Line data    Source code

       1             : /* +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
       2             :    Copyright (c) 2018-2023 The plumed team
       3             :    (see the PEOPLE file at the root of the distribution for a list of names)
       4             : 
       5             :    See http://www.plumed.org for more information.
       6             : 
       7             :    This file is part of plumed, version 2.
       8             : 
       9             :    plumed is free software: you can redistribute it and/or modify
      10             :    it under the terms of the GNU Lesser General Public License as published by
      11             :    the Free Software Foundation, either version 3 of the License, or
      12             :    (at your option) any later version.
      13             : 
      14             :    plumed 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 Lesser General Public License for more details.
      18             : 
      19             :    You should have received a copy of the GNU Lesser General Public License
      20             :    along with plumed.  If not, see <http://www.gnu.org/licenses/>.
      21             : +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */
      22             : #include "Subprocess.h"
      23             : #include "Exception.h"
      24             : #include "Tools.h"
      25             : #ifdef __PLUMED_HAS_SUBPROCESS
      26             : #include <unistd.h>
      27             : #include <csignal>
      28             : #include <sys/wait.h>
      29             : #endif
      30             : 
      31             : namespace PLMD {
      32             : 
      33             : /// Retrieve PLUMED_ENABLE_SIGNALS.
      34             : /// Inline static so that it can store a static variable (for quicker access)
      35             : /// without adding a unique global symbol to a library including this header file.
      36          34 : inline static bool SubprocessPidGetenvSignals() noexcept {
      37          34 :   static const bool res=std::getenv("PLUMED_ENABLE_SIGNALS");
      38          34 :   return res;
      39             : }
      40             : 
      41             : /// Small utility class, used to avoid inclusion of unistd.h> in a header file.
      42             : class SubprocessPid {
      43             : #ifdef __PLUMED_HAS_SUBPROCESS
      44             : public:
      45             :   pid_t pid;
      46       10002 :   explicit SubprocessPid(pid_t pid):
      47       10002 :     pid(pid) {
      48       10002 :     plumed_assert(pid!=0 && pid!=-1);
      49       10002 :   }
      50          18 :   void stop() noexcept {
      51             :     // Signals give problems with MPI on Travis.
      52             :     // I disable them for now.
      53          18 :     if(SubprocessPidGetenvSignals())
      54           0 :       if(pid!=0 && pid!=-1) {
      55           0 :         kill(pid,SIGSTOP);
      56             :       }
      57          18 :   }
      58          16 :   void cont() noexcept {
      59             :     // Signals give problems with MPI on Travis.
      60             :     // I disable them for now.
      61          16 :     if(SubprocessPidGetenvSignals())
      62           0 :       if(pid!=0 && pid!=-1) {
      63           0 :         kill(pid,SIGCONT);
      64             :       }
      65          16 :   }
      66       10002 :   ~SubprocessPid() {
      67             :     // this is apparently working also with MPI on Travis.
      68       10002 :     if(pid!=0 && pid!=-1) {
      69             :       int status;
      70       10002 :       kill(pid,SIGINT);
      71       10002 :       waitpid(pid, &status, 0); // Wait for the child process to terminate
      72             :     }
      73       10002 :   }
      74             : #endif
      75             : };
      76             : 
      77       10002 : Subprocess::Subprocess(const std::string & cmd) {
      78             : #ifdef __PLUMED_HAS_SUBPROCESS
      79       10002 :   char* arr [] = {
      80             :     // const_cast are necessary here due to the declaration of execv
      81             :     const_cast<char*>("/bin/sh"),
      82             :     const_cast<char*>("-c"),
      83             :     const_cast<char*>(cmd.c_str()),
      84             :     nullptr
      85       10002 :   };
      86             :   int cp[2];
      87             :   int pc[2];
      88       10002 :   if(pipe(pc)<0) {
      89           0 :     plumed_error()<<"error creating parent to child pipe";
      90             :   }
      91       10002 :   if(pipe(cp)<0) {
      92           0 :     plumed_error()<<"error creating child to parent pipe";
      93             :   }
      94       10002 :   pid_t pid=fork();
      95       10002 :   switch(pid) {
      96           0 :   case -1:
      97           0 :     plumed_error()<<"error forking";
      98             :     break;
