Bug 797900 - Crash caused by Quitting while Check and Repair All is running

The account tree page didn't have a "finish" function normally used to verify a page can close.
I added one, along with two flags that indicate whether a scrubbing operation is currently ongoing
and whether we should quit when the scrubbing is done.
The result is: If a user attempts to quit while scrubbing isn't done, an alert pops up asking whether the
user wants to abort the scrub. If so, the scrub is aborted (safely) and GC quits.
If not the app does not quit.

I have to say, I'm not sure this is the right way to do this. In my view, the right way would be:
- Disable the "quit" menu when scrubbing is happening (for some reason gnc_suspend_gui_refresh() does
not cause the quit menu to be grayed) so there's no chance of quitting while scrubbing is ongoing
- If needed, add an abort scrubbing button to the main window. Not sure whether that's desirable or not.

Let me know what you think: is what I have what we need, or would the above be better.

libgnucash/engine/Scrub.c

@@ -57,6 +57,20 @@
 #define G_LOG_DOMAIN "gnc.engine.scrub"
 
 static QofLogModule log_module = G_LOG_DOMAIN;
+static gboolean abort_now = FALSE;
+static gint scrub_depth = 0;
+
+void
+gnc_set_abort_scrub (gboolean abort)
+{
+    abort_now = abort;
+}
+
+gboolean
+gnc_get_ongoing_scrub (void)
+{
+    return scrub_depth > 0;
+}
 
 /* ================================================================ */
 
@@ -64,10 +78,11 @@ void
 xaccAccountTreeScrubOrphans (Account *acc, QofPercentageFunc percentagefunc)
 {
     if (!acc) return;
-
+    scrub_depth ++;
     xaccAccountScrubOrphans (acc, percentagefunc);
     gnc_account_foreach_descendant(acc,
                                    (AccountCb)xaccAccountScrubOrphans, percentagefunc);
+    scrub_depth--;
 }
 
 static void
@@ -83,6 +98,7 @@ TransScrubOrphansFast (Transaction *trans, Account *root)
     {
         Split *split = node->data;
         Account *orph;
+        if (abort_now) break;
 
         if (split->acc) continue;
 
@@ -110,6 +126,7 @@ xaccAccountScrubOrphans (Account *acc, QofPercentageFunc percentagefunc)
     guint current_split = 0;
 
     if (!acc) return;
+    scrub_depth++;
 
     str = xaccAccountGetName (acc);
     str = str ? str : "(null)";
@@ -120,12 +137,12 @@ xaccAccountScrubOrphans (Account *acc, QofPercentageFunc percentagefunc)
     for (node = splits; node; node = node->next)
     {
         Split *split = node->data;
-
         if (current_split % 100 == 0)
         {
             char *progress_msg = g_strdup_printf (message, str, current_split, total_splits);
             (percentagefunc)(progress_msg, (100 * current_split) / total_splits);
             g_free (progress_msg);
+            if (abort_now) break;
         }
 
         TransScrubOrphansFast (xaccSplitGetParent (split),
@@ -133,6 +150,7 @@ xaccAccountScrubOrphans (Account *acc, QofPercentageFunc percentagefunc)
         current_split++;
     }
     (percentagefunc)(NULL, -1.0);
+    scrub_depth--;
 }
 
 
@@ -148,6 +166,7 @@ xaccTransScrubOrphans (Transaction *trans)
     for (node = trans->splits; node; node = node->next)
     {
         Split *split = node->data;
+        if (abort_now) break;
 
         if (split->acc)
         {
@@ -183,9 +202,13 @@ void
 xaccAccountScrubSplits (Account *account)
 {
     GList *node;
-
+    scrub_depth++;
     for (node = xaccAccountGetSplitList (account); node; node = node->next)
+    {
+        if (abort_now) break;
         xaccSplitScrub (node->data);
+    }
+    scrub_depth--;
 }
 
