1 /* -*- mode: C; c-file-style: "gnu" -*- */

     2 /* dbus-spawn.c Wrapper around fork/exec

     3  * 

     4  * Copyright (C) 2002, 2003, 2004  Red Hat, Inc.

     5  * Copyright (C) 2003 CodeFactory AB

     6  * Portion Copyright © 2008 Nokia Corporation and/or its subsidiary(-ies). All rights reserved.

     7  * Licensed under the Academic Free License version 2.1

     8  * 

     9  * This program is free software; you can redistribute it and/or modify

    10  * it under the terms of the GNU General Public License as published by

    11  * the Free Software Foundation; either version 2 of the License, or

    12  * (at your option) any later version.

    13  *

    14  * This program is distributed in the hope that it will be useful,

    15  * but WITHOUT ANY WARRANTY; without even the implied warranty of

    16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    17  * GNU General Public License for more details.

    18  * 

    19  * You should have received a copy of the GNU General Public License

    20  * along with this program; if not, write to the Free Software

    21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    22  *

    23  */

    24 #include "dbus-spawn.h"

    25 #include "dbus-sysdeps.h"

    26 #include "dbus-internals.h"

    27 #include "dbus-test.h"

    28 #include "dbus-protocol.h"

    29 

    30 #include <unistd.h>

    31 #include <fcntl.h>

    32 #ifndef __SYMBIAN32__

    33 #include <signal.h>

    34 #endif

    35 #include <sys/wait.h>

    36 #include <errno.h>

    37 #include <stdlib.h>

    38 #include <spawn.h>

    39 #include <pthread.h> 

    40 /**

    41  * @addtogroup DBusInternalsUtils

    42  * @{

    43  */

    44 

    45 /*

    46  * I'm pretty sure this whole spawn file could be made simpler,

    47  * if you thought about it a bit.

    48  */

    49 

    50 /**

    51  * Enumeration for status of a read()

    52  */

    53 typedef enum

    54 {

    55   READ_STATUS_OK,    /**< Read succeeded */

    56   READ_STATUS_ERROR, /**< Some kind of error */

    57   READ_STATUS_EOF    /**< EOF returned */

    58 } ReadStatus;

    59 

    60 static ReadStatus

    61 read_ints (int        fd,

    62 	   int       *buf,

    63 	   int        n_ints_in_buf,

    64 	   int       *n_ints_read,

    65 	   DBusError *error)

    66 {

    67   size_t bytes = 0;    

    68   ReadStatus retval;

    69   

    70   _DBUS_ASSERT_ERROR_IS_CLEAR (error);

    71 

    72   retval = READ_STATUS_OK;

    73   

    74   while (TRUE)

    75     {

    76       size_t chunk;

    77       size_t to_read;

    78 

    79       to_read = sizeof (int) * n_ints_in_buf - bytes;

    80 

    81       if (to_read == 0)

    82         break;

    83 

    84     again:

    85       

    86       chunk = read (fd,

    87                     ((char*)buf) + bytes,

    88                     to_read);

    89       

    90       if (chunk < 0 && errno == EINTR)

    91         goto again;

    92           

    93       if (chunk < 0)

    94         {

    95           dbus_set_error (error,

    96 			  DBUS_ERROR_SPAWN_FAILED,

    97 			  "Failed to read from child pipe (%s)",

    98 			  _dbus_strerror (errno));

    99 

   100           retval = READ_STATUS_ERROR;

   101           break;

   102         }

   103       else if (chunk == 0)

   104         {

   105           retval = READ_STATUS_EOF;

   106           break; /* EOF */

   107         }

   108       else /* chunk > 0 */

   109 	bytes += chunk;

   110     }

   111 

   112   *n_ints_read = (int)(bytes / sizeof(int));

   113 

   114   return retval;

   115 }

   116 

   117 static ReadStatus

   118 read_pid (int        fd,

   119           pid_t     *buf,

   120           DBusError *error)

   121 {

   122   size_t bytes = 0;    

   123   ReadStatus retval;

   124   

   125   _DBUS_ASSERT_ERROR_IS_CLEAR (error);

   126 

   127   retval = READ_STATUS_OK;

   128   

   129   while (TRUE)

   130     {

   131       size_t chunk;    

   132       size_t to_read;

   133       

   134       to_read = sizeof (pid_t) - bytes;

   135 

   136       if (to_read == 0)

   137         break;

   138 

   139     again:

   140       

   141       chunk = read (fd,

   142                     ((char*)buf) + bytes,

   143                     to_read);

   144       if (chunk < 0 && errno == EINTR)

   145         goto again;

   146           

   147       if (chunk < 0)

   148         {

   149           dbus_set_error (error,

   150 			  DBUS_ERROR_SPAWN_FAILED,

   151 			  "Failed to read from child pipe (%s)",

   152 			  _dbus_strerror (errno));

   153 

   154           retval = READ_STATUS_ERROR;

   155           break;

   156         }

   157       else if (chunk == 0)

   158         {

   159           retval = READ_STATUS_EOF;

   160           break; /* EOF */

   161         }

   162       else /* chunk > 0 */

   163 	bytes += chunk;

   164     }

   165 

   166   return retval;

   167 }

   168 

   169 /* The implementation uses an intermediate child between the main process

   170  * and the grandchild. The grandchild is our spawned process. The intermediate

   171  * child is a babysitter process; it keeps track of when the grandchild

   172  * exits/crashes, and reaps the grandchild.

