Annotation of src/usr.bin/rdist/child.c, Revision 1.11
1.11 ! mpech 1: /* $OpenBSD: child.c,v 1.10 2001/11/19 19:02:15 mpech Exp $ */
1.3 deraadt 2:
1.1 dm 3: /*
4: * Copyright (c) 1983 Regents of the University of California.
5: * All rights reserved.
6: *
7: * Redistribution and use in source and binary forms, with or without
8: * modification, are permitted provided that the following conditions
9: * are met:
10: * 1. Redistributions of source code must retain the above copyright
11: * notice, this list of conditions and the following disclaimer.
12: * 2. Redistributions in binary form must reproduce the above copyright
13: * notice, this list of conditions and the following disclaimer in the
14: * documentation and/or other materials provided with the distribution.
15: * 3. All advertising materials mentioning features or use of this software
16: * must display the following acknowledgement:
17: * This product includes software developed by the University of
18: * California, Berkeley and its contributors.
19: * 4. Neither the name of the University nor the names of its contributors
20: * may be used to endorse or promote products derived from this software
21: * without specific prior written permission.
22: *
23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33: * SUCH DAMAGE.
34: */
35:
36: #ifndef lint
1.7 millert 37: #if 0
1.1 dm 38: static char RCSid[] =
1.7 millert 39: "$From: child.c,v 6.28 1996/02/22 19:30:09 mcooper Exp $";
40: #else
41: static char RCSid[] =
1.11 ! mpech 42: "$OpenBSD: child.c,v 1.10 2001/11/19 19:02:15 mpech Exp $";
1.7 millert 43: #endif
1.1 dm 44:
45: static char sccsid[] = "@(#)docmd.c 5.1 (Berkeley) 6/6/85";
46:
47: static char copyright[] =
48: "@(#) Copyright (c) 1983 Regents of the University of California.\n\
49: All rights reserved.\n";
50: #endif /* not lint */
51:
52: /*
53: * Functions for rdist related to children
54: */
55:
56: #include "defs.h"
57: #include <sys/types.h>
58: #include <sys/wait.h>
59: #if defined(NEED_SYS_SELECT_H)
60: #include <sys/select.h>
61: #endif /* NEED_SYS_SELECT_H */
62:
63: typedef enum _PROCSTATE {
64: PSrunning,
65: PSdead
66: } PROCSTATE;
67:
68: /*
69: * Structure for child rdist processes mainted by the parent
70: */
71: struct _child {
72: char *c_name; /* Name of child */
73: int c_readfd; /* Read file descriptor */
74: pid_t c_pid; /* Process ID */
75: PROCSTATE c_state; /* Running? */
76: struct _child *c_next; /* Next entry */
77: };
78: typedef struct _child CHILD;
79:
80: static CHILD *childlist = NULL; /* List of children */
81: int activechildren = 0; /* Number of active children */
82: extern int maxchildren; /* Max active children */
83: static int needscan = FALSE; /* Need to scan children */
84:
85: /*
86: * Remove a child that has died (exited)
87: * from the list of active children
88: */
89: static void removechild(child)
90: CHILD *child;
91: {
1.10 mpech 92: CHILD *pc, *prevpc;
1.1 dm 93:
1.11 ! mpech 94: debugmsg(DM_CALL, "removechild(%s, %ld, %d) start",
! 95: child->c_name, (long)child->c_pid, child->c_readfd);
1.1 dm 96:
97: /*
98: * Find the child in the list
99: */
100: for (pc = childlist, prevpc = NULL; pc != NULL;
101: prevpc = pc, pc = pc->c_next)
102: if (pc == child)
103: break;
104:
105: if (pc == NULL)
1.11 ! mpech 106: error("RemoveChild called with bad child %s %ld %d",
! 107: child->c_name, (long)child->c_pid, child->c_readfd);
1.1 dm 108: else {
109: /*
110: * Remove the child
111: */
112: #if defined(POSIX_SIGNALS)
113: sigset_t set;
114:
115: sigemptyset(&set);
116: sigaddset(&set, SIGCHLD);
1.7 millert 117: sigprocmask(SIG_BLOCK, &set, NULL);
1.1 dm 118: #else /* !POSIX_SIGNALS */
119: int oldmask;
120:
121: oldmask = sigblock(sigmask(SIGCHLD));
122: #endif /* POSIX_SIGNALS */
123:
124: if (prevpc != NULL)
125: prevpc->c_next = pc->c_next;
126: else
127: childlist = pc->c_next;
128:
129: #if defined(POSIX_SIGNALS)
1.7 millert 130: sigprocmask(SIG_UNBLOCK, &set, NULL);
1.1 dm 131: #else
132: sigsetmask(oldmask);
133: #endif /* POSIX_SIGNALS */
134:
135: (void) free(child->c_name);
136: --activechildren;
137: (void) close(child->c_readfd);
138: (void) free(pc);
139: }
140:
141: debugmsg(DM_CALL, "removechild() end");
142: }
143:
144: /*
145: * Create a totally new copy of a child.
