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