assert datadir available

lib/blockchain.py

@@ -200,8 +200,10 @@ class Blockchain(util.PrintError):
         parent_id = self.parent_id
         checkpoint = self.checkpoint
         parent = self.parent()
+        self.assert_headers_file_available(self.path())
         with open(self.path(), 'rb') as f:
             my_data = f.read()
+        self.assert_headers_file_available(parent.path())
         with open(parent.path(), 'rb') as f:
             f.seek((checkpoint - parent.checkpoint)*80)
             parent_data = f.read(parent_branch_size*80)
@@ -224,9 +226,18 @@ class Blockchain(util.PrintError):
         blockchains[self.checkpoint] = self
         blockchains[parent.checkpoint] = parent
 
+    def assert_headers_file_available(self, path):
+        if os.path.exists(path):
+            return
+        elif not os.path.exists(util.get_headers_dir(self.config)):
+            raise FileNotFoundError('Electrum headers_dir does not exist. Was it deleted while running?')
+        else:
+            raise FileNotFoundError('Cannot find headers file but headers_dir is there. Should be at {}'.format(path))
+
     def write(self, data, offset, truncate=True):
         filename = self.path()
         with self.lock:
+            self.assert_headers_file_available(filename)
             with open(filename, 'rb+') as f:
                 if truncate and offset != self._size*80:
                     f.seek(offset)
@@ -255,16 +266,12 @@ class Blockchain(util.PrintError):
             return
         delta = height - self.checkpoint
         name = self.path()
-        if os.path.exists(name):
-            with open(name, 'rb') as f:
-                f.seek(delta * 80)
-                h = f.read(80)
-                if len(h) < 80:
-                    raise Exception('Expected to read a full header. This was only {} bytes'.format(len(h)))
-        elif not os.path.exists(util.get_headers_dir(self.config)):
-            raise Exception('Electrum datadir does not exist. Was it deleted while running?')
-        else:
-            raise Exception('Cannot find headers file but datadir is there. Should be at {}'.format(name))
+        self.assert_headers_file_available(name)
+        with open(name, 'rb') as f:
+            f.seek(delta * 80)
+            h = f.read(80)
+            if len(h) < 80:
+                raise Exception('Expected to read a full header. This was only {} bytes'.format(len(h)))
         if h == bytes([0])*80:
             return None
         return deserialize_header(h, height)

lib/interface.py

@@ -172,6 +172,7 @@ class TcpConnection(threading.Thread, util.PrintError):
                 # workaround android bug
                 cert = re.sub("([^\n])-----END CERTIFICATE-----","\\1\n-----END CERTIFICATE-----",cert)
                 temporary_path = cert_path + '.temp'
+                util.assert_datadir_available(self.config_path)
                 with open(temporary_path, "w", encoding='utf-8') as f:
                     f.write(cert)
                     f.flush()
@@ -201,6 +202,7 @@ class TcpConnection(threading.Thread, util.PrintError):
                         os.unlink(rej)
                     os.rename(temporary_path, rej)
                 else:
+                    util.assert_datadir_available(self.config_path)
                     with open(cert_path, encoding='utf-8') as f:
                         cert = f.read()
                     try:

lib/simple_config.py

@@ -6,6 +6,7 @@ import stat
 
 from copy import deepcopy
 
+from . import util
 from .util import (user_dir, print_error, PrintError,
                    NoDynamicFeeEstimates, format_fee_satoshis)
 from .i18n import _
@@ -236,10 +237,7 @@ class SimpleConfig(PrintError):
             return path
 
         # default path
-        if not os.path.exists(self.path):
-            raise FileNotFoundError(
-                _('Electrum datadir does not exist. Was it deleted while running?') + '\n' +
-                _('Should be at {}').format(self.path))
+        util.assert_datadir_available(self.path)
         dirpath = os.path.join(self.path, "wallets")
         if not os.path.exists(dirpath):
             if os.path.islink(dirpath):

lib/util.py

@@ -326,10 +326,31 @@ def android_check_data_dir():
         shutil.move(old_electrum_dir, data_dir)
     return data_dir
 
+
 def get_headers_dir(config):
     return android_headers_dir() if 'ANDROID_DATA' in os.environ else config.path
 
 
+def assert_datadir_available(config_path):
+    path = config_path
+    if os.path.exists(path):
+        return
+    else:
+        raise FileNotFoundError(
+            'Electrum datadir does not exist. Was it deleted while running?' + '\n' +
+            'Should be at {}'.format(path))
+
+
+def assert_file_in_datadir_available(path, config_path):
+    if os.path.exists(path):
+        return
+    else:
+        assert_datadir_available(config_path)
+        raise FileNotFoundError(
+            'Cannot find file but datadir is there.' + '\n' +
+            'Should be at {}'.format(path))
+
+
 def assert_bytes(*args):
     """
     porting helper, assert args type