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             :   {
      49       10002 :     plumed_assert(pid!=0 && pid!=-1);
      50       10002 :   }
      51          18 :   void stop() noexcept {
      52             :     // Signals give problems with MPI on Travis.
      53             :     // I disable them for now.
      54          18 :     if(SubprocessPidGetenvSignals()) if(pid!=0 && pid!=-1) kill(pid,SIGSTOP);
      55          18 :   }
      56          16 :   void cont() noexcept {
      57             :     // Signals give problems with MPI on Travis.
      58             :     // I disable them for now.
      59          16 :     if(SubprocessPidGetenvSignals()) if(pid!=0 && pid!=-1) kill(pid,SIGCONT);
      60          16 :   }
      61       10002 :   ~SubprocessPid() {
      62             :     // this is apparently working also with MPI on Travis.
      63       10002 :     if(pid!=0 && pid!=-1) {
      64             :       int status;
      65       10002 :       kill(pid,SIGINT);
      66       10002 :       waitpid(pid, &status, 0); // Wait for the child process to terminate
      67             :     }
      68       10002 :   }
      69             : #endif
      70             : };
      71             : 
      72       10002 : Subprocess::Subprocess(const std::string & cmd) {
      73             : #ifdef __PLUMED_HAS_SUBPROCESS
      74       10002 :   char* arr [] = {
      75             :     // const_cast are necessary here due to the declaration of execv
      76             :     const_cast<char*>("/bin/sh"),
      77             :     const_cast<char*>("-c"),
      78             :     const_cast<char*>(cmd.c_str()),
      79             :     nullptr
      80       10002 :   };
      81             :   int cp[2];
      82             :   int pc[2];
      83       10002 :   if(pipe(pc)<0) plumed_error()<<"error creating parent to child pipe";
      84       10002 :   if(pipe(cp)<0) plumed_error()<<"error creating child to parent pipe";
      85       10002 :   pid_t pid=fork();
      86       10002 :   switch(pid) {
      87           0 :   case -1:
      88           0 :     plumed_error()<<"error forking";
      89             :     break;
      90             : // CHILD:
      91           0 :   case 0:
      92             :   {
      93           0 :     if(close(1)<0) plumed_error()<<"error closing file";
      94           0 :     if(dup(cp[1])<0) plumed_error()<<"error duplicating file";
      95           0 :     if(close(0)<0) plumed_error()<<"error closing file";
      96           0 :     if(dup(pc[0])<0) plumed_error()<<"error duplicating file";
      97           0 :     if(close(pc[1])<0) plumed_error()<<"error closing file";
      98           0 :     if(close(cp[0])<0) plumed_error()<<"error closing file";
      99           0 :     execv(arr[0],arr);
     100           0 :     plumed_error()<<"error in script file";
     101             :   }
     102             : // PARENT::
     103       10002 :   default:
     104       20004 :     this->pid=Tools::make_unique<SubprocessPid>(pid);
     105       10002 :     if(close(pc[0])<0) plumed_error()<<"error closing file";
     106       10002 :     if(close(cp[1])<0) plumed_error()<<"error closing file";
     107       10002 :     fpc=pc[1];
     108       10002 :     fcp=cp[0];
     109       10002 :     fppc=fdopen(fpc,"w");
     110       10002 :     parent_to_child.link(fppc);
     111       10002 :     fpcp=fdopen(fcp,"r");
     112       10002 :     child_to_parent.link(fpcp);
     113             :   }
     114             : #else
     115             :   plumed_error()<<"Subprocess not supported";
     116             : #endif
     117       10002 : }
     118             : 
     119       10002 : Subprocess::~Subprocess() {
     120             : #ifdef __PLUMED_HAS_SUBPROCESS
     121             : // close files:
     122       10002 :   fclose(fppc);
     123       10002 :   fclose(fpcp);
     124             : // fclose also closes the underlying descriptors,
     125             : // so this is not needed:
     126       10002 :   close(fpc);
     127       10002 :   close(fcp);
     128             : // after closing the communication, the subprocess is killed
     129             : // in pid's destructor
     130             : #endif
     131       10002 : }
     132             : 
     133          83 : bool Subprocess::available() noexcept {
     134             : #ifdef __PLUMED_HAS_SUBPROCESS
     135          83 :   return true;
     136             : #else
     137             :   return false;
     138             : #endif
     139             : }
     140             : 
     141          18 : void Subprocess::stop() noexcept {
     142             : #ifdef __PLUMED_HAS_SUBPROCESS
     143          18 :   pid->stop();
     144             : #endif
     145          18 : }
     146             : 
     147          16 : void Subprocess::cont() noexcept {
     148             : #ifdef __PLUMED_HAS_SUBPROCESS
     149          16 :   pid->cont();
     150             : #endif
     151          16 : }
     152             : 
     153          16 : void Subprocess::flush() {
     154          16 :   parent_to_child.flush();
     155          16 : }
     156             : 
     157          16 : Subprocess & Subprocess::getline(std::string & line) {
     158          16 :   child_to_parent.getline(line);
     159          16 :   if(!child_to_parent) plumed_error() <<"error reading subprocess";
     160          16 :   return (*this);
     161             : }
     162             : 
     163          16 : Subprocess::Handler::Handler(Subprocess *sp) noexcept:
     164          16 :   sp(sp)
     165             : {
     166          16 :   sp->cont();
     167          16 : }
     168             : 
     169          16 : Subprocess::Handler::~Handler() {
     170          16 :   if(sp) sp->stop();
     171          16 : }
     172             : 
     173           0 : Subprocess::Handler::Handler(Handler && handler) noexcept :
     174           0 :   sp(handler.sp)
     175             : {
     176           0 :   handler.sp=nullptr;
     177           0 : }
     178             : 
     179           0 : Subprocess::Handler & Subprocess::Handler::operator=(Handler && handler) noexcept {
     180           0 :   if(this!=&handler) {
     181           0 :     if(sp) sp->stop();
     182           0 :     sp=handler.sp;
     183           0 :     handler.sp=nullptr;
     184             :   }
     185           0 :   return *this;
     186             : }
     187             : 
     188             : 
     189             : }