From d4045c9c138d077f607ccb81371dbb6d53cda694 Mon Sep 17 00:00:00 2001
From: Mike Auty <mike.auty@gmail.com>
Date: Sat, 2 Mar 2019 22:44:51 +0000
Subject: [PATCH] Significant fix for reading from the start of SegmentedLayers
 (including Lime) when ignoring errors.

---
 volatility/framework/interfaces/layers.py |  3 ++-
 volatility/framework/layers/segmented.py  | 15 +++++++--------
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/volatility/framework/interfaces/layers.py b/volatility/framework/interfaces/layers.py
index 487e72a2e..d489bb9f2 100644
--- a/volatility/framework/interfaces/layers.py
+++ b/volatility/framework/interfaces/layers.py
@@ -383,7 +383,8 @@ class TranslationLayerInterface(DataLayerInterface, metaclass = ABCMeta):
                 current_offset = offset
             elif offset < current_offset:
                 raise exceptions.LayerException("Mapping returned an overlapping element")
-            output += [self._context.memory.read(layer, mapped_offset, mapped_length, pad)]
+            if mapped_length > 0:
+                output += [self._context.memory.read(layer, mapped_offset, mapped_length, pad)]
             current_offset += mapped_length
         recovered_data = b"".join(output)
         return recovered_data + b"\x00" * (length - len(recovered_data))
diff --git a/volatility/framework/layers/segmented.py b/volatility/framework/layers/segmented.py
index 97bc6b86e..82aa21f5d 100644
--- a/volatility/framework/layers/segmented.py
+++ b/volatility/framework/layers/segmented.py
@@ -73,14 +73,13 @@ class SegmentedLayer(interfaces.layers.TranslationLayerInterface, metaclass = AB
 
         # Find rightmost value less than or equal to x
         i = bisect_right(self._segments, (offset, self.context.memory[self._base_layer].maximum_address))
-        if i:
-            if not next:
-                segment = self._segments[i - 1]
-                if segment[0] <= offset < segment[0] + segment[2]:
-                    return segment
-            else:
-                if i < len(self._segments):
-                    return self._segments[i]
+        if i and not next:
+            segment = self._segments[i - 1]
+            if segment[0] <= offset < segment[0] + segment[2]:
+                return segment
+        if next:
+            if i < len(self._segments):
+                return self._segments[i]
         raise exceptions.InvalidAddressException(self.name, offset, "Invalid address at {:0x}".format(offset))
 
     def mapping(self, offset: int, length: int, ignore_errors: bool = False) -> Iterable[Tuple[int, int, int, str]]: