html/generate.py: improve cache file handling

Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>

1 files changed, 12 insertions, 4 deletions

diff --git a/html/generate.py b/html/generate.py
index 8eb7622..8d79cbe 100755
--- a/html/generate.py
+++ b/html/generate.py
@@ -15,6 +15,8 @@
 
 import datetime
 import socket
+import os
+import tempfile
 import urllib.request, json
 import xml.etree.ElementTree as ET
 import jinja2
@@ -81,8 +83,12 @@ def renderStatsTemplate(templateEnv, page):
 
 
 # read the cache
-with open(cache_path) as json_file:
-    cache_data = json.load(json_file)
+if os.path.exists(cache_path):
+    with open(cache_path, mode='rt') as json_file:
+        try:
+            cache_data = json.load(json_file)
+        except:
+            pass
 
 #
 # The all mirrors that are present in the given list
@@ -169,8 +175,10 @@ template.stream(lastUpdate=lastUpdate).dump(html_folder + "help.html")
 #
 # write the cache
 #
-with open(cache_path, 'w') as fp:
-    json.dump(cache_data, fp)
+with tempfile.NamedTemporaryFile(dir=os.path.dirname(cache_path), delete=False, mode='wt') as fout:
+    json.dump(cache_data, fout)
+    os.chmod(fout.name, '0644')
+    os.replace(fout.name, cache_path)
 
 
 #