git.sur5r.net Git - openldap/blob - servers/slapd/back-shell/fork.c

   1 /* fork.c - fork and exec a process, connecting stdin/out w/pipes */
   2 /* $OpenLDAP$ */
   3 /*
   4  * Copyright 1998-2002 The OpenLDAP Foundation, All Rights Reserved.
   5  * COPYING RESTRICTIONS APPLY, see COPYRIGHT file
   6  */
   7
   8 #include "portable.h"
   9
  10 #include <stdio.h>
  11
  12 #include <ac/string.h>
  13 #include <ac/socket.h>
  14 #include <ac/unistd.h>
  15
  16 #include "slap.h"
  17 #include "shell.h"
  18
  19 pid_t
  20 forkandexec(
  21     char        **args,
  22     FILE        **rfp,
  23     FILE        **wfp
  24 )
  25 {
  26         int     p2c[2], c2p[2];
  27         pid_t   pid;
  28
  29         if ( pipe( p2c ) != 0 || pipe( c2p ) != 0 ) {
  30                 Debug( LDAP_DEBUG_ANY, "pipe failed\n", 0, 0, 0 );
  31                 return( -1 );
  32         }
  33
  34         /*
  35          * what we're trying to set up looks like this:
  36          *      parent *wfp -> p2c[1] | p2c[0] -> stdin child
  37          *      parent *rfp <- c2p[0] | c2p[1] <- stdout child
  38          */
  39
  40 #ifdef HAVE_THR
  41         switch ( (pid = fork1()) )
  42 #else
  43         switch ( (pid = fork()) )
  44 #endif
  45         {
  46         case 0:         /* child */
  47                 /*
  48                  * child could deadlock here due to resources locked
  49                  * by our parent
  50                  *
  51                  * If so, configure --without-threads or implement forking
  52                  * via a surrogate parent.
  53                  */
  54                 close( p2c[1] );
  55                 close( c2p[0] );
  56                 if ( dup2( p2c[0], 0 ) == -1 || dup2( c2p[1], 1 ) == -1 ) {
  57                         Debug( LDAP_DEBUG_ANY, "dup2 failed\n", 0, 0, 0 );
  58                         exit( EXIT_FAILURE );
  59                 }
  60
  61                 execv( args[0], args );
  62
  63                 Debug( LDAP_DEBUG_ANY, "execv failed\n", 0, 0, 0 );
  64                 exit( EXIT_FAILURE );
  65
  66         case -1:        /* trouble */
  67                 Debug( LDAP_DEBUG_ANY, "fork failed\n", 0, 0, 0 );
  68                 return( -1 );
  69
  70         default:        /* parent */
  71                 close( p2c[0] );
  72                 close( c2p[1] );
  73                 break;
  74         }
  75
  76         if ( (*rfp = fdopen( c2p[0], "r" )) == NULL || (*wfp = fdopen( p2c[1],
  77             "w" )) == NULL ) {
  78                 Debug( LDAP_DEBUG_ANY, "fdopen failed\n", 0, 0, 0 );
  79                 close( c2p[0] );
  80                 close( p2c[1] );
  81
  82                 return( -1 );
  83         }
  84
  85         return( pid );
  86 }