popen.c

   1 /*@ S-nail - a mail user agent derived from Berkeley Mail.
   2  *@ Handling of pipes, child processes, temporary files, file enwrapping
   3  *
   4  * Copyright (c) 2000-2004 Gunnar Ritter, Freiburg i. Br., Germany.
   5  * Copyright (c) 2012 - 2014 Steffen "Daode" Nurpmeso <sdaoden@users.sf.net>.
   6  */
   7 /*
   8  * Copyright (c) 1980, 1993
   9  *      The Regents of the University of California.  All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. All advertising materials mentioning features or use of this software
  20  *    must display the following acknowledgement:
  21  *      This product includes software developed by the University of
  22  *      California, Berkeley and its contributors.
  23  * 4. Neither the name of the University nor the names of its contributors
  24  *    may be used to endorse or promote products derived from this software
  25  *    without specific prior written permission.
  26  *
  27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  37  * SUCH DAMAGE.
  38  */
  39
  40 #ifndef HAVE_AMALGAMATION
  41 # include "nail.h"
  42 #endif
  43
  44 #include <sys/wait.h>
  45
  46 #include <fcntl.h>
  47
  48 #define READ    0
  49 #define WRITE   1
  50
  51 struct fp {
  52         FILE *fp;
  53         struct fp *link;
  54         char *realfile;
  55         long offset;
  56         int omode;
  57         int pipe;
  58         int pid;
  59         enum {
  60                 FP_UNCOMPRESSED = 00,
  61                 FP_GZIPPED      = 01,
  62                 FP_BZIP2ED      = 02,
  63                 FP_IMAP         = 03,
  64                 FP_MAILDIR      = 04,
  65                 FP_MASK         = 0177,
  66                 FP_READONLY     = 0200
  67         } compressed;
  68 };
  69 static struct fp *fp_head;
  70
  71 struct child {
  72         int pid;
  73         char done;
  74         char free;
  75         int status;
  76         struct child *link;
  77 };
  78 static struct child     *_popen_child;
  79
  80 static int scan_mode(const char *mode, int *omode);
  81 static void register_file(FILE *fp, int omode, int ispipe, int pid,
  82                 int compressed, const char *realfile, long offset);
  83 static enum okay compress(struct fp *fpp);
  84 static int decompress(int compression, int infd, int outfd);
  85 static enum okay unregister_file(FILE *fp);
  86 static int file_pid(FILE *fp);
  87 static int wait_command(int pid);
  88 static struct child *findchild(int pid);
  89 static void delchild(struct child *cp);
  90
  91 static int
  92 scan_mode(const char *mode, int *omode)
  93 {
  94
  95         if (!strcmp(mode, "r")) {
  96                 *omode = O_RDONLY;
  97         } else if (!strcmp(mode, "w")) {
  98                 *omode = O_WRONLY | O_CREAT | O_TRUNC;
  99         } else if (!strcmp(mode, "wx")) {
 100                 *omode = O_WRONLY | O_CREAT | O_EXCL;
 101         } else if (!strcmp(mode, "a")) {
 102                 *omode = O_WRONLY | O_APPEND | O_CREAT;
 103         } else if (!strcmp(mode, "a+")) {
 104                 *omode = O_RDWR | O_APPEND;
 105         } else if (!strcmp(mode, "r+")) {
 106                 *omode = O_RDWR;
 107         } else if (!strcmp(mode, "w+")) {
 108                 *omode = O_RDWR   | O_CREAT | O_EXCL;
 109         } else {
 110                 fprintf(stderr, tr(152,
 111                         "Internal error: bad stdio open mode %s\n"), mode);
 112                 errno = EINVAL;
 113                 *omode = 0; /* (silence CC) */
 114                 return -1;
 115         }
 116         return 0;
 117 }
 118
 119 FL FILE *
 120 safe_fopen(const char *file, const char *mode, int *omode)
 121 {
 122         int  fd;
 123
 124         if (scan_mode(mode, omode) < 0)
 125                 return NULL;
 126         if ((fd = open(file, *omode, 0666)) < 0)
 127                 return NULL;
 128         return fdopen(fd, mode);
 129 }
 130
 131 FL FILE *
 132 Fopen(const char *file, const char *mode)
 133 {
 134         FILE *fp;
