summaryrefslogtreecommitdiff
path: root/ext/pty/pty.c
blob: 3e5fa8ea9987ad0889a92a29efcfc625fe706fcb (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
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
#include	"ruby/config.h"
#ifdef RUBY_EXTCONF_H
#include RUBY_EXTCONF_H
#endif
#include	<stdlib.h>
#include	<stdio.h>
#include	<sys/types.h>
#include	<sys/stat.h>
#include	<sys/file.h>
#include	<fcntl.h>
#include	<errno.h>
#include	<pwd.h>
#ifdef HAVE_SYS_IOCTL_H
#include	<sys/ioctl.h>
#endif
#ifdef HAVE_LIBUTIL_H
#include	<libutil.h>
#endif
#ifdef HAVE_UTIL_H
#include	<util.h>
#endif
#ifdef HAVE_PTY_H
#include	<pty.h>
#endif
#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h>
#else
#define WIFSTOPPED(status)    (((status) & 0xff) == 0x7f)
#endif
#include <ctype.h>

#include "ruby/ruby.h"
#include "ruby/io.h"
#include "ruby/util.h"

#include <signal.h>
#ifdef HAVE_SYS_STROPTS_H
#include <sys/stropts.h>
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#define	DEVICELEN	16

#if !defined(HAVE_OPENPTY)
#if defined(__hpux)
static const
char	MasterDevice[] = "/dev/ptym/pty%s",
	SlaveDevice[] =  "/dev/pty/tty%s",
	*const deviceNo[] = {
		"p0","p1","p2","p3","p4","p5","p6","p7",
		"p8","p9","pa","pb","pc","pd","pe","pf",
		"q0","q1","q2","q3","q4","q5","q6","q7",
		"q8","q9","qa","qb","qc","qd","qe","qf",
		"r0","r1","r2","r3","r4","r5","r6","r7",
		"r8","r9","ra","rb","rc","rd","re","rf",
		"s0","s1","s2","s3","s4","s5","s6","s7",
		"s8","s9","sa","sb","sc","sd","se","sf",
		"t0","t1","t2","t3","t4","t5","t6","t7",
		"t8","t9","ta","tb","tc","td","te","tf",
		"u0","u1","u2","u3","u4","u5","u6","u7",
		"u8","u9","ua","ub","uc","ud","ue","uf",
		"v0","v1","v2","v3","v4","v5","v6","v7",
		"v8","v9","va","vb","vc","vd","ve","vf",
		"w0","w1","w2","w3","w4","w5","w6","w7",
		"w8","w9","wa","wb","wc","wd","we","wf",
		0,
	};
#elif defined(_IBMESA)  /* AIX/ESA */
static const
char	MasterDevice[] = "/dev/ptyp%s",
  	SlaveDevice[] = "/dev/ttyp%s",
	*const deviceNo[] = {
"00","01","02","03","04","05","06","07","08","09","0a","0b","0c","0d","0e","0f",
"10","11","12","13","14","15","16","17","18","19","1a","1b","1c","1d","1e","1f",
"20","21","22","23","24","25","26","27","28","29","2a","2b","2c","2d","2e","2f",
"30","31","32","33","34","35","36","37","38","39","3a","3b","3c","3d","3e","3f",
"40","41","42","43","44","45","46","47","48","49","4a","4b","4c","4d","4e","4f",
"50","51","52","53","54","55","56","57","58","59","5a","5b","5c","5d","5e","5f",
"60","61","62","63","64","65","66","67","68","69","6a","6b","6c","6d","6e","6f",
"70","71","72","73","74","75","76","77","78","79","7a","7b","7c","7d","7e","7f",
"80","81","82","83","84","85","86","87","88","89","8a","8b","8c","8d","8e","8f",
"90","91","92","93","94","95","96","97","98","99","9a","9b","9c","9d","9e","9f",
"a0","a1","a2","a3","a4","a5","a6","a7","a8","a9","aa","ab","ac","ad","ae","af",
"b0","b1","b2","b3","b4","b5","b6","b7","b8","b9","ba","bb","bc","bd","be","bf",
"c0","c1","c2","c3","c4","c5","c6","c7","c8","c9","ca","cb","cc","cd","ce","cf",
"d0","d1","d2","d3","d4","d5","d6","d7","d8","d9","da","db","dc","dd","de","df",
"e0","e1","e2","e3","e4","e5","e6","e7","e8","e9","ea","eb","ec","ed","ee","ef",
"f0","f1","f2","f3","f4","f5","f6","f7","f8","f9","fa","fb","fc","fd","fe","ff",
		};
#elif !defined(HAVE_PTSNAME)
static const
char	MasterDevice[] = "/dev/pty%s",
	SlaveDevice[] = "/dev/tty%s",
	*const deviceNo[] = {
		"p0","p1","p2","p3","p4","p5","p6","p7",
		"p8","p9","pa","pb","pc","pd","pe","pf",
		"q0","q1","q2","q3","q4","q5","q6","q7",
		"q8","q9","qa","qb","qc","qd","qe","qf",
		"r0","r1","r2","r3","r4","r5","r6","r7",
		"r8","r9","ra","rb","rc","rd","re","rf",
		"s0","s1","s2","s3","s4","s5","s6","s7",
		"s8","s9","sa","sb","sc","sd","se","sf",
		0,
	};
#endif
#endif /* !defined(HAVE_OPENPTY) */

