1 /*-
2 * Copyright (c) 1990, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
4 *
5 * %sccs.include.redist.c%
6 */
7
8 #ifndef lint
9 static char copyright[] =
10 "@(#) Copyright (c) 1990, 1993, 1994\n\
11 The Regents of the University of California. All rights reserved.\n";
12 #endif /* not lint */
13
14 #ifndef lint
15 static char sccsid[] = "@(#)mail.local.c 8.22 (Berkeley) 06/21/95";
16 #endif /* not lint */
17
18 /*
19 * This is not intended to compile on System V derived systems
20 * such as Solaris or HP-UX, since they use a totally different
21 * approach to mailboxes (essentially, they have a setgid program
22 * rather than setuid, and they rely on the ability to "give away"
23 * files to do their work). IT IS NOT A BUG that this doesn't
24 * compile on such architectures.
25 */
26
27 #include <sys/param.h>
28 #include <sys/stat.h>
29 #include <sys/socket.h>
30
31 #include <netinet/in.h>
32
33 #include <errno.h>
34 #include <fcntl.h>
35 #include <netdb.h>
36 #include <pwd.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <string.h>
40 #include <sysexits.h>
41 #include <syslog.h>
42 #include <time.h>
43 #include <unistd.h>
44 #include <ctype.h>
45
46 #if __STDC__
47 #include <stdarg.h>
48 #else
49 #include <varargs.h>
50 #endif
51
52 #ifndef LOCK_EX
53 # include <sys/file.h>
54 #endif
55
56 #ifdef BSD4_4
57 # include "pathnames.h"
58 #endif
59
60 #ifndef __P
61 # ifdef __STDC__
62 # define __P(protos) protos
63 # else
64 # define __P(protos) ()
65 # define const
66 # endif
67 #endif
68 #ifndef __dead
69 # if defined(__GNUC__) && (__GNUC__ < 2 || __GNUC_MINOR__ < 5) && !defined(__STRICT_ANSI__)
70 # define __dead __volatile
71 # else
72 # define __dead
73 # endif
74 #endif
75
76 #ifndef BSD4_4
77 # define _BSD_VA_LIST_ va_list
78 extern char *strerror __P((int));
79 extern int snprintf __P((char *, int, const char *, ...));
80 #endif
81
82 /*
83 * If you don't have setreuid, and you have saved uids, and you have
84 * a seteuid() call that doesn't try to emulate using setuid(), then
85 * you can try defining USE_SETEUID.
86 */
87 #ifdef USE_SETEUID
88 # define setreuid(r, e) seteuid(e)
89 #endif
90
91 #ifndef _PATH_LOCTMP
92 # define _PATH_LOCTMP "/tmp/local.XXXXXX"
93 #endif
94 #ifndef _PATH_MAILDIR
95 # define _PATH_MAILDIR "/var/spool/mail"
96 #endif
97
98 #ifndef S_ISREG
99 # define S_ISREG(mode) (((mode) & _S_IFMT) == S_IFREG)
100 #endif
101
102 int eval = EX_OK; /* sysexits.h error value. */
103
104 void deliver __P((int, char *));
105 void e_to_sys __P((int));
106 __dead void err __P((const char *, ...));
107 void notifybiff __P((char *));
108 int store __P((char *));
109 void usage __P((void));
110 void vwarn __P((const char *, _BSD_VA_LIST_));
111 void warn __P((const char *, ...));
112
113 int
main(argc,argv)114 main(argc, argv)
115 int argc;
116 char *argv[];
117 {
118 struct passwd *pw;
119 int ch, fd;
120 uid_t uid;
121 char *from;
122 extern char *optarg;
123 extern int optind;
124
125 /* make sure we have some open file descriptors */
126 for (fd = 10; fd < 30; fd++)
127 (void) close(fd);
128
129 /* use a reasonable umask */
130 (void) umask(0077);
131
132 #ifdef LOG_MAIL
133 openlog("mail.local", 0, LOG_MAIL);
134 #else
135 openlog("mail.local", 0);
136 #endif
137
138 from = NULL;
139 while ((ch = getopt(argc, argv, "df:r:")) != EOF)
140 switch(ch) {
141 case 'd': /* Backward compatible. */
142 break;
143 case 'f':
144 case 'r': /* Backward compatible. */
145 if (from != NULL) {
146 warn("multiple -f options");
147 usage();
148 }
149 from = optarg;
150 break;
151 case '?':
152 default:
153 usage();
154 }
155 argc -= optind;
156 argv += optind;
157
158 if (!*argv)
159 usage();
160
161 /*
162 * If from not specified, use the name from getlogin() if the
163 * uid matches, otherwise, use the name from the password file
164 * corresponding to the uid.
