Replace opendir/closedir calls throughout the backend with AllocateDir

and FreeDir routines modeled on the existing AllocateFile/FreeFile.
Like the latter, these routines will avoid failing on EMFILE/ENFILE
conditions whenever possible, and will prevent leakage of directory
descriptors if an elog() occurs while one is open.
Also, reduce PANIC to ERROR in MoveOfflineLogs() --- this is not
critical code and there is no reason to force a DB restart on failure.
All per recent trouble report from Olivier Hubaut.

src/port/copydir.c

@@ -3,16 +3,16 @@
  *	it requires a Window handle which prevents it from working when invoked
  *	as a service.
  *
- * $Header: /cvsroot/pgsql/src/port/Attic/copydir.c,v 1.5 2003/09/10 20:12:01 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/port/Attic/copydir.c,v 1.5.2.1 2004/02/23 23:03:43 tgl Exp $
  */
 
 #include "postgres.h"
 
+#include "storage/fd.h"
+
 #undef mkdir					/* no reason to use that macro because we
 								 * ignore the 2nd arg */
 
-#include <dirent.h>
-
 
 /*
  * copydir: copy a directory (we only need to go one level deep)
@@ -37,7 +37,7 @@ copydir(char *fromdir, char *todir)
 				 errmsg("could not create directory \"%s\": %m", todir)));
 		return -1;
 	}
-	xldir = opendir(fromdir);
+	xldir = AllocateDir(fromdir);
 	if (xldir == NULL)
 	{
 		ereport(WARNING,
@@ -55,11 +55,11 @@ copydir(char *fromdir, char *todir)
 			ereport(WARNING,
 					(errcode_for_file_access(),
 					 errmsg("could not copy file \"%s\": %m", fromfl)));
-			closedir(xldir);
+			FreeDir(xldir);
 			return -1;
 		}
 	}
 
-	closedir(xldir);
+	FreeDir(xldir);
 	return 0;
 }