Fix incorrect and O(n^2) check for overlapping sections (triggered in the new ManySections test).

Author: filipnavara

Diff for: src/LibObjectFile/Elf/ElfReader{TDecoder}.cs

@@ -512,7 +512,7 @@ private void VerifyAndFixProgramHeadersAndSections()
             // Make sure to pre-sort all sections by offset
             var orderedSections = new List<ElfSection>(ObjectFile.Sections.Count);
             orderedSections.AddRange(ObjectFile.Sections);
-            orderedSections.Sort(CompareSectionOffsetsDelegate);
+            orderedSections.Sort(CompareSectionOffsetsAndSizesDelegate);
             // Store the stream index to recover the same order when saving back.
             for(int i = 0; i < orderedSections.Count; i++)
             {
@@ -548,10 +548,10 @@ private void VerifyAndFixProgramHeadersAndSections()
                 lastOffset = section.Offset + section.Size - 1;
 
                 // Verify overlapping sections and generate and error
-                for (int j = i + 1; j < orderedSections.Count; j++)
+                if (i + 1 < orderedSections.Count)
                 {
-                    var otherSection = orderedSections[j];
-                    if (section.Contains(otherSection) || otherSection.Contains(section))
+                    var otherSection = orderedSections[i + 1];
+                    if (otherSection.Offset < section.Offset + section.Size)
                     {
                         Diagnostics.Warning(DiagnosticId.ELF_ERR_InvalidOverlappingSections, $"The section {section} [{section.Offset} : {section.Offset + section.Size - 1}] is overlapping with the section {otherSection} [{otherSection.Offset} : {otherSection.Offset + otherSection.Size - 1}]");
                     }
@@ -844,11 +844,16 @@ public override ushort Decode(ElfNative.Elf64_Versym src)
             return _decoder.Decode(src);
         }
 
-        private static readonly Comparison<ElfSection> CompareSectionOffsetsDelegate = new Comparison<ElfSection>(CompareSectionOffsets);
+        private static readonly Comparison<ElfSection> CompareSectionOffsetsAndSizesDelegate = new Comparison<ElfSection>(CompareSectionOffsetsAndSizes);
 
-        private static int CompareSectionOffsets(ElfSection left, ElfSection right)
+        private static int CompareSectionOffsetsAndSizes(ElfSection left, ElfSection right)
         {
-            return left.Offset.CompareTo(right.Offset);
+            int result = left.Offset.CompareTo(right.Offset);
+            if (result == 0)
+            {
+                result = left.Size.CompareTo(right.Size);
+            }
+            return result;
         }
     }
 }

Diff for: src/LibObjectFile/Elf/Sections/ElfSymbolTableSectionHeaderIndices.cs

@@ -4,7 +4,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Reflection.PortableExecutable;
 
 namespace LibObjectFile.Elf
 {