TNetXNGFile::Open fails with double slash (//) in path

[bfonta]

Describe the bug

When passing a path containing a double slash (//) to TChain, the last characters are trimmed. The bug has been described here. This is error-prone.

Expected behavior

Even if ones does not want to automatically convert the double slash into a single slash in some scenarios, a warning should be expected. The behavior also goes against what any Linux user would expect.

To Reproduce

I took the example from the original bug report:

TChain* mychain = new TChain("DecayTree");
mychain->AddFile("root://eoslhcb.cern.ch//eos/lhcb/user/<letter>/<username>/test2//mytestfile.root")
(int) 1
mychain->GetEntries()
Error in <TNetXNGFile::Open>: [ERROR] Server responded with an error: [3011] Unable to open file /eos/lhcb/user/<letter>/<usern>; No such file or directory

Setup

1. ROOT Version: 6.20/02
2. OS: Linux, SLC7
3. How you obtained ROOT: binary install

[vepadulano]

The following test works on my machine with the latest ROOT master

 #include <TFile.h>
#include <TChain.h>

#include <iostream>
#include <memory>

constexpr auto netFile = "root://eospublic.cern.ch//eos//root-eos//h1//dstarmb.root";

void testWithFile()
{
    std::unique_ptr<TFile> f{TFile::Open(netFile)};
    f->ls();
}

void testWithChain()
{
    TChain c{"h42"};
    c.Add(netFile);
    std::cout << "Number of entries in the chain: " << c.GetEntries() << "\n";
}

void testWithChainLocalName()
{
    TChain c;
    std::string fullpath{netFile};
    fullpath += "?#h42";
    c.Add(fullpath.c_str());
    std::cout << "Number of entries in the chain: " << c.GetEntries() << "\n";
}

int main()
{
    testWithFile();
    testWithChain();
    testWithChainLocalName();
}

With output

./repro.out
TNetXNGFile**		root://eospublic.cern.ch//eos/root-eos/h1/dstarmb.root	HBOOK file: dstarmb.hbook converted to ROOT
 TNetXNGFile*		root://eospublic.cern.ch//eos/root-eos/h1/dstarmb.root	HBOOK file: dstarmb.hbook converted to ROOT
  KEY: TTree	h42;1	dstar
Number of entries in the chain: 21920
Number of entries in the chain: 21920

I could not have access to the same file (under LHCb EOS), but I used another public EOS file and it should be equivalent. I will try to build an older version of ROOT and see if the problem was present at the time with the same file.

[vepadulano]

I went as far back as ROOT 6.24 and the issue doesn't seem to be there

[vpadulan@lxplus717 ~]$./repro_7159.out
Warning in <UnknownClass::SetDisplay>: DISPLAY not set, setting it to vpadulan-macbook.dyndns6.cern.ch:0.0
TNetXNGFile**		root://eospublic.cern.ch//eos/root-eos/h1/dstarmb.root	HBOOK file: dstarmb.hbook converted to ROOT
 TNetXNGFile*		root://eospublic.cern.ch//eos/root-eos/h1/dstarmb.root	HBOOK file: dstarmb.hbook converted to ROOT
  KEY: TTree	h42;1	dstar
Number of entries in the chain: 21920
Number of entries in the chain: 21920
[vpadulan@lxplus717 ~]$root --version
ROOT Version: 6.24/00
Built for linuxx8664gcc on Apr 14 2021, 14:33:50
From tags/v6-24-00@v6-24-00