Dont pass on requests to open executables to the OS from ebooks/metadata

This is because some OSes (windows) actually launch these executables
without asking the user

src/calibre/gui2/__init__.py

@@ -1144,6 +1144,16 @@ def open_url(qurl):
         QDesktopServices.openUrl(qurl)
 
 
+def safe_open_url(qurl):
+    if qurl.scheme() in ('', 'file'):
+        path = qurl.toLocalFile()
+        ext = os.path.splitext(path)[-1].lower()[1:]
+        if ext in ('exe', 'com', 'cmd', 'bat', 'sh', 'psh', 'ps1', 'vbs', 'js', 'wsf', 'vba', 'py', 'rb', 'pl'):
+            prints('Refusing to open file:', path)
+            return
+    open_url(qurl)
+
+
 def get_current_db():
     '''
     This method will try to return the current database in use by the user as

src/calibre/gui2/book_details.py

@@ -25,7 +25,7 @@ from calibre.ebooks.metadata.search_internet import (
 )
 from calibre.gui2 import (
     NO_URL_FORMATTING, choose_save_file, config, default_author_link, gprefs,
-    open_url, pixmap_to_data, rating_font
+    safe_open_url, pixmap_to_data, rating_font
 )
 from calibre.gui2.dnd import (
     dnd_get_files, dnd_get_image, dnd_has_extension, dnd_has_image, image_extensions
@@ -627,7 +627,7 @@ class BookInfo(QWebView):
     def link_activated(self, link):
         self._link_clicked = True
         if unicode_type(link.scheme()) in ('http', 'https'):
-            return open_url(link)
+            return safe_open_url(link)
         link = unicode_type(link.toString(NO_URL_FORMATTING))
         self.link_clicked.emit(link)
 
@@ -864,7 +864,7 @@ class BookDetails(QWidget):  # {{{
                 url = url_for_book_search(data.where, title=self.last_data['title'], author=self.last_data['authors'][0])
             else:
                 url = url_for_author_search(data.where, author=data.author)
-            open_url(url)
+            safe_open_url(url)
 
     def handle_click(self, link):
         typ, val = link.partition(':')[0::2]
@@ -879,7 +879,7 @@ class BookDetails(QWidget):  # {{{
             self.search_requested.emit(from_hex_unicode(val))
         else:
             try:
-                open_url(QUrl(link, QUrl.TolerantMode))
+                safe_open_url(QUrl(link, QUrl.TolerantMode))
             except:
                 import traceback
                 traceback.print_exc()

src/calibre/gui2/viewer/documentview.py

@@ -17,7 +17,7 @@ from PyQt5.QtWebKit import QWebSettings, QWebElement
 
 from calibre.gui2.viewer.flip import SlideFlip
 from calibre.gui2.shortcuts import Shortcuts
-from calibre.gui2 import open_url, secure_web_page, error_dialog
+from calibre.gui2 import safe_open_url, secure_web_page, error_dialog
 from calibre import prints
 from calibre.customize.ui import all_viewer_plugins
 from calibre.gui2.viewer.keys import SHORTCUTS
@@ -806,7 +806,7 @@ class DocumentView(QWebView):  # {{{
         url = self.document.search_online_url.replace('{text}', QUrl().toPercentEncoding(text))
         if not isinstance(url, bytes):
             url = url.encode('utf-8')
-        open_url(QUrl.fromEncoded(url))
+        safe_open_url(QUrl.fromEncoded(url))
 
     def set_manager(self, manager):
         self.manager = manager

src/calibre/gui2/viewer/main.py

@@ -23,7 +23,7 @@ from calibre.customize.ui import available_input_formats
 from calibre.ebooks.oeb.iterator.book import EbookIterator
 from calibre.gui2 import (
     Application, add_to_recent_docs, choose_files, error_dialog, info_dialog,
-    open_url, setup_gui_option_parser
+    safe_open_url, setup_gui_option_parser
 )
 from calibre.gui2.viewer.toc import TOC
 from calibre.gui2.viewer.ui import Main as MainWindow
@@ -433,7 +433,7 @@ class EbookViewer(MainWindow):
                     'Failed to use the custom dictionary for language: %s Falling back to default dictionary.') % lang,
                              det_msg=traceback.format_exc(), show=True)
             url = default_lookup_website(lang).format(word=word)
-        open_url(url)
+        safe_open_url(url)
 
     def print_book(self):
         if self.iterator is None:
@@ -743,7 +743,7 @@ class EbookViewer(MainWindow):
                     # entry, since this one did not cause any scrolling at all.
                     QTimer.singleShot(10, self.update_indexing_state)
         else:
-            open_url(url)
+            safe_open_url(url)
 
     def load_started(self):
         self.open_progress_indicator(_('Loading flow...'))

src/calibre/gui2/viewer/ui.py

@@ -13,7 +13,7 @@ from PyQt5.Qt import (
     QRegExpValidator, QRegExp, QPalette, QColor, QBrush, QPainter,
     QDockWidget, QSize, QWebView, QLabel, QVBoxLayout)
 
-from calibre.gui2 import rating_font, error_dialog, open_url
+from calibre.gui2 import rating_font, error_dialog, safe_open_url
 from calibre.gui2.main_window import MainWindow
 from calibre.gui2.search_box import SearchBox2
 from calibre.gui2.viewer.documentview import DocumentView
@@ -83,7 +83,7 @@ class Metadata(QWebView):  # {{{
 
     def link_clicked(self, qurl):
         if qurl.scheme() in ('http', 'https'):
-            return open_url(qurl)
+            return safe_open_url(qurl)
 
     def update_layout(self):
         self.setGeometry(0, 0, self.parent().width(), self.parent().height())