libiberty/pex-unix.c

   1 /* Utilities to execute a program in a subprocess (possibly linked by pipes
   2    with other subprocesses), and wait for it.  Generic Unix version
   3    (also used for UWIN and VMS).
   4    Copyright (C) 1996-2020 Free Software Foundation, Inc.
   5
   6 This file is part of the libiberty library.
   7 Libiberty is free software; you can redistribute it and/or
   8 modify it under the terms of the GNU Library General Public
   9 License as published by the Free Software Foundation; either
  10 version 2 of the License, or (at your option) any later version.
  11
  12 Libiberty is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 Library General Public License for more details.
  16
  17 You should have received a copy of the GNU Library General Public
  18 License along with libiberty; see the file COPYING.LIB.  If not,
  19 write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
  20 Boston, MA 02110-1301, USA.  */
  21
  22 #include "config.h"
  23 #include "libiberty.h"
  24 #include "pex-common.h"
  25 #include "environ.h"
  26
  27 #include <stdio.h>
  28 #include <signal.h>
  29 #include <errno.h>
  30 #ifdef NEED_DECLARATION_ERRNO
  31 extern int errno;
  32 #endif
  33 #ifdef HAVE_STDLIB_H
  34 #include <stdlib.h>
  35 #endif
  36 #ifdef HAVE_STRING_H
  37 #include <string.h>
  38 #endif
  39 #ifdef HAVE_UNISTD_H
  40 #include <unistd.h>
  41 #endif
  42
  43 #include <sys/types.h>
  44
  45 #ifdef HAVE_FCNTL_H
  46 #include <fcntl.h>
  47 #endif
  48 #ifdef HAVE_SYS_WAIT_H
  49 #include <sys/wait.h>
  50 #endif
  51 #ifdef HAVE_GETRUSAGE
  52 #include <sys/time.h>
  53 #include <sys/resource.h>
  54 #endif
  55 #ifdef HAVE_SYS_STAT_H
  56 #include <sys/stat.h>
  57 #endif
  58 #ifdef HAVE_PROCESS_H
  59 #include <process.h>
  60 #endif
  61
  62 #ifdef vfork /* Autoconf may define this to fork for us. */
  63 # define VFORK_STRING "fork"
  64 #else
  65 # define VFORK_STRING "vfork"
  66 #endif
  67 #ifdef HAVE_VFORK_H
  68 #include <vfork.h>
  69 #endif
  70 #if defined(VMS) && defined (__LONG_POINTERS)
  71 #ifndef __CHAR_PTR32
  72 typedef char * __char_ptr32
  73 __attribute__ ((mode (SI)));
  74 #endif
  75
  76 typedef __char_ptr32 *__char_ptr_char_ptr32
  77 __attribute__ ((mode (SI)));
  78
  79 /* Return a 32 bit pointer to an array of 32 bit pointers
  80    given a 64 bit pointer to an array of 64 bit pointers.  */
  81
  82 static __char_ptr_char_ptr32
  83 to_ptr32 (char **ptr64)
  84 {
  85   int argc;
  86   __char_ptr_char_ptr32 short_argv;
  87
  88   /* Count number of arguments.  */
  89   for (argc = 0; ptr64[argc] != NULL; argc++)
  90     ;
  91
  92   /* Reallocate argv with 32 bit pointers.  */
  93   short_argv = (__char_ptr_char_ptr32) decc$malloc
  94     (sizeof (__char_ptr32) * (argc + 1));
  95
  96   for (argc = 0; ptr64[argc] != NULL; argc++)
  97     short_argv[argc] = (__char_ptr32) decc$strdup (ptr64[argc]);
  98
  99   short_argv[argc] = (__char_ptr32) 0;
 100   return short_argv;
 101
 102 }
 103 #else
 104 #define to_ptr32(argv) argv
 105 #endif
 106
 107 /* File mode to use for private and world-readable files.  */
 108
 109 #if defined (S_IRUSR) && defined (S_IWUSR) && defined (S_IRGRP) && defined (S_IWGRP) && defined (S_IROTH) && defined (S_IWOTH)
 110 #define PUBLIC_MODE  \
 111     (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH)
 112 #else
 113 #define PUBLIC_MODE 0666
 114 #endif
 115
 116 /* Get the exit status of a particular process, and optionally get the
 117    time that it took.  This is simple if we have wait4, slightly
 118    harder if we have waitpid, and is a pain if we only have wait.  */
 119
 120 static pid_t pex_wait (struct pex_obj *, pid_t, int *, struct pex_time *);
 121
 122 #ifdef HAVE_WAIT4
 123
 124 static pid_t
 125 pex_wait (struct pex_obj *obj ATTRIBUTE_UNUSED, pid_t pid, int *status,
 126           struct pex_time *time)
 127 {
 128   pid_t ret;
 129   struct rusage r;
 130
 131 #ifdef HAVE_WAITPID
 132   if (time == NULL)
 133     return waitpid (pid, status, 0);
 134 #endif
 135
 136   ret = wait4 (pid, status, 0, &r);
 137
 138   if (time != NULL)
 139     {
 140       time->user_seconds = r.ru_utime.tv_sec;
 141       time->user_microseconds= r.ru_utime.tv_usec;
 142       time->system_seconds = r.ru_stime.tv_sec;
 143       time->system_microseconds= r.ru_stime.tv_usec;
 144     }
 145
 146   return ret;
 147 }
 148
 149 #else /* ! defined (HAVE_WAIT4) */
 150
 151 #ifdef HAVE_WAITPID
 152
 153 #ifndef HAVE_GETRUSAGE
 154
 155 static pid_t
 156 pex_wait (struct pex_obj *obj ATTRIBUTE_UNUSED, pid_t pid, int *status,
 157           struct pex_time *time)
 158 {
 159   if (time != NULL)
 160     memset (time, 0, sizeof (struct pex_time));
 161   return waitpid (pid, status, 0);
 162 }
 163
 164 #else /* defined (HAVE_GETRUSAGE) */
 165
 166 static pid_t
 167 pex_wait (struct pex_obj *obj ATTRIBUTE_UNUSED, pid_t pid, int *status,
 168           struct pex_time *time)
 169 {
 170   struct rusage r1, r2;
 171   pid_t ret;
 172
 173   if (time == NULL)
 174     return waitpid (pid, status, 0);
 175
 176   getrusage (RUSAGE_CHILDREN, &r1);
 177
 178   ret = waitpid (pid, status, 0);
 179   if (ret < 0)
 180     return ret;
 181
 182   getrusage (RUSAGE_CHILDREN, &r2);
 183
 184   time->user_seconds = r2.ru_utime.tv_sec - r1.ru_utime.tv_sec;
 185   time->user_microseconds = r2.ru_utime.tv_usec - r1.ru_utime.tv_usec;
 186   if (r2.ru_utime.tv_usec < r1.ru_utime.tv_usec)
 187     {
 188       --time->user_seconds;
 189       time->user_microseconds += 1000000;
 190     }
 191
 192   time->system_seconds = r2.ru_stime.tv_sec - r1.ru_stime.tv_sec;
 193   time->system_microseconds = r2.ru_stime.tv_usec - r1.ru_stime.tv_usec;
 194   if (r2.ru_stime.tv_usec < r1.ru_stime.tv_usec)
 195     {
 196       --time->system_seconds;
 197       time->system_microseconds += 1000000;
 198     }
 199
 200   return ret;
 201 }
 202
 203 #endif /* defined (HAVE_GETRUSAGE) */
 204
 205 #else /* ! defined (HAVE_WAITPID) */
 206
 207 struct status_list
 208 {
 209   struct status_list *next;
 210   pid_t pid;
 211   int status;
 212   struct pex_time time;
 213 };
 214
 215 static pid_t
 216 pex_wait (struct pex_obj *obj, pid_t pid, int *status, struct pex_time *time)
 217 {
 218   struct status_list **pp;
 219
 220   for (pp = (struct status_list **) &obj->sysdep;
 221        *pp != NULL;
 222        pp = &(*pp)->next)
 223     {
 224       if ((*pp)->pid == pid)
 225         {
 226           struct status_list *p;
 227
 228           p = *pp;
 229           *status = p->status;
 230           if (time != NULL)
 231             *time = p->time;
 232           *pp = p->next;
 233           free (p);
 234           return pid;
 235         }
 236     }
 237
 238   while (1)
 239     {
 240       pid_t cpid;
 241       struct status_list *psl;
 242       struct pex_time pt;
 243 #ifdef HAVE_GETRUSAGE
 244       struct rusage r1, r2;
 245 #endif
 246
 247       if (time != NULL)
 248         {
 249 #ifdef HAVE_GETRUSAGE
 250           getrusage (RUSAGE_CHILDREN, &r1);
 251 #else
 252           memset (&pt, 0, sizeof (struct pex_time));
 253 #endif
 254         }
 255
 256       cpid = wait (status);
 257
 258 #ifdef HAVE_GETRUSAGE
 259       if (time != NULL && cpid >= 0)
 260         {
 261           getrusage (RUSAGE_CHILDREN, &r2);
 262
 263           pt.user_seconds = r2.ru_utime.tv_sec - r1.ru_utime.tv_sec;
 264           pt.user_microseconds = r2.ru_utime.tv_usec - r1.ru_utime.tv_usec;
 265           if (pt.user_microseconds < 0)
 266             {
 267               --pt.user_seconds;
