PyInt_AsInt(res);
454             Py_DECREF(res);
455             if (fileno == -1 && PyErr_Occurred())
456                 goto error;
457 
458             if (fstat(fileno, &st) >= 0 && st.st_blksize > 1)
459                 buffering = st.st_blksize;
460         }
461 #endif
462     }
463     if (buffering < 0) {
464         PyErr_SetString(PyExc_ValueError,
465                         "invalid buffering size");
466         goto error;
467     }
468 
469     /* if not buffering, returns the raw file object */
470     if (buffering == 0) {
471         if (!binary) {
472             PyErr_SetString(PyExc_ValueError,
473                             "can't have unbuffered text I/O");
474             goto error;
475         }
476 
477         Py_DECREF(modeobj);
478         return result;
479     }
480 
481     /* wraps into a buffered file */
482     {
483         PyObject *Buffered_class;
484 
485         if (updating)
486             Buffered_class = (PyObject *)&PyBufferedRandom_Type;
487         else if (writing || appending)
488             Buffered_class = (PyObject *)&PyBufferedWriter_Type;
489         else if (reading)
490             Buffered_class = (PyObject *)&PyBufferedReader_Type;
491         else {
492             PyErr_Format(PyExc_ValueError,
493                          "unknown mode: '%s'", mode);
494             goto error;
495         }
496 
497         buffer = PyObject_CallFunction(Buffered_class, "Oi", raw, buffering);
498     }
499     if (buffer == NULL)
500         goto error;
501     result = buffer;
502     Py_DECREF(raw);
503 
504 
505     /* if binary, returns the buffered file */
506     if (binary) {
507         Py_DECREF(modeobj);
508         return result;
509     }
510 
511     /* wraps into a TextIOWrapper */
512     wrapper = PyObject_CallFunction((PyObject *)&PyTextIOWrapper_Type,
513 				    "Osssi",
514 				    buffer,
515 				    encoding, errors, newline,
516 				    line_buffering);
517     if (wrapper == NULL)
518         goto error;
519     result = wrapper;
520     Py_DECREF(buffer);
521 
522     if (PyObject_SetAttrString(wrapper, "mode", modeobj) < 0)
523         goto error;
524     Py_DECREF(modeobj);
525     return result;
526 
527   error:
528     if (result != NULL) {
529         PyObject *exc, *val, *tb, *close_result;
530         PyErr_Fetch(&exc, &val, &tb);
531         close_result = PyObject_CallMethod(result, "close", NULL);
532         _PyErr_ReplaceException(exc, val, tb);
533         Py_XDECREF(close_result);
534         Py_DECREF(result);
535     }
536     Py_XDECREF(modeobj);
537     return NULL;
538 }
539 
540 /*
541  * Private helpers for the io module.
542  */
543 
544 Py_off_t
PyNumber_AsOff_t(PyObject * item,PyObject * err)545 PyNumber_AsOff_t(PyObject *item, PyObject *err)
546 {
547     Py_off_t result;
548     PyObject *runerr;
549     PyObject *value = PyNumber_Index(item);
550     if (value == NULL)
551         return -1;
552 
553     if (PyInt_Check(value)) {
554         /* We assume a long always fits in a Py_off_t... */
555         result = (Py_off_t) PyInt_AS_LONG(value);
556         goto finish;
557     }
558 
559     /* We're done if PyLong_AsSsize_t() returns without error. */
560     result = PyLong_AsOff_t(value);
561     if (result != -1 || !(runerr = PyErr_Occurred()))
562         goto finish;
563 
564     /* Error handling code -- only manage OverflowError differently */
565     if (!PyErr_GivenExceptionMatches(runerr, PyExc_OverflowError))
566         goto finish;
567 
568     PyErr_Clear();
569     /* If no error-handling desired then the default clipping
570        is sufficient.
