From efe680e8138aa06926eb8665f72b5b656e9c03e9 Mon Sep 17 00:00:00 2001
From: timeshifter <timeshifter@sumatrae>
Date: Thu, 2 Dec 2021 16:53:39 +0100
Subject: [PATCH] add: skip decrypt if already decrypted

---
 zfs-backup.py | 57 +++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 44 insertions(+), 13 deletions(-)

diff --git a/zfs-backup.py b/zfs-backup.py
index 1dcca33..6ef6279 100755
--- a/zfs-backup.py
+++ b/zfs-backup.py
@@ -47,7 +47,6 @@ def main():
 # TODO tests
 # TODO docstrings
 # TODO first backup
-# TODO --skip-decrypt
 # TODO --skip-import
 # TODO --skip-post-backup-scrub
 # TODO print time estimation while scrub is in progress
@@ -362,25 +361,16 @@ class Time:
 class Disk:
     def __init__(self, uuid: UUID, name: str):
         self.uuid = uuid
-        self._decrypted = False
+        self._decrypted: bool = False
+        self._was_already_decrypted: bool = False
         self._name = name
 
     def decrypt(self) -> None:
         if self._decrypted:
             raise ValueError(ALREADY_DECRYPTED, self._name)
-        self._verify_mapper_entry_not_in_use()
-        self._decrypt_with_cryptsetup()
+        self._was_already_decrypted = Cryptsetup.decrypt(self._path, self._mapper_entry)
         self._decrypted = True
 
-    def _decrypt_with_cryptsetup(self):
-        Command.run([config.CRYPTSETUP, "open", self._path, self._mapper_entry])
-
-    def _verify_mapper_entry_not_in_use(self):
-        for item in MAPPER_PATH.iterdir():
-            if self._mapper_entry == item.name:
-                print(MAPPER_ENTRY_ALREADY_EXISTS, self._mapper_entry)
-                exit(EXIT_ERROR)
-
     @property
     def _path(self) -> Path:
         return DISK_BY_UUID / str(self.uuid)
@@ -392,10 +382,51 @@ class Disk:
     def encrypt(self):
         if not self._decrypted:
             raise ValueError(NOT_DECRYPTED, self._name)
+        if self._was_already_decrypted:
+            return
         Command.run([config.CRYPTSETUP, "close", self._mapper_entry])
         self._decrypted = False
 
 
+class Cryptsetup:
+    @classmethod
+    def _status(cls, name: str) -> str:
+        return Command.get_output([config.CRYPTSETUP, "status", name])
+
+    @classmethod
+    def decrypt(cls, path: Path, mapper_entry: str) -> bool:
+        if cls._mapper_entry_in_use(mapper_entry):
+            if cls._already_decrypted(path, mapper_entry):
+                return True
+            print(MAPPER_ENTRY_ALREADY_EXISTS)
+            exit(EXIT_ERROR)
+        Command.run([config.CRYPTSETUP, "open", str(path), mapper_entry])
+        return False
+
+    @classmethod
+    def _mapper_entry_in_use(cls, mapper_entry: str) -> bool:
+        return (MAPPER_PATH / mapper_entry).exists()
+
+    @classmethod
+    def _get_device_from_status(cls, status: str) -> Path:
+        for line in status.split("\n"):
+            if line.startswith("  device:"):
+                device = Path(line.split(":")[-1].strip())
+                break
+        else:
+            print("panic")
+            exit(EXIT_ERROR)
+        for item in DISK_BY_UUID.iterdir():
+            # noinspection PyUnboundLocalVariable
+            if item.readlink() == device:
+                return item
+
+    @classmethod
+    def _already_decrypted(cls, path: Path, mapper_entry: str) -> bool:
+        decrypted_disk_path = cls._get_device_from_status(cls._status(mapper_entry))
+        return decrypted_disk_path == path
+
+
 class Pool:
     def __init__(self, name: str):
         self._name = name