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             :   const pid_t pid;
      46       10030 :   explicit SubprocessPid(pid_t pid):
      47       10030 :     pid(pid) {
      48       10030 :     plumed_assert(pid!=0 && pid!=-1);
      49       10030 :   }
      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 :       kill(pid,SIGSTOP);
      55             :     }
      56          18 :   }
      57          16 :   void cont() noexcept {
      58             :     // Signals give problems with MPI on Travis.
      59             :     // I disable them for now.
      60          16 :     if(SubprocessPidGetenvSignals()) {
      61           0 :       kill(pid,SIGCONT);
      62             :     }
      63          16 :   }
      64       10030 :   ~SubprocessPid() {
      65             :     // the destructor implies we do not need the subprocess anymore, so SIGKILL
      66             :     // is the fastest exit.
      67             :     // if we want to gracefully kill the process with a delay, it would be cleaner
      68             :     // to have another member function
      69       10030 :     kill(pid,SIGKILL);
      70             :     // Wait for the child process to terminate
      71             :     // This is anyway required to avoid leaks
      72             :     int status;
      73       10030 :     waitpid(pid, &status, 0);
      74       10030 :   }
      75             : #endif
      76             : };
      77             : 
      78       10030 : Subprocess::Subprocess(const std::string & cmd) {
      79             : #ifdef __PLUMED_HAS_SUBPROCESS
      80       10030 :   char* arr [] = {
      81             :     // const_cast are necessary here due to the declaration of execv
      82             :     const_cast<char*>("/bin/sh"),
      83             :     const_cast<char*>("-c"),
      84             :     const_cast<char*>(cmd.c_str()),
      85             :     nullptr
      86       10030 :   };
      87             :   int cp[2];
      88             :   int pc[2];
      89       10030 :   if(pipe(pc)<0) {
      90           0 :     plumed_error()<<"error creating parent to child pipe";
      91             :   }
      92       10030 :   if(pipe(cp)<0) {
      93           0 :     plumed_error()<<"error creating child to parent pipe";
      94             :   }
      95       10030 :   pid_t pid=fork();
      96       10030 :   switch(pid) {
      97           0 :   case -1:
      98           0 :     plumed_error()<<"error forking";
      99             :     break;
     100             : // CHILD:
     101           0 :   case 0: {
     102           0 :     if(close(1)<0) {
     103           0 :       plumed_error()<<"error closing file";
     104             :     }
     105           0 :     if(dup(cp[1])<0) {
     106           0 :       plumed_error()<<"error duplicating file";
     107             :     }
     108           0 :     if(close(0)<0) {
     109           0 :       plumed_error()<<"error closing file";
     110             :     }
     111           0 :     if(dup(pc[0])<0) {
     112           0 :       plumed_error()<<"error duplicating file";
     113             :     }
     114           0 :     if(close(pc[1])<0) {
     115           0 :       plumed_error()<<"error closing file";
     116             :     }
     117           0 :     if(close(cp[0])<0) {
     118           0 :       plumed_error()<<"error closing file";
     119             :     }
     120           0 :     auto err=execv(arr[0],arr);
     121           0 :     plumed_error()<<"error in script file " << cmd << ", execv returned "<<err;
     122             :   }
     123             : // PARENT::
     124       10030 :   default:
     125       10030 :     this->pid=Tools::make_unique<SubprocessPid>(pid);
     126       10030 :     if(close(pc[0])<0) {
     127           0 :       plumed_error()<<"error closing file";
     128             :     }
     129       10030 :     if(close(cp[1])<0) {
     130           0 :       plumed_error()<<"error closing file";
     131             :     }
     132       10030 :     fpc=pc[1];
     133       10030 :     fcp=cp[0];
     134       10030 :     fppc=fdopen(fpc,"w");
     135       10030 :     parent_to_child.link(fppc);
     136       10030 :     fpcp=fdopen(fcp,"r");
     137       10030 :     child_to_parent.link(fpcp);
     138             :   }
     139             : #else
     140             :   plumed_error()<<"Subprocess not supported";
     141             : #endif
     142       10030 : }
     143             : 
     144       10030 : Subprocess::~Subprocess() {
     145             : #ifdef __PLUMED_HAS_SUBPROCESS
     146             : // close files:
     147       10030 :   fclose(fppc);
     148       10030 :   fclose(fpcp);
     149             : // fclose also closes the underlying descriptors,
     150             : // so this is not needed:
     151       10030 :   close(fpc);
     152       10030 :   close(fcp);
     153             : // after closing the communication, the subprocess is killed
     154             : // in pid's destructor
     155             : #endif
     156       10030 : }
     157             : 
     158         144 : bool Subprocess::available() noexcept {
     159             : #ifdef __PLUMED_HAS_SUBPROCESS
     160         144 :   return true;
     161             : #else
     162             :   return false;
     163             : #endif
     164             : }
     165             : 
     166          18 : void Subprocess::stop() noexcept {
     167             : #ifdef __PLUMED_HAS_SUBPROCESS
     168          18 :   pid->stop();
     169             : #endif
     170          18 : }
     171             : 
     172          16 : void Subprocess::cont() noexcept {
     173             : #ifdef __PLUMED_HAS_SUBPROCESS
     174          16 :   pid->cont();
     175             : #endif
     176          16 : }
     177             : 
     178          16 : void Subprocess::flush() {
     179          16 :   parent_to_child.flush();
     180          16 : }
     181             : 
     182          44 : Subprocess & Subprocess::getline(std::string & line) {
     183          44 :   child_to_parent.getline(line);
     184          44 :   if(!child_to_parent) {
     185           0 :     plumed_error() <<"error reading subprocess";
     186             :   }
     187          44 :   return (*this);
     188             : }
     189             : 
     190          16 : Subprocess::Handler::Handler(Subprocess *sp) noexcept:
     191          16 :   sp(sp) {
     192          16 :   sp->cont();
     193          16 : }
     194             : 
     195          16 : Subprocess::Handler::~Handler() {
     196          16 :   if(sp) {
     197          16 :     sp->stop();
     198             :   }
     199          16 : }
     200             : 
     201           0 : Subprocess::Handler::Handler(Handler && handler) noexcept :
     202           0 :   sp(handler.sp) {
     203           0 :   handler.sp=nullptr;
     204           0 : }
     205             : 
     206           0 : Subprocess::Handler & Subprocess::Handler::operator=(Handler && handler) noexcept {
     207           0 :   if(this!=&handler) {
     208           0 :     if(sp) {
     209           0 :       sp->stop();
     210             :     }
     211           0 :     sp=handler.sp;
     212           0 :     handler.sp=nullptr;
     213             :   }
     214           0 :   return *this;
     215             : }
     216             : 
     217             : 
     218             : }