165 */
166 uid = getuid();
167 if (!from && (!(from = getlogin()) ||
168 !(pw = getpwnam(from)) || pw->pw_uid != uid))
169 from = (pw = getpwuid(uid)) ? pw->pw_name : "???";
170
171 /*
172 * There is no way to distinguish the error status of one delivery
173 * from the rest of the deliveries. So, if we failed hard on one
174 * or more deliveries, but had no failures on any of the others, we
175 * return a hard failure. If we failed temporarily on one or more
176 * deliveries, we return a temporary failure regardless of the other
177 * failures. This results in the delivery being reattempted later
178 * at the expense of repeated failures and multiple deliveries.
179 */
180 for (fd = store(from); *argv; ++argv)
181 deliver(fd, *argv);
182 exit(eval);
183 }
184
185 int
store(from)186 store(from)
187 char *from;
188 {
189 FILE *fp;
190 time_t tval;
191 int fd, eline;
192 char line[2048];
193 char tmpbuf[sizeof _PATH_LOCTMP + 1];
194
195 strcpy(tmpbuf, _PATH_LOCTMP);
196 if ((fd = mkstemp(tmpbuf)) == -1 || (fp = fdopen(fd, "w+")) == NULL) {
197 e_to_sys(errno);
198 err("unable to open temporary file");
199 }
200 (void)unlink(tmpbuf);
201
202 (void)time(&tval);
203 (void)fprintf(fp, "From %s %s", from, ctime(&tval));
204
205 line[0] = '\0';
206 for (eline = 1; fgets(line, sizeof(line), stdin);) {
207 if (line[0] == '\n')
208 eline = 1;
209 else {
210 if (eline && line[0] == 'F' &&
211 !memcmp(line, "From ", 5))
212 (void)putc('>', fp);
213 eline = 0;
214 }
215 (void)fprintf(fp, "%s", line);
216 if (ferror(fp)) {
217 e_to_sys(errno);
218 err("temporary file write error");
219 }
220 }
221
222 /* If message not newline terminated, need an extra. */
223 if (!strchr(line, '\n'))
224 (void)putc('\n', fp);
225 /* Output a newline; note, empty messages are allowed. */
226 (void)putc('\n', fp);
227
228 if (fflush(fp) == EOF || ferror(fp)) {
229 e_to_sys(errno);
230 err("temporary file write error");
231 }
232 return (fd);
233 }
234
235 void
deliver(fd,name)236 deliver(fd, name)
237 int fd;
238 char *name;
239 {
240 struct stat fsb, sb;
241 struct passwd *pw;
242 int mbfd, nr, nw, off;
243 char *p;
244 char biffmsg[100], buf[8*1024], path[MAXPATHLEN];
245 off_t curoff;
246
247 /*
248 * Disallow delivery to unknown names -- special mailboxes can be
249 * handled in the sendmail aliases file.
250 */
251 if (!(pw = getpwnam(name))) {
252 if (eval != EX_TEMPFAIL)
253 eval = EX_UNAVAILABLE;
254 warn("unknown name: %s", name);
255 return;
256 }
257 endpwent();
258
259 /*
260 * Keep name reasonably short to avoid buffer overruns.
261 * This isn't necessary on BSD because of the proper
262 * definition of snprintf(), but it can cause problems
263 * on other systems.
264 * Also, clear out any bogus characters.
265 */
266
267 if (strlen(name) > 40)
268 name[40] = '\0';
269 for (p = name; *p != '\0'; p++)
270 {
271 if (!isascii(*p))
272 *p &= 0x7f;
273 else if (!isprint(*p))
274 *p = '.';
275 }
276
277 (void)snprintf(path, sizeof(path), "%s/%s", _PATH_MAILDIR, name);
278
279 /*
280 * If the mailbox is linked or a symlink, fail. There's an obvious
281 * race here, that the file was replaced with a symbolic link after
282 * the lstat returned, but before the open. We attempt to detect
283 * this by comparing the original stat information and information
284 * returned by an fstat of the file descriptor returned by the open.