   173  */

   174 

   175 /* Messages from children to parents */

   176 enum

   177 {

   178   CHILD_EXITED,            /* This message is followed by the exit status int */

   179   CHILD_FORK_FAILED,       /* Followed by errno */

   180   CHILD_EXEC_FAILED,       /* Followed by errno */

   181   CHILD_PID                /* Followed by pid_t */

   182 };

   183 

   184 /**

   185  * Babysitter implementation details

   186  */

   187 struct DBusBabysitter

   188 {

   189   int refcount; /**< Reference count */

   190 

   191   char *executable; /**< executable name to use in error messages */

   192   

   193   int socket_to_babysitter; /**< Connection to the babysitter process */

   194   int error_pipe_from_child; /**< Connection to the process that does the exec() */

   195   

   196   pid_t sitter_pid;  /**< PID Of the babysitter */

   197   pid_t grandchild_pid; /**< PID of the grandchild */

   198 

   199   DBusWatchList *watches; /**< Watches */

   200 

   201   DBusWatch *error_watch; /**< Error pipe watch */

   202   DBusWatch *sitter_watch; /**< Sitter pipe watch */

   203 

   204   int errnum; /**< Error number */

   205   int status; /**< Exit status code */

   206   unsigned int have_child_status : 1; /**< True if child status has been reaped */

   207   unsigned int have_fork_errnum : 1; /**< True if we have an error code from fork() */

   208   unsigned int have_exec_errnum : 1; /**< True if we have an error code from exec() */

   209 };

   210 

   211 static DBusBabysitter*

   212 _dbus_babysitter_new (void)

   213 {

   214   DBusBabysitter *sitter;

   215 

   216   sitter = dbus_new0 (DBusBabysitter, 1);

   217   if (sitter == NULL)

   218     return NULL;

   219 

   220   sitter->refcount = 1;

   221 

   222   sitter->socket_to_babysitter = -1;

   223   sitter->error_pipe_from_child = -1;

   224   

   225   sitter->sitter_pid = -1;

   226   sitter->grandchild_pid = -1;

   227 

   228   sitter->watches = _dbus_watch_list_new ();

   229   if (sitter->watches == NULL)

   230     goto failed;

   231   

   232   return sitter;

   233 

   234  failed:

   235   _dbus_babysitter_unref (sitter);

   236   return NULL;

   237 }

   238 

   239 /**

   240  * Increment the reference count on the babysitter object.

   241  *

   242  * @param sitter the babysitter

   243  * @returns the babysitter

   244  */

   245 #ifdef __SYMBIAN32__

   246 EXPORT_C

   247 #endif

   248 DBusBabysitter *

   249 _dbus_babysitter_ref (DBusBabysitter *sitter)

   250 {

   251   _dbus_assert (sitter != NULL);

   252   _dbus_assert (sitter->refcount > 0);

   253   

   254   sitter->refcount += 1;

   255 

   256   return sitter;

   257 }

   258 

   259 /**

   260  * Decrement the reference count on the babysitter object.

   261  * When the reference count of the babysitter object reaches

   262  * zero, the babysitter is killed and the child that was being

   263  * babysat gets emancipated.

   264  *

   265  * @param sitter the babysitter

   266  */

   267 #ifdef __SYMBIAN32__

   268 EXPORT_C

   269 #endif

   270 void

   271 _dbus_babysitter_unref (DBusBabysitter *sitter)

   272 {

   273   _dbus_assert (sitter != NULL);

   274   _dbus_assert (sitter->refcount > 0);

   275   

   276   sitter->refcount -= 1;

   277   if (sitter->refcount == 0)

   278     {      

   279       if (sitter->socket_to_babysitter >= 0)

   280         {

   281           /* If we haven't forked other babysitters

   282            * since this babysitter and socket were

   283            * created then this close will cause the

   284            * babysitter to wake up from poll with

   285            * a hangup and then the babysitter will

   286            * quit itself.