571      */
572     if (!err) {
573         assert(PyLong_Check(value));
574         /* Whether or not it is less than or equal to
575            zero is determined by the sign of ob_size
576         */
577         if (_PyLong_Sign(value) < 0)
578             result = PY_OFF_T_MIN;
579         else
580             result = PY_OFF_T_MAX;
581     }
582     else {
583         /* Otherwise replace the error with caller's error object. */
584         PyErr_Format(err,
585                      "cannot fit '%.200s' into an offset-sized integer",
586                      item->ob_type->tp_name);
587     }
588 
589  finish:
590     Py_DECREF(value);
591     return result;
592 }
593 
594 
595 /* Basically the "n" format code with the ability to turn None into -1. */
596 int
_PyIO_ConvertSsize_t(PyObject * obj,void * result)597 _PyIO_ConvertSsize_t(PyObject *obj, void *result) {
598     Py_ssize_t limit;
599     if (obj == Py_None) {
600         limit = -1;
601     }
602     else if (PyNumber_Check(obj)) {
603         limit = PyNumber_AsSsize_t(obj, PyExc_OverflowError);
604         if (limit == -1 && PyErr_Occurred())
605             return 0;
606     }
607     else {
608         PyErr_Format(PyExc_TypeError,
609                      "integer argument expected, got '%.200s'",
610                      Py_TYPE(obj)->tp_name);
611         return 0;
612     }
613     *((Py_ssize_t *)result) = limit;
614     return 1;
615 }
616 
617 
618 /*
619  * Module definition
620  */
621 
622 PyObject *_PyIO_os_module = NULL;
623 PyObject *_PyIO_locale_module = NULL;
624 PyObject *_PyIO_unsupported_operation = NULL;
625 
626 static PyMethodDef module_methods[] = {
627     {"open", (PyCFunction)io_open, METH_VARARGS|METH_KEYWORDS, open_doc},
628     {NULL, NULL}
629 };
630 
631 PyMODINIT_FUNC
init_io(void)632 init_io(void)
633 {
634     PyObject *m = Py_InitModule4("_io", module_methods,
635                                  module_doc, NULL, PYTHON_API_VERSION);
636     if (m == NULL)
637         return;
638 
639     /* put os in the module state */
640     _PyIO_os_module = PyImport_ImportModule("os");
641     if (_PyIO_os_module == NULL)
642         goto fail;
643 
644 #define ADD_TYPE(type, name) \
645     if (PyType_Ready(type) < 0) \
646         goto fail; \
647     Py_INCREF(type); \
648     if (PyModule_AddObject(m, name, (PyObject *)type) < 0) {  \
649         Py_DECREF(type); \
650         goto fail; \
651     }
652 
653     /* DEFAULT_BUFFER_SIZE */
654     if (PyModule_AddIntMacro(m, DEFAULT_BUFFER_SIZE) < 0)
655         goto fail;
656 
657     /* UnsupportedOperation inherits from ValueError and IOError */
658     _PyIO_unsupported_operation = PyObject_CallFunction(
659         (PyObject *)&PyType_Type, "s(OO){}",
660         "UnsupportedOperation", PyExc_ValueError, PyExc_IOError);
661     if (_PyIO_unsupported_operation == NULL)
662         goto fail;
663     Py_INCREF(_PyIO_unsupported_operation);
664     if (PyModule_AddObject(m, "UnsupportedOperation",
665                            _PyIO_unsupported_operation) < 0)
666         goto fail;
667 
668     /* BlockingIOError */
669     _PyExc_BlockingIOError.tp_base = (PyTypeObject *) PyExc_IOError;
670     ADD_TYPE(&_PyExc_BlockingIOError, "BlockingIOError");
671 
672     /* Concrete base types of the IO ABCs.