285 *
286 * NB: this is a symptom of a larger problem, that the mail spooling
287 * directory is writeable by the wrong users. If that directory is
288 * writeable, system security is compromised for other reasons, and
289 * it cannot be fixed here.
290 *
291 * If we created the mailbox, set the owner/group. If that fails,
292 * just return. Another process may have already opened it, so we
293 * can't unlink it. Historically, binmail set the owner/group at
294 * each mail delivery. We no longer do this, assuming that if the
295 * ownership or permissions were changed there was a reason.
296 *
297 * XXX
298 * open(2) should support flock'ing the file.
299 */
300 tryagain:
301 lockmbox(path);
302 if (lstat(path, &sb)) {
303 mbfd = open(path,
304 O_APPEND|O_CREAT|O_EXCL|O_WRONLY, S_IRUSR|S_IWUSR);
305 if (mbfd == -1) {
306 if (errno == EEXIST)
307 goto tryagain;
308 } else if (fchown(mbfd, pw->pw_uid, pw->pw_gid)) {
309 e_to_sys(errno);
310 warn("chown %u.%u: %s", pw->pw_uid, pw->pw_gid, name);
311 goto err1;
312 }
313 } else if (sb.st_nlink != 1 || !S_ISREG(sb.st_mode)) {
314 e_to_sys(errno);
315 warn("%s: irregular file", path);
316 goto err0;
317 } else if (sb.st_uid != pw->pw_uid) {
318 warn("%s: wrong ownership (%d)", path, sb.st_uid);
319 unlockmbox();
320 return;
321 } else {
322 mbfd = open(path, O_APPEND|O_WRONLY, 0);
323 if (mbfd != -1 &&
324 (fstat(mbfd, &fsb) || fsb.st_nlink != 1 ||
325 !S_ISREG(fsb.st_mode) || sb.st_dev != fsb.st_dev ||
326 sb.st_ino != fsb.st_ino || sb.st_uid != fsb.st_uid)) {
327 warn("%s: file changed after open", path);
328 goto err1;
329 }
330 }
331
332 if (mbfd == -1) {
333 e_to_sys(errno);
334 warn("%s: %s", path, strerror(errno));
335 goto err0;
336 }
337
338 /* Wait until we can get a lock on the file. */
339 if (flock(mbfd, LOCK_EX)) {
340 e_to_sys(errno);
341 warn("%s: %s", path, strerror(errno));
342 goto err1;
343 }
344
345 /* Get the starting offset of the new message for biff. */
346 curoff = lseek(mbfd, (off_t)0, SEEK_END);
347 (void)snprintf(biffmsg, sizeof(biffmsg),
348 sizeof curoff > sizeof(long) ? "%s@%qd\n" : "%s@%ld\n",
349 name, curoff);
350
351 /* Copy the message into the file. */
352 if (lseek(fd, (off_t)0, SEEK_SET) == (off_t)-1) {
353 e_to_sys(errno);
354 warn("temporary file: %s", strerror(errno));
355 goto err1;
356 }
357 if (setreuid(0, pw->pw_uid) < 0) {
358 e_to_sys(errno);
359 warn("setreuid(0, %d): %s (r=%d, e=%d)",
360 pw->pw_uid, strerror(errno), getuid(), geteuid());
361 goto err1;
362 }
363 #ifdef DEBUG
364 printf("new euid = %d\n", geteuid());
365 #endif
366 while ((nr = read(fd, buf, sizeof(buf))) > 0)
367 for (off = 0; off < nr; off += nw)
368 if ((nw = write(mbfd, buf + off, nr - off)) < 0) {
369 e_to_sys(errno);
370 warn("%s: %s", path, strerror(errno));
371 goto err3;
372 }
373 if (nr < 0) {
374 e_to_sys(errno);
375 warn("temporary file: %s", strerror(errno));
376 goto err3;
377 }
378
379 /* Flush to disk, don't wait for update. */
380 if (fsync(mbfd)) {
381 e_to_sys(errno);
382 warn("%s: %s", path, strerror(errno));
383 err3:
384 if (setreuid(0, 0) < 0) {
385 e_to_sys(errno);
386 warn("setreuid(0, 0): %s", strerror(errno));
387 }
388 #ifdef DEBUG
389 printf("reset euid = %d\n", geteuid());
390 #endif
391 err2: (void)ftruncate(mbfd, curoff);
392 err1: (void)close(mbfd);
393 err0: unlockmbox();
394 return;
395 }
396
397 /* Close and check -- NFS doesn't write until the close. */
398 if (close(mbfd)) {
399 e_to_sys(errno);
400 warn("%s: %s", path, strerror(errno));
401 unlockmbox();
402 return;
403 }
404
405 if (setreuid(0, 0) < 0) {
406 e_to_sys(errno);
407 warn("setreuid(0, 0): %s", strerror(errno));
408 }
409 #ifdef DEBUG
410 printf("reset euid = %d\n", geteuid());
411 #endif
412 unlockmbox();
413 notifybiff(biffmsg);
414 }
415
416 /*
417 * user.lock files are necessary for compatibility with other
418 * systems, e.g., when the mail spool file is NFS exported.