 135         int omode;
 136
 137         if ((fp = safe_fopen(file, mode, &omode)) != NULL) {
 138                 (void)fcntl(fileno(fp), F_SETFD, FD_CLOEXEC);
 139                 register_file(fp, omode, 0, 0, FP_UNCOMPRESSED, NULL, 0L);
 140         }
 141         return fp;
 142 }
 143
 144 FL FILE *
 145 Fdopen(int fd, const char *mode)
 146 {
 147         FILE *fp;
 148         int omode;
 149
 150         scan_mode(mode, &omode);
 151         if ((fp = fdopen(fd, mode)) != NULL) {
 152                 (void)fcntl(fileno(fp), F_SETFD, FD_CLOEXEC);
 153                 register_file(fp, omode, 0, 0, FP_UNCOMPRESSED, NULL, 0L);
 154         }
 155         return fp;
 156 }
 157
 158 FL int
 159 Fclose(FILE *fp)
 160 {
 161         int     i = 0;
 162         if (unregister_file(fp) == OKAY)
 163                 i |= 1;
 164         if (fclose(fp) == 0)
 165                 i |= 2;
 166         return i == 3 ? 0 : EOF;
 167 }
 168
 169 FL FILE *
 170 Zopen(const char *file, const char *mode, int *compression) /* TODO MESS!
 171         * TODO maybe we shouldn't be simple and run commands but instead
 172         * TODO links against any of available zlib.h, bzlib.h, lzma.h!
 173         * TODO even libzip?  Much faster, not that much more work, and we're
 174         * TODO *so* fixed anyway!!
 175         * TODO *or*: make it all hookable via BOXEXTENSION/DECOMPRESS etc.
 176         * TODO by the user;  but not like this, Coverity went grazy about it */
 177 {
 178         int     infd;
 179         FILE    *outf;
 180         const char      *rp;
 181         int     omode;
 182         char    *tempfn;
 183         int     bits;
 184         int     _compression;
 185         long    offset;
 186         char    *extension;
 187         enum protocol   p;
 188
 189         if (scan_mode(mode, &omode) < 0)
 190                 return NULL;
 191         if (compression == NULL)
 192                 compression = &_compression;
 193         bits = R_OK | (omode == O_RDONLY ? 0 : W_OK);
 194         if (omode & O_APPEND && ((p = which_protocol(file)) == PROTO_IMAP ||
 195                         p == PROTO_MAILDIR)) {
 196                 *compression = p == PROTO_IMAP ? FP_IMAP : FP_MAILDIR;
 197                 omode = O_RDWR | O_APPEND | O_CREAT;
 198                 rp = file;
 199                 infd = -1;
 200                 goto open;
 201         }
 202         if ((extension = strrchr(file, '.')) != NULL) {
 203                 rp = file;
 204                 if (strcmp(extension, ".gz") == 0)
 205                         goto gzip;
 206                 if (strcmp(extension, ".bz2") == 0)
 207                         goto bz2;
 208         }
 209
 210         if (access(file, F_OK) == 0) {
 211                 *compression = FP_UNCOMPRESSED;
 212                 return Fopen(file, mode);
 213         } else if (access(rp=savecat(file, ".gz"), bits) == 0) {
 214         gzip:   *compression = FP_GZIPPED;
 215         } else if (access(rp=savecat(file, ".bz2"), bits) == 0) {
 216         bz2:    *compression = FP_BZIP2ED;
 217         } else {
 218                 *compression = FP_UNCOMPRESSED;
 219                 return Fopen(file, mode);
 220         }
 221         if (access(rp, W_OK) < 0)
 222                 *compression |= FP_READONLY;
 223
 224         if ((infd = open(rp, bits & W_OK ? O_RDWR : O_RDONLY)) < 0
 225                         && ((omode&O_CREAT) == 0 || errno != ENOENT))
 226                 return NULL;
 227 open:   if ((outf = Ftemp(&tempfn, "Rz", "w+", 0600, 0)) == NULL) {
 228                 perror(tr(167, "tmpfile"));
 229                 if (infd >= 0)
 230                         close(infd);
 231                 return NULL;
 232         }
 233         unlink(tempfn);
 234         Ftfree(&tempfn);
 235
 236         if (infd >= 0 || (*compression&FP_MASK) == FP_IMAP ||
 237                         (*compression&FP_MASK) == FP_MAILDIR) {
 238                 if (decompress(*compression, infd, fileno(outf)) < 0) {