 268               pt.user_microseconds += 1000000;
 269             }
 270
 271           pt.system_seconds = r2.ru_stime.tv_sec - r1.ru_stime.tv_sec;
 272           pt.system_microseconds = r2.ru_stime.tv_usec - r1.ru_stime.tv_usec;
 273           if (pt.system_microseconds < 0)
 274             {
 275               --pt.system_seconds;
 276               pt.system_microseconds += 1000000;
 277             }
 278         }
 279 #endif
 280
 281       if (cpid < 0 || cpid == pid)
 282         {
 283           if (time != NULL)
 284             *time = pt;
 285           return cpid;
 286         }
 287
 288       psl = XNEW (struct status_list);
 289       psl->pid = cpid;
 290       psl->status = *status;
 291       if (time != NULL)
 292         psl->time = pt;
 293       psl->next = (struct status_list *) obj->sysdep;
 294       obj->sysdep = (void *) psl;
 295     }
 296 }
 297
 298 #endif /* ! defined (HAVE_WAITPID) */
 299 #endif /* ! defined (HAVE_WAIT4) */
 300
 301 static int pex_unix_open_read (struct pex_obj *, const char *, int);
 302 static int pex_unix_open_write (struct pex_obj *, const char *, int, int);
 303 static pid_t pex_unix_exec_child (struct pex_obj *, int, const char *,
 304                                  char * const *, char * const *,
 305                                  int, int, int, int,
 306                                  const char **, int *);
 307 static int pex_unix_close (struct pex_obj *, int);
 308 static int pex_unix_wait (struct pex_obj *, pid_t, int *, struct pex_time *,
 309                           int, const char **, int *);
 310 static int pex_unix_pipe (struct pex_obj *, int *, int);
 311 static FILE *pex_unix_fdopenr (struct pex_obj *, int, int);
 312 static FILE *pex_unix_fdopenw (struct pex_obj *, int, int);
 313 static void pex_unix_cleanup (struct pex_obj *);
 314
 315 /* The list of functions we pass to the common routines.  */
 316
 317 const struct pex_funcs funcs =
 318 {
 319   pex_unix_open_read,
 320   pex_unix_open_write,
 321   pex_unix_exec_child,
 322   pex_unix_close,
 323   pex_unix_wait,
 324   pex_unix_pipe,
 325   pex_unix_fdopenr,
 326   pex_unix_fdopenw,
 327   pex_unix_cleanup
 328 };
 329
 330 /* Return a newly initialized pex_obj structure.  */
 331
 332 struct pex_obj *
 333 pex_init (int flags, const char *pname, const char *tempbase)
 334 {
 335   return pex_init_common (flags, pname, tempbase, &funcs);
 336 }
 337
 338 /* Open a file for reading.  */
 339
 340 static int
 341 pex_unix_open_read (struct pex_obj *obj ATTRIBUTE_UNUSED, const char *name,
 342                     int binary ATTRIBUTE_UNUSED)
 343 {
 344   return open (name, O_RDONLY);
 345 }
 346
 347 /* Open a file for writing.  */
 348
 349 static int
 350 pex_unix_open_write (struct pex_obj *obj ATTRIBUTE_UNUSED, const char *name,
 351                      int binary ATTRIBUTE_UNUSED, int append)
 352 {
 353   /* Note that we can't use O_EXCL here because gcc may have already
 354      created the temporary file via make_temp_file.  */
 355   return open (name, O_WRONLY | O_CREAT
 356                      | (append ? O_APPEND : O_TRUNC), PUBLIC_MODE);
 357 }
 358
 359 /* Close a file.  */
 360
 361 static int
 362 pex_unix_close (struct pex_obj *obj ATTRIBUTE_UNUSED, int fd)
 363 {
 364   return close (fd);
 365 }
 366
 367 /* Execute a child.  */
 368
 369 #if defined(HAVE_SPAWNVE) && defined(HAVE_SPAWNVPE)
 370 /* Implementation of pex->exec_child using the Cygwin spawn operation.  */
 371
 372 /* Subroutine of pex_unix_exec_child.  Move OLD_FD to a new file descriptor
 373    to be stored in *PNEW_FD, save the flags in *PFLAGS, and arrange for the
 374    saved copy to be close-on-exec.  Move CHILD_FD into OLD_FD.  If CHILD_FD
 375    is -1, OLD_FD is to be closed.  Return -1 on error.  */
 376
 377 static int
