op-mode: T6514: rework the "show system storage" code

to handle live CD systems correctly
and allow reusing the functions from other scripts

1 files changed, 50 insertions, 1 deletions

diff --git a/python/vyos/utils/disk.py b/python/vyos/utils/disk.py
index ee540b107..d4271ebe1 100644
--- a/python/vyos/utils/disk.py
+++ b/python/vyos/utils/disk.py
@@ -1,4 +1,4 @@
-# Copyright 2023 VyOS maintainers and contributors <maintainers@vyos.io>
+# Copyright 2023-2024 VyOS maintainers and contributors <maintainers@vyos.io>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -21,3 +21,52 @@ def device_from_id(id):
     for device in path.iterdir():
         if device.name.endswith(id):
             return device.readlink().stem
+
+def get_storage_stats(directory, human_units=True):
+    """ Return basic storage stats for given directory """
+    from re import sub as re_sub
+    from vyos.utils.process import cmd
+    from vyos.utils.convert import human_to_bytes
+
+    # XXX: using `df -h` and converting human units to bytes
+    # may seem pointless, but there's a reason.
+    # df uses different header field names with `-h` and without it ("Size" vs "1K-blocks")
+    # and outputs values in 1K blocks without `-h`,
+    # so some amount of conversion is needed anyway.
+    # Using `df -h` by default seems simpler.
+    #
+    # This is what the output looks like, as of Debian Buster/Bullseye:
+    # $ df -h -t ext4 --output=source,size,used,avail,pcent
+    # Filesystem      Size  Used Avail Use%
+    # /dev/sda1        16G  7.6G  7.3G  51%
+
+    out = cmd(f"df -h --output=source,size,used,avail,pcent {directory}")
+    lines = out.splitlines()
+    lists = [l.split() for l in lines]
+    res = {lists[0][i]: lists[1][i] for i in range(len(lists[0]))}
+
+    convert = (lambda x: x) if human_units else human_to_bytes
+
+    stats = {}
+
+    stats["filesystem"] = res["Filesystem"]
+    stats["size"] = convert(res["Size"])
+    stats["used"] = convert(res["Used"])
+    stats["avail"] = convert(res["Avail"])
+    stats["use_percentage"] = re_sub(r'%', '', res["Use%"])
+
+    return stats
+
+def get_persistent_storage_stats(human_units=True):
+    from os.path import exists as path_exists
+
+    persistence_dir = "/usr/lib/live/mount/persistence"
+    if path_exists(persistence_dir):
+        stats = get_storage_stats(persistence_dir, human_units=human_units)
+    else:
+        # If the persistence path doesn't exist,
+        # the system is running from a live CD
+        # and the concept of persistence storage stats is not applicable
+        stats = None
+
+    return stats