 void
@@ -291,9 +314,11 @@ xaccSplitScrub (Split *split)
 void
 xaccAccountTreeScrubImbalance (Account *acc, QofPercentageFunc percentagefunc)
 {
+    scrub_depth++;
     xaccAccountScrubImbalance (acc, percentagefunc);
     gnc_account_foreach_descendant(acc,
                                    (AccountCb)xaccAccountScrubImbalance, percentagefunc);
+    scrub_depth--;
 }
 
 void
@@ -305,6 +330,7 @@ xaccAccountScrubImbalance (Account *acc, QofPercentageFunc percentagefunc)
     gint split_count = 0, curr_split_no = 0;
 
     if (!acc) return;
+    scrub_depth++;
 
     str = xaccAccountGetName(acc);
     str = str ? str : "(null)";
@@ -316,6 +342,7 @@ xaccAccountScrubImbalance (Account *acc, QofPercentageFunc percentagefunc)
     {
         Split *split = node->data;
         Transaction *trans = xaccSplitGetParent(split);
+        if (abort_now) break;
 
         PINFO("Start processing split %d of %d",
               curr_split_no + 1, split_count);
@@ -340,6 +367,7 @@ xaccAccountScrubImbalance (Account *acc, QofPercentageFunc percentagefunc)
         curr_split_no++;
     }
     (percentagefunc)(NULL, -1.0);
+    scrub_depth--;
 }
 
 static Split *
@@ -1243,19 +1271,22 @@ scrub_trans_currency_helper (Transaction *t, gpointer data)
 static void
 scrub_account_commodity_helper (Account *account, gpointer data)
 {
+    scrub_depth++;
     xaccAccountScrubCommodity (account);
     xaccAccountDeleteOldData (account);
+    scrub_depth--;
 }
 
 void
 xaccAccountTreeScrubCommodities (Account *acc)
 {
     if (!acc) return;
-
+    scrub_depth++;
     xaccAccountTreeForEachTransaction (acc, scrub_trans_currency_helper, NULL);
 
     scrub_account_commodity_helper (acc, NULL);
     gnc_account_foreach_descendant (acc, scrub_account_commodity_helper, NULL);
+    scrub_depth--;
 }
 
 /* ================================================================ */
@@ -1315,13 +1346,14 @@ xaccAccountTreeScrubQuoteSources (Account *root, gnc_commodity_table *table)
         LEAVE("Oops");
         return;
     }
-
+    scrub_depth++;
     gnc_commodity_table_foreach_commodity (table, check_quote_source, &new_style);
 
     move_quote_source(root, GINT_TO_POINTER(new_style));
     gnc_account_foreach_descendant (root, move_quote_source,
                                     GINT_TO_POINTER(new_style));
     LEAVE("Migration done");
+    scrub_depth--;
 }
 
 /* ================================================================ */
@@ -1333,6 +1365,7 @@ xaccAccountScrubKvp (Account *account)
     gchar *str2;
 
     if (!account) return;
+    scrub_depth++;
 
     qof_instance_get_kvp (QOF_INSTANCE (account), &v, 1, "notes");
     if (G_VALUE_HOLDS_STRING (&v))
@@ -1350,6 +1383,7 @@ xaccAccountScrubKvp (Account *account)
         qof_instance_slot_delete (QOF_INSTANCE (account), "placeholder");
 
     qof_instance_slot_delete_if_empty (QOF_INSTANCE (account), "hbci");
+    scrub_depth--;
 }
 
 /* ================================================================ */

libgnucash/engine/Scrub.h

@@ -69,6 +69,16 @@
     for orphaned inodes.
     @{  */
 
+/** The gnc_set_abort_scrub () method causes a currently running scrub operation
+ *    to stop, if abort is TRUE; gnc_set_abort_scrub(FALSE) must be called before
+ *    any scrubbing operation.
+ */
+void gnc_set_abort_scrub (gboolean abort);
+
+/** The gnc_get_ongoing_scrub () method returns TRUE if a scrub operation is ongoing.
+ */
+gboolean gnc_get_ongoing_scrub (void);
+
 /** The xaccTransScrubOrphans() method scrubs only the splits in the
  *    given transaction.
  */