summaryrefslogtreecommitdiff
path: root/usr.bin/rdist/child.c
blob: 59a8f2c8c872f8bd9b30aa9882041995f2e9cda1 (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
/*	$OpenBSD: child.c,v 1.12 2003/05/14 01:34:35 millert Exp $	*/

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "defs.h"

#ifndef lint
#if 0
static char RCSid[] __attribute__((__unused__)) = 
"$From: child.c,v 1.3 1999/11/01 00:20:55 christos Exp $";
#else
static char RCSid[] __attribute__((__unused__)) = 
"$OpenBSD: child.c,v 1.12 2003/05/14 01:34:35 millert Exp $";
#endif

static char sccsid[] __attribute__((__unused__)) =
"@(#)docmd.c	5.1 (Berkeley) 6/6/85";

static char copyright[] __attribute__((__unused__)) =
"@(#) Copyright (c) 1983 Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

/*
 * Functions for rdist related to children
 */

#include <sys/types.h>
#include <sys/wait.h>
#if	defined(NEED_SYS_SELECT_H)
#include <sys/select.h>
#endif	/* NEED_SYS_SELECT_H */

typedef enum _PROCSTATE {
    PSrunning,
    PSdead
} PROCSTATE;

/*
 * Structure for child rdist processes mainted by the parent
 */
struct _child {
	char	       *c_name;			/* Name of child */
	int		c_readfd;		/* Read file descriptor */
	pid_t		c_pid;			/* Process ID */
	PROCSTATE       c_state;		/* Running? */
	struct _child  *c_next;			/* Next entry */
};
typedef struct _child CHILD;

static CHILD	       *childlist = NULL;	/* List of children */
int     		activechildren = 0;	/* Number of active children */
extern int		maxchildren;		/* Max active children */
static int 		needscan = FALSE;	/* Need to scan children */

static void removechild(CHILD *);
static CHILD *copychild(CHILD *);
static void addchild(CHILD *);
static void readchild(CHILD *);
static pid_t waitproc(int *, int);
static void reap(int);
static void childscan(void);

/*
 * Remove a child that has died (exited) 
 * from the list of active children
 */
static void
removechild(CHILD *child)
{
	CHILD *pc, *prevpc;

	debugmsg(DM_CALL, "removechild(%s, %d, %d) start",
		 child->c_name, child->c_pid, child->c_readfd);

	/*
	 * Find the child in the list
	 */
	for (pc = childlist, prevpc = NULL; pc != NULL; 
	     prevpc = pc, pc = pc->c_next)
		if (pc == child) 
			break;

	if (pc == NULL)
		error("RemoveChild called with bad child %s %d %d",
		      child->c_name, child->c_pid, child->c_readfd);
	else {
		/*
		 * Remove the child
		 */
#if	defined(POSIX_SIGNALS)
		sigset_t set;

		sigemptyset(&set);
		sigaddset(&set, SIGCHLD);
		sigprocmask(SIG_BLOCK, &set, NULL);
#else	/* !POSIX_SIGNALS */
		int oldmask;

		oldmask = sigblock(sigmask(SIGCHLD));
#endif	/* POSIX_SIGNALS */

		if (prevpc != NULL)
			prevpc->c_next = pc->c_next;
		else
			childlist = pc->c_next;

#if	defined(POSIX_SIGNALS)
		sigprocmask(SIG_UNBLOCK, &set, NULL);
#else
		sigsetmask(oldmask);
#endif	/* POSIX_SIGNALS */

		(void) free(child->c_name);
		--activechildren;
		(void) close(child->c_readfd);
		(void) free(pc);
	}

	debugmsg(DM_CALL, "removechild() end");
}

/*
 * Create a totally new copy of a child.
 */
static CHILD *
copychild(CHILD *child)
{
	CHILD *newc;

	newc = (CHILD *) xmalloc(sizeof(CHILD));

	newc->c_name = xstrdup(child->c_name);
	newc->c_readfd = child->c_readfd;
	newc->c_pid = child->c_pid;
	newc->c_state = child->c_state;
	newc->c_next = NULL;

	return(newc);
}

/*
 * Add a child to the list of children.
 */			
static void
addchild(CHILD *child)
{
	CHILD *pc;

	debugmsg(DM_CALL, "addchild() start\n");

	pc = copychild(child);
	pc->c_next = childlist;
	childlist = pc;