#ifndef HAVE_SETEUID
# ifdef HAVE_SETREUID
#  define seteuid(e)	setreuid(-1, (e))
# else /* NOT HAVE_SETREUID */
#  ifdef HAVE_SETRESUID
#   define seteuid(e)	setresuid(-1, (e), -1)
#  else /* NOT HAVE_SETRESUID */
    /* I can't set euid. (;_;) */
#  endif /* HAVE_SETRESUID */
# endif /* HAVE_SETREUID */
#endif /* NO_SETEUID */

static VALUE eChildExited;

/* Returns the exit status of the child for which PTY#check
 * raised this exception
 */
static VALUE
echild_status(VALUE self)
{
    return rb_ivar_get(self, rb_intern("status"));
}

struct pty_info {
    int fd;
    rb_pid_t child_pid;
};

static void getDevice(int*, int*, char [DEVICELEN], int);

struct child_info {
    int master, slave;
    char *slavename;
    int argc;
    VALUE *argv;
};

static int
chfunc(void *data, char *errbuf, size_t errbuf_len)
{
    struct child_info *carg = data;
    int master = carg->master;
    int slave = carg->slave;
    int argc = carg->argc;
    VALUE *argv = carg->argv;

#define ERROR_EXIT(str) do { \
	strlcpy(errbuf, (str), errbuf_len); \
	return -1; \
    } while (0)

    rb_thread_atfork_before_exec();

    /*
     * Set free from process group and controlling terminal
     */
#ifdef HAVE_SETSID
    (void) setsid();
#else /* HAS_SETSID */
# ifdef HAVE_SETPGRP
#  ifdef SETGRP_VOID
    if (setpgrp() == -1)
        ERROR_EXIT("setpgrp()");
#  else /* SETGRP_VOID */
    if (setpgrp(0, getpid()) == -1)
        ERROR_EXIT("setpgrp()");
    {
        int i = open("/dev/tty", O_RDONLY);
        if (i < 0) ERROR_EXIT("/dev/tty");
        if (ioctl(i, TIOCNOTTY, (char *)0))
            ERROR_EXIT("ioctl(TIOCNOTTY)");
        close(i);
    }
#  endif /* SETGRP_VOID */
# endif /* HAVE_SETPGRP */
#endif /* HAS_SETSID */

    /*
     * obtain new controlling terminal
     */
#if defined(TIOCSCTTY)
    close(master);
    (void) ioctl(slave, TIOCSCTTY, (char *)0);
    /* errors ignored for sun */
#else
    close(slave);
    slave = open(carg->slavename, O_RDWR);
    if (slave < 0) {
        ERROR_EXIT("open: pty slave");
    }
    close(master);
#endif
    dup2(slave,0);
    dup2(slave,1);
    dup2(slave,2);
    close(slave);
#if defined(HAVE_SETEUID) || defined(HAVE_SETREUID) || defined(HAVE_SETRESUID)
    seteuid(getuid());
#endif

