src: stop using hardcoded paths to cache image directory

Use the constant OG_CACHE_IMAGE_PATH from cache.py to obtain the
location of the directory where images are stored.
This way the path can be changed from one single point.

src/live/ogOperations.py

@@ -39,7 +39,6 @@ from src.log import OgError
 
 
 OG_SHELL = '/bin/bash'
-OG_CACHE_PATH = '/opt/opengnsys/cache/opt/opengnsys/images'
 
 class OgLiveOperations:
     def __init__(self, config):
@@ -181,7 +180,7 @@ class OgLiveOperations:
         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'
+        dst = f'{OG_CACHE_IMAGE_PATH}{image_name}.img'
         try:
             r = shutil.copy(src, dst)
             tip_write_csum(image_name)
@@ -194,7 +193,7 @@ class OgLiveOperations:
             raise OgError(f'Cannot change repository to {repo}')
 
         if cache:
-            image_path = f'/opt/opengnsys/cache/opt/opengnsys/images/{name}.img'
+            image_path = f'{OG_CACHE_IMAGE_PATH}{name}.img'
             if (not os.path.exists(image_path) or
                 not tip_check_csum(repo, name)):
                 self._copy_image_to_cache(name)
@@ -203,10 +202,10 @@ class OgLiveOperations:
         self._restore_image(image_path, devpath)
 
     def _restore_image_tiptorrent(self, repo, name, devpath):
-        if not os.path.exists(OG_CACHE_PATH):
+        if not os.path.exists(OG_CACHE_IMAGE_PATH):
             raise OgError('No cache partition is mounted')
 
-        image_path = f'/opt/opengnsys/cache/opt/opengnsys/images/{name}.img'
+        image_path = f'{OG_CACHE_IMAGE_PATH}{name}.img'
         try:
             if (not os.path.exists(image_path) or not tip_check_csum(repo, name)):
                 tip_client_get(repo, name)

src/utils/tiptorrent.py

@@ -14,7 +14,7 @@ import shutil
 import subprocess
 import urllib.request
 from src.log import OgError
-from src.utils.cache import mount_cache
+from src.utils.cache import *
 
 def _compute_md5(path, bs=2**20):
     m = hashlib.md5()
@@ -45,7 +45,7 @@ def tip_write_csum(image_name):
     if not mount_cache():
         raise OgError(f'Failed to checksum {image_name}: cache partition is not available')
 
-    image_path = f'/opt/opengnsys/cache/opt/opengnsys/images/{image_name}.img'
+    image_path = f'{OG_CACHE_IMAGE_PATH}{image_name}.img'
 
     if not os.path.exists(image_path):
         raise OgError(f'Invalid image path {image_path} for tiptorrent checksum writing')
@@ -65,7 +65,7 @@ def tip_check_csum(tip_addr, image_name):
     """
     """
     logging.info(f'Verifying checksum for {image_name}.img, please wait...')
-    image_path = f'/opt/opengnsys/cache/opt/opengnsys/images/{image_name}.img'
+    image_path = f'{OG_CACHE_IMAGE_PATH}{image_name}.img'
     if not os.path.exists(image_path):
         raise OgError(f'Invalid image path {image_path} for tiptorrent image csum comparison')
 
@@ -93,7 +93,7 @@ def tip_client_get(tip_addr, image_name):
     try:
         proc = subprocess.Popen(shlex.split(cmd),
                                 stdout=logfile,
-                                cwd='/opt/opengnsys/cache/opt/opengnsys/images/')
+                                cwd=OG_CACHE_IMAGE_PATH)
         proc.communicate()
     except OSError as e:
         raise OgError('Unexpected error running tiptorrent subprocess: {e}') from e