aboutsummaryrefslogtreecommitdiffstats
path: root/include/unistd.h
blob: f259d5f336621c5b4215348d65d9e3028f161c17 (plain) (blame)
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
/**
 * slibc — Yet another C library
 * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef _UNISTD_H
#define _UNISTD_H
#include <slibc/version.h>
#include <slibc/features.h>



#define __NEED_size_t
#define __NEED_ssize_t
#define __NEED_uid_t
#define __NEED_gid_t
#define __NEED_off_t
#define __NEED_pid_t
#define __NEED_ptrdiff_t
#define __NEED_intptr_t
#define __NEED_useconds_t
#include <bits/types.h>


/**
 * `NULL`'s canonical header is <stddef.h>.
 */
#ifndef NULL
# define NULL  ((void*)0)
#endif


/**
 * The file descriptor for stdin.
 * The file with input.
 */
#define STDIN_FILENO  0

/**
 * The file descriptor for stdout.
 * The file for output.
 */
#define STDOUT_FILENO  1

/**
 * The file descriptor for stderr.
 * The file for error messages and warnings.
 */
#define STDERR_FILENO  2


/* TODO temporary values */
#define F_OK  0
#define X_OK  1
#define W_OK  2
#define R_OK  4


/**
 * Set the high end of the calling process's
 * data segment.
 * 
 * The high end is defined as the last byte
 * in the segment plus 1.
 * 
 * Using `brk` is highly discouraged. `malloc`,
 * `calloc` and `free`, and its related functions,
 * fall be used instead as they are much more
 * conformable. Use of `brk` can couse errors
 * when using `malloc`, `free`, &c. Thus, `brk`
 * shall (bascially) only be used if you are
 * writting an alterantive malloc-implementation.
 * 
 * `brk` was marked LEGACY in SUSv2, and it
 * was removed from the POSIX standard in revision
 * POSIX.1-2001. It is however fundamental in
 * implementing a fast `malloc`-implementation.
 * 
 * @param   address  The process's new high end of its data segment.
 *                   If lower than the current low end, nothing will
 *                   happen and the function will return with a success
 *                   status.
 * @return           Zero on succes, -1 on error. On error, `errno`
 *                   is set to indicate the error.
 * 
 * @throws  ENOMEM  The process can allocate the requested amount
 *                  of memory. Either the process store limit would
 *                  have been exceeded, RAM and swap memory would
 *                  have been exhausted, or the request would cause
 *                  the data segment to overlap another segment.
 */
int brk(void*) /* TODO implement brk */
  __GCC_ONLY(__attribute__((__warn_unused_result__)));

/**
 * Set and get the current high end of the calling
 * process's data segment.
 * 
 * There is some documents that state that the new,
 * rather than the previous, high end is returned.
 * Additionally, some documentions do not document
 * possible failure. Thus only `sbrk(0)` is guaranteed
 * to be portable. The return type differs between
 * implementations; common return types are `int`,
 * `ssize_t`, `ptrdiff_t`, `ptrdiff_t`, `intptr_t`,
 * and `void*`. Note that `int` is
 * microarchitecture-portable.
 * 
 * `sbrk` was marked LEGACY in SUSv2, and it
 * was removed from the POSIX standard in revision
 * POSIX.1-2001. It is however fundamental in
 * implementing a fast `malloc`-implementation.
 * 
 * @param   delta  The incremant of the size of the data segment,
 *                 zero means that the high end shall not be moved
 *                 (thus the current high end is returned,) a
 *                 positive value will cause the segment to grow,
 *                 a negative value will cause the segment to shrink.
 * @return         The previous high end. `(void*)-1` is returned on error.
 * 
 * @throws  ENOMEM  The process can allocate the requested amount
 *                  of memory. Either the process store limit would
 *                  have been exceeded, RAM and swap memory would
 *                  have been exhausted, or the request would cause
 *                  the data segment to overlap another segment.
 */
void* sbrk(ptrdiff_t) /* TODO implement sbrk */
  __GCC_ONLY(__attribute__((__warn_unused_result__)));



