summaryrefslogtreecommitdiffstats
path: root/Modules/fcntlmodule.c
blob: cabff06269f187b64c47e2a04b3b05227fc2bf41 (plain)
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

/* fcntl module */

#define PY_SSIZE_T_CLEAN

#include "Python.h"

#ifdef HAVE_SYS_FILE_H
#include <sys/file.h>
#endif

#include <sys/ioctl.h>
#include <fcntl.h>
#ifdef HAVE_STROPTS_H
#include <stropts.h>
#endif

/*[clinic input]
module fcntl
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=124b58387c158179]*/

static int
conv_descriptor(PyObject *object, int *target)
{
    int fd = PyObject_AsFileDescriptor(object);

    if (fd < 0)
    return 0;
    *target = fd;
    return 1;
}

/* Must come after conv_descriptor definition. */
#include "clinic/fcntlmodule.c.h"

/*[clinic input]
fcntl.fcntl

    fd: object(type='int', converter='conv_descriptor')
    cmd as code: int
    arg: object(c_default='NULL') = 0
    /

Perform the operation `cmd` on file descriptor fd.

The values used for `cmd` are operating system dependent, and are available
as constants in the fcntl module, using the same names as used in
the relevant C header files.  The argument arg is optional, and
defaults to 0; it may be an int or a string.  If arg is given as a string,
the return value of fcntl is a string of that length, containing the
resulting value put in the arg buffer by the operating system.  The length
of the arg string is not allowed to exceed 1024 bytes.  If the arg given
is an integer or if none is specified, the result value is an integer
corresponding to the return value of the fcntl call in the C code.
[clinic start generated code]*/

static PyObject *
fcntl_fcntl_impl(PyModuleDef *module, int fd, int code, PyObject *arg)
/*[clinic end generated code: output=afc5bfa74a03ef0d input=8cefbe59b29efbe2]*/
{
    unsigned int int_arg = 0;
    int ret;
    char *str;
    Py_ssize_t len;
    char buf[1024];

    if (arg != NULL) {
        int parse_result;

        if (PyArg_Parse(arg, "s#", &str, &len)) {
            if ((size_t)len > sizeof buf) {
                PyErr_SetString(PyExc_ValueError,
                                "fcntl string arg too long");
                return NULL;
            }
            memcpy(buf, str, len);
            Py_BEGIN_ALLOW_THREADS
            ret = fcntl(fd, code, buf);
            Py_END_ALLOW_THREADS
            if (ret < 0) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
            }
            return PyBytes_FromStringAndSize(buf, len);
        }

        PyErr_Clear();
        parse_result = PyArg_Parse(arg,
            "I;fcntl requires a file or file descriptor,"
            " an integer and optionally a third integer or a string",
            &int_arg);
        if (!parse_result) {
          return NULL;
        }
    }

    Py_BEGIN_ALLOW_THREADS
    ret = fcntl(fd, code, (int)int_arg);
    Py_END_ALLOW_THREADS
    if (ret < 0) {
        PyErr_SetFromErrno(PyExc_IOError);
        return NULL;
    }
    return PyLong_FromLong((long)ret);
}


/*[clinic input]
fcntl.ioctl

    fd: object(type='int', converter='conv_descriptor')
    request as code: unsigned_int(bitwise=True)
    arg as ob_arg: object(c_default='NULL') = 0
    mutate_flag as mutate_arg: bool = True
    /

Perform the operation `request` on file descriptor `fd`.

The values used for `request` are operating system dependent, and are available
as constants in the fcntl or termios library modules, using the same names as
used in the relevant C header files.

The argument `arg` is optional, and defaults to 0; it may be an int or a
buffer containing character data (most likely a string or an array).

If the argument is a mutable buffer (such as an array) and if the
mutate_flag argument (which is only allowed in this case) is true then the
buffer is (in effect) passed to the operating system and changes made by
the OS will be reflected in the contents of the buffer after the call has
returned.  The return value is the integer returned by the ioctl system
call.

If the argument is a mutable buffer and the mutable_flag argument is false,
the behavior is as if a string had been passed.

If the argument is an immutable buffer (most likely a string) then a copy
of the buffer is passed to the operating system and the return value is a
string of the same length containing whatever the operating system put in
the buffer.  The length of the arg buffer in this case is not allowed to
exceed 1024 bytes.