    rb_f_exec(argc, argv);
    return 0;
#undef ERROR_EXIT
}

static void
establishShell(int argc, VALUE *argv, struct pty_info *info,
	       char SlaveName[DEVICELEN])
{
    int 		master,slave;
    rb_pid_t		pid;
    char		*p, *getenv();
    struct passwd	*pwent;
    VALUE		v;
    struct child_info   carg;
    char		errbuf[32];

    if (argc == 0) {
	const char *shellname;

	if ((p = getenv("SHELL")) != NULL) {
	    shellname = p;
	}
	else {
	    pwent = getpwuid(getuid());
	    if (pwent && pwent->pw_shell)
		shellname = pwent->pw_shell;
	    else
		shellname = "/bin/sh";
	}
	v = rb_str_new2(shellname);
	argc = 1;
	argv = &v;
    }

    getDevice(&master, &slave, SlaveName, 0);

    carg.master = master;
    carg.slave = slave;
    carg.slavename = SlaveName;
    carg.argc = argc;
    carg.argv = argv;
    errbuf[0] = '\0';
    pid = rb_fork_err(0, chfunc, &carg, Qnil, errbuf, sizeof(errbuf));

    if (pid < 0) {
	int e = errno;
	close(master);
	close(slave);
	errno = e;
	rb_sys_fail(errbuf[0] ? errbuf : "fork failed");
    }

    close(slave);

    info->child_pid = pid;
    info->fd = master;
}

static int
no_mesg(char *slavedevice, int nomesg)
{
    if (nomesg)
        return chmod(slavedevice, 0600);
    else
        return 0;
}

static int
get_device_once(int *master, int *slave, char SlaveName[DEVICELEN], int nomesg, int fail)
{
#if defined(HAVE_POSIX_OPENPT)
    int masterfd = -1, slavefd = -1;
    char *slavedevice;
    struct sigaction dfl, old;

    dfl.sa_handler = SIG_DFL;
    dfl.sa_flags = 0;
    sigemptyset(&dfl.sa_mask);

    if ((masterfd = posix_openpt(O_RDWR|O_NOCTTY)) == -1) goto error;
    if (sigaction(SIGCHLD, &dfl, &old) == -1) goto error;
    if (grantpt(masterfd) == -1) goto grantpt_error;
    if (sigaction(SIGCHLD, &old, NULL) == -1) goto error;
    if (unlockpt(masterfd) == -1) goto error;
    if ((slavedevice = ptsname(masterfd)) == NULL) goto error;
    if (no_mesg(slavedevice, nomesg) == -1) goto error;
    if ((slavefd = open(slavedevice, O_RDWR|O_NOCTTY, 0)) == -1) goto error;

#if defined I_PUSH && !defined linux
    if (ioctl(slavefd, I_PUSH, "ptem") == -1) goto error;
    if (ioctl(slavefd, I_PUSH, "ldterm") == -1) goto error;
    if (ioctl(slavefd, I_PUSH, "ttcompat") == -1) goto error;
#endif

    *master = masterfd;
    *slave = slavefd;
    strlcpy(SlaveName, slavedevice, DEVICELEN);
    return 0;

  grantpt_error:
    sigaction(SIGCHLD, &old, NULL);
  error:
    if (slavefd != -1) close(slavefd);
    if (masterfd != -1) close(masterfd);
    if (fail) {
        rb_raise(rb_eRuntimeError, "can't get Master/Slave device");
    }
    return -1;
#elif defined HAVE_OPENPTY
/*
 * Use openpty(3) of 4.3BSD Reno and later,
 * or the same interface function.
 */
    if (openpty(master, slave, SlaveName,
		(struct termios *)0, (struct winsize *)0) == -1) {
	if (!fail) return -1;
	rb_raise(rb_eRuntimeError, "openpty() failed");
    }
    if (no_mesg(SlaveName, nomesg) == -1) {
	if (!fail) return -1;
	rb_raise(rb_eRuntimeError, "can't chmod slave pty");
    }

    return 0;

#elif defined HAVE__GETPTY
    char *name;
    mode_t mode = nomesg ? 0600 : 0622;

    if (!(name = _getpty(master, O_RDWR, mode, 0))) {
	if (!fail) return -1;
	rb_raise(rb_eRuntimeError, "_getpty() failed");
    }