 378 save_and_install_fd(int *pnew_fd, int *pflags, int old_fd, int child_fd)
 379 {
 380   int new_fd, flags;
 381
 382   flags = fcntl (old_fd, F_GETFD);
 383
 384   /* If we could not retrieve the flags, then OLD_FD was not open.  */
 385   if (flags < 0)
 386     {
 387       new_fd = -1, flags = 0;
 388       if (child_fd >= 0 && dup2 (child_fd, old_fd) < 0)
 389         return -1;
 390     }
 391   /* If we wish to close OLD_FD, just mark it CLOEXEC.  */
 392   else if (child_fd == -1)
 393     {
 394       new_fd = old_fd;
 395       if ((flags & FD_CLOEXEC) == 0 && fcntl (old_fd, F_SETFD, FD_CLOEXEC) < 0)
 396         return -1;
 397     }
 398   /* Otherwise we need to save a copy of OLD_FD before installing CHILD_FD.  */
 399   else
 400     {
 401 #ifdef F_DUPFD_CLOEXEC
 402       new_fd = fcntl (old_fd, F_DUPFD_CLOEXEC, 3);
 403       if (new_fd < 0)
 404         return -1;
 405 #else
 406       /* Prefer F_DUPFD over dup in order to avoid getting a new fd
 407          in the range 0-2, right where a new stderr fd might get put.  */
 408       new_fd = fcntl (old_fd, F_DUPFD, 3);
 409       if (new_fd < 0)
 410         return -1;
 411       if (fcntl (new_fd, F_SETFD, FD_CLOEXEC) < 0)
 412         return -1;
 413 #endif
 414       if (dup2 (child_fd, old_fd) < 0)
 415         return -1;
 416     }
 417
 418   *pflags = flags;
 419   if (pnew_fd)
 420     *pnew_fd = new_fd;
 421   else if (new_fd != old_fd)
 422     abort ();
 423
 424   return 0;
 425 }
 426
 427 /* Subroutine of pex_unix_exec_child.  Move SAVE_FD back to OLD_FD
 428    restoring FLAGS.  If SAVE_FD < 0, OLD_FD is to be closed.  */
 429
 430 static int
 431 restore_fd(int old_fd, int save_fd, int flags)
 432 {
 433   /* For SAVE_FD < 0, all we have to do is restore the
 434      "closed-ness" of the original.  */
 435   if (save_fd < 0)
 436     return close (old_fd);
 437
 438   /* For SAVE_FD == OLD_FD, all we have to do is restore the
 439      original setting of the CLOEXEC flag.  */
 440   if (save_fd == old_fd)
 441     {
 442       if (flags & FD_CLOEXEC)
 443         return 0;
 444       return fcntl (old_fd, F_SETFD, flags);
 445     }
 446
 447   /* Otherwise we have to move the descriptor back, restore the flags,
 448      and close the saved copy.  */
 449 #ifdef HAVE_DUP3
 450   if (flags == FD_CLOEXEC)
 451     {
 452       if (dup3 (save_fd, old_fd, O_CLOEXEC) < 0)
 453         return -1;
 454     }
 455   else
 456 #endif
 457     {
 458       if (dup2 (save_fd, old_fd) < 0)
 459         return -1;
 460       if (flags != 0 && fcntl (old_fd, F_SETFD, flags) < 0)
 461         return -1;
 462     }
 463   return close (save_fd);
 464 }
 465
 466 static pid_t
 467 pex_unix_exec_child (struct pex_obj *obj ATTRIBUTE_UNUSED,
 468                      int flags, const char *executable,
 469                      char * const * argv, char * const * env,
 470                      int in, int out, int errdes, int toclose,
 471                      const char **errmsg, int *err)
 472 {
 473   int fl_in = 0, fl_out = 0, fl_err = 0, fl_tc = 0;
 474   int save_in = -1, save_out = -1, save_err = -1;
 475   int max, retries;
 476   pid_t pid;
 477
 478   if (flags & PEX_STDERR_TO_STDOUT)
 479     errdes = out;
 480
 481   /* We need the three standard file descriptors to be set up as for
 482      the child before we perform the spawn.  The file descriptors for
 483      the parent need to be moved and marked for close-on-exec.  */
 484   if (in != STDIN_FILE_NO
 485       && save_and_install_fd (&save_in, &fl_in, STDIN_FILE_NO, in) < 0)
 486     goto error_dup2;
 487   if (out != STDOUT_FILE_NO
 488       && save_and_install_fd (&save_out, &fl_out, STDOUT_FILE_NO, out) < 0)
 489     goto error_dup2;
 490   if (errdes != STDERR_FILE_NO