/* TODO implement exit-functions */
__noreturn void _exit(int);


/* TODO implement I/O */
int isatty(int);



/**
 * Replace the current process image with a new process image.
 * 
 * @param   path  The pathname of the file to execute.
 * @param   ...   The arguments with which to execute the file.
 *                The arguments should have the type `const char*`.
 *                As a slibc extension, it can be empty.
 *                This list shall be terminated by a `NULL` sentinel.
 * @return        This function does not return on success,
 *                on error, -1 is returned and `errno` is
 *                set to describe the error.
 * 
 * @throws        Any error specified for execve(2).
 */
int execl(const char*, ... /*, NULL */)
  __GCC_ONLY(__attribute__((__sentinel__(0), __nonnull__(1))));

/**
 * Replace the current process image with a new process image.
 * 
 * @param   file  The pathname of the file to execute,
 *                or the filename of a file in $PATH,
 *                to execute. If $PATH is not set, the current
 *                working directory (yes, you read that right,)
 *                and a default value for $PATH will be used.
 * @param   ...   The arguments with which to execute the file.
 *                The arguments should have the type `const char*`.
 *                As a slibc extension, it can be empty.
 *                This list shall be terminated by a `NULL` sentinel.
 * @return        This function does not return on success,
 *                on error, -1 is returned and `errno` is
 *                set to describe the error.
 * 
 * @throws        Any error specified for execve(2).
 */
int execlp(const char*, ... /*, NULL */)
  __GCC_ONLY(__attribute__((__sentinel__(0), __nonnull__(1))));

/**
 * Replace the current process image with a new process image.
 * 
 * @param   path  The pathname of the file to execute.
 * @param   ...   The arguments with which to execute the file.
 *                The arguments should have the type `const char*`.
 *                As a slibc extension, it can be empty.
 *                This list shall be terminated by a `NULL` sentinel.
 * @param   envp  The list of environment variables the new program shall
 *                have set. Each element shall be formatted $name=$value.
 *                This list shall be `NULL`-terminated. The behaviour
 *                is system-dependant if this argument is `NULL`.
 * @return        This function does not return on success,
 *                on error, -1 is returned and `errno` is
 *                set to describe the error.
 * 
 * @throws        Any error specified for execve(2).
 */
int execle(const char*, ... /*, NULL, char* const[] */)
  __GCC_ONLY(__attribute__((__sentinel__(1), __nonnull__(1))));

#if defined(__SLIBC_SOURCE)
/**
 * Replace the current process image with a new process image.
 * 
 * This is a slibc extension, added for completeness.
 * 
 * @param   file  The pathname of the file to execute,
 *                or the filename of a file in $PATH,
 *                to execute. If $PATH is not set, the current
 *                working directory (yes, you read that right,)
 *                and a default value for $PATH will be used.
 * @param   ...   The arguments with which to execute the file.
 *                The arguments should have the type `const char*`.
 *                As a slibc extension, it can be empty.
 *                This list shall be terminated by a `NULL` sentinel.
 * @param   envp  The list of environment variables the new program shall
 *                have set. Each element shall be formatted $name=$value.
 *                This list shall be `NULL`-terminated. The behaviour
 *                is system-dependant if this argument is `NULL`.
 * @return        This function does not return on success,
 *                on error, -1 is returned and `errno` is
 *                set to describe the error.
 * 
 * @throws        Any error specified for execve(2).
 */
int execlpe(const char*, ... /*, NULL, char* const[] */)
  __GCC_ONLY(__attribute__((__sentinel__(1), __nonnull__(1))));
#endif

