live: support native unicast cache image restore

UNICAST-CACHE consist of:

1. Checking if the target image is already present at the opengnsys
   cache partition. If so, check for integrity (local and remote
   checksum). If the image is not present in the cache partition,
   download the target image into it.
2. Restore the image from cache partition.

This commit add support for this operation natively from ogClient
Python's code.

src/live/ogOperations.py

@@ -119,11 +119,34 @@ class OgLiveOperations:
         with open(filename, 'w') as f:
             f.write(dig)
 
-    def _restore_image_unicast(self, repo, name, devpath):
+    def _copy_image_to_cache(self, image_name):
-        image_path = f'/opt/opengnsys/images/{name}.img'
+        """
+        Copies /opt/opengnsys/image/{image_name} into
+        /opt/opengnsys/cache/opt/opengnsys/images/
+
+        Implies a unicast transfer. Does not use tiptorrent.
+        """
+        src = f'/opt/opengnsys/images/{image_name}.img'
+        dst = f'/opt/opengnsys/cache/opt/opengnsys/images/{image_name}.img'
+        try:
+            r = shutil.copy(src, dst)
+            tip_write_csum(image_name)
+        except:
+            logging.error('Error copying image to cache', repo)
+            raise ValueError(f'Error: Cannot copy image {image_name} to cache')
+
+    def _restore_image_unicast(self, repo, name, devpath, cache=False):
         if ogChangeRepo(repo).returncode != 0:
             logging.error('ogChangeRepo could not change repository to %s', repo)
             raise ValueError(f'Error: Cannot change repository to {repo}')
+        logging.debug(f'restore_image_unicast: name => {name}')
+        if cache:
+            image_path = f'/opt/opengnsys/cache/opt/opengnsys/images/{name}.img'
+            if (not os.path.exists(image_path) or
+                not tip_check_csum(repo, name)):
+                self._copy_image_to_cache(name)
+        else:
+            image_path = f'/opt/opengnsys/images/{name}.img'
         self._restore_image(image_path, devpath)
 
     def _restore_image_tiptorrent(self, repo, name, devpath):
@@ -134,10 +157,15 @@ class OgLiveOperations:
         self._restore_image(image_path, devpath)
 
     def _restore_image(self, image_path, devpath):
+        logging.debug(f'Restoring image at {image_path} into {devpath}')
         cmd_lzop = shlex.split(f'lzop -dc {image_path}')
         cmd_pc = shlex.split(f'partclone.restore -d0 -C -I -o {devpath}')
         cmd_mbuffer = shlex.split('mbuffer -q -m 40M') if shutil.which('mbuffer') else None
 
+        if not os.path.exists(image_path):
+            logging.error('f{image_path} does not exist, exiting.')
+            raise ValueError(f'Error: Image not found at {image_path}')
+
         with open('/tmp/command.log', 'wb', 0) as logfile:
             proc_lzop = subprocess.Popen(cmd_lzop,
                                          stdout=subprocess.PIPE)
@@ -309,7 +337,8 @@ class OgLiveOperations:
         if shutil.which('restoreImageCustom'):
             restoreImageCustom(repo, name, disk, partition, ctype)
         elif 'UNICAST' in ctype:
-            self._restore_image_unicast(repo, name, partdev)
+            cache = 'DIRECT' not in ctype
+            self._restore_image_unicast(repo, name, partdev, cache)
         elif ctype == 'TIPTORRENT':
             self._restore_image_tiptorrent(repo, name, partdev)