 239                         if (infd >= 0)
 240                                 close(infd);
 241                         Fclose(outf);
 242                         return NULL;
 243                 }
 244         } else {
 245                 if ((infd = creat(rp, 0666)) < 0) {
 246                         Fclose(outf);
 247                         return NULL;
 248                 }
 249         }
 250         if (infd >= 0)
 251                 close(infd);
 252         fflush(outf);
 253
 254         if (omode & O_APPEND) {
 255                 int     flags;
 256
 257                 if ((flags = fcntl(fileno(outf), F_GETFL)) < 0 ||
 258                                 fcntl(fileno(outf), F_SETFL, flags|O_APPEND)
 259                                 < 0 || (offset = ftell(outf)) < 0) {
 260                         Fclose(outf);
 261                         return NULL;
 262                 }
 263         } else {
 264                 rewind(outf);
 265                 offset = 0;
 266         }
 267
 268         register_file(outf, omode, 0, 0, *compression, rp, offset);
 269         return outf;
 270 }
 271
 272 FL FILE *
 273 Ftemp(char **fn, char const *prefix, char const *mode, int bits,
 274         int doregfile)
 275 {
 276         FILE *fp = NULL;
 277         char *cp;
 278         int fd;
 279
 280         *fn =
 281         cp = smalloc(strlen(tempdir) + 1 + sizeof("mail") + strlen(prefix) +
 282                 + 7 + 1);
 283         cp = sstpcpy(cp, tempdir);
 284         *cp++ = '/';
 285         cp = sstpcpy(cp, "mail");
 286         if (*prefix) {
 287                 *cp++ = '-';
 288                 cp = sstpcpy(cp, prefix);
 289         }
 290         sstpcpy(cp, ".XXXXXX");
 291
 292 #ifdef HAVE_MKSTEMP
 293         if ((fd = mkstemp(*fn)) < 0)
 294                 goto jtemperr;
 295         if (bits != (S_IRUSR|S_IWUSR) && fchmod(fd, bits) < 0)
 296                 goto jtemperr;
 297 #else
 298         if (mktemp(*fn) == NULL)
 299                 goto Ftemperr;
 300         if ((fd = open(*fn, O_CREAT|O_EXCL|O_RDWR, bits)) < 0)
 301                 goto jtemperr;
 302 #endif
 303
 304         if (doregfile)
 305                 fp = Fdopen(fd, mode);
 306         else {
 307                 (void)fcntl(fd, F_SETFD, FD_CLOEXEC);
 308                 fp = fdopen(fd, mode);
 309         }
 310 jleave:
 311         return fp;
 312 jtemperr:
 313         Ftfree(fn);
 314         goto jleave;
 315 }
 316
 317 FL void
 318 Ftfree(char **fn)
 319 {
 320         char *cp = *fn;
 321
 322         *fn = NULL;
 323         free(cp);
 324 }
 325
 326 FL bool_t
 327 pipe_cloexec(int fd[2])
 328 {
 329         bool_t rv = FAL0;
 330
 331         if (pipe(fd) < 0)
 332                 goto jleave;
 333         fcntl(fd[0], F_SETFD, FD_CLOEXEC);
 334         fcntl(fd[1], F_SETFD, FD_CLOEXEC);
 335         rv = TRU1;
 336 jleave:
 337         return rv;
 338 }
 339
 340 FL FILE *
 341 Popen(const char *cmd, const char *mode, const char *sh, int newfd1)
 342 {
 343         int p[2];
 344         int myside, hisside, fd0, fd1;
 345         int pid;
 346         char mod[2] = { '0', '\0' };
 347         sigset_t nset;
 348         FILE *fp;
 349
 350         if (! pipe_cloexec(p))
 351                 return NULL;
 352
 353         if (*mode == 'r') {
 354                 myside = p[READ];
 355                 fd0 = -1;
 356                 hisside = fd1 = p[WRITE];
 357                 mod[0] = *mode;
 358         } else if (*mode == 'W') {
 359                 myside = p[WRITE];
 360                 hisside = fd0 = p[READ];
 361                 fd1 = newfd1;
 362                 mod[0] = 'w';
 363         } else {
 364                 myside = p[WRITE];
 365                 hisside = fd0 = p[READ];
 366                 fd1 = -1;
 367                 mod[0] = 'w';
 368         }
 369         sigemptyset(&nset);
 370         if (sh == NULL) {
 371                 pid = start_command(cmd, &nset, fd0, fd1, NULL, NULL, NULL);
 372         } else {
 373                 pid = start_command(sh, &nset, fd0, fd1, "-c", cmd, NULL);
