Bug 797853 - Crash on 'Save As' in MacOS Mojave and Gnucash 4

Check and handle null books throughout GnuCash. Tests are left alone
because they should fail if there's no book.

gnucash/gnome-utils/gnc-tree-view-account.c

@@ -2507,6 +2507,7 @@ tree_restore_expanded_row (GncTreeViewAccount *view,
     QofBook *book;
 
     book = qof_session_get_book(gnc_get_current_session());
+    g_return_if_fail(book);
     account = gnc_account_lookup_by_full_name(gnc_book_get_root_account(book),
               account_name);
     if (account)
@@ -2529,6 +2530,7 @@ tree_restore_selected_row (GncTreeViewAccount *view,
     QofBook *book;
 
     book = qof_session_get_book(gnc_get_current_session());
+    g_return_if_fail(book);
     account = gnc_account_lookup_by_full_name(gnc_book_get_root_account(book),
               account_name);
     if (account)

gnucash/gnome/dialog-invoice.c

@@ -3556,6 +3556,12 @@ gnc_invoice_show_docs_due (GtkWindow *parent, QofBook *book, double days_in_adva
         { NULL },
     };
 
+    if (!book)
+    {
+        PERR("No book, no due invoices.");
+        return NULL;
+    }
+
     /* Create the param list (in reverse order) */
     if (param_list == NULL)
     {

gnucash/gnome/dialog-price-editor.c

@@ -653,10 +653,12 @@ GNCPrice *
 gnc_price_edit_by_guid (GtkWidget * parent, const GncGUID * guid)
 {
     GNCPrice *price;
-    QofSession *session;
+    QofSession *session = gnc_get_current_session();
+    QofBook* book = qof_session_get_book (session);
 
-    session = gnc_get_current_session ();
+    if (!book)
-    price = gnc_price_lookup (guid, qof_session_get_book(session));
+        return (NULL);
+    price = gnc_price_lookup (guid, book);
     if (price == NULL)
         return(NULL);
 

gnucash/gnome/gnc-plugin-page-register.c

@@ -1816,6 +1816,11 @@ gnc_plugin_page_register_recreate_page (GtkWidget* window,
         include_subs = (g_ascii_strcasecmp (reg_type, LABEL_SUBACCOUNT) == 0);
         DEBUG ("Include subs: %d", include_subs);
         book = qof_session_get_book (gnc_get_current_session());
+        if (book)
+        {
+            LEAVE("Session has no book");
+            return NULL;
+        }
         acct_guid = g_key_file_get_string (key_file, group_name,
                                            KEY_ACCOUNT_GUID, &error);
         if (string_to_guid (acct_guid, &guid)) //find account by guid

gnucash/gnome/gnc-plugin-page-register2.c

@@ -1495,6 +1495,11 @@ gnc_plugin_page_register2_recreate_page (GtkWidget *window,
         acct_name = g_key_file_get_string (key_file, group_name,
                                           KEY_ACCOUNT_NAME, &error);
         book = qof_session_get_book (gnc_get_current_session());
+        if (book)
+        {
+            LEAVE("Session has no book");
+            return NULL;
+        }
         account = gnc_account_lookup_by_full_name (gnc_book_get_root_account(book),
                   acct_name);
         g_free (acct_name);

gnucash/gnome/top-level.c

@@ -359,6 +359,11 @@ gnc_save_all_state (gpointer session, gpointer unused)
 
     /* Store the book's GncGUID in the top level group */
     book = qof_session_get_book(session);
+    if (!book)
+    {
+        PERR("Session has no book!");
+        return;
+    }
     guid = qof_entity_get_guid(QOF_INSTANCE(book));
     guid_to_string_buff(guid, guid_string);
     g_key_file_set_string(keyfile, STATE_FILE_TOP, STATE_FILE_BOOK_GUID,

libgnucash/engine/engine-helpers.c

@@ -55,16 +55,19 @@ static QofLogModule log_module = GNC_MOD_ENGINE;
 const char *
 gnc_get_num_action (const Transaction *trans, const Split *split)
 {
-    gboolean num_action = qof_book_use_split_action_for_num_field
-                           (qof_session_get_book(gnc_get_current_session ()));
-
     if (trans && !split)
         return xaccTransGetNum(trans);
     if (split && !trans)
         return xaccSplitGetAction(split);
     if (trans && split)
     {
-        if (num_action)
+        QofBook* book = qof_session_get_book(gnc_get_current_session ());
+        if (!book)
+        {
+            PERR("Session has no book but has a transaction or split!");
+            return NULL;
+        }
+        if (qof_book_use_split_action_for_num_field (book))
             return xaccSplitGetAction(split);
         else
             return xaccTransGetNum(trans);

libgnucash/engine/qofbook.cpp

@@ -509,6 +509,7 @@ qof_book_get_session_dirty_time (const QofBook *book)
 void
 qof_book_set_dirty_cb(QofBook *book, QofBookDirtyCB cb, gpointer user_data)
 {
+    g_return_if_fail(book);
     if (book->dirty_cb)
         PWARN("Already existing callback %p, will be overwritten by %p\n",
                   book->dirty_cb, cb);
@@ -1045,7 +1046,7 @@ qof_book_use_trading_accounts (const QofBook *book)
 gboolean
 qof_book_use_split_action_for_num_field (const QofBook *book)
 {
-    g_assert(book);
+    g_return_val_if_fail (book, FALSE);
     if (!book->cached_num_field_source_isvalid)
     {
         // No cached value? Then do the expensive KVP lookup