146: */
147: static CHILD *copychild(child)
148: CHILD *child;
149: {
1.10 mpech 150: CHILD *newc;
1.1 dm 151:
152: newc = (CHILD *) xmalloc(sizeof(CHILD));
153:
1.8 millert 154: newc->c_name = xstrdup(child->c_name);
1.1 dm 155: newc->c_readfd = child->c_readfd;
156: newc->c_pid = child->c_pid;
157: newc->c_state = child->c_state;
158: newc->c_next = NULL;
159:
160: return(newc);
161: }
162:
163: /*
164: * Add a child to the list of children.
165: */
166: static void addchild(child)
167: CHILD *child;
168: {
1.10 mpech 169: CHILD *pc;
1.1 dm 170:
171: debugmsg(DM_CALL, "addchild() start\n");
172:
173: pc = copychild(child);
174: pc->c_next = childlist;
175: childlist = pc;
176:
177: ++activechildren;
178:
179: debugmsg(DM_MISC,
1.11 ! mpech 180: "addchild() created '%s' pid %ld fd %d (active=%d)\n",
! 181: child->c_name, (long)child->c_pid, child->c_readfd,
! 182: activechildren);
1.1 dm 183: }
184:
185: /*
186: * Read input from a child process.
187: */
188: static void readchild(child)
189: CHILD *child;
190: {
191: char rbuf[BUFSIZ];
192: int amt;
193:
1.11 ! mpech 194: debugmsg(DM_CALL, "[readchild(%s, %ld, %d) start]",
! 195: child->c_name, (long)child->c_pid, child->c_readfd);
1.1 dm 196:
197: /*
198: * Check that this is a valid child.
199: */
200: if (child->c_name == NULL || child->c_readfd <= 0) {
1.11 ! mpech 201: debugmsg(DM_MISC, "[readchild(%s, %ld, %d) bad child]",
! 202: child->c_name, (long)child->c_pid, child->c_readfd);
1.1 dm 203: return;
204: }
205:
206: /*
207: * Read from child and display the result.
208: */
209: while ((amt = read(child->c_readfd, rbuf, sizeof(rbuf))) > 0) {
210: /* XXX remove these debug calls */
1.11 ! mpech 211: debugmsg(DM_MISC, "[readchild(%s, %ld, %d) got %d bytes]",
! 212: child->c_name, (long)child->c_pid, child->c_readfd, amt);
1.1 dm 213:
214: (void) xwrite(fileno(stdout), rbuf, amt);
215:
1.11 ! mpech 216: debugmsg(DM_MISC, "[readchild(%s, %ld, %d) write done]",
! 217: child->c_name, (long)child->c_pid, child->c_readfd);
1.1 dm 218: }
219:
1.11 ! mpech 220: debugmsg(DM_MISC, "readchild(%s, %ld, %d) done: amt = %d errno = %d\n",
! 221: child->c_name, (long)child->c_pid, child->c_readfd, amt, errno);
1.1 dm 222:
223: /*
224: * See if we've reached EOF
225: */
226: if (amt == 0)
1.11 ! mpech 227: debugmsg(DM_MISC, "readchild(%s, %ld, %d) at EOF\n",
! 228: child->c_name, (long)child->c_pid, child->c_readfd);
1.1 dm 229: }
230:
231: /*
232: * Wait for processes to exit. If "block" is true, then we block
233: * until a process exits. Otherwise, we return right away. If
234: * a process does exit, then the pointer "statval" is set to the
235: * exit status of the exiting process, if statval is not NULL.