 374         }
 375         if (pid < 0) {
 376                 close(p[READ]);
 377                 close(p[WRITE]);
 378                 return NULL;
 379         }
 380         close(hisside);
 381         if ((fp = fdopen(myside, mod)) != NULL)
 382                 register_file(fp, 0, 1, pid, FP_UNCOMPRESSED, NULL, 0L);
 383         return fp;
 384 }
 385
 386 FL bool_t
 387 Pclose(FILE *ptr, bool_t dowait)
 388 {
 389         sigset_t nset, oset;
 390         bool_t rv = FAL0;
 391         int pid;
 392
 393         pid = file_pid(ptr);
 394         if (pid < 0)
 395                 goto jleave;
 396         unregister_file(ptr);
 397         fclose(ptr);
 398         if (dowait) {
 399                 sigemptyset(&nset);
 400                 sigaddset(&nset, SIGINT);
 401                 sigaddset(&nset, SIGHUP);
 402                 sigprocmask(SIG_BLOCK, &nset, &oset);
 403                 rv = wait_child(pid, NULL);
 404                 sigprocmask(SIG_SETMASK, &oset, (sigset_t*)NULL);
 405         } else {
 406                 free_child(pid);
 407                 rv = TRU1;
 408         }
 409 jleave:
 410         return rv;
 411 }
 412
 413 FL void
 414 close_all_files(void)
 415 {
 416         while (fp_head)
 417                 if (fp_head->pipe)
 418                         Pclose(fp_head->fp, TRU1);
 419                 else
 420                         Fclose(fp_head->fp);
 421 }
 422
 423 static void
 424 register_file(FILE *fp, int omode, int ispipe, int pid, int compressed,
 425                 const char *realfile, long offset)
 426 {
 427         struct fp *fpp;
 428
 429         fpp = (struct fp*)smalloc(sizeof *fpp);
 430         fpp->fp = fp;
 431         fpp->omode = omode;
 432         fpp->pipe = ispipe;
 433         fpp->pid = pid;
 434         fpp->link = fp_head;
 435         fpp->compressed = compressed;
 436         fpp->realfile = realfile ? sstrdup(realfile) : NULL;
 437         fpp->offset = offset;
 438         fp_head = fpp;
 439 }
 440
 441 static enum okay
 442 compress(struct fp *fpp)
 443 {
 444         int     outfd;
 445         char const *command[2];
 446         enum okay       ok;
 447
 448         if (fpp->omode == O_RDONLY)
 449                 return OKAY;
 450         fflush(fpp->fp);
 451         clearerr(fpp->fp);
 452         if (fseek(fpp->fp, fpp->offset, SEEK_SET) < 0)
 453                 return STOP;
 454 #ifdef HAVE_IMAP
 455         if ((fpp->compressed&FP_MASK) == FP_IMAP) {
 456                 return imap_append(fpp->realfile, fpp->fp);
 457         }
 458 #endif
 459         if ((fpp->compressed&FP_MASK) == FP_MAILDIR) {
 460                 return maildir_append(fpp->realfile, fpp->fp);
 461         }
 462         if ((outfd = open(fpp->realfile,
 463                         (fpp->omode|O_CREAT)&~O_EXCL,
 464                         0666)) < 0) {
 465                 fprintf(stderr, "Fatal: cannot create ");
 466                 perror(fpp->realfile);
 467                 return STOP;
 468         }
 469         if ((fpp->omode & O_APPEND) == 0)
 470                 ftruncate(outfd, 0);
 471         switch (fpp->compressed & FP_MASK) {
 472         case FP_GZIPPED:
 473                 command[0] = "gzip"; command[1] = "-c"; break;
 474         case FP_BZIP2ED:
 475                 command[0] = "bzip2"; command[1] = "-c"; break;
 476         default:
 477                 command[0] = "cat"; command[1] = NULL; break;
 478         }
 479         if (run_command(command[0], 0, fileno(fpp->fp), outfd,
 480                                 command[1], NULL, NULL) < 0)
 481                 ok = STOP;
 482         else
 483                 ok = OKAY;
 484         close(outfd);
 485         return ok;
 486 }
 487
 488 static int
 489 decompress(int compression, int infd, int outfd)
 490 {
 491         char const *command[2];
 492
 493         /*
 494          * Note that it is not possible to handle 'pack' or 'compress'
 495          * formats because appending data does not work with them.
