fix open/3 munging filenames in write mode

H/YapGFlagInfo.h

@@ -291,7 +291,7 @@ Read-only flag telling the maximum arity of a functor. Takes the value
              "256", NULL),
     YAP_FLAG(OCCURS_CHECK_FLAG, "occurs_check", true, booleanFlag, "false", NULL),
     YAP_FLAG(OPEN_EXPANDS_FILENAME_FLAG, "open_expands_filename", true, booleanFlag,
-             "true", NULL), /**< `open_expands_filename `
+             "false", NULL), /**< `open_expands_filename `
 
 If `true` the open/3 builtin performs filename-expansion
 before opening a file (SICStus Prolog like). If `false` it does not

os/edio.yap

@@ -129,6 +129,7 @@ simultaneously opened streams is 17.
 
 */
 told :- current_output(Stream),
+        flush_output(Stream),
         !,
 	set_output(user),
 	close(Stream).

os/sysbits.c

@@ -7,7 +7,6 @@
  * Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997	 *
  *									 *
  **************************************************************************
- *				PrologPathProkoh
  *									 *
  * File:		sysbits.c *
  * Last rev:	4/03/88							 *
@@ -519,12 +518,13 @@ static const char *myrealpath(const char *path, char *out) {
     }
     // rc = NULL;
     if (errno == ENOENT || errno == EACCES) {
-      char base[YAP_FILENAME_MAX];
+      char base[YAP_FILENAME_MAX+1];
       strncpy(base, path, YAP_FILENAME_MAX - 1);
       rc = realpath(dirname(base), NULL);
 
       if (rc) {
-        const char *b = basename(base);
+	// base may haave been destroyed
+        const char *b = basename(path);
         size_t e = strlen(rc);
         size_t bs = strlen(b);
 
@@ -585,6 +585,11 @@ static const char *expandVars(const char *spec, char *u) {
 const char *Yap_AbsoluteFile(const char *spec, char *rc0, bool ok) {
   const char *p;
   const char *rc;
+  if (!ok) {
+    if (!rc0)
+      rc0 = malloc(strlen(spec)+1);
+    return strcpy(rc0, spec);
+  }
   rc = PlExpandVars(spec, NULL, rc0);
   if (!rc)
     rc = spec;