419 * Alas, mailbox locking is more than just a local matter.
420 * EPA 11/94.
421 */
422
423 char lockname[MAXPATHLEN];
424 int locked = 0;
425
lockmbox(path)426 lockmbox(path)
427 char *path;
428 {
429 int statfailed = 0;
430
431 if (locked)
432 return;
433 sprintf(lockname, "%s.lock", path);
434 for (;; sleep(5)) {
435 int fd;
436 struct stat st;
437 time_t now;
438
439 fd = open(lockname, O_WRONLY|O_EXCL|O_CREAT, 0);
440 if (fd >= 0) {
441 locked = 1;
442 close(fd);
443 return;
444 }
445 if (stat(lockname, &st) < 0) {
446 if (statfailed++ > 5)
447 return;
448 continue;
449 }
450 statfailed = 0;
451 time(&now);
452 if (now < st.st_ctime + 300)
453 continue;
454 unlink(lockname);
455 }
456 }
457
unlockmbox()458 unlockmbox()
459 {
460 if (!locked)
461 return;
462 unlink(lockname);
463 locked = 0;
464 }
465
466 void
notifybiff(msg)467 notifybiff(msg)
468 char *msg;
469 {
470 static struct sockaddr_in addr;
471 static int f = -1;
472 struct hostent *hp;
473 struct servent *sp;
474 int len;
475
476 if (!addr.sin_family) {
477 /* Be silent if biff service not available. */
478 if (!(sp = getservbyname("biff", "udp")))
479 return;
480 if (!(hp = gethostbyname("localhost"))) {
481 warn("localhost: %s", strerror(errno));
482 return;
483 }
484 addr.sin_family = hp->h_addrtype;
485 memcpy(&addr.sin_addr, hp->h_addr, hp->h_length);
486 addr.sin_port = sp->s_port;
487 }
488 if (f < 0 && (f = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
489 warn("socket: %s", strerror(errno));
490 return;
491 }
492 len = strlen(msg) + 1;
493 if (sendto(f, msg, len, 0, (struct sockaddr *)&addr, sizeof(addr))
494 != len)
495 warn("sendto biff: %s", strerror(errno));
496 }
497
498 void
usage()499 usage()
500 {
501 eval = EX_USAGE;
502 err("usage: mail.local [-f from] user ...");
503 }
504
505 #if __STDC__
506 void
err(const char * fmt,...)507 err(const char *fmt, ...)
508 #else
509 void
510 err(fmt, va_alist)
511 const char *fmt;
512 va_dcl
513 #endif
514 {
515 va_list ap;
516
517 #if __STDC__
518 va_start(ap, fmt);
519 #else
520 va_start(ap);
521 #endif
522 vwarn(fmt, ap);
523 va_end(ap);
524
525 exit(eval);
526 }
527
528 void
529 #if __STDC__
warn(const char * fmt,...)530 warn(const char *fmt, ...)
531 #else
532 warn(fmt, va_alist)
533 const char *fmt;
534 va_dcl
535 #endif
536 {
537 va_list ap;
538
539 #if __STDC__
540 va_start(ap, fmt);
541 #else
542 va_start(ap);
543 #endif
544 vwarn(fmt, ap);
545 va_end(ap);
546 }
547
548 void
vwarn(fmt,ap)549 vwarn(fmt, ap)
550 const char *fmt;
551 _BSD_VA_LIST_ ap;
552 {
553 /*
554 * Log the message to stderr.