 496          */
 497         switch (compression & FP_MASK) {
 498         case FP_GZIPPED:        command[0] = "gzip"; command[1] = "-cd"; break;
 499         case FP_BZIP2ED:        command[0] = "bzip2"; command[1] = "-cd"; break;
 500         case FP_IMAP:           return 0;
 501         case FP_MAILDIR:        return 0;
 502         default:                command[0] = "cat"; command[1] = NULL;
 503         }
 504         return run_command(command[0], 0, infd, outfd, command[1], NULL, NULL);
 505 }
 506
 507 static enum okay
 508 unregister_file(FILE *fp)
 509 {
 510         struct fp **pp, *p;
 511         enum okay       ok = OKAY;
 512
 513         for (pp = &fp_head; (p = *pp) != (struct fp *)NULL; pp = &p->link)
 514                 if (p->fp == fp) {
 515                         if ((p->compressed&FP_MASK) != FP_UNCOMPRESSED)
 516                                 ok = compress(p);
 517                         *pp = p->link;
 518                         free(p);
 519                         return ok;
 520                 }
 521         panic(tr(153, "Invalid file pointer"));
 522         /*NOTREACHED*/
 523         return STOP;
 524 }
 525
 526 static int
 527 file_pid(FILE *fp)
 528 {
 529         struct fp *p;
 530
 531         for (p = fp_head; p; p = p->link)
 532                 if (p->fp == fp)
 533                         return (p->pid);
 534         return -1;
 535 }
 536
 537 /*
 538  * Run a command without a shell, with optional arguments and splicing
 539  * of stdin and stdout.  The command name can be a sequence of words.
 540  * Signals must be handled by the caller.
 541  * "Mask" contains the signals to ignore in the new process.
 542  * SIGINT is enabled unless it's in the mask.
 543  */
 544 /*VARARGS4*/
 545 FL int
 546 run_command(char const *cmd, sigset_t *mask, int infd, int outfd,
 547                 char const *a0, char const *a1, char const *a2)
 548 {
 549         int pid;
 550
 551         if ((pid = start_command(cmd, mask, infd, outfd, a0, a1, a2)) < 0)
 552                 return -1;
 553         return wait_command(pid);
 554 }
 555
 556 /*VARARGS4*/
 557 FL int
 558 start_command(const char *cmd, sigset_t *mask, int infd, int outfd,
 559                 const char *a0, const char *a1, const char *a2)
 560 {
 561         int pid;
 562
 563         if ((pid = fork()) < 0) {
 564                 perror("fork");
 565                 return -1;
 566         }
 567         if (pid == 0) {
 568                 char *argv[100];
 569                 int i = getrawlist(cmd, strlen(cmd),
 570                                 argv, sizeof argv / sizeof *argv, 0);
 571
 572                 if ((argv[i++] = UNCONST(a0)) != NULL &&
 573                     (argv[i++] = UNCONST(a1)) != NULL &&
 574                     (argv[i++] = UNCONST(a2)) != NULL)
 575                         argv[i] = NULL;
 576                 prepare_child(mask, infd, outfd);
 577                 execvp(argv[0], argv);
 578                 perror(argv[0]);
 579                 _exit(1);
 580         }
 581         return pid;
 582 }
 583
 584 FL void
 585 prepare_child(sigset_t *nset, int infd, int outfd)
 586 {
 587         int i;
 588         sigset_t fset;
 589
 590         /* All file descriptors other than 0, 1, and 2 are supposed to be
 591          * close-on-exec */
 592         if (infd >= 0)
 593                 dup2(infd, 0);