 491       && save_and_install_fd (&save_err, &fl_err, STDERR_FILE_NO, errdes) < 0)
 492     goto error_dup2;
 493   if (toclose >= 0
 494       && save_and_install_fd (NULL, &fl_tc, toclose, -1) < 0)
 495     goto error_dup2;
 496
 497   /* Now that we've moved the file descriptors for the child into place,
 498      close the originals.  Be careful not to close any of the standard
 499      file descriptors that we just set up.  */
 500   max = -1;
 501   if (errdes >= 0)
 502     max = STDERR_FILE_NO;
 503   else if (out >= 0)
 504     max = STDOUT_FILE_NO;
 505   else if (in >= 0)
 506     max = STDIN_FILE_NO;
 507   if (in > max)
 508     close (in);
 509   if (out > max)
 510     close (out);
 511   if (errdes > max && errdes != out)
 512     close (errdes);
 513
 514   /* If we were not given an environment, use the global environment.  */
 515   if (env == NULL)
 516     env = environ;
 517
 518   /* Launch the program.  If we get EAGAIN (normally out of pid's), try
 519      again a few times with increasing backoff times.  */
 520   retries = 0;
 521   while (1)
 522     {
 523       typedef const char * const *cc_cp;
 524
 525       if (flags & PEX_SEARCH)
 526         pid = spawnvpe (_P_NOWAITO, executable, (cc_cp)argv, (cc_cp)env);
 527       else
 528         pid = spawnve (_P_NOWAITO, executable, (cc_cp)argv, (cc_cp)env);
 529
 530       if (pid > 0)
 531         break;
 532
 533       *err = errno;
 534       *errmsg = "spawn";
 535       if (errno != EAGAIN || ++retries == 4)
 536         return (pid_t) -1;
 537       sleep (1 << retries);
 538     }
 539
 540   /* Success.  Restore the parent's file descriptors that we saved above.  */
 541   if (toclose >= 0
 542       && restore_fd (toclose, toclose, fl_tc) < 0)
 543     goto error_dup2;
 544   if (in != STDIN_FILE_NO
 545       && restore_fd (STDIN_FILE_NO, save_in, fl_in) < 0)
 546     goto error_dup2;
 547   if (out != STDOUT_FILE_NO
 548       && restore_fd (STDOUT_FILE_NO, save_out, fl_out) < 0)
 549     goto error_dup2;
 550   if (errdes != STDERR_FILE_NO
 551       && restore_fd (STDERR_FILE_NO, save_err, fl_err) < 0)
 552     goto error_dup2;
 553
 554   return pid;
 555
 556  error_dup2:
 557   *err = errno;
 558   *errmsg = "dup2";
 559   return (pid_t) -1;
 560 }
 561
 562 #else
 563 /* Implementation of pex->exec_child using standard vfork + exec.  */
 564
 565 static pid_t
 566 pex_unix_exec_child (struct pex_obj *obj, int flags, const char *executable,
 567                      char * const * argv, char * const * env,
 568                      int in, int out, int errdes,
 569                      int toclose, const char **errmsg, int *err)
 570 {
 571   pid_t pid = -1;
 572   /* Tuple to communicate error from child to parent.  We can safely
 573      transfer string literal pointers as both run with identical
 574      address mappings.  */
 575   struct fn_err
 576   {
 577     const char *fn;
 578     int err;
 579   };
 580   volatile int do_pipe = 0;
 581   volatile int pipes[2]; /* [0]:reader,[1]:writer.  */
 582 #ifdef O_CLOEXEC
 583   do_pipe = 1;
 584 #endif
 585   if (do_pipe)
 586     {
 587 #ifdef HAVE_PIPE2
 588       if (pipe2 ((int *)pipes, O_CLOEXEC))
 589         do_pipe = 0;
 590 #else
 591       if (pipe ((int *)pipes))
 592         do_pipe = 0;
 593       else
 594         {
 595           if (fcntl (pipes[1], F_SETFD, FD_CLOEXEC) == -1)
 596             {
 597               close (pipes[0]);
 598               close (pipes[1]);
 599               do_pipe = 0;
 600             }
 601         }
 602 #endif
 603     }
 604
 605   /* We declare these to be volatile to avoid warnings from gcc about
 606      them being clobbered by vfork.  */
 607   volatile int sleep_interval = 1;
 608   volatile int retries;
 609
 610   /* We vfork and then set environ in the child before calling execvp.
