ExpressionEvaluator.cc

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#include "CommonTools/Utils/interface/ExpressionEvaluator.h"
#include "FWCore/Utilities/interface/GetEnvironmentVariable.h"
#include "FWCore/Utilities/interface/Exception.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"

#include "popenCPP.h"

#include <fstream>
#include <regex>
#include <dlfcn.h>

// #define VI_DEBUG

#ifdef VI_DEBUG
#include <iostream>
#define COUT std::cout
#else
#define COUT LogDebug("ExpressionEvaluator")
#endif

using namespace reco::exprEvalDetails;

namespace {
  std::string generateName() {
    auto n1 = execSysCommand("uuidgen | sed 's/-//g'");
    n1.pop_back();
    return n1;
  }

  void remove(std::string const& name, std::string const& tmpDir = "/tmp") {
    std::string sfile = tmpDir + "/" + name + ".cc";
    std::string ofile = tmpDir + "/" + name + ".so";

    std::string rm = "rm -f ";
    rm += sfile + ' ' + ofile;

    system(rm.c_str());
  }

}  // namespace

namespace reco {

  ExpressionEvaluator::ExpressionEvaluator(const char* pkg, const char* iname, std::string const& iexpr)
      : m_name("VI_" + generateName()) {
    std::string pch = pkg;
    pch += "/src/precompile.h";
    std::string quote("\"");

    auto arch = edm::getEnvironmentVariable("SCRAM_ARCH");
    auto baseDir = edm::getEnvironmentVariable("CMSSW_BASE");
    auto relDir = edm::getEnvironmentVariable("CMSSW_RELEASE_BASE");

    std::string sfile = baseDir + "/tmp/" + m_name + ".cc";
    std::string ofile = baseDir + "/tmp/" + m_name + ".so";

    std::string incDir = "/include/" + arch + "/";
    std::string cxxf;
    {
      // look in local dir
      std::string file = baseDir + incDir + pch + ".cxxflags";
      std::ifstream ss(file.c_str());
      COUT << "local file: " << file << std::endl;
      if (ss) {
        std::getline(ss, cxxf);
        incDir = baseDir + incDir;
      } else {
        // look in release area
        std::string file = relDir + incDir + pch + ".cxxflags";
        COUT << "file in release area: " << file << std::endl;
        std::ifstream ss(file.c_str());
        if (ss) {
          std::getline(ss, cxxf);
          incDir = relDir + incDir;
        } else {
          // look in release is a patch area
          auto paDir = edm::getEnvironmentVariable("CMSSW_FULL_RELEASE_BASE");
          if (paDir.empty())
            throw cms::Exception("ExpressionEvaluator", "error in opening patch area for " + baseDir);
          std::string file = paDir + incDir + pch + ".cxxflags";
          COUT << "file in base release area: " << file << std::endl;
          std::ifstream ss(file.c_str());
          if (!ss)
            throw cms::Exception(
                "ExpressionEvaluator",
                pch + " file not found neither in " + baseDir + " nor in " + relDir + " nor in " + paDir);
          std::getline(ss, cxxf);
          incDir = paDir + incDir;
        }
      }

      {
        std::regex rq("-I[^ ]+");
        cxxf = std::regex_replace(cxxf, rq, std::string(""));
      }
      {
        std::regex rq("=\"");
        cxxf = std::regex_replace(cxxf, rq, std::string("='\""));
      }
      {
        std::regex rq("\" ");
        cxxf = std::regex_replace(cxxf, rq, std::string("\"' "));
      }
      COUT << '|' << cxxf << "|\n" << std::endl;
    }

    std::string cpp = "c++ -H -Wall -shared -Winvalid-pch ";
    cpp += cxxf;
    cpp += " -I" + incDir;
    cpp += " -o " + ofile + ' ' + sfile + " 2>&1\n";

    COUT << cpp << std::endl;

    //  prepare the file to compile
    std::string factory = "factory" + m_name;

    std::string source = std::string("#include ") + quote + pch + quote + "\n";
    source += "struct " + m_name + " final : public " + iname + "{\n";
    source += iexpr;
    source += "\n};\n";

    source += "extern " + quote + 'C' + quote + ' ' + std::string(iname) + "* " + factory + "() {\n";
    source += "static " + m_name + " local;\n";
    source += "return &local;\n}\n";

    COUT << source << std::endl;

    {
      std::ofstream tmp(sfile.c_str());
      tmp << source << std::endl;
    }

    // compile
    auto ss = execSysCommand(cpp);
    COUT << ss << std::endl;

    void* dl = dlopen(ofile.c_str(), RTLD_LAZY);
    if (!dl) {
      remove(m_name, baseDir + "/tmp");
      throw cms::Exception("ExpressionEvaluator",
                           std::string("compilation/linking failed\n") + cpp + ss + "dlerror " + dlerror());
      return;
    }

    m_expr = dlsym(dl, factory.c_str());
    remove(m_name, baseDir + "/tmp");
  }

  ExpressionEvaluator::~ExpressionEvaluator() { remove(m_name, edm::getEnvironmentVariable("CMSSW_BASE") + "/tmp"); }

}  // namespace reco