From 7c820b7fd291381a8ac9385807cddf0c2d88c102 Mon Sep 17 00:00:00 2001
From: Matt Nadareski <mnadareski@outlook.com>
Date: Tue, 20 Dec 2022 13:03:25 -0800
Subject: [PATCH] Start re-adding entry point

---
 BurnOutSharp.Builder/Extensions.cs          | 38 +++++++++++++++++++++
 BurnOutSharp.Wrappers/PortableExecutable.cs | 14 ++++++++
 Developer Guide.md                          |  1 +
 3 files changed, 53 insertions(+)

diff --git a/BurnOutSharp.Builder/Extensions.cs b/BurnOutSharp.Builder/Extensions.cs
index 21b5d8fb..7aa7bd88 100644
--- a/BurnOutSharp.Builder/Extensions.cs
+++ b/BurnOutSharp.Builder/Extensions.cs
@@ -112,6 +112,44 @@ namespace BurnOutSharp.Builder
             return 0;
         }
 
+        /// <summary>
+        /// Find the section a revlative virtual address lives in
+        /// </summary>
+        /// <param name="rva">Relative virtual address to convert</param>
+        /// <param name="sections">Array of sections to check against</param>
+        /// <returns>Section index, null on error</returns>
+        public static int ContainingSectionIndex(this uint rva, Models.PortableExecutable.SectionHeader[] sections)
+        {
+            // If we have an invalid section table, we can't do anything
+            if (sections == null || sections.Length == 0)
+                return -1;
+
+            // If the RVA is 0, we just return -1 because it's invalid
+            if (rva == 0)
+                return -1;
+
+            // Loop through all of the sections
+            for (int i = 0; i < sections.Length; i++)
+            {
+                // If the section is invalid, just skip it
+                if (sections[i] == null)
+                    continue;
+
+                // If the section "starts" at 0, just skip it
+                if (sections[i].PointerToRawData == 0)
+                    continue;
+
+                // Attempt to derive the physical address from the current section
+                var section = sections[i];
+                if (rva >= section.VirtualAddress && section.VirtualSize != 0 && rva <= section.VirtualAddress + section.VirtualSize)
+                    return i;
+                else if (rva >= section.VirtualAddress && section.SizeOfRawData != 0 && rva <= section.VirtualAddress + section.SizeOfRawData)
+                    return i;
+            }
+
+            return -1;
+        }
+
         /// <summary>
         /// Read overlay data as a SecuROM AddD overlay data
         /// </summary>
diff --git a/BurnOutSharp.Wrappers/PortableExecutable.cs b/BurnOutSharp.Wrappers/PortableExecutable.cs
index e3c5bc68..e4c054ed 100644
--- a/BurnOutSharp.Wrappers/PortableExecutable.cs
+++ b/BurnOutSharp.Wrappers/PortableExecutable.cs
@@ -3239,6 +3239,20 @@ namespace BurnOutSharp.Wrappers
                 return SectionNames.Any(n => n.StartsWith(sectionName));
         }
 
+        /// <summary>
+        /// Get the section index corresponding to the entry point, if possible
+        /// </summary>
+        /// <returns>Section index on success, null on error</returns>
+        public int FindEntryPointSectionIndex()
+        {
+            // If we don't have an entry point
+            if (OH_AddressOfEntryPoint.ConvertVirtualAddress(SectionTable) == 0)
+                return -1;
+
+            // Otherwise, find the section it exists within
+            return OH_AddressOfEntryPoint.ContainingSectionIndex(SectionTable);
+        }
+
         /// <summary>
         /// Get the first section based on name, if possible
         /// </summary>
diff --git a/Developer Guide.md b/Developer Guide.md
index 6a3c825e..0f13a196 100644
--- a/Developer Guide.md	
+++ b/Developer Guide.md	
@@ -74,6 +74,7 @@ Below are all current helper methods along with a brief description.
 |  | `GetFirstSectionStrings(string, bool)` | Get the first section found ASCII and Unicode wide character strings (length >= 5) whose name matches the provided value, if it exists. |
 |  | `GetLastSectionStrings(string, bool)` | Get the last section found ASCII and Unicode wide character strings (length >= 5) whose name matches the provided value, if it exists. |
 |  | `GetSectionStrings(int)` | Get the section found ASCII and Unicode wide character strings (length >= 5) whose index matches the provided value, if it exists. |
+|  | `FindEntryPointSection()` | Get the section header for the section that contains the entry point, if it exists. |
 |  | `GetTableData(int)` | Get the table raw data whose index matches the provided value, if it exists. |
 |  | `GetTableStrings(int)` | Get the table found ASCII and Unicode wide character strings (length >= 5) whose index matches the provided value, if it exists. |