X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Flanguage%2Fdictionary%2Fdelete-variables.c;h=1c38074f63c13c43be475b9c1fa009dbad01a61a;hb=06b59daf76fdd55f29302f02ea66e06b35043e5b;hp=526fa1cd41f5e755ca86d55322670c57facbf521;hpb=81579d9e9f994fb2908f50af41c3eb033d216e58;p=pspp

diff --git a/src/language/dictionary/delete-variables.c b/src/language/dictionary/delete-variables.c
index 526fa1cd41..1c38074f63 100644
--- a/src/language/dictionary/delete-variables.c
+++ b/src/language/dictionary/delete-variables.c
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2006, 2007, 2011 Free Software Foundation, Inc.
+   Copyright (C) 2006, 2007, 2010, 2011, 2013 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -19,8 +19,8 @@
 #include <stdlib.h>
 
 #include "data/casereader.h"
+#include "data/dataset.h"
 #include "data/dictionary.h"
-#include "data/procedure.h"
 #include "language/command.h"
 #include "language/lexer/variable-parser.h"
 #include "libpspp/message.h"
@@ -33,27 +33,72 @@ 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 "
-                 "from the active file dictionary.  Use NEW FILE instead."));
+      msg (SE, _("%s may not be used to delete all variables "
+                 "from the active dataset dictionary.  "
+                 "Use %s instead."), "DELETE VARIABLES", "NEW FILE");
       goto error;
     }
 
-  ok = casereader_destroy (proc_open (ds));
+  ok = casereader_destroy (proc_open_filtering (ds, false));
+  ok = proc_commit (ds) && ok;
+  if (!ok)
+    goto error;
+
+  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;
-  dict_delete_vars (dataset_dict (ds), vars, var_cnt);
 
   free (vars);