236: */
1.11 ! mpech 237: static pid_t waitproc(statval, block)
1.1 dm 238: int *statval;
239: int block;
240: {
241: WAIT_ARG_TYPE status;
1.11 ! mpech 242: int exitval;
! 243: pid_t pid;
1.1 dm 244:
245: debugmsg(DM_CALL, "waitproc() %s, active children = %d...\n",
246: (block) ? "blocking" : "nonblocking", activechildren);
247:
248: #if WAIT_TYPE == WAIT_WAITPID
249: pid = waitpid(-1, &status, (block) ? 0 : WNOHANG);
250: #else
251: #if WAIT_TYPE == WAIT_WAIT3
252: pid = wait3(&status, (block) ? 0 : WNOHANG, NULL);
253: #endif /* WAIT_WAIT3 */
254: #endif /* WAIT_WAITPID */
255:
256: #if defined(WEXITSTATUS)
257: exitval = WEXITSTATUS(status);
258: #else
259: exitval = status.w_retcode;
260: #endif /* defined(WEXITSTATUS) */
261:
262: if (pid > 0 && exitval != 0) {
263: nerrs++;
264: debugmsg(DM_MISC,
1.11 ! mpech 265: "Child process %ld exited with status %d.\n",
! 266: (long)pid, exitval);
1.1 dm 267: }
268:
269: if (statval)
270: *statval = exitval;
271:
272: debugmsg(DM_CALL, "waitproc() done (activechildren = %d)\n",
273: activechildren);
274:
275: return(pid);
276: }
277:
278: /*
279: * Check to see if any children have exited, and if so, read any unread
280: * input and then remove the child from the list of children.
281: */
282: static void reap()
283: {
1.10 mpech 284: CHILD *pc;
1.5 deraadt 285: int save_errno = errno;
1.1 dm 286: int status = 0;
287: pid_t pid;
288:
289: debugmsg(DM_CALL, "reap() called\n");
290:
291: /*
292: * Reap every child that has exited. Break out of the
293: * loop as soon as we run out of children that have
294: * exited so far.
295: */
296: for ( ; ; ) {
297: /*
298: * Do a non-blocking check for exiting processes
299: */
300: pid = waitproc(&status, FALSE);
301: debugmsg(DM_MISC,
1.11 ! mpech 302: "reap() pid = %ld status = %d activechildren=%d\n",
! 303: (long)pid, status, activechildren);
1.1 dm 304:
305: /*
306: * See if a child really exited
307: */
308: if (pid == 0)
309: break;
310: if (pid < 0) {
311: if (errno != ECHILD)
312: error("Wait failed: %s", SYSERR);
313: break;
314: }
315:
316: /*
317: * Find the process (pid) and mark it as dead.
318: */
319: for (pc = childlist; pc; pc = pc->c_next)
320: if (pc->c_pid == pid) {
321: needscan = TRUE;
322: pc->c_state = PSdead;
323: }
324:
325: }
326:
327: /*
328: * Reset signals
329: */
330: (void) signal(SIGCHLD, reap);
331:
332: debugmsg(DM_CALL, "reap() done\n");
1.5 deraadt 333: errno = save_errno;
1.1 dm 334: }
335:
336: /*
337: * Scan the children list to find the child that just exited,
338: * read any unread input, then remove it from the list of active children.
339: */
340: static void childscan()
341: {
1.10 mpech 342: CHILD *pc, *nextpc;
1.1 dm 343:
344: debugmsg(DM_CALL, "childscan() start");
345:
346: for (pc = childlist; pc; pc = nextpc) {
347: nextpc = pc->c_next;
348: if (pc->c_state == PSdead) {
349: readchild(pc);
350: removechild(pc);
351: }
352: }
353:
354: needscan = FALSE;
355: debugmsg(DM_CALL, "childscan() end");
356: }
357:
358: /*
359: #if defined HAVE_SELECT
360: *
361: * Wait for children to send output for us to read.
