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             :   {
      49       10030 :     plumed_assert(pid!=0 && pid!=-1);
      50       10030 :   }
      51          18 :   void stop() noexcept {
      52             :     // Signals give problems with MPI on Travis.
      53             :     // I disable them for now.
      54          18 :     if(SubprocessPidGetenvSignals()) 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()) kill(pid,SIGCONT);
      60          16 :   }
      61       10030 :   ~SubprocessPid() {
      62             :     // the destructor implies we do not need the subprocess anymore, so SIGKILL
      63             :     // is the fastest exit.
      64             :     // if we want to gracefully kill the process with a delay, it would be cleaner
      65             :     // to have another member function
      66       10030 :     kill(pid,SIGKILL);
      67             :     // Wait for the child process to terminate
      68             :     // This is anyway required to avoid leaks
      69             :     int status;
      70       10030 :     waitpid(pid, &status, 0);
      71       10030 :   }
      72             : #endif
      73             : };
      74             : 
      75       10030 : Subprocess::Subprocess(const std::string & cmd) {
      76             : #ifdef __PLUMED_HAS_SUBPROCESS
      77       10030 :   char* arr [] = {
      78             :     // const_cast are necessary here due to the declaration of execv
      79             :     const_cast<char*>("/bin/sh"),
      80             :     const_cast<char*>("-c"),
      81             :     const_cast<char*>(cmd.c_str()),
      82             :     nullptr
      83       10030 :   };
      84             :   int cp[2];
      85             :   int pc[2];
      86       10030 :   if(pipe(pc)<0) plumed_error()<<"error creating parent to child pipe";
      87       10030 :   if(pipe(cp)<0) plumed_error()<<"error creating child to parent pipe";
      88       10030 :   pid_t pid=fork();
      89       10030 :   switch(pid) {
      90           0 :   case -1:
      91           0 :     plumed_error()<<"error forking";
      92             :     break;
      93             : // CHILD:
      94           0 :   case 0:
      95             :   {
      96           0 :     if(close(1)<0) plumed_error()<<"error closing file";
      97           0 :     if(dup(cp[1])<0) plumed_error()<<"error duplicating file";
      98           0 :     if(close(0)<0) plumed_error()<<"error closing file";
      99           0 :     if(dup(pc[0])<0) plumed_error()<<"error duplicating file";
     100           0 :     if(close(pc[1])<0) plumed_error()<<"error closing file";
     101           0 :     if(close(cp[0])<0) plumed_error()<<"error closing file";
     102           0 :     auto err=execv(arr[0],arr);
     103           0 :     plumed_error()<<"error in script file " << cmd << ", execv returned "<<err;
     104             :   }
     105             : // PARENT::
     106       10030 :   default:
     107       10030 :     this->pid=Tools::make_unique<SubprocessPid>(pid);
     108       10030 :     if(close(pc[0])<0) plumed_error()<<"error closing file";
     109       10030 :     if(close(cp[1])<0) plumed_error()<<"error closing file";
     110       10030 :     fpc=pc[1];
     111       10030 :     fcp=cp[0];
     112       10030 :     fppc=fdopen(fpc,"w");
     113       10030 :     parent_to_child.link(fppc);
     114       10030 :     fpcp=fdopen(fcp,"r");
     115       10030 :     child_to_parent.link(fpcp);
     116             :   }
     117             : #else
     118             :   plumed_error()<<"Subprocess not supported";
     119             : #endif
     120       10030 : }
     121             : 
     122       10030 : Subprocess::~Subprocess() {
     123             : #ifdef __PLUMED_HAS_SUBPROCESS
     124             : // close files:
     125       10030 :   fclose(fppc);
     126       10030 :   fclose(fpcp);
     127             : // fclose also closes the underlying descriptors,
     128             : // so this is not needed:
     129       10030 :   close(fpc);
     130       10030 :   close(fcp);
     131             : // after closing the communication, the subprocess is killed
     132             : // in pid's destructor
     133             : #endif
     134       10030 : }
     135             : 
     136         124 : bool Subprocess::available() noexcept {
     137             : #ifdef __PLUMED_HAS_SUBPROCESS
     138         124 :   return true;
     139             : #else
     140             :   return false;
     141             : #endif
     142             : }
     143             : 
     144          18 : void Subprocess::stop() noexcept {
     145             : #ifdef __PLUMED_HAS_SUBPROCESS
     146          18 :   pid->stop();
     147             : #endif
     148          18 : }
     149             : 
     150          16 : void Subprocess::cont() noexcept {
     151             : #ifdef __PLUMED_HAS_SUBPROCESS
     152          16 :   pid->cont();
     153             : #endif
     154          16 : }
     155             : 
     156          16 : void Subprocess::flush() {
     157          16 :   parent_to_child.flush();
     158          16 : }
     159             : 
     160          44 : Subprocess & Subprocess::getline(std::string & line) {
     161          44 :   child_to_parent.getline(line);
     162          44 :   if(!child_to_parent) plumed_error() <<"error reading subprocess";
     163          44 :   return (*this);
     164             : }
     165             : 
     166          16 : Subprocess::Handler::Handler(Subprocess *sp) noexcept:
     167          16 :   sp(sp)
     168             : {
     169          16 :   sp->cont();
     170          16 : }
     171             : 
     172          16 : Subprocess::Handler::~Handler() {
     173          16 :   if(sp) sp->stop();
     174          16 : }
     175             : 
     176           0 : Subprocess::Handler::Handler(Handler && handler) noexcept :
     177           0 :   sp(handler.sp)
     178             : {
     179           0 :   handler.sp=nullptr;
     180           0 : }
     181             : 
     182           0 : Subprocess::Handler & Subprocess::Handler::operator=(Handler && handler) noexcept {
     183           0 :   if(this!=&handler) {
     184           0 :     if(sp) sp->stop();
     185           0 :     sp=handler.sp;
     186           0 :     handler.sp=nullptr;
     187             :   }
     188           0 :   return *this;
     189             : }
     190             : 
     191             : 
     192             : }