 594         if (outfd >= 0)
 595                 dup2(outfd, 1);
 596
 597         if (nset) {
 598                 for (i = 1; i < NSIG; i++)
 599                         if (sigismember(nset, i))
 600                                 safe_signal(i, SIG_IGN);
 601                 if (!sigismember(nset, SIGINT))
 602                         safe_signal(SIGINT, SIG_DFL);
 603         }
 604
 605         sigemptyset(&fset);
 606         sigprocmask(SIG_SETMASK, &fset, NULL);
 607 }
 608
 609 static int
 610 wait_command(int pid)
 611 {
 612         int rv = 0;
 613
 614         if (!wait_child(pid, NULL)) {
 615                 if (ok_blook(bsdcompat) || ok_blook(bsdmsgs))
 616                         fprintf(stderr, tr(154, "Fatal error in process.\n"));
 617                 rv = -1;
 618         }
 619         return rv;
 620 }
 621
 622 static struct child *
 623 findchild(int pid)
 624 {
 625         struct child **cpp;
 626
 627         for (cpp = &_popen_child; *cpp != NULL && (*cpp)->pid != pid;
 628              cpp = &(*cpp)->link)
 629                         ;
 630         if (*cpp == NULL) {
 631                 *cpp = smalloc(sizeof (struct child));
 632                 (*cpp)->pid = pid;
 633                 (*cpp)->done = (*cpp)->free = 0;
 634                 (*cpp)->link = NULL;
 635         }
 636         return *cpp;
 637 }
 638
 639 static void
 640 delchild(struct child *cp)
 641 {
 642         struct child **cpp;
 643
 644         for (cpp = &_popen_child; *cpp != cp; cpp = &(*cpp)->link)
 645                 ;
 646         *cpp = cp->link;
 647         free(cp);
 648 }
 649
 650 /*ARGSUSED*/
 651 FL void
 652 sigchild(int signo)
 653 {
 654         int pid, status;
 655         struct child *cp;
 656         UNUSED(signo);
 657
 658 jagain:
 659         while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
 660                 cp = findchild(pid);
 661                 if (cp->free)
 662                         delchild(cp);
 663                 else {
 664                         cp->done = 1;
 665                         cp->status = status;
 666                 }
 667         }
 668         if (pid == -1 && errno == EINTR)
 669                 goto jagain;
 670 }
 671
 672 /*
 673  * Mark a child as don't care.
 674  */
 675 FL void
 676 free_child(int pid)
 677 {
 678         sigset_t nset, oset;
 679         struct child *cp;
 680
 681         sigemptyset(&nset);
 682         sigaddset(&nset, SIGCHLD);
 683         sigprocmask(SIG_BLOCK, &nset, &oset);
 684
 685         cp = findchild(pid);
 686         if (cp->done)
 687                 delchild(cp);
 688         else
 689                 cp->free = 1;
 690
 691         sigprocmask(SIG_SETMASK, &oset, NULL);
 692 }
 693
 694 FL bool_t
 695 wait_child(int pid, int *wait_status)
 696 {
 697         sigset_t nset, oset;
 698         struct child *cp;
 699         int ws;
 700
 701         sigemptyset(&nset);
 702         sigaddset(&nset, SIGCHLD);
 703         sigprocmask(SIG_BLOCK, &nset, &oset);
 704
 705         cp = findchild(pid);
 706         while (!cp->done)
 707                 sigsuspend(&oset);
 708         ws = cp->status;
 709         delchild(cp);
 710
 711         sigprocmask(SIG_SETMASK, &oset, NULL);
 712
 713         if (wait_status != NULL)
 714                 *wait_status = ws;
 715         return (WIFEXITED(ws) && WEXITSTATUS(ws) == 0);
 716 }