	++activechildren;

	debugmsg(DM_MISC,
		 "addchild() created '%s' pid %d fd %d (active=%d)\n",
		 child->c_name, child->c_pid, child->c_readfd, activechildren);
}

/*
 * Read input from a child process.
 */
static void
readchild(CHILD *child)
{
	char rbuf[BUFSIZ];
	int amt;

	debugmsg(DM_CALL, "[readchild(%s, %d, %d) start]", 
		 child->c_name, child->c_pid, child->c_readfd);

	/*
	 * Check that this is a valid child.
	 */
	if (child->c_name == NULL || child->c_readfd <= 0) {
		debugmsg(DM_MISC, "[readchild(%s, %d, %d) bad child]",
			 child->c_name, child->c_pid, child->c_readfd);
		return;
	}

	/*
	 * Read from child and display the result.
	 */
	while ((amt = read(child->c_readfd, rbuf, sizeof(rbuf))) > 0) {
		/* XXX remove these debug calls */
		debugmsg(DM_MISC, "[readchild(%s, %d, %d) got %d bytes]", 
			 child->c_name, child->c_pid, child->c_readfd, amt);

		(void) xwrite(fileno(stdout), rbuf, amt);

		debugmsg(DM_MISC, "[readchild(%s, %d, %d) write done]",
			 child->c_name, child->c_pid, child->c_readfd);
	}

	debugmsg(DM_MISC, "readchild(%s, %d, %d) done: amt = %d errno = %d\n",
		 child->c_name, child->c_pid, child->c_readfd, amt, errno);

	/* 
	 * See if we've reached EOF 
	 */
	if (amt == 0)
		debugmsg(DM_MISC, "readchild(%s, %d, %d) at EOF\n",
			 child->c_name, child->c_pid, child->c_readfd);
}

/*
 * Wait for processes to exit.  If "block" is true, then we block
 * until a process exits.  Otherwise, we return right away.  If
 * a process does exit, then the pointer "statval" is set to the
 * exit status of the exiting process, if statval is not NULL.
 */
static pid_t
waitproc(int *statval, int block)
{
	WAIT_ARG_TYPE status;
	pid_t pid;
	int exitval;

	debugmsg(DM_CALL, "waitproc() %s, active children = %d...\n", 
		 (block) ? "blocking" : "nonblocking", activechildren);

#if	WAIT_TYPE == WAIT_WAITPID
	pid = waitpid(-1, &status, (block) ? 0 : WNOHANG);
#else
#if	WAIT_TYPE == WAIT_WAIT3
	pid = wait3(&status, (block) ? 0 : WNOHANG, NULL);
#endif	/* WAIT_WAIT3 */
#endif	/* WAIT_WAITPID */

#if	defined(WEXITSTATUS)
	exitval = WEXITSTATUS(status);
#else
	exitval = status.w_retcode;
#endif	/* defined(WEXITSTATUS) */

	if (pid > 0 && exitval != 0) {
		nerrs++;
		debugmsg(DM_MISC, 
			 "Child process %d exited with status %d.\n",
			 pid, exitval);
	}

	if (statval)
		*statval = exitval;

	debugmsg(DM_CALL, "waitproc() done (activechildren = %d)\n", 
		 activechildren);

	return(pid);
}

/*
 * Check to see if any children have exited, and if so, read any unread
 * input and then remove the child from the list of children.
 */
static void
reap(int dummy)
{
	CHILD *pc;
	int save_errno = errno;
	int status = 0;
	pid_t pid;

	debugmsg(DM_CALL, "reap() called\n");