 611      This clobbers the parent's environ so we need to restore it.
 612      It would be nice to use one of the exec* functions that takes an
 613      environment as a parameter, but that may have portability
 614      issues.  It is marked volatile so the child doesn't consider it a
 615      dead variable and therefore clobber where ever it is stored.  */
 616   char **volatile save_environ = environ;
 617
 618   for (retries = 0; retries < 4; ++retries)
 619     {
 620       pid = vfork ();
 621       if (pid >= 0)
 622         break;
 623       sleep (sleep_interval);
 624       sleep_interval *= 2;
 625     }
 626
 627   switch (pid)
 628     {
 629     case -1:
 630       if (do_pipe)
 631         {
 632           close (pipes[0]);
 633           close (pipes[1]);
 634         }
 635       *err = errno;
 636       *errmsg = VFORK_STRING;
 637       return (pid_t) -1;
 638
 639     case 0:
 640       /* Child process.  */
 641       {
 642         struct fn_err failed;
 643         failed.fn = NULL;
 644
 645         if (do_pipe)
 646           close (pipes[0]);
 647         if (!failed.fn && in != STDIN_FILE_NO)
 648           {
 649             if (dup2 (in, STDIN_FILE_NO) < 0)
 650               failed.fn = "dup2", failed.err = errno;
 651             else if (close (in) < 0)
 652               failed.fn = "close", failed.err = errno;
 653           }
 654         if (!failed.fn && out != STDOUT_FILE_NO)
 655           {
 656             if (dup2 (out, STDOUT_FILE_NO) < 0)
 657               failed.fn = "dup2", failed.err = errno;
 658             else if (close (out) < 0)
 659               failed.fn = "close", failed.err = errno;
 660           }
 661         if (!failed.fn && errdes != STDERR_FILE_NO)
 662           {
 663             if (dup2 (errdes, STDERR_FILE_NO) < 0)
 664               failed.fn = "dup2", failed.err = errno;
 665             else if (close (errdes) < 0)
 666               failed.fn = "close", failed.err = errno;
 667           }
 668         if (!failed.fn && toclose >= 0)
 669           {
 670             if (close (toclose) < 0)
 671               failed.fn = "close", failed.err = errno;
 672           }
 673         if (!failed.fn && (flags & PEX_STDERR_TO_STDOUT) != 0)
 674           {
 675             if (dup2 (STDOUT_FILE_NO, STDERR_FILE_NO) < 0)
 676               failed.fn = "dup2", failed.err = errno;
 677           }
 678         if (!failed.fn)
 679           {
 680             if (env)
 681               /* NOTE: In a standard vfork implementation this clobbers
 682                  the parent's copy of environ "too" (in reality there's
 683                  only one copy).  This is ok as we restore it below.  */
 684               environ = (char**) env;
 685             if ((flags & PEX_SEARCH) != 0)
 686               {
 687                 execvp (executable, to_ptr32 (argv));
 688                 failed.fn = "execvp", failed.err = errno;
 689               }
 690             else
 691               {
 692                 execv (executable, to_ptr32 (argv));
 693                 failed.fn = "execv", failed.err = errno;
 694               }
 695           }
 696
 697         /* Something failed, report an error.  We don't use stdio
 698            routines, because we might be here due to a vfork call.  */
 699         ssize_t retval = 0;
 700
 701         if (!do_pipe
 702             || write (pipes[1], &failed, sizeof (failed)) != sizeof (failed))
 703           {
 704             /* The parent will not see our scream above, so write to
 705                stdout.  */
 706 #define writeerr(s) (retval |= write (STDERR_FILE_NO, s, strlen (s)))
 707             writeerr (obj->pname);
 708             writeerr (": error trying to exec '");
