Allow as input ROOT file from ZIP archives

Since the size of a single PLUTO file is very small the preferred storage
solution for them is to store a large number of them in a archive.
ROOT is able to handle ROOT files stored in a ZIP archive so the file
handling in the class was adapted for the ZIP file usage.

sim/transport/generators/CbmPlutoGenerator.cxx

@@ -11,6 +11,7 @@
 #include "PParticle.h"    // for PParticle
 #include "PStaticData.h"  // for PStaticData
 
+#include "TArchiveFile.h"    // for TArchiveFile
 #include "TChain.h"          // for TChain
 #include "TClonesArray.h"    // for TClonesArray
 #include "TDatabasePDG.h"    // for TDatabasePDG
@@ -47,10 +48,15 @@ CbmPlutoGenerator::CbmPlutoGenerator(const Char_t* fileName)
   , fParticles(new TClonesArray("PParticle", 100))
   , fPDGmanual(0) {
   fInputChain = new TChain("data");
-  CheckFileExist(fileName);
 
-  fInputChain->Add(fileName);
-  fInputChain->SetBranchAddress("Particles", &fParticles);
+  if (CheckFileExist(fileName)) {
+    fInputChain->Add(fileName);
+    fInputChain->SetBranchAddress("Particles", &fParticles);
+    LOG(info) << "CbmPlutoGenerator: Add file " << fileName
+              << " to input chain";
+  } else {
+    LOG(fatal) << "Problem opening file " << fileName;
+  }
 }
 // ------------------------------------------------------------------------
 
@@ -66,9 +72,14 @@ CbmPlutoGenerator::CbmPlutoGenerator(std::vector<std::string> fileNames)
   , fPDGmanual(0) {
   fInputChain = new TChain("data");
   for (auto& name : fileNames) {
-    CheckFileExist(name);
-    fInputChain->Add(name.c_str());
+    if (CheckFileExist(name)) {
+      fInputChain->Add(name.c_str());
+      LOG(info) << "CbmPlutoGenerator: Add file " << name << " to input chain";
+    } else {
+      LOG(fatal) << "Problem opening file " << name;
+    }
   }
+
   fInputChain->SetBranchAddress("Particles", &fParticles);
 }
 
@@ -178,14 +189,65 @@ void CbmPlutoGenerator::CloseInput() {
 }
 // ------------------------------------------------------------------------
 
-void CbmPlutoGenerator::CheckFileExist(std::string filename) {
+Bool_t CbmPlutoGenerator::CheckFileExist(std::string filename) {
+
+  // In case the filename contains a hash (e.g. multi.zip#file.root) assume that the hash
+  // separates the name of a zipfile (multi.zip) which contains the real root file
+  // (file.root). Split the filename at the # in the name of the zipfile and
+  // the name of the contained root file.
+  std::string checkFilename {""};
+  std::string membername {""};
+  std::size_t found = filename.find("#");
+  if (found != std::string::npos) {
+    checkFilename = filename.substr(0, found);
+    membername    = filename.substr(found + 1);
+  } else {
+    checkFilename = filename;
+  }
+
+  Bool_t wasfound = kFALSE;
+
+  // Check if the file exist
+  // In case of a root file contained in a zip archive check if the zip file
+  // exist
   struct stat buffer;
-  if (stat(filename.c_str(), &buffer) == 0) {
-    LOG(info) << "CbmPlutoGenerator: Add file " << filename
-              << " to input chain";
+  if (stat(checkFilename.c_str(), &buffer) == 0) {
+    wasfound = kTRUE;
   } else {
-    LOG(fatal) << "Input File " << filename << " not found";
+    wasfound = kFALSE;
+    LOG(error) << "Input File " << checkFilename << " not found";
   }
+
+  // In case of a zip archive check if the archive contains the root file
+  if (membername.compare("") != 0) {
+    TFile* fzip = TFile::Open(checkFilename.c_str());
+    if (fzip->IsOpen()) {
+      TArchiveFile* archive = fzip->GetArchive();
+      if (archive) {
+        TObjArray* members = archive->GetMembers();
+        if (members->FindObject(membername.c_str()) == 0) {
+          LOG(error) << "File " << membername << " not found in zipfile "
+                     << checkFilename;
+          wasfound = kFALSE;
+        } else {
+          LOG(info) << "File " << membername << " found in zipfile "
+                    << checkFilename;
+          wasfound = kTRUE;
+        }
+      } else {
+        LOG(error) << "Zipfile " << checkFilename
+                   << " does not contain an archive";
+        wasfound = kFALSE;
+      }
+      fzip->Close();
+      delete fzip;
+    } else {
+      LOG(error) << "Could not open zipfile " << checkFilename;
+      wasfound = kFALSE;
+    }
+  }
+
+  return wasfound;
 }
 
 ClassImp(CbmPlutoGenerator)

sim/transport/generators/CbmPlutoGenerator.h

@@ -78,7 +78,7 @@ private:
   void CloseInput();
 
   /** Check if file exists. Break fatal when it doesn't exist **/
-  void CheckFileExist(std::string filename);
+  Bool_t CheckFileExist(std::string filename);
 
   ClassDef(CbmPlutoGenerator, 4);
 };