	/*
	 * Reap every child that has exited.  Break out of the
	 * loop as soon as we run out of children that have
	 * exited so far.
	 */
	for ( ; ; ) {
		/*
		 * Do a non-blocking check for exiting processes
		 */
		pid = waitproc(&status, FALSE);
		debugmsg(DM_MISC, 
			 "reap() pid = %d status = %d activechildren=%d\n",
			 pid, status, activechildren);

		/*
		 * See if a child really exited
		 */
		if (pid == 0)
			break;
		if (pid < 0) {
			if (errno != ECHILD)
				error("Wait failed: %s", SYSERR);
			break;
		}

		/*
		 * Find the process (pid) and mark it as dead.
		 */
		for (pc = childlist; pc; pc = pc->c_next)
			if (pc->c_pid == pid) {
				needscan = TRUE;
				pc->c_state = PSdead;
			}

	}

	/*
	 * Reset signals
	 */
	(void) signal(SIGCHLD, reap);

	debugmsg(DM_CALL, "reap() done\n");
	errno = save_errno;
}

/*
 * Scan the children list to find the child that just exited, 
 * read any unread input, then remove it from the list of active children.
 */
static void
childscan(void)
{
	CHILD *pc, *nextpc;
	
	debugmsg(DM_CALL, "childscan() start");

	for (pc = childlist; pc; pc = nextpc) {
		nextpc = pc->c_next;
		if (pc->c_state == PSdead) {
			readchild(pc);
			removechild(pc);
		}
	}

	needscan = FALSE;
	debugmsg(DM_CALL, "childscan() end");
}

/*
#if	defined HAVE_SELECT
 *
 * Wait for children to send output for us to read.
 *
#else	!HAVE_SELECT
 *
 * Wait up for children to exit.
 *
#endif
 */
void
waitup(void)
{
#if	defined(HAVE_SELECT)
	int count;
	CHILD *pc;
	fd_set *rchildfdsp = NULL;
	int rchildfdsn = 0;
	size_t bytes;

	debugmsg(DM_CALL, "waitup() start\n");

	if (needscan)
		childscan();

	if (activechildren <= 0)
		return;

	/*
	 * Settup which children we want to select() on.
	 */
	for (pc = childlist; pc; pc = pc->c_next)
		if (pc->c_readfd > rchildfdsn)
			rchildfdsn = pc->c_readfd;
	bytes = howmany(rchildfdsn+1, NFDBITS) * sizeof(fd_mask);
	if ((rchildfdsp = (fd_set *)malloc(bytes)) == NULL)
		return;

	memset(rchildfdsp, 0, bytes);
	for (pc = childlist; pc; pc = pc->c_next)
		if (pc->c_readfd > 0) {
			debugmsg(DM_MISC, "waitup() select on %d (%s)\n",
				 pc->c_readfd, pc->c_name);
			FD_SET(pc->c_readfd, rchildfdsp);
		}

	/*
	 * Actually call select()
	 */
	/* XXX remove debugmsg() calls */
	debugmsg(DM_MISC, "waitup() Call select(), activechildren=%d\n", 
		 activechildren);

	count = select(rchildfdsn+1, (SELECT_FD_TYPE *) rchildfdsp, 
		       NULL, NULL, NULL);

	debugmsg(DM_MISC, "waitup() select returned %d activechildren = %d\n", 
		 count, activechildren);

	/*
	 * select() will return count < 0 and errno == EINTR when
	 * there are no active children left.
	 */
	if (count < 0) {
		if (errno != EINTR)
			error("Select failed reading children input: %s", 
			      SYSERR);
		free(rchildfdsp);
		return;
	}

	/*
	 * This should never happen.
	 */
	if (count == 0) {
		error("Select returned an unexpected count of 0.");
		free(rchildfdsp);
		return;
	}

	/*
	 * Go through the list of children and read from each child
	 * which select() detected as ready for reading.
	 */
	for (pc = childlist; pc && count > 0; pc = pc->c_next) {
		/* 
		 * Make sure child still exists 
		 */
		if (pc->c_name && kill(pc->c_pid, 0) < 0 && 
		    errno == ESRCH) {
			debugmsg(DM_MISC, 
				 "waitup() proc %d (%s) died unexpectedly!",
				 pc->c_pid, pc->c_name);
			pc->c_state = PSdead;
			needscan = TRUE;
		}

		if (pc->c_name == NULL ||
		    !FD_ISSET(pc->c_readfd, rchildfdsp))
			continue;

		readchild(pc);
		--count;
	}
	free(rchildfdsp);