362: *
363: #else !HAVE_SELECT
364: *
365: * Wait up for children to exit.
366: *
367: #endif
368: */
369: extern void waitup()
370: {
371: #if defined(HAVE_SELECT)
1.10 mpech 372: int count;
373: CHILD *pc;
1.6 deraadt 374: fd_set *rchildfdsp = NULL;
375: int rchildfdsn = 0;
1.7 millert 376: size_t bytes;
1.1 dm 377:
378: debugmsg(DM_CALL, "waitup() start\n");
379:
380: if (needscan)
381: childscan();
382:
383: if (activechildren <= 0)
384: return;
385:
386: /*
387: * Settup which children we want to select() on.
388: */
1.6 deraadt 389: for (pc = childlist; pc; pc = pc->c_next)
390: if (pc->c_readfd > rchildfdsn)
391: rchildfdsn = pc->c_readfd;
392: bytes = howmany(rchildfdsn+1, NFDBITS) * sizeof(fd_mask);
393: if ((rchildfdsp = (fd_set *)malloc(bytes)) == NULL)
394: return;
395:
396: memset(rchildfdsp, 0, bytes);
1.1 dm 397: for (pc = childlist; pc; pc = pc->c_next)
398: if (pc->c_readfd > 0) {
399: debugmsg(DM_MISC, "waitup() select on %d (%s)\n",
400: pc->c_readfd, pc->c_name);
1.6 deraadt 401: FD_SET(pc->c_readfd, rchildfdsp);
1.1 dm 402: }
403:
404: /*
405: * Actually call select()
406: */
407: /* XXX remove debugmsg() calls */
408: debugmsg(DM_MISC, "waitup() Call select(), activechildren=%d\n",
409: activechildren);
410:
1.9 millert 411: count = select(rchildfdsn+1, (SELECT_FD_TYPE *) rchildfdsp,
1.7 millert 412: NULL, NULL, NULL);
1.1 dm 413:
414: debugmsg(DM_MISC, "waitup() select returned %d activechildren = %d\n",
415: count, activechildren);
416:
417: /*
418: * select() will return count < 0 and errno == EINTR when
419: * there are no active children left.
420: */
421: if (count < 0) {
422: if (errno != EINTR)
423: error("Select failed reading children input: %s",
424: SYSERR);
1.6 deraadt 425: free(rchildfdsp);
1.1 dm 426: return;
427: }
428:
429: /*
430: * This should never happen.
431: */
432: if (count == 0) {
433: error("Select returned an unexpected count of 0.");
1.6 deraadt 434: free(rchildfdsp);
1.1 dm 435: return;
436: }
437:
438: /*
439: * Go through the list of children and read from each child
440: * which select() detected as ready for reading.
441: */
442: for (pc = childlist; pc && count > 0; pc = pc->c_next) {
443: /*
444: * Make sure child still exists
445: */
446: if (pc->c_name && kill(pc->c_pid, 0) < 0 &&
447: errno == ESRCH) {
448: debugmsg(DM_MISC,
1.11 ! mpech 449: "waitup() proc %ld (%s) died unexpectedly!",
! 450: (long)pc->c_pid, pc->c_name);
1.1 dm 451: pc->c_state = PSdead;
452: needscan = TRUE;
453: }
454:
455: if (pc->c_name == NULL ||
1.6 deraadt 456: !FD_ISSET(pc->c_readfd, rchildfdsp))
1.1 dm 457: continue;
458:
459: readchild(pc);
460: --count;
461: }
1.7 millert 462: free(rchildfdsp);
1.1 dm 463:
464: #else /* !defined(HAVE_SELECT) */
465:
466: /*
467: * The non-select() version of waitproc()
468: */
469: debugmsg(DM_CALL, "waitup() start\n");
470:
1.7 millert 471: if (waitproc(NULL, TRUE) > 0)
1.1 dm 472: --activechildren;
473:
474: #endif /* defined(HAVE_SELECT) */
475: debugmsg(DM_CALL, "waitup() end\n");
476: }
477:
478: /*
479: * Spawn (create) a new child process for "cmd".
