Fix protection of asynch I/O feature.

* NEC SX might not be the only platform without asynchronous I/O facilities.
* Also fix problem where the feature is available at compile time but
  not enabled at run-time.

src/make_cdilib

@@ -57,7 +57,7 @@ cat > ${PROG} << EOR
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
-#ifndef _SX
+#ifdef _POSIX_ASYNCHRONOUS_IO
 #include <aio.h>
 #endif
 #include <stdbool.h>

src/make_cdilib_nc

@@ -61,7 +61,7 @@ cat > ${PROG} << EOR
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
-#ifndef _SX
+#ifdef _POSIX_ASYNCHRONOUS_IO
 #include <aio.h>
 #endif
 #include <stdbool.h>

src/pio_impl.h

@@ -6,6 +6,7 @@
 #endif
 
 #include <stdbool.h>
+#include <unistd.h>
 
 #include <mpi.h>
 
@@ -109,7 +110,7 @@ void pioSendInitialize(void);
 
 
 /* pio_posixasynch.c */
-#ifndef _SX
+#ifdef _POSIX_ASYNCHRONOUS_IO
 void pioWriterAIO(void);
 #endif
 

src/pio_interface.c

@@ -7,6 +7,7 @@
 #include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <unistd.h>
 
 #include <mpi.h>
 #include <yaxt.h>
@@ -478,10 +479,12 @@ cdiPioInit(MPI_Comm commGlob, int confResH, int *pioNamespace)
   if ( IOMode < PIO_MINIOMODE || IOMode > PIO_MAXIOMODE )
     xabort ( "IOMODE IS NOT VALID." );
 
-#ifdef _SX
-  if ( IOMode ==  PIO_ASYNCH )
-    xabort ( "PIO_ASYNCH DOES NOT WORK ON SX." );
+  if (
+#ifdef _POSIX_ASYNCHRONOUS_IO
+      !sysconf(_SC_ASYNCHRONOUS_IO) &&
 #endif
+      IOMode == PIO_ASYNCH )
+    xabort ( "CDI-PIO Output method PIO_ASYNCH is unsupported on this system!" );
 
   if ((xtInitByCDI = (!xt_initialized() || xt_finalized())))
     xt_initialize(commGlob);
@@ -564,9 +567,7 @@ cdiPioFileWritingInit(const struct cdiPioConf *conf)
     case PIO_MPI:
       initMPINONB();
       break;
-#ifndef _SX
     case PIO_ASYNCH:
-#endif
     case PIO_WRITER:
       pioSendInitialize();
       break;

src/pio_posixasynch.c

@@ -7,8 +7,10 @@
 #endif
 
 
-#ifndef _SX
 
+#include <unistd.h>
+
+#ifdef _POSIX_ASYNCHRONOUS_IO
 #include <aio.h>
 #include <errno.h>
 #include <fcntl.h>
@@ -17,7 +19,6 @@
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <unistd.h>
 
 #include <mpi.h>
 

src/pio_record_send.c

@@ -4,6 +4,7 @@
 
 #include <inttypes.h>
 #include <stdlib.h>
+#include <unistd.h>
 
 #include "cdipio.h"
 #include "dmemory.h"
@@ -313,9 +314,11 @@ pioSendInitialize(void)
       case PIO_WRITER:
         pioWriterStdIO();
         break;
+#ifdef _POSIX_ASYNCHRONOUS_IO
       case PIO_ASYNCH:
         pioWriterAIO();
         break;
+#endif
       }
   else
     {