Fix PCD load crashes on empty files (#5855)

* return -1 from PCDReader::readHeader() when input file is completely empty

* Return empty string from getFieldsList() if input cloud has no fields

* Update io/src/pcd_io.cpp

Co-authored-by: Markus Vieth <39675748+mvieth@users.noreply.github.com>

* Update common/include/pcl/common/io.h

---------

Co-authored-by: Markus Vieth <39675748+mvieth@users.noreply.github.com>

common/include/pcl/common/io.h

@@ -109,8 +109,14 @@ namespace pcl
   inline std::string
   getFieldsList (const pcl::PCLPointCloud2 &cloud)
   {
-    return std::accumulate(std::next (cloud.fields.begin ()), cloud.fields.end (), cloud.fields[0].name,
-        [](const auto& acc, const auto& field) { return acc + " " + field.name; });
+    if (cloud.fields.empty())
+    {
+      return "";
+    } else
+    {
+      return std::accumulate(std::next (cloud.fields.begin ()), cloud.fields.end (), cloud.fields[0].name,
+          [](const auto& acc, const auto& field) { return acc + " " + field.name; });
+    }
   }
 
   /** \brief Obtains the size of a specific field data type in bytes

io/src/pcd_io.cpp

@@ -397,7 +397,14 @@ pcl::PCDReader::readHeader (const std::string &file_name, pcl::PCLPointCloud2 &c
   fs.open (file_name.c_str (), std::ios::binary);
   if (!fs.is_open () || fs.fail ())
   {
-    PCL_ERROR ("[pcl::PCDReader::readHeader] Could not open file '%s'! Error : %s\n", file_name.c_str (), strerror (errno)); 
+    PCL_ERROR ("[pcl::PCDReader::readHeader] Could not open file '%s'! Error : %s\n", file_name.c_str (), strerror (errno));
+    fs.close ();
+    return (-1);
+  }
+
+  if (fs.peek() ==  std::ifstream::traits_type::eof())
+  {
+    PCL_ERROR ("[pcl::PCDReader::readHeader] File '%s' is empty.\n", file_name.c_str ());
     fs.close ();
     return (-1);
   }