480: */
481: extern int spawn(cmd, cmdlist)
482: struct cmd *cmd;
483: struct cmd *cmdlist;
484: {
485: pid_t pid;
486: int fildes[2];
487: char *childname = cmd->c_name;
488:
489: if (pipe(fildes) < 0) {
490: error("Cannot create pipe for %s: %s", childname, SYSERR);
491: return(-1);
492: }
493:
494: pid = fork();
495: if (pid == (pid_t)-1) {
496: error("Cannot spawn child for %s: fork failed: %s",
497: childname, SYSERR);
498: return(-1);
499: } else if (pid > 0) {
500: /*
501: * Parent
502: */
503: static CHILD newchild;
504:
505: #if defined(FORK_MISSES)
506: /*
507: * XXX Some OS's have a bug where fork does not
508: * always return properly to the parent
509: * when a number of forks are done very quicky.
510: */
511: sleep(2);
512: #endif /* FORK_MISSES */
513:
514: /* Receive notification when the child exits */
515: (void) signal(SIGCHLD, reap);
516:
517: /* Settup the new child */
518: newchild.c_next = NULL;
519: newchild.c_name = childname;
520: newchild.c_readfd = fildes[PIPE_READ];
521: newchild.c_pid = pid;
522: newchild.c_state = PSrunning;
523:
524: /* We're not going to write to the child */
525: (void) close(fildes[PIPE_WRITE]);
526:
527: /* Set non-blocking I/O */
528: if (setnonblocking(newchild.c_readfd, TRUE) < 0) {
529: error("Set nonblocking I/O failed: %s", SYSERR);
530: return(-1);
531: }
532:
533: /* Add new child to child list */
534: addchild(&newchild);
535:
536: /* Mark all other entries for this host as assigned */
537: markassigned(cmd, cmdlist);
538:
539: debugmsg(DM_CALL,
540: "spawn() Forked child %d for host %s active = %d\n",
541: pid, childname, activechildren);
542: return(pid);
543: } else {
544: /*
545: * Child
546: */
547:
548: /* We're not going to read from our parent */
549: (void) close(fildes[PIPE_READ]);
550:
551: /* Make stdout and stderr go to PIPE_WRITE (our parent) */
552: if (dup2(fildes[PIPE_WRITE], (int)fileno(stdout)) < 0) {
553: error("Cannot duplicate stdout file descriptor: %s",
554: SYSERR);
555: return(-1);
556: }
557: if (dup2(fildes[PIPE_WRITE], (int)fileno(stderr)) < 0) {
558: error("Cannot duplicate stderr file descriptor: %s",
559: SYSERR);
560: return(-1);
561: }
562:
563: return(0);
564: }
565: }
566:
567:
568: /*
569: * Enable or disable non-blocking I/O mode.
570: *
571: * Code is from INN by Rich Salz.
572: */
573: #if NBIO_TYPE == NBIO_IOCTL
574: #include <sys/ioctl.h>
575:
576: int setnonblocking(fd, flag)
577: int fd;
578: int flag;
579: {
580: int state;
581:
582: state = flag ? 1 : 0;
583: return(ioctl(fd, FIONBIO, (char *)&state));
584: }
585:
586: #endif /* NBIO_IOCTL */
587:
588:
589: #if NBIO_TYPE == NBIO_FCNTL
590: int setnonblocking(fd, flag)
591: int fd;
592: int flag;
593: {
594: int mode;
595:
596: if ((mode = fcntl(fd, F_GETFL, 0)) < 0)
597: return(-1);
598: if (flag)
599: mode |= FNDELAY;
600: else
601: mode &= ~FNDELAY;
602: return(fcntl(fd, F_SETFL, mode));
603: }
604: #endif /* NBIO_FCNTL */
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