pyfdb: Always use array size specified by user

src/pyfdb/pyfdb_type.py

@@ -250,7 +250,8 @@ def read(self, len: int = -1) -> bytes:
         Parameters
         ----------
         `len`: int
-            The amount of bytes to read. If -1 is entered the whole data handle is read.
+            Number of bytes to read. Defaults to -1, which reads the entire buffer.
+            If the requested size exceeds the available data, the result is zero-padded to match the requested size.
 
         Returns
         -------
@@ -272,10 +273,16 @@ def read(self, len: int = -1) -> bytes:
                 "DataHandle: Read occured before the handle was opened. Must be opened first."
             )
 
-        if len == -1:
-            len = self.dataHandle.size()
+        # NB: Some data handles do not implement the size() method. In this case, we just read the requested amount of bytes.
+        try:
+            dh_size = self.dataHandle.size()
+            array_size = dh_size if len == -1 else min(len, dh_size)
+        except RuntimeError:
+            if len == -1:
+                raise
+            array_size = len
 
-        buffer = bytearray(min(len, self.dataHandle.size()))
+        buffer = bytearray(array_size)
         read_bytes = self.dataHandle.read(buffer)
 
         if read_bytes == 0: