E-book viewer: Handle links to missing internal files with an error popup rather than becoming non-functional

src/calibre/srv/render_book.py

@@ -13,7 +13,7 @@ from itertools import count
 
 from lxml.etree import Comment
 
-from calibre import detect_ncpus, force_unicode, prepare_string_for_xml
+from calibre import detect_ncpus, prepare_string_for_xml
 from calibre.customize.ui import plugin_for_input_format
 from calibre.ebooks.oeb.base import EPUB, OEB_DOCS, OEB_STYLES, OPF, SMIL, XHTML, XHTML_NS, XLINK, rewrite_links, urlunquote
 from calibre.ebooks.oeb.base import XPath as _XPath
@@ -33,7 +33,7 @@ from polyglot.binary import as_base64_unicode as encode_component
 from polyglot.binary import from_base64_bytes
 from polyglot.binary import from_base64_unicode as decode_component
 from polyglot.builtins import as_bytes
-from polyglot.urllib import quote, urlparse
+from polyglot.urllib import urlparse
 
 try:
     from calibre_extensions.speedup import get_num_of_significant_chars
@@ -98,9 +98,7 @@ def create_link_replacer(container, link_uid, changed):
                 frag = urlunquote(frag)
                 url = resource_template.format(encode_url(name, frag))
             else:
-                if isinstance(name, str):
+                url = 'missing:' + name
-                    name = name.encode('utf-8')
-                url = 'missing:' + force_unicode(quote(name), 'utf-8')
             changed.add(base)
         return url
 
@@ -475,14 +473,18 @@ def transform_html(container, name, virtualize_resources, link_uid, link_to_map,
                 href = link_replacer(name, href)
             elif attr in a.attrib:
                 a.set(attr, 'javascript:void(0)')
-            if href and href.startswith(link_uid):
+            if href:
-                a.set(attr, 'javascript:void(0)')
+                if href.startswith(link_uid):
-                parts = href.split('|')
+                    a.set(attr, 'javascript:void(0)')
-                if len(parts) > 1:
+                    parts = href.split('|')
-                    parts = decode_url(parts[1])
+                    if len(parts) > 1:
-                    lname, lfrag = parts[0], parts[1]
+                        parts = decode_url(parts[1])
-                    link_to_map.setdefault(lname, {}).setdefault(lfrag or '', set()).add(name)
+                        lname, lfrag = parts[0], parts[1]
-                    a.set('data-' + link_uid, json.dumps({'name':lname, 'frag':lfrag}, ensure_ascii=False))
+                        link_to_map.setdefault(lname, {}).setdefault(lfrag or '', set()).add(name)
+                        a.set('data-' + link_uid, json.dumps({'name':lname, 'frag':lfrag}, ensure_ascii=False))
+                elif href.startswith('missing:'):
+                    a.set(attr, 'javascript:void(0)')
+                    a.set('data-' + link_uid, json.dumps({'name':href[len('missing:'):], 'frag':'', 'missing': True}, ensure_ascii=False))
 
         for a in link_xpath(root):
             handle_link(a)
@@ -519,8 +521,12 @@ def virtualize_html(container, name, link_uid, link_to_map, virtualized_names):
                 link_to_map.setdefault(lname, {}).setdefault(lfrag or '', set()).add(name)
                 a.set('data-' + link_uid, json.dumps({'name':lname, 'frag':lfrag}, ensure_ascii=False))
         elif href:
-            a.set('target', '_blank')
+            if href.startswith('missing:'):
-            a.set('rel', 'noopener noreferrer')
+                a.set(attr, 'javascript:void(0)')
+                a.set('data-' + link_uid, json.dumps({'name':href[len('missing:'):], 'frag':'', 'missing': True}, ensure_ascii=False))
+            else:
+                a.set('target', '_blank')
+                a.set('rel', 'noopener noreferrer')
         elif attr in a.attrib:
             a.set(attr, 'javascript:void(0)')
 
@@ -978,7 +984,7 @@ def develop(max_workers=1, wait_for_input=True):
     with TemporaryDirectory() as tdir:
         render(
             path, tdir, serialize_metadata=True,
-            extract_annotations=True, virtualize_resources=True, max_workers=max_workers
+            extract_annotations=True, virtualize_resources=False, max_workers=max_workers
         )
         print('Extracted to:', tdir)
         if wait_for_input:

src/pyj/read_book/iframe.pyj

@@ -745,7 +745,10 @@ class IframeBoss:
         except:
             print('WARNING: Failed to parse link data {}, ignoring'.format(evt.currentTarget?.getAttribute?(self.link_attr)))
             return
-        self.activate_link(data.name, data.frag, evt.currentTarget)
+        if data.missing:
+            self.send_message('link_to_missing_activated', name=data.name)
+        else:
+            self.activate_link(data.name, data.frag, evt.currentTarget)
 
     def activate_link(self, name, frag, target_elem):
         if not name:

src/pyj/read_book/view.pyj

@@ -254,6 +254,7 @@ class View:
             'report_cfi': self.on_report_cfi,
             'request_size': self.on_request_size,
             'scroll_to_anchor': self.on_scroll_to_anchor,
+            'link_to_missing_activated': self.on_link_to_missing_activated,
             'selectionchange': self.on_selection_change,
             'update_selection_position': self.update_selection_position,
             'columns_per_screen_changed': self.on_columns_per_screen_changed,
@@ -1122,6 +1123,9 @@ class View:
         frag = item.frag or ''
         self.show_name(name, initial_position={'type':'pagelist_ref', 'anchor':frag, 'replace_history':False})
 
+    def on_link_to_missing_activated(self, data):
+        ui_operations.show_error(_('Invalid link'), _('This link points to the file {} which does not exist in the book').format(data.name))
+
     def on_scroll_to_anchor(self, data):
         self.show_name(data.name, initial_position={'type':'anchor', 'anchor':data.frag, 'replace_history':False})