   287            */

   288           _dbus_close_socket (sitter->socket_to_babysitter, NULL);

   289           sitter->socket_to_babysitter = -1;

   290         }

   291 

   292       if (sitter->error_pipe_from_child >= 0)

   293         {

   294           _dbus_close_socket (sitter->error_pipe_from_child, NULL);

   295           sitter->error_pipe_from_child = -1;

   296         }

   297 

   298       if (sitter->sitter_pid > 0)

   299         {

   300           int status;

   301           int ret;

   302 

   303           /* It's possible the babysitter died on its own above 

   304            * from the close, or was killed randomly

   305            * by some other process, so first try to reap it

   306            */

   307           ret = waitpid (sitter->sitter_pid, &status, WNOHANG);

   308 

   309           /* If we couldn't reap the child then kill it, and

   310            * try again

   311            */

   312 #ifndef __SYMBIAN32__           

   313           if (ret == 0)          

   314             kill (sitter->sitter_pid, SIGKILL);

   315 #endif          

   316 

   317         again:

   318           if (ret == 0)

   319             ret = waitpid (sitter->sitter_pid, &status, 0);

   320 

   321           if (ret < 0)

   322             {

   323               if (errno == EINTR)

   324                 goto again;

   325               else if (errno == ECHILD)

   326                 _dbus_warn ("Babysitter process not available to be reaped; should not happen\n");

   327               else

   328                 _dbus_warn ("Unexpected error %d in waitpid() for babysitter: %s\n",

   329                             errno, _dbus_strerror (errno));

   330             }

   331           else

   332             {

   333               _dbus_verbose ("Reaped %ld, waiting for babysitter %ld\n",

   334                              (long) ret, (long) sitter->sitter_pid);

   335               

   336               if (WIFEXITED (sitter->status))

   337                 _dbus_verbose ("Babysitter exited with status %d\n",

   338                                WEXITSTATUS (sitter->status));

   339               else if (WIFSIGNALED (sitter->status))

   340                 _dbus_verbose ("Babysitter received signal %d\n",

   341                                WTERMSIG (sitter->status));

   342               else

   343                 _dbus_verbose ("Babysitter exited abnormally\n");

   344             }

   345 

   346           sitter->sitter_pid = -1;

   347         }

   348       

   349       if (sitter->error_watch)

   350         {

   351           _dbus_watch_invalidate (sitter->error_watch);

   352           _dbus_watch_unref (sitter->error_watch);

   353           sitter->error_watch = NULL;

   354         }

   355 

   356       if (sitter->sitter_watch)

   357         {

   358           _dbus_watch_invalidate (sitter->sitter_watch);

   359           _dbus_watch_unref (sitter->sitter_watch);

   360           sitter->sitter_watch = NULL;

   361         }

   362       

   363       if (sitter->watches)

   364         _dbus_watch_list_free (sitter->watches);

   365 

   366       dbus_free (sitter->executable);

   367       

   368       dbus_free (sitter);

   369     }

   370 }

   371 

   372 static ReadStatus

   373 read_data (DBusBabysitter *sitter,

   374            int             fd)

   375 {

   376   int what;

   377   int got;

   378   DBusError error;

   379   ReadStatus r;

   380   

   381   dbus_error_init (&error);

   382   

   383   r = read_ints (fd, &what, 1, &got, &error);

   384 

   385   switch (r)

   386     {

   387     case READ_STATUS_ERROR:

   388       _dbus_warn ("Failed to read data from fd %d: %s\n", fd, error.message);

   389       dbus_error_free (&error);

   390       return r;

   391 

   392     case READ_STATUS_EOF:

   393       return r;

   394 

   395     case READ_STATUS_OK:

   396       break;

   397     }

   398   

   399   if (got == 1)

   400     {

   401       switch (what)

   402         {

   403         case CHILD_EXITED:

   404         case CHILD_FORK_FAILED:

   405         case CHILD_EXEC_FAILED:

   406           {

   407             int arg;

   408             

   409             r = read_ints (fd, &arg, 1, &got, &error);

   410 

   411             switch (r)

   412               {

   413               case READ_STATUS_ERROR:

   414                 _dbus_warn ("Failed to read arg from fd %d: %s\n", fd, error.message);

   415                 dbus_error_free (&error);

   416                 return r;

   417               case READ_STATUS_EOF:

   418                 return r;

   419               case READ_STATUS_OK:

   420                 break;

   421               }

   422             

   423             if (got == 1)

   424               {

   425                 if (what == CHILD_EXITED)

   426                   {

   427                     sitter->have_child_status = TRUE;

   428                     sitter->status = arg;

   429                     _dbus_verbose ("recorded child status exited = %d signaled = %d exitstatus = %d termsig = %d\n",

   430                                    WIFEXITED (sitter->status), WIFSIGNALED (sitter->status),

   431                                    WEXITSTATUS (sitter->status), WTERMSIG (sitter->status));

   432                   }

   433                 else if (what == CHILD_FORK_FAILED)

   434                   {

   435                     sitter->have_fork_errnum = TRUE;

   436                     sitter->errnum = arg;

   437                     _dbus_verbose ("recorded fork errnum %d\n", sitter->errnum);

