Fix ':close' command

Currently, zathura crashes while performing ':close' command with the
following error:

GThread-ERROR **: file gthread-posix.c: line 226
(g_cond_free_posix_impl): error 'Device or resource busy' during
'pthread_cond_destroy ((pthread_cond_t *) cond)'

The error is because 'render' thread holds condition variable while
waiting for new pages to render. This patch modifies zathura's code to
correctly kill render thread and free allocated resources when the
document is being closed.

NOTE: should be applied on top of "Allow changing of "pages-per-row"
variable at runtime" commit to avoid conflicts in the
'page_view_set_mode()' function.
Signed-off-by: Pavel Borzenkov <pavel.borzenkov@gmail.com>

document.c

@@ -305,6 +305,7 @@ zathura_document_free(zathura_document_t* document)
   for (unsigned int page_id = 0; page_id < document->number_of_pages; page_id++)
   {
     zathura_page_free(document->pages[page_id]);
+    document->pages[page_id] = NULL;
   }
 
   free(document->pages);
@@ -427,6 +428,8 @@ zathura_page_free(zathura_page_t* page)
     return false;
   }
 
+  g_static_mutex_free(&(page->lock));
+
   return page->document->functions.page_free(page);
 }
 

render.c

@@ -17,6 +17,17 @@ render_job(void* data)
       g_cond_wait(render_thread->cond, render_thread->lock);
     }
 
+    if (girara_list_size(render_thread->list) <= 0) {
+      /*
+       * We've been signaled with g_cond_signal(), but the list
+       * is still empty. This means that the signal came from
+       * render_free() and current document is being closed.
+       * We should unlock the mutex and kill the thread.
+       */
+      g_mutex_unlock(render_thread->lock);
+      g_thread_exit(0);
+    }
+
     zathura_page_t* page = (zathura_page_t*) girara_list_nth(render_thread->list, 0);
     girara_list_remove(render_thread->list, page);
     g_mutex_unlock(render_thread->lock);
@@ -104,6 +115,8 @@ render_free(render_thread_t* render_thread)
   }
 
   if (render_thread->cond) {
+    g_cond_signal(render_thread->cond);
+    g_thread_join(render_thread->thread);
     g_cond_free(render_thread->cond);
   }
 

zathura.c

@@ -308,6 +308,16 @@ error_out:
   return false;
 }
 
+static void
+remove_page_from_table(GtkWidget* page, gpointer permanent)
+{
+  if (!permanent) {
+    g_object_ref(G_OBJECT(page));
+  }
+
+  gtk_container_remove(GTK_CONTAINER(page->parent), page);
+}
+
 bool
 document_close(zathura_t* zathura)
 {
@@ -315,11 +325,15 @@ document_close(zathura_t* zathura)
     return false;
   }
 
-  if (zathura->sync.render_thread) {
   render_free(zathura->sync.render_thread);
-  }
+  zathura->sync.render_thread = NULL;
+
+  gtk_container_foreach(GTK_CONTAINER(zathura->ui.page_view), remove_page_from_table, (gpointer)1);
 
   zathura_document_free(zathura->document);
+  zathura->document = NULL;
+
+  gtk_widget_hide_all(zathura->ui.page_view);
 
   return true;
 }
@@ -378,8 +392,6 @@ statusbar_page_number_update(zathura_t* zathura)
 void
 page_view_set_mode(zathura_t* zathura, unsigned int pages_per_row)
 {
-  GList* child;
-
   /* show at least one page */
   if (pages_per_row == 0) {
     pages_per_row = 1;
@@ -389,12 +401,7 @@ page_view_set_mode(zathura_t* zathura, unsigned int pages_per_row)
     return;
   }
 
-  child = gtk_container_get_children(GTK_CONTAINER(zathura->ui.page_view));
-  while (child) {
-    g_object_ref(G_OBJECT(child->data));
-    gtk_container_remove(GTK_CONTAINER(zathura->ui.page_view), GTK_WIDGET(child->data));
-    child = g_list_next(child);
-  }
+  gtk_container_foreach(GTK_CONTAINER(zathura->ui.page_view), remove_page_from_table, (gpointer)0);
 
   gtk_table_resize(GTK_TABLE(zathura->ui.page_view), zathura->document->number_of_pages / pages_per_row + 1, pages_per_row);
   for (unsigned int i = 0; i < zathura->document->number_of_pages; i++)