    *slave = open(name, O_RDWR);
    strlcpy(SlaveName, name, DEVICELEN);

    return 0;
#elif defined(HAVE_PTSNAME)
    int	 masterfd = -1, slavefd = -1;
    char *slavedevice;
    void (*s)();

    extern char *ptsname(int);
    extern int unlockpt(int);
    extern int grantpt(int);

    if((masterfd = open("/dev/ptmx", O_RDWR, 0)) == -1) goto error;
    s = signal(SIGCHLD, SIG_DFL);
    if(grantpt(masterfd) == -1) goto error;
    signal(SIGCHLD, s);
    if(unlockpt(masterfd) == -1) goto error;
    if((slavedevice = ptsname(masterfd)) == NULL) goto error;
    if (no_mesg(slavedevice, nomesg) == -1) goto error;
    if((slavefd = open(slavedevice, O_RDWR, 0)) == -1) goto error;
#if defined I_PUSH && !defined linux
    if(ioctl(slavefd, I_PUSH, "ptem") == -1) goto error;
    if(ioctl(slavefd, I_PUSH, "ldterm") == -1) goto error;
    ioctl(slavefd, I_PUSH, "ttcompat");
#endif
    *master = masterfd;
    *slave = slavefd;
    strlcpy(SlaveName, slavedevice, DEVICELEN);
    return 0;

  error:
    if (slavefd != -1) close(slavefd);
    if (masterfd != -1) close(masterfd);
    if (fail) rb_raise(rb_eRuntimeError, "can't get Master/Slave device");
    return -1;
#else
    int	 masterfd = -1, slavefd = -1;
    const char *const *p;
    char MasterName[DEVICELEN];

    for (p = deviceNo; *p != NULL; p++) {
	snprintf(MasterName, sizeof MasterName, MasterDevice, *p);
	if ((masterfd = open(MasterName,O_RDWR,0)) >= 0) {
	    *master = masterfd;
	    snprintf(SlaveName, DEVICELEN, SlaveDevice, *p);
	    if ((slavefd = open(SlaveName,O_RDWR,0)) >= 0) {
		*slave = slavefd;
		if (chown(SlaveName, getuid(), getgid()) != 0) goto error;
		if (chmod(SlaveName, nomesg ? 0600 : 0622) != 0) goto error;
		return 0;
	    }
	    close(masterfd);
	}
    }
  error:
    if (slavefd != -1) close(slavefd);
    if (masterfd != -1) close(masterfd);
    if (fail) rb_raise(rb_eRuntimeError, "can't get %s", SlaveName);
    return -1;
#endif
}

static void
getDevice(int *master, int *slave, char SlaveName[DEVICELEN], int nomesg)
{
    if (get_device_once(master, slave, SlaveName, nomesg, 0)) {
	rb_gc();
	get_device_once(master, slave, SlaveName, nomesg, 1);
    }
}

static VALUE
pty_close_pty(VALUE assoc)
{
    VALUE io;
    int i;

    for (i = 0; i < 2; i++) {
        io = rb_ary_entry(assoc, i);
        if (TYPE(io) == T_FILE && 0 <= RFILE(io)->fptr->fd)
            rb_io_close(io);
    }
    return Qnil;
}