#else	/* !defined(HAVE_SELECT) */

	/*
	 * The non-select() version of waitproc()
	 */
	debugmsg(DM_CALL, "waitup() start\n");

	if (waitproc(NULL, TRUE) > 0)
		--activechildren;

#endif	/* defined(HAVE_SELECT) */
	debugmsg(DM_CALL, "waitup() end\n");
}

/*
 * Spawn (create) a new child process for "cmd".
 */
int
spawn(struct cmd *cmd, struct cmd *cmdlist)
{
	pid_t pid;
	int fildes[2];
	char *childname = cmd->c_name;

	if (pipe(fildes) < 0) {
		error("Cannot create pipe for %s: %s", childname, SYSERR);
		return(-1);
	}

	pid = fork();
	if (pid == (pid_t)-1) {
		error("Cannot spawn child for %s: fork failed: %s", 
		      childname, SYSERR);
		return(-1);
	} else if (pid > 0) {
		/*
		 * Parent
		 */
		static CHILD newchild;

#if	defined(FORK_MISSES)
		/*
		 * XXX Some OS's have a bug where fork does not
		 * always return properly to the parent
		 * when a number of forks are done very quicky.
		 */
		sleep(2);
#endif	/* FORK_MISSES */

		/* Receive notification when the child exits */
		(void) signal(SIGCHLD, reap);

		/* Settup the new child */
		newchild.c_next = NULL;
		newchild.c_name = childname;
		newchild.c_readfd = fildes[PIPE_READ];
		newchild.c_pid = pid;
		newchild.c_state = PSrunning;

		/* We're not going to write to the child */
		(void) close(fildes[PIPE_WRITE]);

		/* Set non-blocking I/O */
		if (setnonblocking(newchild.c_readfd, TRUE) < 0) {
			error("Set nonblocking I/O failed: %s", SYSERR);
			return(-1);
		}

		/* Add new child to child list */
		addchild(&newchild);

		/* Mark all other entries for this host as assigned */
		markassigned(cmd, cmdlist);

		debugmsg(DM_CALL,
			 "spawn() Forked child %d for host %s active = %d\n",
			 pid, childname, activechildren);
		return(pid);
	} else {
		/* 
		 * Child 
		 */

		/* We're not going to read from our parent */
		(void) close(fildes[PIPE_READ]);

		/* Make stdout and stderr go to PIPE_WRITE (our parent) */
		if (dup2(fildes[PIPE_WRITE], (int)fileno(stdout)) < 0) {
			error("Cannot duplicate stdout file descriptor: %s", 
			      SYSERR);
			return(-1);
		}
		if (dup2(fildes[PIPE_WRITE], (int)fileno(stderr)) < 0) {
			error("Cannot duplicate stderr file descriptor: %s", 
			      SYSERR);
			return(-1);
		}

		return(0);
	}
}


/*
 * Enable or disable non-blocking I/O mode.
 *
 * Code is from INN by Rich Salz.
 */
#if	NBIO_TYPE == NBIO_IOCTL
#include <sys/ioctl.h>

int
setnonblocking(int fd, int flag)
{
	int state;

	state = flag ? 1 : 0;
	return(ioctl(fd, FIONBIO, (char *)&state));
}

#endif	/* NBIO_IOCTL */


#if	NBIO_TYPE == NBIO_FCNTL
int
setnonblocking(int fd, int flag)
{
	int	mode;

	if ((mode = fcntl(fd, F_GETFL, 0)) < 0)
		return(-1);
	if (flag)
		mode |= FNDELAY;
	else
		mode &= ~FNDELAY;
	return(fcntl(fd, F_SETFL, mode));
}
#endif	/* NBIO_FCNTL */