555 *
556 * Don't use LOG_PERROR as an openlog() flag to do this,
557 * it's not portable enough.
558 */
559 if (eval != EX_USAGE)
560 (void)fprintf(stderr, "mail.local: ");
561 (void)vfprintf(stderr, fmt, ap);
562 (void)fprintf(stderr, "\n");
563
564 #if !defined(ultrix) && !defined(__osf__)
565 /* Log the message to syslog. */
566 vsyslog(LOG_ERR, fmt, ap);
567 #else
568 {
569 char fmtbuf[10240];
570
571 (void) sprintf(fmtbuf, fmt, ap);
572 syslog(LOG_ERR, "%s", fmtbuf);
573 }
574 #endif
575 }
576
577 /*
578 * e_to_sys --
579 * Guess which errno's are temporary. Gag me.
580 */
581 void
e_to_sys(num)582 e_to_sys(num)
583 int num;
584 {
585 /* Temporary failures override hard errors. */
586 if (eval == EX_TEMPFAIL)
587 return;
588
589 switch(num) { /* Hopefully temporary errors. */
590 #ifdef EAGAIN
591 case EAGAIN: /* Resource temporarily unavailable */
592 #endif
593 #ifdef EDQUOT
594 case EDQUOT: /* Disc quota exceeded */
595 #endif
596 #ifdef EBUSY
597 case EBUSY: /* Device busy */
598 #endif
599 #ifdef EPROCLIM
600 case EPROCLIM: /* Too many processes */
601 #endif
602 #ifdef EUSERS
603 case EUSERS: /* Too many users */
604 #endif
605 #ifdef ECONNABORTED
606 case ECONNABORTED: /* Software caused connection abort */
607 #endif
608 #ifdef ECONNREFUSED
609 case ECONNREFUSED: /* Connection refused */
610 #endif
611 #ifdef ECONNRESET
612 case ECONNRESET: /* Connection reset by peer */
613 #endif
614 #ifdef EDEADLK
615 case EDEADLK: /* Resource deadlock avoided */
616 #endif
617 #ifdef EFBIG
618 case EFBIG: /* File too large */
619 #endif
620 #ifdef EHOSTDOWN
621 case EHOSTDOWN: /* Host is down */
622 #endif
623 #ifdef EHOSTUNREACH
624 case EHOSTUNREACH: /* No route to host */
625 #endif
626 #ifdef EMFILE
627 case EMFILE: /* Too many open files */
628 #endif
629 #ifdef ENETDOWN
630 case ENETDOWN: /* Network is down */
631 #endif
632 #ifdef ENETRESET
633 case ENETRESET: /* Network dropped connection on reset */
634 #endif
635 #ifdef ENETUNREACH
636 case ENETUNREACH: /* Network is unreachable */
637 #endif
638 #ifdef ENFILE
639 case ENFILE: /* Too many open files in system */
640 #endif
641 #ifdef ENOBUFS
642 case ENOBUFS: /* No buffer space available */
643 #endif
644 #ifdef ENOMEM
645 case ENOMEM: /* Cannot allocate memory */
646 #endif
647 #ifdef ENOSPC
648 case ENOSPC: /* No space left on device */
649 #endif
650 #ifdef EROFS
651 case EROFS: /* Read-only file system */
652 #endif
653 #ifdef ESTALE
654 case ESTALE: /* Stale NFS file handle */
655 #endif
656 #ifdef ETIMEDOUT
657 case ETIMEDOUT: /* Connection timed out */
658 #endif
659 #if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN && EWOULDBLOCK != EDEADLK
660 case EWOULDBLOCK: /* Operation would block. */
661 #endif
662 eval = EX_TEMPFAIL;
663 break;
664 default:
665 eval = EX_UNAVAILABLE;
666 break;
667 }
668 }
669
670 #ifndef BSD4_4
671
672 # ifndef __osf__
673 char *
strerror(eno)674 strerror(eno)
675 int eno;
676 {
677 extern int sys_nerr;
678 extern char *sys_errlist[];
679 static char ebuf[60];
680
681 if (eno >= 0 && eno <= sys_nerr)
682 return sys_errlist[eno];
683 (void) sprintf(ebuf, "Error %d", eno);
684 return ebuf;
685 }
686 # endif
687
688 # if __STDC__
snprintf(char * buf,int bufsiz,const char * fmt,...)689 snprintf(char *buf, int bufsiz, const char *fmt, ...)
