--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/R/rdyncall/src/rutils_str.c	Thu Mar 19 22:26:28 2015 +0100
@@ -0,0 +1,53 @@
+/** ===========================================================================
+ ** R-Package: rdyncall
+ ** File: src/rutils_str.c
+ ** Description: Support functions for handling C string data types.
+ **/
+
+#define USE_RINTERNALS
+#include <Rdefines.h>
+#include <Rinternals.h>
+#include <R_ext/RS.h>
+
+/* String utils */
+
+SEXP r_ptr2str(SEXP extptr)
+{
+  void* addr = R_ExternalPtrAddr(extptr);
+  if (addr == NULL) {
+    return R_NilValue;
+  }
+  return mkString(addr);
+}
+
+SEXP r_strptr(SEXP x)
+{
+  return R_MakeExternalPtr( (void*) CHAR(STRING_ELT(x, 0)), R_NilValue, x );
+}
+
+void do_free(SEXP x)
+{
+  void* addr = R_ExternalPtrAddr(x);
+  R_Free(addr);
+}
+
+SEXP r_strarrayptr(SEXP s)
+{
+  int i;
+  int n;
+  const char ** ptrs;
+
+  n = LENGTH(s);
+
+  // allocate array
+  ptrs = R_Calloc(n, const char*);
+
+  // copy cstring pointers into array
+  for( i=0 ; i<n ; ++i ) ptrs[i] = CHAR( STRING_ELT(s, i) );
+
+  // create external pointer pointing to array
+  SEXP x = PROTECT( R_MakeExternalPtr( ptrs, R_NilValue, s ) );
+  R_RegisterCFinalizerEx( x, do_free, TRUE );
+  UNPROTECT(1);
+  return x;
+}