No error 500 if kindlegen is not excecutable

cps/helper.py

@@ -86,8 +86,14 @@ def make_mobi(book_id, calibrepath):
 
     file_path = os.path.join(calibrepath, book.path, data.name)
     if os.path.exists(file_path + u".epub"):
+        try:
             p = subprocess.Popen((kindlegen + " \"" + file_path + u".epub\"").encode(sys.getfilesystemencoding()),
                                  stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
+        except:
+            error_message = _(u"kindlegen failed, no excecution permissions")
+            app.logger.error("make_mobi: "+error_message)
+            return error_message, RET_FAIL
+
         # Poll process for new output until finished
         while True:
             nextline = p.stdout.readline()
@@ -117,7 +123,7 @@ def make_mobi(book_id, calibrepath):
             return file_path + ".mobi", RET_SUCCESS
         else:
             app.logger.error("make_mobi: kindlegen failed with error while converting book")
-            return error_message, RET_FAIL
+            return None, RET_FAIL
     else:
         app.logger.error("make_mobi: epub not found: %s.epub" % file_path)
         return None, RET_FAIL

cps/web.py

@@ -1261,6 +1261,7 @@ def stats():
         kindlegen = os.path.join(vendorpath, u"kindlegen")
     versions['KindlegenVersion'] = _('not installed')
     if os.path.exists(kindlegen):
+        try:
             p = subprocess.Popen(kindlegen, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
             p.wait()
             for lines in p.stdout.readlines():
@@ -1268,6 +1269,8 @@ def stats():
                     lines = lines.decode('utf-8')
                 if re.search('Amazon kindlegen\(', lines):
                     versions['KindlegenVersion'] = lines
+        except:
+            versions['KindlegenVersion'] = _('Excecution permissions missing')
     versions['PythonVersion'] = sys.version
     versions['babel'] = babelVersion
     versions['sqlalchemy'] = sqlalchemyVersion