673        (the ABCs themselves are declared through inheritance in io.py)
674     */
675     ADD_TYPE(&PyIOBase_Type, "_IOBase");
676     ADD_TYPE(&PyRawIOBase_Type, "_RawIOBase");
677     ADD_TYPE(&PyBufferedIOBase_Type, "_BufferedIOBase");
678     ADD_TYPE(&PyTextIOBase_Type, "_TextIOBase");
679 
680     /* Implementation of concrete IO objects. */
681     /* FileIO */
682     PyFileIO_Type.tp_base = &PyRawIOBase_Type;
683     ADD_TYPE(&PyFileIO_Type, "FileIO");
684 
685     /* BytesIO */
686     PyBytesIO_Type.tp_base = &PyBufferedIOBase_Type;
687     ADD_TYPE(&PyBytesIO_Type, "BytesIO");
688 
689     /* StringIO */
690     PyStringIO_Type.tp_base = &PyTextIOBase_Type;
691     ADD_TYPE(&PyStringIO_Type, "StringIO");
692 
693     /* BufferedReader */
694     PyBufferedReader_Type.tp_base = &PyBufferedIOBase_Type;
695     ADD_TYPE(&PyBufferedReader_Type, "BufferedReader");
696 
697     /* BufferedWriter */
698     PyBufferedWriter_Type.tp_base = &PyBufferedIOBase_Type;
699     ADD_TYPE(&PyBufferedWriter_Type, "BufferedWriter");
700 
701     /* BufferedRWPair */
702     PyBufferedRWPair_Type.tp_base = &PyBufferedIOBase_Type;
703     ADD_TYPE(&PyBufferedRWPair_Type, "BufferedRWPair");
704 
705     /* BufferedRandom */
706     PyBufferedRandom_Type.tp_base = &PyBufferedIOBase_Type;
707     ADD_TYPE(&PyBufferedRandom_Type, "BufferedRandom");
708 
709     /* TextIOWrapper */
710     PyTextIOWrapper_Type.tp_base = &PyTextIOBase_Type;
711     ADD_TYPE(&PyTextIOWrapper_Type, "TextIOWrapper");
712 
713     /* IncrementalNewlineDecoder */
714     ADD_TYPE(&PyIncrementalNewlineDecoder_Type, "IncrementalNewlineDecoder");
715 
716     /* Interned strings */
717     if (!(_PyIO_str_close = PyString_InternFromString("close")))
718         goto fail;
719     if (!(_PyIO_str_closed = PyString_InternFromString("closed")))
720         goto fail;
721     if (!(_PyIO_str_decode = PyString_InternFromString("decode")))
722         goto fail;
723     if (!(_PyIO_str_encode = PyString_InternFromString("encode")))
724         goto fail;
725     if (!(_PyIO_str_fileno = PyString_InternFromString("fileno")))
726         goto fail;
727     if (!(_PyIO_str_flush = PyString_InternFromString("flush")))
728         goto fail;
729     if (!(_PyIO_str_getstate = PyString_InternFromString("getstate")))
730         goto fail;
731     if (!(_PyIO_str_isatty = PyString_InternFromString("isatty")))
732         goto fail;
733     if (!(_PyIO_str_newlines = PyString_InternFromString("newlines")))
734         goto fail;
735     if (!(_PyIO_str_nl = PyString_InternFromString("\n")))
736         goto fail;
737     if (!(_PyIO_str_read = PyString_InternFromString("read")))
738         goto fail;
739     if (!(_PyIO_str_read1 = PyString_InternFromString("read1")))
740         goto fail;
741     if (!(_PyIO_str_readable = PyString_InternFromString("readable")))
742         goto fail;
743     if (!(_PyIO_str_readinto = PyString_InternFromString("readinto")))
744         goto fail;
745     if (!(_PyIO_str_readline = PyString_InternFromString("readline")))
746         goto fail;
747     if (!(_PyIO_str_reset = PyString_InternFromString("reset")))
748         goto fail;
749     if (!(_PyIO_str_seek = PyString_InternFromString("seek")))
750         goto fail;
751     if (!(_PyIO_str_seekable = PyString_InternFromString("seekable")))
752         goto fail;
753     if (!(_PyIO_str_setstate = PyString_InternFromString("setstate")))
754         goto fail;
755     if (!(_PyIO_str_tell = PyString_InternFromString("tell")))
756         goto fail;
757     if (!(_PyIO_str_truncate = PyString_InternFromString("truncate")))
758         goto fail;
759     if (!(_PyIO_str_write = PyString_InternFromString("write")))
760         goto fail;
761     if (!(_PyIO_str_writable = PyString_InternFromString("writable")))
762         goto fail;
763 
764     if (!(_PyIO_empty_str = PyUnicode_FromStringAndSize(NULL, 0)))
765         goto fail;
766     if (!(_PyIO_empty_bytes = PyBytes_FromStringAndSize(NULL, 0)))
767         goto fail;
768     if (!(_PyIO_zero = PyLong_FromLong(0L)))
769         goto fail;
770 
771     return;
772 
773   fail:
774     Py_CLEAR(_PyIO_os_module);
775     Py_CLEAR(_PyIO_unsupported_operation);
776     Py_DECREF(m);
777 }
778