/**
 * Replace the current process image with a new process image.
 * 
 * @param   path  The pathname of the file to execute.
 * @param   argv  The arguments with which to execute the file.
 *                This parameter should really have the type
 *                `const char* const[]`, but that probably not
 *                so because compiles take issue with casts
 *                adding const to any pointer in the type
 *                except the outmost pointer. This list shall
 *                be `NULL`-terminated. The behaviour is
 *                system-dependant if this argument is `NULL`.
 * @return        This function does not return on success,
 *                on error, -1 is returned and `errno` is
 *                set to describe the error.
 * 
 * @throws        Any error specified for execve(2).
 */
int execv(const char*, char* const[])
  __GCC_ONLY(__attribute__((__nonnull__(1))));

/**
 * Replace the current process image with a new process image.
 * 
 * @param   file  The pathname of the file to execute,
 *                or the filename of a file in $PATH,
 *                to execute. If $PATH is not set, the current
 *                working directory (yes, you read that right,)
 *                and a default value for $PATH will be used.
 * @param   argv  The arguments with which to execute the file.
 *                This parameter should really have the type
 *                `const char* const[]`, but that probably not
 *                so because compiles take issue with casts
 *                adding const to any pointer in the type
 *                except the outmost pointer. This list shall
 *                be `NULL`-terminated. The behaviour is
 *                system-dependant if this argument is `NULL`.
 * @return        This function does not return on success,
 *                on error, -1 is returned and `errno` is
 *                set to describe the error.
 * 
 * @throws        Any error specified for execve(2).
 */
int execvp(const char*, char* const[])
  __GCC_ONLY(__attribute__((__nonnull__(1))));

/**
 * Replace the current process image with a new process image.
 * 
 * @param   path  The pathname of the file to execute.
 * @param   argv  The arguments with which to execute the file.
 *                This parameter should really have the type
 *                `const char* const[]`, but that probably not
 *                so because compiles take issue with casts
 *                adding const to any pointer in the type
 *                except the outmost pointer. This list shall
 *                be `NULL`-terminated. The behaviour is
 *                system-dependant if this argument is `NULL`.
 * @param   envp  The list of environment variables the new program shall
 *                have set. Each element shall be formatted $name=$value.
 *                This list shall be `NULL`-terminated. The behaviour
 *                is system-dependant if this argument is `NULL`.
 * @return        This function does not return on success,
 *                on error, -1 is returned and `errno` is
 *                set to describe the error.
 * 
 * @throws        Any error specified for execve(2).
 */
int execve(const char*, char* const[], char* const[])
  __GCC_ONLY(__attribute__((__nonnull__(1))));

#if defined(__GNU_SOURCE) || defined(__SLIBC_SOURCE)
/**
 * Replace the current process image with a new process image.
 * 
 * This is a GNU-compliant slibc extension.
 * 
 * @param   file  The pathname of the file to execute,
 *                or the filename of a file in $PATH,
 *                to execute. If $PATH is not set, the current
 *                working directory (yes, you read that right,)
 *                and a default value for $PATH will be used.
 * @param   argv  The arguments with which to execute the file.
 *                This parameter should really have the type
 *                `const char* const[]`, but that probably not
 *                so because compiles take issue with casts
 *                adding const to any pointer in the type
 *                except the outmost pointer. This list shall
 *                be `NULL`-terminated. The behaviour is
 *                system-dependant if this argument is `NULL`.
 * @param   envp  The list of environment variables the new program shall
 *                have set. Each element shall be formatted $name=$value.
 *                This list shall be `NULL`-terminated. The behaviour
 *                is system-dependant if this argument is `NULL`.
 * @return        This function does not return on success,
 *                on error, -1 is returned and `errno` is
 *                set to describe the error.
 * 
 * @throws        Any error specified for execve(2).
 */
int execvpe(const char*, char* const[], char* const[])
  __GCC_ONLY(__attribute__((__nonnull__(1))));
#endif