   438                   }

   439                 else if (what == CHILD_EXEC_FAILED)

   440                   {

   441                     sitter->have_exec_errnum = TRUE;

   442                     sitter->errnum = arg;

   443                     _dbus_verbose ("recorded exec errnum %d\n", sitter->errnum);

   444                   }

   445               }

   446           }

   447           break;

   448         case CHILD_PID:

   449           {

   450             pid_t pid = -1;

   451 

   452             r = read_pid (fd, &pid, &error);

   453             

   454             switch (r)

   455               {

   456               case READ_STATUS_ERROR:

   457                 _dbus_warn ("Failed to read PID from fd %d: %s\n", fd, error.message);

   458                 dbus_error_free (&error);

   459                 return r;

   460               case READ_STATUS_EOF:

   461                 return r;

   462               case READ_STATUS_OK:

   463                 break;

   464               }

   465             

   466             sitter->grandchild_pid = pid;

   467             

   468             _dbus_verbose ("recorded grandchild pid %d\n", sitter->grandchild_pid);

   469           }

   470           break;

   471         default:

   472           _dbus_warn ("Unknown message received from babysitter process\n");

   473           break;

   474         }

   475     }

   476 

   477   return r;

   478 }

   479 

   480 static void

   481 close_socket_to_babysitter (DBusBabysitter *sitter)

   482 {

   483   _dbus_verbose ("Closing babysitter\n");

   484   _dbus_close_socket (sitter->socket_to_babysitter, NULL);

   485   sitter->socket_to_babysitter = -1;

   486 }

   487 

   488 static void

   489 close_error_pipe_from_child (DBusBabysitter *sitter)

   490 {

   491   _dbus_verbose ("Closing child error\n");

   492   _dbus_close_socket (sitter->error_pipe_from_child, NULL);

   493   sitter->error_pipe_from_child = -1;

   494 }

   495 

   496 static void

   497 handle_babysitter_socket (DBusBabysitter *sitter,

   498                           int             revents)

   499 {

   500   /* Even if we have POLLHUP, we want to keep reading

   501    * data until POLLIN goes away; so this function only

   502    * looks at HUP/ERR if no IN is set.

   503    */

   504   if (revents & _DBUS_POLLIN)

   505     {

   506       _dbus_verbose ("Reading data from babysitter\n");

   507       if (read_data (sitter, sitter->socket_to_babysitter) != READ_STATUS_OK)

   508         close_socket_to_babysitter (sitter);

   509     }

   510   else if (revents & (_DBUS_POLLERR | _DBUS_POLLHUP))

   511     {

   512       close_socket_to_babysitter (sitter);

   513     }

   514 }

   515 

   516 static void

   517 handle_error_pipe (DBusBabysitter *sitter,

   518                    int             revents)

   519 {

   520   if (revents & _DBUS_POLLIN)

   521     {

   522       _dbus_verbose ("Reading data from child error\n");

   523       if (read_data (sitter, sitter->error_pipe_from_child) != READ_STATUS_OK)

   524         close_error_pipe_from_child (sitter);

   525     }

   526   else if (revents & (_DBUS_POLLERR | _DBUS_POLLHUP))

   527     {

   528       close_error_pipe_from_child (sitter);

   529     }

   530 }

   531 

   532 /* returns whether there were any poll events handled */

   533 static dbus_bool_t

   534 babysitter_iteration (DBusBabysitter *sitter,

   535                       dbus_bool_t     block)

   536 {

   537   DBusPollFD fds[2];

   538   int i;

   539   dbus_bool_t descriptors_ready;

   540 

   541   descriptors_ready = FALSE;

   542   

   543   i = 0;

   544 

   545   if (sitter->error_pipe_from_child >= 0)

   546     {

   547       fds[i].fd = sitter->error_pipe_from_child;

   548       fds[i].events = _DBUS_POLLIN;

   549       fds[i].revents = 0;

   550       ++i;

   551     }

   552   

   553   if (sitter->socket_to_babysitter >= 0)

   554     {

   555       fds[i].fd = sitter->socket_to_babysitter;

   556       fds[i].events = _DBUS_POLLIN;

   557       fds[i].revents = 0;

   558       ++i;

   559     }

   560 

   561   if (i > 0)

   562     {

   563       int ret;

   564 

   565       ret = _dbus_poll (fds, i, 0);

   566       if (ret == 0 && block)

   567         ret = _dbus_poll (fds, i, -1);

   568       

   569       if (ret > 0)

   570         {

   571           descriptors_ready = TRUE;

   572           

   573           while (i > 0)

   574             {

   575               --i;

   576               if (fds[i].fd == sitter->error_pipe_from_child)

   577                 handle_error_pipe (sitter, fds[i].revents);

   578               else if (fds[i].fd == sitter->socket_to_babysitter)

   579                 handle_babysitter_socket (sitter, fds[i].revents);

   580             }

   581         }

   582     }

   583 

   584   return descriptors_ready;

   585 }

   586 

   587 /**

   588  * Macro returns #TRUE if the babysitter still has live sockets open to the

   589  * babysitter child or the grandchild.