/*
 * call-seq:
 *   PTY.open => [master_io, slave_file]
 *   PTY.open {|master_io, slave_file| ... } => block value
 *
 * Allocates a pty (pseudo-terminal).
 *
 * In the non-block form, returns a two element array, <tt>[master_io,
 * slave_file]</tt>.
 *
 * In the block form, yields two arguments <tt>master_io, slave_file</tt>
 * and the value of the block is returned from +open+.
 *
 * The IO and File are both closed after the block completes if they haven't
 * been already closed.
 *
 * The arguments in both forms are:
 *
 * <tt>master_io</tt>:: the master of the pty, as an IO.
 * <tt>slave_file</tt>:: the slave of the pty, as a File.  The path to the
 *                       terminal device is available via
 *                       <tt>slave_file.path</tt>
 *
 * === Example
 *
 *   PTY.open {|m, s|
 *     p m      #=> #<IO:masterpty:/dev/pts/1>
 *     p s      #=> #<File:/dev/pts/1>
 *     p s.path #=> "/dev/pts/1"
 *   }
 *
 *   # Change the buffering type in factor command,
 *   # assuming that factor uses stdio for stdout buffering.
 *   # If IO.pipe is used instead of PTY.open,
 *   # this code deadlocks because factor's stdout is fully buffered.
 *   require 'io/console' # for IO#raw!
 *   m, s = PTY.open
 *   s.raw! # disable newline conversion.
 *   r, w = IO.pipe
 *   pid = spawn("factor", :in=>r, :out=>s)
 *   r.close
 *   s.close
 *   w.puts "42"
 *   p m.gets #=> "42: 2 3 7\n"
 *   w.puts "144"
 *   p m.gets #=> "144: 2 2 2 2 3 3\n"
 *   w.close
 *   # The result of read operation when pty slave is closed is platform
 *   # dependent.
 *   ret = begin
 *           m.gets          # FreeBSD returns nil.
 *         rescue Errno::EIO # GNU/Linux raises EIO.
 *           nil
 *         end
 *   p ret #=> nil
 *
 */
static VALUE
pty_open(VALUE klass)
{
    int master_fd, slave_fd;
    char slavename[DEVICELEN];
    VALUE master_io, slave_file;
    rb_io_t *master_fptr, *slave_fptr;
    VALUE assoc;

    getDevice(&master_fd, &slave_fd, slavename, 1);

    master_io = rb_obj_alloc(rb_cIO);
    MakeOpenFile(master_io, master_fptr);
    master_fptr->mode = FMODE_READWRITE | FMODE_SYNC | FMODE_DUPLEX;
    master_fptr->fd = master_fd;
    master_fptr->pathv = rb_obj_freeze(rb_sprintf("masterpty:%s", slavename));

    slave_file = rb_obj_alloc(rb_cFile);
    MakeOpenFile(slave_file, slave_fptr);
    slave_fptr->mode = FMODE_READWRITE | FMODE_SYNC | FMODE_DUPLEX | FMODE_TTY;
    slave_fptr->fd = slave_fd;
    slave_fptr->pathv = rb_obj_freeze(rb_str_new_cstr(slavename));

    assoc = rb_assoc_new(master_io, slave_file);
    if (rb_block_given_p()) {
	return rb_ensure(rb_yield, assoc, pty_close_pty, assoc);
    }
    return assoc;
}

static VALUE
pty_detach_process(struct pty_info *info)
{
    rb_detach_process(info->child_pid);
    return Qnil;
}

/*
 * call-seq:
 *   PTY.spawn(command_line)  { |r, w, pid| ... }
 *   PTY.spawn(command_line)  => [r, w, pid]
 *   PTY.spawn(command, args, ...)  { |r, w, pid| ... }
 *   PTY.spawn(command, args, ...)  => [r, w, pid]
 *   PTY.getpty(command_line)  { |r, w, pid| ... }
 *   PTY.getpty(command_line)  => [r, w, pid]
 *   PTY.getpty(command, args, ...)  { |r, w, pid| ... }
 *   PTY.getpty(command, args, ...)  => [r, w, pid]
 *
 * Spawns the specified command on a newly allocated pty.
 *
 * The command's controlling tty is set to the slave device of the pty
 * and its standard input/output/error is redirected to the slave device.
 *
 * <tt>command_line</tt>:: The full command line to run
 * <tt>command</tt>:: The command to run, as a String.
 * <tt>args</tt>:: Zero or more arguments, as Strings, representing
 *                 the arguments to +command+
 *
 * In the non-block form this returns an array of size three,
 * <tt>[r, w, pid]</tt>.  In the block form the block will be called with
 * these as arguments, <tt>|r,w,pid|</tt>:
 *
 * +r+:: An IO that can be read from that contains the command's
 *       standard output and standard error
 * +w+:: An IO that can be written to that is the command's
 *       standard input
 * +pid+:: The process identifier for the command.
 */
static VALUE
pty_getpty(int argc, VALUE *argv, VALUE self)
{
    VALUE res;
    struct pty_info info;
    rb_io_t *wfptr,*rfptr;
    VALUE rport = rb_obj_alloc(rb_cFile);
    VALUE wport = rb_obj_alloc(rb_cFile);
    char SlaveName[DEVICELEN];