 709             writeerr (executable);
 710             writeerr ("': ");
 711             writeerr (failed.fn);
 712             writeerr (": ");
 713             writeerr (xstrerror (failed.err));
 714             writeerr ("\n");
 715 #undef writeerr
 716           }
 717
 718         /* Exit with -2 if the error output failed, too.  */
 719         _exit (retval < 0 ? -2 : -1);
 720       }
 721       /* NOTREACHED */
 722       return (pid_t) -1;
 723
 724     default:
 725       /* Parent process.  */
 726       {
 727         /* Restore environ.  Note that the parent either doesn't run
 728            until the child execs/exits (standard vfork behaviour), or
 729            if it does run then vfork is behaving more like fork.  In
 730            either case we needn't worry about clobbering the child's
 731            copy of environ.  */
 732         environ = save_environ;
 733
 734         struct fn_err failed;
 735         failed.fn = NULL;
 736         if (do_pipe)
 737           {
 738             close (pipes[1]);
 739             ssize_t len = read (pipes[0], &failed, sizeof (failed));
 740             if (len < 0)
 741               failed.fn = NULL;
 742             close (pipes[0]);
 743           }
 744
 745         if (!failed.fn && in != STDIN_FILE_NO)
 746           if (close (in) < 0)
 747             failed.fn = "close", failed.err = errno;
 748         if (!failed.fn && out != STDOUT_FILE_NO)
 749           if (close (out) < 0)
 750             failed.fn = "close", failed.err = errno;
 751         if (!failed.fn && errdes != STDERR_FILE_NO)
 752           if (close (errdes) < 0)
 753             failed.fn = "close", failed.err = errno;
 754
 755         if (failed.fn)
 756           {
 757             *err = failed.err;
 758             *errmsg = failed.fn;
 759             return (pid_t) -1;
 760           }
 761       }
 762       return pid;
 763     }
 764 }
 765 #endif /* SPAWN */
 766
 767 /* Wait for a child process to complete.  */
 768
 769 static int
 770 pex_unix_wait (struct pex_obj *obj, pid_t pid, int *status,
 771                struct pex_time *time, int done, const char **errmsg,
 772                int *err)
 773 {
 774   /* If we are cleaning up when the caller didn't retrieve process
 775      status for some reason, encourage the process to go away.  */
 776   if (done)
 777     kill (pid, SIGTERM);
 778
 779   if (pex_wait (obj, pid, status, time) < 0)
 780     {
 781       *err = errno;
 782       *errmsg = "wait";
 783       return -1;
 784     }
 785
 786   return 0;
 787 }
 788
 789 /* Create a pipe.  */
 790
 791 static int
 792 pex_unix_pipe (struct pex_obj *obj ATTRIBUTE_UNUSED, int *p,
 793                int binary ATTRIBUTE_UNUSED)
 794 {
 795   return pipe (p);
 796 }
 797
 798 /* Get a FILE pointer to read from a file descriptor.  */
 799
 800 static FILE *
 801 pex_unix_fdopenr (struct pex_obj *obj ATTRIBUTE_UNUSED, int fd,
 802                   int binary ATTRIBUTE_UNUSED)
 803 {
 804   return fdopen (fd, "r");
 805 }
 806
 807 static FILE *
 808 pex_unix_fdopenw (struct pex_obj *obj ATTRIBUTE_UNUSED, int fd,
 809                   int binary ATTRIBUTE_UNUSED)
 810 {
 811   if (fcntl (fd, F_SETFD, FD_CLOEXEC) < 0)
 812     return NULL;
 813   return fdopen (fd, "w");
 814 }
 815
 816 static void
 817 pex_unix_cleanup (struct pex_obj *obj ATTRIBUTE_UNUSED)
 818 {
 819 #if !defined (HAVE_WAIT4) && !defined (HAVE_WAITPID)
 820   while (obj->sysdep != NULL)
 821     {
 822       struct status_list *this;
 823       struct status_list *next;
 824
 825       this = (struct status_list *) obj->sysdep;
 826       next = this->next;
 827       free (this);
 828       obj->sysdep = (void *) next;
 829     }
 830 #endif
 831 }