      99             : // CHILD:
     100           0 :   case 0: {
     101           0 :     if(close(1)<0) {
     102           0 :       plumed_error()<<"error closing file";
     103             :     }
     104           0 :     if(dup(cp[1])<0) {
     105           0 :       plumed_error()<<"error duplicating file";
     106             :     }
     107           0 :     if(close(0)<0) {
     108           0 :       plumed_error()<<"error closing file";
     109             :     }
     110           0 :     if(dup(pc[0])<0) {
     111           0 :       plumed_error()<<"error duplicating file";
     112             :     }
     113           0 :     if(close(pc[1])<0) {
     114           0 :       plumed_error()<<"error closing file";
     115             :     }
     116           0 :     if(close(cp[0])<0) {
     117           0 :       plumed_error()<<"error closing file";
     118             :     }
     119           0 :     execv(arr[0],arr);
     120           0 :     plumed_error()<<"error in script file";
     121             :   }
     122             : // PARENT::
     123       10002 :   default:
     124       20004 :     this->pid=Tools::make_unique<SubprocessPid>(pid);
     125       10002 :     if(close(pc[0])<0) {
     126           0 :       plumed_error()<<"error closing file";
     127             :     }
     128       10002 :     if(close(cp[1])<0) {
     129           0 :       plumed_error()<<"error closing file";
     130             :     }
     131       10002 :     fpc=pc[1];
     132       10002 :     fcp=cp[0];
     133       10002 :     fppc=fdopen(fpc,"w");
     134       10002 :     parent_to_child.link(fppc);
     135       10002 :     fpcp=fdopen(fcp,"r");
     136       10002 :     child_to_parent.link(fpcp);
     137             :   }
     138             : #else
     139             :   plumed_error()<<"Subprocess not supported";
     140             : #endif
     141       10002 : }
     142             : 
     143       10002 : Subprocess::~Subprocess() {
     144             : #ifdef __PLUMED_HAS_SUBPROCESS
     145             : // close files:
     146       10002 :   fclose(fppc);
     147       10002 :   fclose(fpcp);
     148             : // fclose also closes the underlying descriptors,
     149             : // so this is not needed:
     150       10002 :   close(fpc);
     151       10002 :   close(fcp);
     152             : // after closing the communication, the subprocess is killed
     153             : // in pid's destructor
     154             : #endif
     155       10002 : }
     156             : 
     157         108 : bool Subprocess::available() noexcept {
     158             : #ifdef __PLUMED_HAS_SUBPROCESS
     159         108 :   return true;
     160             : #else
     161             :   return false;
     162             : #endif
     163             : }
     164             : 
     165          18 : void Subprocess::stop() noexcept {
     166             : #ifdef __PLUMED_HAS_SUBPROCESS
     167          18 :   pid->stop();
     168             : #endif
     169          18 : }
     170             : 
     171          16 : void Subprocess::cont() noexcept {
     172             : #ifdef __PLUMED_HAS_SUBPROCESS
     173             :   pid->cont();
     174             : #endif
     175          16 : }
     176             : 
     177          16 : void Subprocess::flush() {
     178          16 :   parent_to_child.flush();
     179          16 : }
     180             : 
     181          16 : Subprocess & Subprocess::getline(std::string & line) {
     182          16 :   child_to_parent.getline(line);
     183          16 :   if(!child_to_parent) {
     184           0 :     plumed_error() <<"error reading subprocess";
     185             :   }
     186          16 :   return (*this);
     187             : }
     188             : 
     189          16 : Subprocess::Handler::Handler(Subprocess *sp) noexcept:
     190          16 :   sp(sp) {
     191          16 :   sp->cont();
     192          16 : }
     193             : 
     194          16 : Subprocess::Handler::~Handler() {
     195          16 :   if(sp) {
     196          16 :     sp->stop();
     197             :   }
     198          16 : }
     199             : 
     200           0 : Subprocess::Handler::Handler(Handler && handler) noexcept :
     201           0 :   sp(handler.sp) {
     202           0 :   handler.sp=nullptr;
     203           0 : }
     204             : 
     205           0 : Subprocess::Handler & Subprocess::Handler::operator=(Handler && handler) noexcept {
     206           0 :   if(this!=&handler) {
     207           0 :     if(sp) {
     208           0 :       sp->stop();
     209             :     }
     210           0 :     sp=handler.sp;
     211           0 :     handler.sp=nullptr;
     212             :   }
     213           0 :   return *this;
     214             : }
     215             : 
     216             : 
     217             : }