690 # else
691 snprintf(buf, bufsiz, fmt, va_alist)
692 char *buf;
693 int bufsiz;
694 const char *fmt;
695 va_dcl
696 # endif
697 {
698 va_list ap;
699
700 # if __STDC__
701 va_start(ap, fmt);
702 # else
703 va_start(ap);
704 # endif
705 vsprintf(buf, fmt, ap);
706 va_end(ap);
707 }
708
709 #endif
710
711 #ifdef ultrix
712
713 /*
714 * Copyright (c) 1987, 1993
715 * The Regents of the University of California. All rights reserved.
716 *
717 * Redistribution and use in source and binary forms, with or without
718 * modification, are permitted provided that the following conditions
719 * are met:
720 * 1. Redistributions of source code must retain the above copyright
721 * notice, this list of conditions and the following disclaimer.
722 * 2. Redistributions in binary form must reproduce the above copyright
723 * notice, this list of conditions and the following disclaimer in the
724 * documentation and/or other materials provided with the distribution.
725 * 3. All advertising materials mentioning features or use of this software
726 * must display the following acknowledgement:
727 * This product includes software developed by the University of
728 * California, Berkeley and its contributors.
729 * 4. Neither the name of the University nor the names of its contributors
730 * may be used to endorse or promote products derived from this software
731 * without specific prior written permission.
732 *
733 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
734 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
735 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
736 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
737 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
738 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
739 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
740 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
741 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
742 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
743 * SUCH DAMAGE.
744 */
745
746 #if defined(LIBC_SCCS) && !defined(lint)
747 static char sccsid[] = "@(#)mktemp.c 8.1 (Berkeley) 6/4/93";
748 #endif /* LIBC_SCCS and not lint */
749
750 #include <sys/types.h>
751 #include <sys/stat.h>
752 #include <fcntl.h>
753 #include <errno.h>
754 #include <stdio.h>
755 #include <ctype.h>
756
757 static int _gettemp();
758
mkstemp(path)759 mkstemp(path)
760 char *path;
761 {
762 int fd;
763
764 return (_gettemp(path, &fd) ? fd : -1);
765 }
766
767 /*
768 char *
769 mktemp(path)
770 char *path;
771 {
772 return(_gettemp(path, (int *)NULL) ? path : (char *)NULL);
773 }
774 */
775
776 static
_gettemp(path,doopen)777 _gettemp(path, doopen)
778 char *path;
779 register int *doopen;
780 {
781 extern int errno;
782 register char *start, *trv;
783 struct stat sbuf;
784 u_int pid;
785
786 pid = getpid();
787 for (trv = path; *trv; ++trv); /* extra X's get set to 0's */
788 while (*--trv == 'X') {
789 *trv = (pid % 10) + '0';
790 pid /= 10;
791 }
792
793 /*
794 * check the target directory; if you have six X's and it
795 * doesn't exist this runs for a *very* long time.
796 */
797 for (start = trv + 1;; --trv) {
798 if (trv <= path)
799 break;
800 if (*trv == '/') {
801 *trv = '\0';
802 if (stat(path, &sbuf))
803 return(0);
804 if (!S_ISDIR(sbuf.st_mode)) {
805 errno = ENOTDIR;
806 return(0);
807 }
808 *trv = '/';
809 break;
810 }
811 }
812
813 for (;;) {
814 if (doopen) {
815 if ((*doopen =
816 open(path, O_CREAT|O_EXCL|O_RDWR, 0600)) >= 0)
817 return(1);
818 if (errno != EEXIST)
819 return(0);
820 }
821 else if (stat(path, &sbuf))
822 return(errno == ENOENT ? 1 : 0);
823
824 /* tricky little algorithm for backward compatibility */
825 for (trv = start;;) {
826 if (!*trv)
827 return(0);
828 if (*trv == 'z')
829 *trv++ = 'a';
830 else {
831 if (isdigit(*trv))
832 *trv = 'a';
833 else
834 ++*trv;
835 break;
836 }
837 }
838 }
839 /*NOTREACHED*/
840 }
841
842 #endif
843