#if defined(__SLIBC_SOURCE)
/**
 * Replace the current process image with a new process image.
 * 
 * This is a slibc extension.
 * 
 * @param   dirfd  File descriptor for a directory (opened with
 *                 with the open(2) `O_PATH` flag,) that will
 *                 act as the current working directory.
 *                 If `AT_FDCWD`, the current working directory
 *                 will be used.
 * @param   path   The pathname of the file to execute.
 * @param   ...    The arguments with which to execute the file.
 *                 The arguments should have the type `const char*`.
 *                 As a slibc extension, it can be empty.
 *                 This list shall be terminated by a `NULL` sentinel.
 * @param   flags  Bit mask that can include zero or more of the
 *                 following flags:
 *                   AT_EMPTY_PATH:
 *                     If `path` is an empty string, operate on the
 *                     file (not directory) referred to by `dirfd`.
 *                   AT_SYMLINK_NOFOLLOW:
 *                     If `path` is relative is a symbolic link,
 *                     fail with `errno` set to `ELOOP`.
 * @return         This function does not return on success,
 *                 on error, -1 is returned and `errno` is
 *                 set to describe the error.
 * 
 * @throws         Any error specified for execveat(2).
 */
int execlat(int, const char*, ... /*, NULL, int */)
  __GCC_ONLY(__attribute__((__sentinel__(1), __nonnull__(2))));

/**
 * Replace the current process image with a new process image.
 * 
 * This is a slibc extension.
 * 
 * @param   dirfd  File descriptor for a directory (opened with
 *                 with the open(2) `O_PATH` flag,) that will
 *                 act as the current working directory.
 *                 If `AT_FDCWD`, the current working directory
 *                 will be used.
 * @param   file   The pathname of the file to execute,
 *                 or the filename of a file in $PATH,
 *                 to execute. If $PATH is not set, the current
 *                 working directory (yes, you read that right,)
 *                 and a default value for $PATH will be used.
 * @param   ...    The arguments with which to execute the file.
 *                 The arguments should have the type `const char*`.
 *                 As a slibc extension, it can be empty.
 *                 This list shall be terminated by a `NULL` sentinel.
 * @param   flags  Bit mask that can include zero or more of the
 *                 following flags:
 *                   AT_EMPTY_PATH:
 *                     If `file` is an empty string, operate on the
 *                     file (not directory) referred to by `dirfd`.
 *                   AT_SYMLINK_NOFOLLOW:
 *                     If `file` is relative is a symbolic link,
 *                     fail with `errno` set to `ELOOP`.
 * @return         This function does not return on success,
 *                 on error, -1 is returned and `errno` is
 *                 set to describe the error.
 * 
 * @throws         Any error specified for execveat(2).
 */
int execlpat(int, const char*, ... /*, NULL, int */)
  __GCC_ONLY(__attribute__((__sentinel__(1), __nonnull__(2))));

/**
 * Replace the current process image with a new process image.
 * 
 * This is a slibc extension.
 * 
 * @param   dirfd  File descriptor for a directory (opened with
 *                 with the open(2) `O_PATH` flag,) that will
 *                 act as the current working directory.
 *                 If `AT_FDCWD`, the current working directory
 *                 will be used.
 * @param   path   The pathname of the file to execute.
 * @param   ...    The arguments with which to execute the file.
 *                 The arguments should have the type `const char*`.
 *                 As a slibc extension, it can be empty.
 *                 This list shall be terminated by a `NULL` sentinel.
 * @param   envp   The list of environment variables the new program shall
 *                 have set. Each element shall be formatted $name=$value.
 *                 This list shall be `NULL`-terminated. The behaviour
 *                 is system-dependant if this argument is `NULL`.
 * @param   flags  Bit mask that can include zero or more of the
 *                 following flags:
 *                   AT_EMPTY_PATH:
 *                     If `path` is an empty string, operate on the
 *                     file (not directory) referred to by `dirfd`.
 *                   AT_SYMLINK_NOFOLLOW:
 *                     If `path` is relative is a symbolic link,
 *                     fail with `errno` set to `ELOOP`.
 * @return         This function does not return on success,
 *                 on error, -1 is returned and `errno` is
 *                 set to describe the error.
 * 
 * @throws         Any error specified for execveat(2).
 */
int execleat(int, const char*, ... /*, NULL, char* const[], int */)
  __GCC_ONLY(__attribute__((__sentinel__(2), __nonnull__(2))));

