[PATCH 3/3] cve-update-db: refresh once every 24 hours

[Ross Burton <ross.burton@intel.com>]

Check the mtime of the database before updating, and if it's less than 24 hours
ago don't refresh.  This saves the HTTP fetches to determine if the data has
been updated.

Signed-off-by: Ross Burton <ross.burton@intel.com>
---
 meta/recipes-core/meta/cve-update-db-native.bb | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/meta/recipes-core/meta/cve-update-db-native.bb b/meta/recipes-core/meta/cve-update-db-native.bb
index cabbde5066c..2afca94fc6b 100644
--- a/meta/recipes-core/meta/cve-update-db-native.bb
+++ b/meta/recipes-core/meta/cve-update-db-native.bb
@@ -22,7 +22,7 @@ python do_populate_cve_db() {
     Update NVD database with json data feed
     """
 
-    import sqlite3, urllib, shutil, gzip, re
+    import sqlite3, urllib, shutil, gzip, re, time
     from datetime import date
 
     BASE_URL = "https://nvd.nist.gov/feeds/json/cve/1.0/nvdcve-1.0-"
@@ -37,6 +37,11 @@ python do_populate_cve_db() {
     if not os.path.isdir(db_dir):
         os.mkdir(db_dir)
 
+    expiry = time.time() - (60*60*24) # This time yesterday
+    if os.path.exists(db_file) and expiry < os.path.getmtime(db_file):
+        bb.note("CVE data updated less than 24 hours ago, not refreshing. Delete %s to force update." % db_file)
+        return
+
     # Connect to database
     conn = sqlite3.connect(db_file)
     c = conn.cursor()
-- 
2.20.1