Add support for CreateReaderAtFileOffset to read from EOF data.

Washi1337 · Jun 10, 2023 · 5821428 · 5821428
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commit 5821428
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Showing 2 changed files with 29 additions and 2 deletions.
diff --git a/src/AsmResolver.PE.File/PEFile.cs b/src/AsmResolver.PE.File/PEFile.cs
@@ -282,8 +282,9 @@ public bool TryCreateDataDirectoryReader(DataDirectory dataDirectory, out Binary
         /// <inheritdoc />
         public BinaryStreamReader CreateReaderAtFileOffset(uint fileOffset)
         {
-            var section = GetSectionContainingOffset(fileOffset);
-            return section.CreateReader(fileOffset);
+            return !TryCreateReaderAtFileOffset(fileOffset, out var reader)
+                ? throw new ArgumentOutOfRangeException(nameof(fileOffset))
+                : reader;
         }
 
         /// <inheritdoc />
@@ -295,6 +296,14 @@ public bool TryCreateReaderAtFileOffset(uint fileOffset, out BinaryStreamReader
                 return true;
             }
 
+            if (EofData is IReadableSegment eofData
+                && fileOffset >= eofData.Offset
+                && fileOffset < eofData.Offset + eofData.GetPhysicalSize())
+            {
+                reader = eofData.CreateReader(fileOffset);
+                return true;
+            }
+
             reader = default;
             return false;
         }
@@ -315,6 +324,14 @@ public bool TryCreateReaderAtFileOffset(uint fileOffset, uint size, out BinarySt
                 return true;
             }
 
+            if (EofData is IReadableSegment eofData
+                && fileOffset >= eofData.Offset
+                && fileOffset < eofData.Offset + eofData.GetPhysicalSize())
+            {
+                reader = eofData.CreateReader(fileOffset, size);
+                return true;
+            }
+
             reader = default;
             return false;
         }

diff --git a/test/AsmResolver.PE.File.Tests/PEFileTest.cs b/test/AsmResolver.PE.File.Tests/PEFileTest.cs
@@ -185,6 +185,16 @@ public void ReadEofData()
             Assert.Equal(Encoding.ASCII.GetBytes("abcdefghijklmnopqrstuvwxyz"), data);
         }
 
+        [Fact]
+        public void ReadEofDataFromFileOffset()
+        {
+            var file = PEFile.FromBytes(Properties.Resources.HelloWorld_EOF);
+            Assert.NotNull(file.EofData);
+            Assert.True(file.TryCreateReaderAtFileOffset((uint) file.EofData.Offset, out var reader));
+            byte[] data = reader.ReadToEnd();
+            Assert.Equal(Encoding.ASCII.GetBytes("abcdefghijklmnopqrstuvwxyz"), data);
+        }
+
         [Fact]
         public void AddNewEofData()
         {