If the arg given is an integer or if none is specified, the result value is
an integer corresponding to the return value of the ioctl call in the C
code.
[clinic start generated code]*/

static PyObject *
fcntl_ioctl_impl(PyModuleDef *module, int fd, unsigned int code, PyObject *ob_arg, int mutate_arg)
/*[clinic end generated code: output=ad47738c118622bf input=ede70c433cccbbb2]*/
{
#define IOCTL_BUFSZ 1024
    /* We use the unsigned non-checked 'I' format for the 'code' parameter
       because the system expects it to be a 32bit bit field value
       regardless of it being passed as an int or unsigned long on
       various platforms.  See the termios.TIOCSWINSZ constant across
       platforms for an example of this.

       If any of the 64bit platforms ever decide to use more than 32bits
       in their unsigned long ioctl codes this will break and need
       special casing based on the platform being built on.
     */
    int arg = 0;
    int ret;
    Py_buffer pstr;
    char *str;
    Py_ssize_t len;
    char buf[IOCTL_BUFSZ+1];  /* argument plus NUL byte */

    if (ob_arg != NULL) {
        if (PyArg_Parse(ob_arg, "w*:ioctl", &pstr)) {
            char *arg;
            str = pstr.buf;
            len = pstr.len;

            if (mutate_arg) {
                if (len <= IOCTL_BUFSZ) {
                    memcpy(buf, str, len);
                    buf[len] = '\0';
                    arg = buf;
                }
                else {
                    arg = str;
                }
            }
            else {
                if (len > IOCTL_BUFSZ) {
                    PyBuffer_Release(&pstr);
                    PyErr_SetString(PyExc_ValueError,
                        "ioctl string arg too long");
                    return NULL;
                }
                else {
                    memcpy(buf, str, len);
                    buf[len] = '\0';
                    arg = buf;
                }
            }
            if (buf == arg) {
                Py_BEGIN_ALLOW_THREADS /* think array.resize() */
                ret = ioctl(fd, code, arg);
                Py_END_ALLOW_THREADS
            }
            else {
                ret = ioctl(fd, code, arg);
            }
            if (mutate_arg && (len <= IOCTL_BUFSZ)) {
                memcpy(str, buf, len);
            }
            PyBuffer_Release(&pstr); /* No further access to str below this point */
            if (ret < 0) {
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
            }
            if (mutate_arg) {
                return PyLong_FromLong(ret);
            }
            else {
                return PyBytes_FromStringAndSize(buf, len);
            }
        }

        PyErr_Clear();
        if (PyArg_Parse(ob_arg, "s*:ioctl", &pstr)) {
            str = pstr.buf;
            len = pstr.len;
            if (len > IOCTL_BUFSZ) {
                PyBuffer_Release(&pstr);
                PyErr_SetString(PyExc_ValueError,
                                "ioctl string arg too long");
                return NULL;
            }
            memcpy(buf, str, len);
            buf[len] = '\0';
            Py_BEGIN_ALLOW_THREADS
            ret = ioctl(fd, code, buf);
            Py_END_ALLOW_THREADS
            if (ret < 0) {
                PyBuffer_Release(&pstr);
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
            }
            PyBuffer_Release(&pstr);
            return PyBytes_FromStringAndSize(buf, len);
        }

        PyErr_Clear();
        if (!PyArg_Parse(ob_arg,
             "i;ioctl requires a file or file descriptor,"
             " an integer and optionally an integer or buffer argument",
             &arg)) {
          return NULL;
        }
        // Fall-through to outside the 'if' statement.
    }
    Py_BEGIN_ALLOW_THREADS
    ret = ioctl(fd, code, arg);
    Py_END_ALLOW_THREADS
    if (ret < 0) {
        PyErr_SetFromErrno(PyExc_IOError);
        return NULL;
    }
    return PyLong_FromLong((long)ret);
#undef IOCTL_BUFSZ
}

/*[clinic input]
fcntl.flock

    fd: object(type='int', converter='conv_descriptor')
    operation as code: int
    /

Perform the lock operation `operation` on file descriptor `fd`.

See the Unix manual page for flock(2) for details (On some systems, this
function is emulated using fcntl()).
[clinic start generated code]*/

static PyObject *
fcntl_flock_impl(PyModuleDef *module, int fd, int code)
/*[clinic end generated code: output=c9035133a7dbfc96 input=b70a0a41ca22a8a0]*/
{
    int ret;

#ifdef HAVE_FLOCK
    Py_BEGIN_ALLOW_THREADS
    ret = flock(fd, code);
    Py_END_ALLOW_THREADS
#else

#ifndef LOCK_SH
#define LOCK_SH         1       /* shared lock */
#define LOCK_EX         2       /* exclusive lock */
#define LOCK_NB         4       /* don't block when locking */
#define LOCK_UN         8       /* unlock */
#endif
    {
        struct flock l;
        if (code == LOCK_UN)
            l.l_type = F_UNLCK;
        else if (code & LOCK_SH)
            l.l_type = F_RDLCK;
        else if (code & LOCK_EX)
            l.l_type = F_WRLCK;
        else {
            PyErr_SetString(PyExc_ValueError,
                            "unrecognized flock argument");
            return NULL;
        }
        l.l_whence = l.l_start = l.l_len = 0;
        Py_BEGIN_ALLOW_THREADS
        ret = fcntl(fd, (code & LOCK_NB) ? F_SETLK : F_SETLKW, &l);
        Py_END_ALLOW_THREADS
    }
#endif /* HAVE_FLOCK */
    if (ret < 0) {
        PyErr_SetFromErrno(PyExc_IOError);
        return NULL;
    }
    Py_RETURN_NONE;
}


/*[clinic input]
fcntl.lockf

    fd: object(type='int', converter='conv_descriptor')
    cmd as code: int
    len as lenobj: object(c_default='NULL') = 0
    start as startobj: object(c_default='NULL') = 0
    whence: int = 0
    /

A wrapper around the fcntl() locking calls.

`fd` is the file descriptor of the file to lock or unlock, and operation is one
of the following values:

    LOCK_UN - unlock
    LOCK_SH - acquire a shared lock
    LOCK_EX - acquire an exclusive lock

When operation is LOCK_SH or LOCK_EX, it can also be bitwise ORed with
LOCK_NB to avoid blocking on lock acquisition.  If LOCK_NB is used and the
lock cannot be acquired, an IOError will be raised and the exception will
have an errno attribute set to EACCES or EAGAIN (depending on the operating
system -- for portability, check for either value).

`len` is the number of bytes to lock, with the default meaning to lock to
EOF.  `start` is the byte offset, relative to `whence`, to that the lock
starts.  `whence` is as with fileobj.seek(), specifically:

    0 - relative to the start of the file (SEEK_SET)
    1 - relative to the current buffer position (SEEK_CUR)
    2 - relative to the end of the file (SEEK_END)
[clinic start generated code]*/

static PyObject *
fcntl_lockf_impl(PyModuleDef *module, int fd, int code, PyObject *lenobj, PyObject *startobj, int whence)
/*[clinic end generated code: output=5536df2892bf3ce9 input=9c594391de821f24]*/
{
    int ret;

#ifndef LOCK_SH
#define LOCK_SH         1       /* shared lock */
#define LOCK_EX         2       /* exclusive lock */
#define LOCK_NB         4       /* don't block when locking */
#define LOCK_UN         8       /* unlock */
#endif  /* LOCK_SH */
    {
        struct flock l;
        if (code == LOCK_UN)
            l.l_type = F_UNLCK;
        else if (code & LOCK_SH)
            l.l_type = F_RDLCK;
        else if (code & LOCK_EX)
            l.l_type = F_WRLCK;
        else {
            PyErr_SetString(PyExc_ValueError,
                            "unrecognized lockf argument");
            return NULL;
        }
        l.l_start = l.l_len = 0;
        if (startobj != NULL) {
#if !defined(HAVE_LARGEFILE_SUPPORT)
            l.l_start = PyLong_AsLong(startobj);
#else
            l.l_start = PyLong_Check(startobj) ?
                            PyLong_AsLongLong(startobj) :
                    PyLong_AsLong(startobj);
#endif
            if (PyErr_Occurred())
                return NULL;
        }
        if (lenobj != NULL) {
#if !defined(HAVE_LARGEFILE_SUPPORT)
            l.l_len = PyLong_AsLong(lenobj);
#else
            l.l_len = PyLong_Check(lenobj) ?
                            PyLong_AsLongLong(lenobj) :
                    PyLong_AsLong(lenobj);
#endif
            if (PyErr_Occurred())
                return NULL;
        }
        l.l_whence = whence;
        Py_BEGIN_ALLOW_THREADS
        ret = fcntl(fd, (code & LOCK_NB) ? F_SETLK : F_SETLKW, &l);
        Py_END_ALLOW_THREADS
    }
    if (ret < 0) {
        PyErr_SetFromErrno(PyExc_IOError);
        return NULL;
    }
    Py_RETURN_NONE;
}

/* List of functions */

static PyMethodDef fcntl_methods[] = {
    FCNTL_FCNTL_METHODDEF
    FCNTL_IOCTL_METHODDEF
    FCNTL_FLOCK_METHODDEF
    FCNTL_LOCKF_METHODDEF
    {NULL, NULL}  /* sentinel */
};


PyDoc_STRVAR(module_doc,
"This module performs file control and I/O control on file \n\
descriptors.  It is an interface to the fcntl() and ioctl() Unix\n\
routines.  File descriptors can be obtained with the fileno() method of\n\
a file or socket object.");

/* Module initialisation */


static int
all_ins(PyObject* m)
{
    if (PyModule_AddIntMacro(m, LOCK_SH)) return -1;
    if (PyModule_AddIntMacro(m, LOCK_EX)) return -1;
    if (PyModule_AddIntMacro(m, LOCK_NB)) return -1;
    if (PyModule_AddIntMacro(m, LOCK_UN)) return -1;
/* GNU extensions, as of glibc 2.2.4 */
#ifdef LOCK_MAND
    if (PyModule_AddIntMacro(m, LOCK_MAND)) return -1;
#endif
#ifdef LOCK_READ
    if (PyModule_AddIntMacro(m, LOCK_READ)) return -1;
#endif
#ifdef LOCK_WRITE
    if (PyModule_AddIntMacro(m, LOCK_WRITE)) return -1;
#endif
#ifdef LOCK_RW
    if (PyModule_AddIntMacro(m, LOCK_RW)) return -1;
#endif

#ifdef F_DUPFD
    if (PyModule_AddIntMacro(m, F_DUPFD)) return -1;
#endif
#ifdef F_DUPFD_CLOEXEC
    if (PyModule_AddIntMacro(m, F_DUPFD_CLOEXEC)) return -1;
#endif
#ifdef F_GETFD
    if (PyModule_AddIntMacro(m, F_GETFD)) return -1;
#endif
#ifdef F_SETFD
    if (PyModule_AddIntMacro(m, F_SETFD)) return -1;
#endif
#ifdef F_GETFL
    if (PyModule_AddIntMacro(m, F_GETFL)) return -1;
#endif
#ifdef F_SETFL
    if (PyModule_AddIntMacro(m, F_SETFL)) return -1;
#endif
#ifdef F_GETLK
    if (PyModule_AddIntMacro(m, F_GETLK)) return -1;
#endif
#ifdef F_SETLK
    if (PyModule_AddIntMacro(m, F_SETLK)) return -1;
#endif
#ifdef F_SETLKW
    if (PyModule_AddIntMacro(m, F_SETLKW)) return -1;
#endif
#ifdef F_GETOWN
    if (PyModule_AddIntMacro(m, F_GETOWN)) return -1;
#endif
#ifdef F_SETOWN
    if (PyModule_AddIntMacro(m, F_SETOWN)) return -1;
#endif
#ifdef F_GETSIG
    if (PyModule_AddIntMacro(m, F_GETSIG)) return -1;
#endif
#ifdef F_SETSIG
    if (PyModule_AddIntMacro(m, F_SETSIG)) return -1;
#endif
#ifdef F_RDLCK
    if (PyModule_AddIntMacro(m, F_RDLCK)) return -1;
#endif
#ifdef F_WRLCK
    if (PyModule_AddIntMacro(m, F_WRLCK)) return -1;
#endif
#ifdef F_UNLCK
    if (PyModule_AddIntMacro(m, F_UNLCK)) return -1;
#endif
/* LFS constants */
#ifdef F_GETLK64
    if (PyModule_AddIntMacro(m, F_GETLK64)) return -1;
#endif
#ifdef F_SETLK64
    if (PyModule_AddIntMacro(m, F_SETLK64)) return -1;
#endif
#ifdef F_SETLKW64
    if (PyModule_AddIntMacro(m, F_SETLKW64)) return -1;
#endif
/* GNU extensions, as of glibc 2.2.4. */
#ifdef FASYNC
    if (PyModule_AddIntMacro(m, FASYNC)) return -1;
#endif
#ifdef F_SETLEASE
    if (PyModule_AddIntMacro(m, F_SETLEASE)) return -1;
#endif
#ifdef F_GETLEASE
    if (PyModule_AddIntMacro(m, F_GETLEASE)) return -1;
#endif
#ifdef F_NOTIFY
    if (PyModule_AddIntMacro(m, F_NOTIFY)) return -1;
#endif
/* Old BSD flock(). */
#ifdef F_EXLCK
    if (PyModule_AddIntMacro(m, F_EXLCK)) return -1;
#endif
#ifdef F_SHLCK
    if (PyModule_AddIntMacro(m, F_SHLCK)) return -1;
#endif