    MakeOpenFile(rport, rfptr);
    MakeOpenFile(wport, wfptr);

    establishShell(argc, argv, &info, SlaveName);

    rfptr->mode = rb_io_mode_flags("r");
    rfptr->fd = info.fd;
    rfptr->pathv = rb_obj_freeze(rb_str_new_cstr(SlaveName));

    wfptr->mode = rb_io_mode_flags("w") | FMODE_SYNC;
    wfptr->fd = dup(info.fd);
    if (wfptr->fd == -1)
        rb_sys_fail("dup()");
    wfptr->pathv = rfptr->pathv;

    res = rb_ary_new2(3);
    rb_ary_store(res,0,(VALUE)rport);
    rb_ary_store(res,1,(VALUE)wport);
    rb_ary_store(res,2,PIDT2NUM(info.child_pid));

    if (rb_block_given_p()) {
	rb_ensure(rb_yield, res, pty_detach_process, (VALUE)&info);
	return Qnil;
    }
    return res;
}

static void
raise_from_check(pid_t pid, int status)
{
    const char *state;
    char buf[1024];
    VALUE exc;

#if defined(WIFSTOPPED)
#elif defined(IF_STOPPED)
#define WIFSTOPPED(status) IF_STOPPED(status)
#else
---->> Either IF_STOPPED or WIFSTOPPED is needed <<----
#endif /* WIFSTOPPED | IF_STOPPED */
    if (WIFSTOPPED(status)) { /* suspend */
	state = "stopped";
    }
    else if (kill(pid, 0) == 0) {
	state = "changed";
    }
    else {
	state = "exited";
    }
    snprintf(buf, sizeof(buf), "pty - %s: %ld", state, (long)pid);
    exc = rb_exc_new2(eChildExited, buf);
    rb_iv_set(exc, "status", rb_last_status_get());
    rb_exc_raise(exc);
}

/*
 * call-seq:
 *   PTY.check(pid, raise = false) => Process::Status or nil
 *   PTY.check(pid, true)          => nil or raises PTY::ChildExited
 *
 * Checks the status of the child process specified by +pid+.
 * Returns +nil+ if the process is still alive.  If the process
 * is not alive, will return a <tt>Process::Status</tt> or raise
 * a <tt>PTY::ChildExited</tt> (if +raise+ was true).
 *
 * +pid+:: The process id of the process to check
 * +raise+:: If true and the process identified by +pid+ is no longer
 *           alive a <tt>PTY::ChildExited</tt> is raised.
 *
 * Returns nil or a <tt>Process::Status</tt> when +raise+ is false.
 */
static VALUE
pty_check(int argc, VALUE *argv, VALUE self)
{
    VALUE pid, exc;
    pid_t cpid;
    int status;

    rb_scan_args(argc, argv, "11", &pid, &exc);
    cpid = rb_waitpid(NUM2PIDT(pid), &status, WNOHANG|WUNTRACED);
    if (cpid == -1) return Qnil;

    if (!RTEST(exc)) return rb_last_status_get();
    raise_from_check(cpid, status);
    return Qnil;
}

static VALUE cPTY;

/*
 * Document-class: PTY::ChildExited
 *
 * Thrown when PTY#check is called for a pid that represents a process that
 * has exited.
 */

/*
 * Document-class: PTY
 *
 * Creates and managed pseudo terminals (PTYs).  See also
 * http://en.wikipedia.org/wiki/Pseudo_terminal
 */

void
Init_pty()
{
    cPTY = rb_define_module("PTY");
    rb_define_module_function(cPTY,"getpty",pty_getpty,-1);
    rb_define_module_function(cPTY,"spawn",pty_getpty,-1);
    rb_define_singleton_method(cPTY,"check",pty_check,-1);
    rb_define_singleton_method(cPTY,"open",pty_open,0);

    eChildExited = rb_define_class_under(cPTY,"ChildExited",rb_eRuntimeError);
    rb_define_method(eChildExited,"status",echild_status,0);
}