   590  */

   591 #define LIVE_CHILDREN(sitter) ((sitter)->socket_to_babysitter >= 0 || (sitter)->error_pipe_from_child >= 0)

   592 

   593 /**

   594  * Blocks until the babysitter process gives us the PID of the spawned grandchild,

   595  * then kills the spawned grandchild.

   596  *

   597  * @param sitter the babysitter object

   598  */

   599 #ifdef __SYMBIAN32__

   600 EXPORT_C

   601 #endif

   602 void

   603 _dbus_babysitter_kill_child (DBusBabysitter *sitter)

   604 {

   605   /* be sure we have the PID of the child */

   606   while (LIVE_CHILDREN (sitter) &&

   607          sitter->grandchild_pid == -1)

   608     babysitter_iteration (sitter, TRUE);

   609 

   610   _dbus_verbose ("Got child PID %ld for killing\n",

   611                  (long) sitter->grandchild_pid);

   612   

   613   if (sitter->grandchild_pid == -1)

   614     return; /* child is already dead, or we're so hosed we'll never recover */

   615 #ifndef __SYMBIAN32__

   616   kill (sitter->grandchild_pid, SIGKILL);

   617 #endif  

   618 }

   619 

   620 /**

   621  * Checks whether the child has exited, without blocking.

   622  *

   623  * @param sitter the babysitter

   624  */

   625 #ifdef __SYMBIAN32__

   626 EXPORT_C

   627 #endif

   628 dbus_bool_t

   629 _dbus_babysitter_get_child_exited (DBusBabysitter *sitter)

   630 {

   631 

   632   /* Be sure we're up-to-date */

   633   while (LIVE_CHILDREN (sitter) &&

   634          babysitter_iteration (sitter, FALSE))

   635     ;

   636 

   637   /* We will have exited the babysitter when the child has exited */

   638   return sitter->socket_to_babysitter < 0;

   639 }

   640 

   641 /**

   642  * Sets the #DBusError with an explanation of why the spawned

   643  * child process exited (on a signal, or whatever). If

   644  * the child process has not exited, does nothing (error

   645  * will remain unset).

   646  *

   647  * @param sitter the babysitter

   648  * @param error an error to fill in

   649  */

   650 #ifdef __SYMBIAN32__

   651 EXPORT_C

   652 #endif

   653 void

   654 _dbus_babysitter_set_child_exit_error (DBusBabysitter *sitter,

   655                                        DBusError      *error)

   656 {

   657   if (!_dbus_babysitter_get_child_exited (sitter))

   658     return;

   659 

   660   /* Note that if exec fails, we will also get a child status

   661    * from the babysitter saying the child exited,

   662    * so we need to give priority to the exec error

   663    */

   664   if (sitter->have_exec_errnum)

   665     {

   666       dbus_set_error (error, DBUS_ERROR_SPAWN_EXEC_FAILED,

   667                       "Failed to execute program %s: %s",

   668                       sitter->executable, _dbus_strerror (sitter->errnum));

   669     }

   670   else if (sitter->have_fork_errnum)

   671     {

   672       dbus_set_error (error, DBUS_ERROR_NO_MEMORY,

   673                       "Failed to fork a new process %s: %s",

   674                       sitter->executable, _dbus_strerror (sitter->errnum));

   675     }

   676   else if (sitter->have_child_status)

   677     {

   678       if (WIFEXITED (sitter->status))

   679         dbus_set_error (error, DBUS_ERROR_SPAWN_CHILD_EXITED,

   680                         "Process %s exited with status %d",

   681                         sitter->executable, WEXITSTATUS (sitter->status));

   682       else if (WIFSIGNALED (sitter->status))

   683         dbus_set_error (error, DBUS_ERROR_SPAWN_CHILD_SIGNALED,

   684                         "Process %s received signal %d",

   685                         sitter->executable, WTERMSIG (sitter->status));

   686       else

   687         dbus_set_error (error, DBUS_ERROR_FAILED,

   688                         "Process %s exited abnormally",

   689                         sitter->executable);

   690     }

   691   else

   692     {

   693       dbus_set_error (error, DBUS_ERROR_FAILED,

   694                       "Process %s exited, reason unknown",

   695                       sitter->executable);

   696     }

   697 }

   698 

   699 /**

   700  * Sets watch functions to notify us when the

   701  * babysitter object needs to read/write file descriptors.

   702  *

   703  * @param sitter the babysitter

   704  * @param add_function function to begin monitoring a new descriptor.

   705  * @param remove_function function to stop monitoring a descriptor.

   706  * @param toggled_function function to notify when the watch is enabled/disabled

   707  * @param data data to pass to add_function and remove_function.

