add convenience function to get the output of strerror(errno) as c++ string

src/utils.cpp

@@ -14,6 +14,7 @@
 #include "utils.h"
 #include <cstring>
 #include <cstdlib>
+#include <cerrno>
 #include "lammps.h"
 #include "error.h"
 #include "tokenizer.h"
@@ -99,6 +100,14 @@ void utils::logmesg(LAMMPS *lmp, const std::string &mesg)
   if (lmp->logfile) fputs(mesg.c_str(), lmp->logfile);
 }
 
+/* define this here, so we won't have to include the headers
+   everywhere and utils.h will more likely be included anyway. */
+
+std::string utils::getsyserror()
+{
+  return std::string(strerror(errno));
+}
+
 /** \brief try to detect pathname from FILE pointer. Currently only supported on Linux, otherwise will report "(unknown)".
  *
  *  \param buf  storage buffer for pathname. output will be truncated if not large enough

src/utils.h

@@ -43,6 +43,14 @@ namespace LAMMPS_NS {
      */
     void logmesg(LAMMPS *lmp, const std::string &mesg);
 
+    /** \brief return a string representing the current system error status
+     *
+     *  This is a wrapper around calling strerror(errno).
+     *
+     *  \return  error string
+     */
+    std::string getsyserror();
+
     /** \brief safe wrapper around fgets() which aborts on errors
      *  or EOF and prints a suitable error message to help debugging
      *