/**
 * Replace the current process image with a new process image.
 * 
 * This is a slibc extension.
 * 
 * @param   dirfd  File descriptor for a directory (opened with
 *                 with the open(2) `O_PATH` flag,) that will
 *                 act as the current working directory.
 *                 If `AT_FDCWD`, the current working directory
 *                 will be used.
 * @param   file   The pathname of the file to execute,
 *                 or the filename of a file in $PATH,
 *                 to execute. If $PATH is not set, the current
 *                 working directory (yes, you read that right,)
 *                 and a default value for $PATH will be used.
 * @param   ...    The arguments with which to execute the file.
 *                 The arguments should have the type `const char*`.
 *                 As a slibc extension, it can be empty.
 *                 This list shall be terminated by a `NULL` sentinel.
 * @param   envp   The list of environment variables the new program shall
 *                 have set. Each element shall be formatted $name=$value.
 *                 This list shall be `NULL`-terminated. The behaviour
 *                 is system-dependant if this argument is `NULL`.
 * @param   flags  Bit mask that can include zero or more of the
 *                 following flags:
 *                   AT_EMPTY_PATH:
 *                     If `file` is an empty string, operate on the
 *                     file (not directory) referred to by `dirfd`.
 *                   AT_SYMLINK_NOFOLLOW:
 *                     If `file` is relative is a symbolic link,
 *                     fail with `errno` set to `ELOOP`.
 * @return         This function does not return on success,
 *                 on error, -1 is returned and `errno` is
 *                 set to describe the error.
 * 
 * @throws         Any error specified for execveat(2).
 */
int execlpeat(int, const char*, ... /*, NULL, char* const[], int */)
  __GCC_ONLY(__attribute__((__sentinel__(2), __nonnull__(2))));

/**
 * Replace the current process image with a new process image.
 * 
 * This is a slibc extension.
 * 
 * @param   dirfd  File descriptor for a directory (opened with
 *                 with the open(2) `O_PATH` flag,) that will
 *                 act as the current working directory.
 *                 If `AT_FDCWD`, the current working directory
 *                 will be used.
 * @param   path   The pathname of the file to execute.
 * @param   argv   The arguments with which to execute the file.
 *                 This parameter should really have the type
 *                 `const char* const[]`, but that probably not
 *                 so because compiles take issue with casts
 *                 adding const to any pointer in the type
 *                 except the outmost pointer. This list shall
 *                 be `NULL`-terminated. The behaviour is
 *                 system-dependant if this argument is `NULL`.
 * @param   flags  Bit mask that can include zero or more of the
 *                 following flags:
 *                   AT_EMPTY_PATH:
 *                     If `path` is an empty string, operate on the
 *                     file (not directory) referred to by `dirfd`.
 *                   AT_SYMLINK_NOFOLLOW:
 *                     If `path` is relative is a symbolic link,
 *                     fail with `errno` set to `ELOOP`.
 * @return         This function does not return on success,
 *                 on error, -1 is returned and `errno` is
 *                 set to describe the error.
 * 
 * @throws         Any error specified for execveat(2).
 */
int execvat(int, const char*, char* const[], int)
  __GCC_ONLY(__attribute__((__nonnull__(2))));

