live: generate cache.txt file in refresh

Generates a cache.txt file if a cache partition is detected.

OpenGnsys stores information about stored images in its 'cache'
partition via a text file.

The file is stored in a samba shared directory, mounted at
'/opt/opengnsys/log/' in a live client. The file name is '{ip}.cache.txt'.

Previously, the generation of this file was delegated to external bash
scripts.

1 files changed, 69 insertions, 0 deletions

diff --git a/src/utils/cache.py b/src/utils/cache.py
new file mode 100644
index 0000000..150a5df
--- /dev/null
+++ b/src/utils/cache.py
@@ -0,0 +1,69 @@
+#
+# Copyright (C) 2022 Soleta Networks <info@soleta.eu>
+#
+# This program is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the
+# Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+import os
+
+from src.utils.fs import mount_mkdir, umount
+from src.utils.net import getifaddr
+from src.utils.probe import cache_probe
+
+OGIMG='/opt/opengnsys/images/'
+OGCACHE_MOUNTPOINT='/opt/opengnsys/cache'
+OGCLIENT_LOG_CACHE='/opt/opengnsys/log/{ip}.cache.txt'
+
+def mount_cache():
+    """
+    Probes for cache and mounts if succesful.
+
+    Returns the mountpoint or an empty string.
+    """
+    cache_dev = cache_probe()
+
+    if cache_dev:
+        # cache_target = cache_dev.replace('dev', 'mnt')
+        mount_mkdir(cache_dev, OGCACHE_MOUNTPOINT)
+        return OGCACHE_MOUNTPOINT
+
+    return ''
+
+def umount_cache():
+    """
+    If OGCACHE_MOUNTPOINT is a mountpoint, umounts.
+    If not, does nothing.
+    """
+    if os.path.ismount(OGCACHE_MOUNTPOINT):
+        umount(OGCACHE_MOUNTPOINT)
+
+def write_cache_txt(content):
+    """
+    Dumps content to /opt/opengnsys/log/{ip}.cache.txt
+    """
+    client_ip = getifaddr(os.getenv('DEVICE'))
+    with open(OGCLIENT_LOG_CACHE.format(ip=client_ip), 'w') as f:
+        print("About to write")
+        f.write(content)
+
+def generate_cache_txt():
+    """
+    If no OpenGnsys cache partition is detected this function will
+    do nothing.
+
+    Generates a *.cache.txt file from a given path.
+
+    A .cache.txt file is just a comma separated list of
+    the files contained in the images folder in the OpenGnsys cache.
+    """
+    cache_path = mount_cache()
+
+    if cache_path:
+        try:
+            files = os.listdir(f'{cache_path}{OGIMG}')
+        except FileNotFoundError:
+            return
+        content = ','.join(files)
+        write_cache_txt(content)