create_disk_images: modify image filenames

Include computer name in filename for each disk and use a shorter hash
placed immediately after task name. The hash is now based only on
student ID and class_name, so it is always the same for each student.
This should make images easier to locate in a large directory.

1 files changed, 5 insertions, 5 deletions

diff --git a/kpov_judge/create_disk_images.py b/kpov_judge/create_disk_images.py
index 6777226..2f8fffe 100755
--- a/kpov_judge/create_disk_images.py
+++ b/kpov_judge/create_disk_images.py
@@ -23,11 +23,11 @@ def get_prepare_disks(db, class_id, task_id):
     exec(compile(prepare_disks_source, 'prepare_disks.py', 'exec'), globals(), d)
     return d['prepare_disks']
 
-def create_snapshot(class_id, task_id, student_id, disk_name, fmt='vmdk', overwrite=True):
+def create_snapshot(class_id, task_id, student_id, computer_name, disk_name, fmt='vmdk', overwrite=True):
     # add a hash to filename to allow multiple students using the same directory
-    snap_hash = hashlib.sha1((disk_name+class_id+task_id+student_id).encode()).hexdigest()[:4]
-    snap = '{}-{}-{}.{}'.format(
-        task_id, disk_name, snap_hash, fmt)
+    snap_hash = hashlib.sha1((student_id+class_id).encode()).hexdigest()[:3]
+    snap = '{}-{}-{}-{}.{}'.format(
+        task_id, snap_hash, computer_name, disk_name, fmt)
     backing = []
 
     template = disk_name + '.' + fmt
@@ -85,7 +85,7 @@ def prepare_task_disks(class_id, task_id, student_id, fmt, computers):
         g = guestfs.GuestFS()
         for disk in computer['disks']:
             lock_fp.write("register " + disk['name'] + '\n')
-            task_dir, snap, backing = create_snapshot(class_id, task_id, student_id, disk['name'], fmt=fmt)
+            task_dir, snap, backing = create_snapshot(class_id, task_id, student_id, computer['name'], disk['name'], fmt=fmt)
             snap_file = os.path.join(settings.STUDENT_DISK_PATH, task_dir, snap)
             if 'options' in disk:
                 g.add_drive_opts(snap_file, **(disk['options']))