/* OS X specifics */
#ifdef F_FULLFSYNC
    if (PyModule_AddIntMacro(m, F_FULLFSYNC)) return -1;
#endif
#ifdef F_NOCACHE
    if (PyModule_AddIntMacro(m, F_NOCACHE)) return -1;
#endif

/* For F_{GET|SET}FL */
#ifdef FD_CLOEXEC
    if (PyModule_AddIntMacro(m, FD_CLOEXEC)) return -1;
#endif

/* For F_NOTIFY */
#ifdef DN_ACCESS
    if (PyModule_AddIntMacro(m, DN_ACCESS)) return -1;
#endif
#ifdef DN_MODIFY
    if (PyModule_AddIntMacro(m, DN_MODIFY)) return -1;
#endif
#ifdef DN_CREATE
    if (PyModule_AddIntMacro(m, DN_CREATE)) return -1;
#endif
#ifdef DN_DELETE
    if (PyModule_AddIntMacro(m, DN_DELETE)) return -1;
#endif
#ifdef DN_RENAME
    if (PyModule_AddIntMacro(m, DN_RENAME)) return -1;
#endif
#ifdef DN_ATTRIB
    if (PyModule_AddIntMacro(m, DN_ATTRIB)) return -1;
#endif
#ifdef DN_MULTISHOT
    if (PyModule_AddIntMacro(m, DN_MULTISHOT)) return -1;
#endif

#ifdef HAVE_STROPTS_H
    /* Unix 98 guarantees that these are in stropts.h. */
    if (PyModule_AddIntMacro(m, I_PUSH)) return -1;
    if (PyModule_AddIntMacro(m, I_POP)) return -1;
    if (PyModule_AddIntMacro(m, I_LOOK)) return -1;
    if (PyModule_AddIntMacro(m, I_FLUSH)) return -1;
    if (PyModule_AddIntMacro(m, I_FLUSHBAND)) return -1;
    if (PyModule_AddIntMacro(m, I_SETSIG)) return -1;
    if (PyModule_AddIntMacro(m, I_GETSIG)) return -1;
    if (PyModule_AddIntMacro(m, I_FIND)) return -1;
    if (PyModule_AddIntMacro(m, I_PEEK)) return -1;
    if (PyModule_AddIntMacro(m, I_SRDOPT)) return -1;
    if (PyModule_AddIntMacro(m, I_GRDOPT)) return -1;
    if (PyModule_AddIntMacro(m, I_NREAD)) return -1;
    if (PyModule_AddIntMacro(m, I_FDINSERT)) return -1;
    if (PyModule_AddIntMacro(m, I_STR)) return -1;
    if (PyModule_AddIntMacro(m, I_SWROPT)) return -1;
#ifdef I_GWROPT
    /* despite the comment above, old-ish glibcs miss a couple... */
    if (PyModule_AddIntMacro(m, I_GWROPT)) return -1;
#endif
    if (PyModule_AddIntMacro(m, I_SENDFD)) return -1;
    if (PyModule_AddIntMacro(m, I_RECVFD)) return -1;
    if (PyModule_AddIntMacro(m, I_LIST)) return -1;
    if (PyModule_AddIntMacro(m, I_ATMARK)) return -1;
    if (PyModule_AddIntMacro(m, I_CKBAND)) return -1;
    if (PyModule_AddIntMacro(m, I_GETBAND)) return -1;
    if (PyModule_AddIntMacro(m, I_CANPUT)) return -1;
    if (PyModule_AddIntMacro(m, I_SETCLTIME)) return -1;
#ifdef I_GETCLTIME
    if (PyModule_AddIntMacro(m, I_GETCLTIME)) return -1;
#endif
    if (PyModule_AddIntMacro(m, I_LINK)) return -1;
    if (PyModule_AddIntMacro(m, I_UNLINK)) return -1;
    if (PyModule_AddIntMacro(m, I_PLINK)) return -1;
    if (PyModule_AddIntMacro(m, I_PUNLINK)) return -1;
#endif

    return 0;
}


static struct PyModuleDef fcntlmodule = {
    PyModuleDef_HEAD_INIT,
    "fcntl",
    module_doc,
    -1,
    fcntl_methods,
    NULL,
    NULL,
    NULL,
    NULL
};

PyMODINIT_FUNC
PyInit_fcntl(void)
{
    PyObject *m;

    /* Create the module and add the functions and documentation */
    m = PyModule_Create(&fcntlmodule);
    if (m == NULL)
        return NULL;

    /* Add some symbolic constants to the module */
    if (all_ins(m) < 0)
        return NULL;

    return m;
}