/**
 * Replace the current process image with a new process image.
 * 
 * This is a slibc extension.
 * 
 * @param   dirfd  File descriptor for a directory (opened with
 *                 with the open(2) `O_PATH` flag,) that will
 *                 act as the current working directory.
 *                 If `AT_FDCWD`, the current working directory
 *                 will be used.
 * @param   file   The pathname of the file to execute,
 *                 or the filename of a file in $PATH,
 *                 to execute. If $PATH is not set, the current
 *                 working directory (yes, you read that right,)
 *                 and a default value for $PATH will be used.
 * @param   argv   The arguments with which to execute the file.
 *                 This parameter should really have the type
 *                 `const char* const[]`, but that probably not
 *                 so because compiles take issue with casts
 *                 adding const to any pointer in the type
 *                 except the outmost pointer. This list shall
 *                 be `NULL`-terminated. The behaviour is
 *                 system-dependant if this argument is `NULL`.
 * @param   flags  Bit mask that can include zero or more of the
 *                 following flags:
 *                   AT_EMPTY_PATH:
 *                     If `file` is an empty string, operate on the
 *                     file (not directory) referred to by `dirfd`.
 *                   AT_SYMLINK_NOFOLLOW:
 *                     If `file` is relative is a symbolic link,
 *                     fail with `errno` set to `ELOOP`.
 * @return         This function does not return on success,
 *                 on error, -1 is returned and `errno` is
 *                 set to describe the error.
 * 
 * @throws         Any error specified for execveat(2).
 */
int execvpat(int, const char*, char* const[], int)
  __GCC_ONLY(__attribute__((__nonnull__(2))));
#endif

/**
 * Replace the current process image with a new process image.
 * 
 * @param   dirfd  File descriptor for a directory (opened with
 *                 with the open(2) `O_PATH` flag,) that will
 *                 act as the current working directory.
 *                 If `AT_FDCWD`, the current working directory
 *                 will be used.
 * @param   path   The pathname of the file to execute.
 * @param   argv   The arguments with which to execute the file.
 *                 This parameter should really have the type
 *                 `const char* const[]`, but that probably not
 *                 so because compiles take issue with casts
 *                 adding const to any pointer in the type
 *                 except the outmost pointer. This list shall
 *                 be `NULL`-terminated. The behaviour is
 *                 system-dependant if this argument is `NULL`.
 * @param   envp   The list of environment variables the new program shall
 *                 have set. Each element shall be formatted $name=$value.
 *                 This list shall be `NULL`-terminated. The behaviour
 *                 is system-dependant if this argument is `NULL`.
 * @param   flags  Bit mask that can include zero or more of the
 *                 following flags:
 *                   AT_EMPTY_PATH:
 *                     If `path` is an empty string, operate on the
 *                     file (not directory) referred to by `dirfd`.
 *                   AT_SYMLINK_NOFOLLOW:
 *                     If `path` is relative is a symbolic link,
 *                     fail with `errno` set to `ELOOP`.
 * @return         This function does not return on success,
 *                 on error, -1 is returned and `errno` is
 *                 set to describe the error.
 * 
 * @throws         Any error specified for execveat(2).
 */
int execveat(int, const char*, char* const[], char* const[], int)
  __GCC_ONLY(__attribute__((__nonnull__(2))));

#if defined(__SLIBC_SOURCE)
/**
 * Replace the current process image with a new process image.
 * 
 * This is a slibc extension.
 * 
 * @param   dirfd  File descriptor for a directory (opened with
 *                 with the open(2) `O_PATH` flag,) that will
 *                 act as the current working directory.
 *                 If `AT_FDCWD`, the current working directory
 *                 will be used.
 * @param   file   The pathname of the file to execute,
 *                 or the filename of a file in $PATH,
 *                 to execute. If $PATH is not set, the current
 *                 working directory (yes, you read that right,)
 *                 and a default value for $PATH will be used.
 * @param   argv   The arguments with which to execute the file.
 *                 This parameter should really have the type
 *                 `const char* const[]`, but that probably not
 *                 so because compiles take issue with casts
 *                 adding const to any pointer in the type
 *                 except the outmost pointer. This list shall
 *                 be `NULL`-terminated. The behaviour is
 *                 system-dependant if this argument is `NULL`.
 * @param   envp   The list of environment variables the new program shall
 *                 have set. Each element shall be formatted $name=$value.
 *                 This list shall be `NULL`-terminated. The behaviour
 *                 is system-dependant if this argument is `NULL`.
 * @param   flags  Bit mask that can include zero or more of the
 *                 following flags:
 *                   AT_EMPTY_PATH:
 *                     If `file` is an empty string, operate on the
 *                     file (not directory) referred to by `dirfd`.
 *                   AT_SYMLINK_NOFOLLOW:
 *                     If `file` is relative is a symbolic link,
 *                     fail with `errno` set to `ELOOP`.
 * @return         This function does not return on success,
 *                 on error, -1 is returned and `errno` is
 *                 set to describe the error.
 * 
 * @throws         Any error specified for execveat(2).
 */
int execvpeat(int, const char*, char* const[], char* const[], int)
  __GCC_ONLY(__attribute__((__nonnull__(2))));
#endif