   708  * @param free_data_function function to be called to free the data.

   709  * @returns #FALSE on failure (no memory)

   710  */

   711 #ifdef __SYMBIAN32__

   712 EXPORT_C

   713 #endif

   714 dbus_bool_t

   715 _dbus_babysitter_set_watch_functions (DBusBabysitter            *sitter,

   716                                       DBusAddWatchFunction       add_function,

   717                                       DBusRemoveWatchFunction    remove_function,

   718                                       DBusWatchToggledFunction   toggled_function,

   719                                       void                      *data,

   720                                       DBusFreeFunction           free_data_function)

   721 {

   722   return _dbus_watch_list_set_functions (sitter->watches,

   723                                          add_function,

   724                                          remove_function,

   725                                          toggled_function,

   726                                          data,

   727                                          free_data_function);

   728 }

   729 

   730 static dbus_bool_t

   731 handle_watch (DBusWatch       *watch,

   732               unsigned int     condition,

   733               void            *data)

   734 {

   735   DBusBabysitter *sitter = data;

   736   int revents;

   737   int fd;

   738   

   739   revents = 0;

   740   if (condition & DBUS_WATCH_READABLE)

   741     revents |= _DBUS_POLLIN;

   742   if (condition & DBUS_WATCH_ERROR)

   743     revents |= _DBUS_POLLERR;

   744   if (condition & DBUS_WATCH_HANGUP)

   745     revents |= _DBUS_POLLHUP;

   746 

   747   fd = dbus_watch_get_fd (watch);

   748 

   749   if (fd == sitter->error_pipe_from_child)

   750     handle_error_pipe (sitter, revents);

   751   else if (fd == sitter->socket_to_babysitter)

   752     handle_babysitter_socket (sitter, revents);

   753 

   754   while (LIVE_CHILDREN (sitter) &&

   755          babysitter_iteration (sitter, FALSE))

   756     ;

   757   

   758   return TRUE;

   759 }

   760 

   761 /** Helps remember which end of the pipe is which */

   762 #define READ_END 0

   763 /** Helps remember which end of the pipe is which */

   764 #define WRITE_END 1

   765 

   766 

   767 /* Avoids a danger in threaded situations (calling close()

   768  * on a file descriptor twice, and another thread has

   769  * re-opened it since the first close)

   770  */

   771 static int

   772 close_and_invalidate (int *fd)

   773 {

   774   int ret;

   775 

   776   if (*fd < 0)

   777     return -1;

   778   else

   779     {

   780       ret = _dbus_close_socket (*fd, NULL);

   781       *fd = -1;

   782     }

   783 

   784   return ret;

   785 }

   786 

   787 static dbus_bool_t

   788 make_pipe (int         p[2],

   789            DBusError  *error)

   790 {

   791   _DBUS_ASSERT_ERROR_IS_CLEAR (error);

   792   

   793   if (pipe (p) < 0)

   794     {

   795       dbus_set_error (error,

   796 		      DBUS_ERROR_SPAWN_FAILED,

   797 		      "Failed to create pipe for communicating with child process (%s)",

   798 		      _dbus_strerror (errno));

   799       return FALSE;

   800     }

   801 

   802   return TRUE;

   803 }

   804 

   805 static void

   806 do_write (int fd, const void *buf, size_t count)

   807 {

   808   size_t bytes_written;

   809   int ret;

   810   

   811   bytes_written = 0;

   812   

   813  again:

   814   

   815   ret = write (fd, ((const char*)buf) + bytes_written, count - bytes_written);

   816 

   817   if (ret < 0)

   818     {

   819       if (errno == EINTR)

   820         goto again;

   821       else

   822         {

   823           _dbus_warn ("Failed to write data to pipe!\n");

   824           exit (1); /* give up, we suck */

   825         }

   826     }

   827   else

   828     bytes_written += ret;

   829   

   830   if (bytes_written < count)

   831     goto again;

   832 }

   833 

   834 static void

   835 write_err_and_exit (int fd, int msg)

   836 {

   837   int en = errno;

   838 

   839   do_write (fd, &msg, sizeof (msg));

   840   do_write (fd, &en, sizeof (en));

   841   

   842   exit (1);

   843 }

   844 

   845 static void

   846 write_pid (int fd, pid_t pid)

   847 {

   848   int msg = CHILD_PID;

   849   

   850   do_write (fd, &msg, sizeof (msg));

   851   do_write (fd, &pid, sizeof (pid));

   852 }

   853 

   854 static void

   855 write_status_and_exit (int fd, int status)

   856 {

   857   int msg = CHILD_EXITED;

   858   

   859   do_write (fd, &msg, sizeof (msg));

   860   do_write (fd, &status, sizeof (status));

   861   

   862   exit (0);

   863 }

   864 

   865 static void

   866 do_exec (int                       child_err_report_fd,

   867 	 char                    **argv,

   868 	 DBusSpawnChildSetupFunc   child_setup,

   869 	 void                     *user_data)

