treewide: Replace <name>_cnt by n_<name>s and <name>_cap by allocated_<name>.

[pspp] / src / language / dictionary / delete-variables.c

diff --git a/src/language/dictionary/delete-variables.c b/src/language/dictionary/delete-variables.c
index ec5d45371551ed5824101337b0e02bd7ef9757da..1c38074f63c13c43be475b9c1fa009dbad01a61a 100644 (file)
--- a/src/language/dictionary/delete-variables.c
+++ b/src/language/dictionary/delete-variables.c
@@ -33,20 +33,21 @@ int
 cmd_delete_variables (struct lexer *lexer, struct dataset *ds)
 {
   struct variable **vars;
-  size_t var_cnt;
+  size_t n_vars;
   bool ok;
 
   if (proc_make_temporary_transformations_permanent (ds))
-    msg (SE, _("DELETE VARIABLES may not be used after TEMPORARY.  "
-               "Temporary transformations will be made permanent."));
+    msg (SE, _("%s may not be used after %s.  "
+               "Temporary transformations will be made permanent."),
+        "DELETE VARIABLES", "TEMPORARY");
 
-  if (!parse_variables (lexer, dataset_dict (ds), &vars, &var_cnt, PV_NONE))
+  if (!parse_variables (lexer, dataset_dict (ds), &vars, &n_vars, PV_NONE))
     goto error;
-  if (var_cnt == dict_get_var_cnt (dataset_dict (ds)))
+  if (n_vars == dict_get_n_vars (dataset_dict (ds)))
     {
-      msg (SE, _("DELETE VARIABLES may not be used to delete all variables "
+      msg (SE, _("%s may not be used to delete all variables "
                  "from the active dataset dictionary.  "
-                 "Use NEW FILE instead."));
+                 "Use %s instead."), "DELETE VARIABLES", "NEW FILE");
       goto error;
     }
 
@@ -54,7 +55,50 @@ cmd_delete_variables (struct lexer *lexer, struct dataset *ds)
   ok = proc_commit (ds) && ok;
   if (!ok)
     goto error;
-  dict_delete_vars (dataset_dict (ds), vars, var_cnt);
+
+  dict_delete_vars (dataset_dict (ds), vars, n_vars);
+
+  /* XXX A bunch of bugs conspire to make executing transformations again here
+     necessary, even though it shouldn't be.
+
+     Consider the following (which is included in delete-variables.at):
+
+        DATA LIST NOTABLE /s1 TO s2 1-2(A).
+        BEGIN DATA
+        12
+        END DATA.
+        DELETE VARIABLES s1.
+        NUMERIC n1.
+        LIST.
+
+     The DATA LIST gives us a caseproto with widths 1,1.  DELETE VARIABLES
+     deletes the first variable so we now have -1,1.  This already is
+     technically a problem because proc_casereader_read() calls
+     case_unshare_and_resize() from the former to the latter caseproto, and
+     these caseprotos are not conformable (which is a requirement for
+     case_resize()).  It doesn't cause an assert by default because
+     case_resize() uses expensive_assert() to check for it though.  However, in
+     practice we don't see a problem yet because case_resize() only does work
+     if the number of widths in the source and dest caseproto are different.
+
+     Executing NUMERIC adds a third variable, though, so we have -1,1,0.  This
+     makes caseproto_resize() notice that there are fewer strings in the new
+     caseproto.  Therefore it destroys the second one (s2).  It should destroy
+     the first one (s1), but if the caseprotos were really conformable then it
+     would have destroyed the right one.  This mistake eventually causes a bad
+     memory reference.
+
+     Executing transformations a second time after DELETE VARIABLES, like we do
+     below, works around the problem because we can never run into a situation
+     where we've got both new variables (triggering a resize) and deleted
+     variables (triggering the bad free).
+
+     We should fix this in a better way.  Doing it cleanly seems hard.  This
+     seems to work for now. */
+  ok = casereader_destroy (proc_open_filtering (ds, false));
+  ok = proc_commit (ds) && ok;
+  if (!ok)
+    goto error;
 
   free (vars);