#if defined(__SLIBC_SOURCE)
/**
 * Replace the current process image with a new process image.
 * 
 * This is a slibc extension.
 * 
 * @param   fd   File descriptor for the file to execute.
 * @param   ...  The arguments with which to execute the file.
 *               The arguments should have the type `const char*`.
 *               As a slibc extension, it can be empty.
 *               This list shall be terminated by a `NULL` sentinel.
 * @return       This function does not return on success,
 *               on error, -1 is returned and `errno` is
 *               set to describe the error.
 * 
 * @throws       Any error specified for execve(2).
 */
int fexecl(int, ... /*, NULL */)
  __GCC_ONLY(__attribute__((__sentinel__(0))));

/**
 * Replace the current process image with a new process image.
 * 
 * This is a slibc extension.
 * 
 * @param   fd    File descriptor for the file to execute.
 * @param   ...   The arguments with which to execute the file.
 *                The arguments should have the type `const char*`.
 *                As a slibc extension, it can be empty.
 *                This list shall be terminated by a `NULL` sentinel.
 * @param   envp  The list of environment variables the new program shall
 *                have set. Each element shall be formatted $name=$value.
 *                This list shall be `NULL`-terminated. The behaviour
 *                is system-dependant if this argument is `NULL`.
 * @return        This function does not return on success,
 *                on error, -1 is returned and `errno` is
 *                set to describe the error.
 * 
 * @throws        Any error specified for execve(2).
 */
int fexecle(int, ... /*, NULL, char* const[] */)
  __GCC_ONLY(__attribute__((__sentinel__(1))));

/**
 * Replace the current process image with a new process image.
 * 
 * This is a slibc extension.
 * 
 * @param   fd    File descriptor for the file to execute.
 * @param   argv  The arguments with which to execute the file.
 *                This parameter should really have the type
 *                `const char* const[]`, but that probably not
 *                so because compiles take issue with casts
 *                adding const to any pointer in the type
 *                except the outmost pointer. This list shall
 *                be `NULL`-terminated. The behaviour is
 *                system-dependant if this argument is `NULL`.
 * @return        This function does not return on success,
 *                on error, -1 is returned and `errno` is
 *                set to describe the error.
 * 
 * @throws        Any error specified for execve(2).
 */
int fexecv(int, char* const[]);
#endif

/**
 * Replace the current process image with a new process image.
 * 
 * @param   fd    File descriptor for the file to execute.
 * @param   argv  The arguments with which to execute the file.
 *                This parameter should really have the type
 *                `const char* const[]`, but that probably not
 *                so because compiles take issue with casts
 *                adding const to any pointer in the type
 *                except the outmost pointer. This list shall
 *                be `NULL`-terminated. The behaviour is
 *                system-dependant if this argument is `NULL`.
 * @param   envp  The list of environment variables the new program shall
 *                have set. Each element shall be formatted $name=$value.
 *                This list shall be `NULL`-terminated. The behaviour
 *                is system-dependant if this argument is `NULL`.
 * @return        This function does not return on success,
 *                on error, -1 is returned and `errno` is
 *                set to describe the error.
 * 
 * @throws        Any error specified for execve(2).
 */
int fexecve(int, char* const[], char* const[]);



#endif

/*
  TODO readn(plan9), writen, preadn, pwriten
  readn: read that can only return with a short read on error
  writen: write that can only return with a short write on error
  preadn: pread that can only return with a short read on error
  pwriten: pwrite that can only return with a short write on error
*/