Fix: POSIX Open from BPFileReader

source/adios2/engine/bp/BPFileReader.cpp

@@ -126,8 +126,12 @@ void BPFileReader::ReadVariables(
             const std::string subFile(
                 m_BP3Deserializer.GetBPSubFileName(m_Name, subFileIndex));
 
-            m_SubFileManager.OpenFiles({subFile}, adios2::Mode::Read,
-                                       {{{"transport", "File"}}}, profile);
+            // TODO: fix this part
+            if (m_SubFileManager.m_Transports.count(subFileIndex) == 0)
+            {
+                m_SubFileManager.OpenFiles({subFile}, adios2::Mode::Read,
+                                           {{{"transport", "File"}}}, profile);
+            }
 
             for (const auto &stepPair : subFileIndexPair.second) // step
             {

source/adios2/toolkit/transport/file/FilePOSIX.cpp

@@ -165,7 +165,8 @@ void FilePOSIX::Read(char *buffer, size_t size, size_t start)
             throw std::ios_base::failure(
                 "ERROR: couldn't move to start position " +
                 std::to_string(start) + " in file " + m_Name +
-                ", in call to POSIX lseek\n");
+                ", in call to POSIX lseek errno " + std::to_string(errno) +
+                "\n");
         }
     }
 

source/adios2/toolkit/transport/file/FileStdio.cpp

@@ -145,9 +145,12 @@ void FileStdio::Read(char *buffer, size_t size, size_t start)
 
     if (start != MaxSizeT)
     {
-        std::fseek(m_File, static_cast<long int>(start), SEEK_SET);
+        const auto result =
+            std::fseek(m_File, static_cast<long int>(start), SEEK_SET);
         CheckFile("couldn't move to start position " + std::to_string(start) +
-                  " in file " + m_Name + ", in call to stdio fseek for read");
+                  " in file " + m_Name +
+                  ", in call to stdio fseek for read, result=" +
+                  std::to_string(result));
     }
 
     if (size > DefaultMaxFileBatchSize)