   870 {

   871 #ifdef DBUS_BUILD_TESTS

   872   int i, max_open;

   873 #endif

   874 

   875   _dbus_verbose_reset ();

   876   _dbus_verbose ("Child process has PID %lu\n",

   877                  _dbus_getpid ());

   878   

   879   if (child_setup)

   880     (* child_setup) (user_data);

   881 

   882 #ifdef DBUS_BUILD_TESTS

   883   max_open = sysconf (_SC_OPEN_MAX);

   884   

   885   for (i = 3; i < max_open; i++)

   886     {

   887       int retval;

   888 

   889       if (i == child_err_report_fd)

   890         continue;

   891       

   892       retval = fcntl (i, F_GETFD);

   893 

   894       if (retval != -1 && !(retval & FD_CLOEXEC))

   895 	_dbus_warn ("Fd %d did not have the close-on-exec flag set!\n", i);

   896     }

   897 #endif

   898   #ifndef __SYMBIAN32__

   899   execv (argv[0], argv);

   900   #endif

   901   /* Exec failed */

   902   write_err_and_exit (child_err_report_fd,

   903                       CHILD_EXEC_FAILED);

   904 }

   905 

   906 static void

   907 check_babysit_events (pid_t grandchild_pid,

   908                       int   parent_pipe,

   909                       int   revents)

   910 {

   911   pid_t ret;

   912   int status;

   913   

   914   do

   915     {

   916       ret = waitpid (grandchild_pid, &status, WNOHANG);

   917       /* The man page says EINTR can't happen with WNOHANG,

   918        * but there are reports of it (maybe only with valgrind?)

   919        */

   920     }

   921   while (ret < 0 && errno == EINTR);

   922 

   923   if (ret == 0)

   924     {

   925       _dbus_verbose ("no child exited\n");

   926       

   927       ; /* no child exited */

   928     }

   929   else if (ret < 0)

   930     {

   931       /* This isn't supposed to happen. */

   932       _dbus_warn ("unexpected waitpid() failure in check_babysit_events(): %s\n",

   933                   _dbus_strerror (errno));

   934       exit (1);

   935     }

   936   else if (ret == grandchild_pid)

   937     {

   938       /* Child exited */

   939       _dbus_verbose ("reaped child pid %ld\n", (long) ret);

   940       

   941       write_status_and_exit (parent_pipe, status);

   942     }

   943   else

   944     {

   945       _dbus_warn ("waitpid() reaped pid %d that we've never heard of\n",

   946                   (int) ret);

   947       exit (1);

   948     }

   949 

   950   if (revents & _DBUS_POLLIN)

   951     {

   952       _dbus_verbose ("babysitter got POLLIN from parent pipe\n");

   953     }

   954 

   955   if (revents & (_DBUS_POLLERR | _DBUS_POLLHUP))

   956     {

   957       /* Parent is gone, so we just exit */

   958       _dbus_verbose ("babysitter got POLLERR or POLLHUP from parent\n");

   959       exit (0);

   960     }

   961 }

   962 

   963 static int babysit_sigchld_pipe = -1;

   964 

   965 static void

   966 babysit_signal_handler (int signo)

   967 {

   968   char b = '\0';

   969  again:

   970   write (babysit_sigchld_pipe, &b, 1);

   971   if (errno == EINTR)

   972     goto again;

   973 }

   974 

   975 static void

   976 babysit (pid_t grandchild_pid,

   977          int   parent_pipe)

   978 {

   979   int sigchld_pipe[2];

   980 

   981   /* We don't exec, so we keep parent state, such as the pid that

   982    * _dbus_verbose() uses. Reset the pid here.

   983    */

   984   _dbus_verbose_reset ();

   985   

   986   /* I thought SIGCHLD would just wake up the poll, but

   987    * that didn't seem to work, so added this pipe.

   988    * Probably the pipe is more likely to work on busted

   989    * operating systems anyhow.

   990    */

   991   if (pipe (sigchld_pipe) < 0)

   992     {

   993       _dbus_warn ("Not enough file descriptors to create pipe in babysitter process\n");

   994       exit (1);

   995     }

   996 

   997   babysit_sigchld_pipe = sigchld_pipe[WRITE_END];

   998 #ifndef __SYMBIAN32__

   999   _dbus_set_signal_handler (SIGCHLD, babysit_signal_handler);

  1000 #endif  

  1001   

  1002   write_pid (parent_pipe, grandchild_pid);

  1003 

  1004   check_babysit_events (grandchild_pid, parent_pipe, 0);

  1005 

  1006   while (TRUE)

  1007     {

  1008       DBusPollFD pfds[2];

  1009       

  1010       pfds[0].fd = parent_pipe;

  1011       pfds[0].events = _DBUS_POLLIN;

  1012       pfds[0].revents = 0;

  1013 

  1014       pfds[1].fd = sigchld_pipe[READ_END];

  1015       pfds[1].events = _DBUS_POLLIN;

  1016       pfds[1].revents = 0;

  1017       

  1018       _dbus_poll (pfds, _DBUS_N_ELEMENTS (pfds), -1);

  1019 

  1020       if (pfds[0].revents != 0)

  1021         {

  1022           check_babysit_events (grandchild_pid, parent_pipe, pfds[0].revents);

  1023         }

  1024       else if (pfds[1].revents & _DBUS_POLLIN)

  1025         {

  1026           char b;

  1027           read (sigchld_pipe[READ_END], &b, 1);

  1028           /* do waitpid check */

  1029           check_babysit_events (grandchild_pid, parent_pipe, 0);

  1030         }

  1031     }

  1032   

  1033   exit (1);

  1034 }

  1035 

  1036 /**

  1037  * Spawns a new process. The executable name and argv[0]

  1038  * are the same, both are provided in argv[0]. The child_setup

  1039  * function is passed the given user_data and is run in the child

  1040  * just before calling exec().

  1041  *

  1042  * Also creates a "babysitter" which tracks the status of the

  1043  * child process, advising the parent if the child exits.

  1044  * If the spawn fails, no babysitter is created.

  1045  * If sitter_p is #NULL, no babysitter is kept.

  1046  *

  1047  * @param sitter_p return location for babysitter or #NULL

  1048  * @param argv the executable and arguments

  1049  * @param child_setup function to call in child pre-exec()

  1050  * @param user_data user data for setup function

  1051  * @param error error object to be filled in if function fails

  1052  * @returns #TRUE on success, #FALSE if error is filled in

  1053  */

  1054 #ifdef __SYMBIAN32__

  1055 #include <stdio.h>

  1056 #include <sys/types.h>

  1057 #include <sys/stat.h>

  1058 #include <sys/time.h>

  1059 #include <unistd.h>

  1060 #include <fcntl.h>

  1061 #include <sys/select.h>

  1062 #include <stdlib.h>

  1063 #include <string.h>

  1064 

  1065 

  1066 void thread_fun();

  1067 

  1068 

  1069 

  1070 #endif 

  1071  

  1072 #ifdef __SYMBIAN32__

  1073 EXPORT_C

  1074 #endif

  1075 dbus_bool_t

  1076 _dbus_spawn_async_with_babysitter (DBusBabysitter          **sitter_p,

  1077                                    char                    **argv,

  1078                                    DBusSpawnChildSetupFunc   child_setup,

  1079                                    void                     *user_data,

  1080                                    DBusError                *error)

  1081 {

  1082 

  1083 #ifndef __SYMBIAN32__

  1084   DBusBabysitter *sitter;

  1085   int child_err_report_pipe[2] = { -1, -1 };

  1086   int babysitter_pipe[2] = { -1, -1 };

  1087   pid_t pid;

  1088   

  1089   #ifndef __SYMBIAN32__

  1090   _DBUS_ASSERT_ERROR_IS_CLEAR (error);

  1091 

  1092   *sitter_p = NULL;

  1093   sitter = NULL;

  1094 

  1095   sitter = _dbus_babysitter_new ();

  1096   if (sitter == NULL)

  1097     {

  1098       dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);

  1099       return FALSE;

  1100     }

  1101 

  1102   sitter->executable = _dbus_strdup (argv[0]);

  1103   if (sitter->executable == NULL)

  1104     {

  1105       dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);

  1106       goto cleanup_and_fail;

  1107     }

  1108   

  1109   if (!make_pipe (child_err_report_pipe, error))

  1110     goto cleanup_and_fail;

  1111 

  1112   _dbus_fd_set_close_on_exec (child_err_report_pipe[READ_END]);

  1113   _dbus_fd_set_close_on_exec (child_err_report_pipe[WRITE_END]);

  1114 

  1115   if (!_dbus_full_duplex_pipe (&babysitter_pipe[0], &babysitter_pipe[1], TRUE, error))

  1116     goto cleanup_and_fail;

  1117 

  1118   _dbus_fd_set_close_on_exec (babysitter_pipe[0]);

  1119   _dbus_fd_set_close_on_exec (babysitter_pipe[1]);

  1120 

  1121   /* Setting up the babysitter is only useful in the parent,

  1122    * but we don't want to run out of memory and fail

  1123    * after we've already forked, since then we'd leak

  1124    * child processes everywhere.

  1125    */

  1126   sitter->error_watch = _dbus_watch_new (child_err_report_pipe[READ_END],

  1127                                          DBUS_WATCH_READABLE,

  1128                                          TRUE, handle_watch, sitter, NULL);

  1129   if (sitter->error_watch == NULL)

  1130     {

  1131       dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);

  1132       goto cleanup_and_fail;

  1133     }

  1134