From 93209423471ebda393667784f874faf13fdcc22a Mon Sep 17 00:00:00 2001
From: Maschell <Maschell@gmx.de>
Date: Tue, 2 Jul 2024 11:40:09 +0200
Subject: [PATCH] Elf2rpl: Fix order of sections inside the .rpx (#11)

* elf2rpl: Fix "LOADER" section relocation inside .elf
* elf2rpl: Fix detecting failed offset calculations
---
 src/elf2rpl/main.cpp | 48 ++++++++++++++++++--------------------------
 1 file changed, 19 insertions(+), 29 deletions(-)

diff --git a/src/elf2rpl/main.cpp b/src/elf2rpl/main.cpp
index 25fa859..884e3cb 100644
--- a/src/elf2rpl/main.cpp
+++ b/src/elf2rpl/main.cpp
@@ -717,6 +717,11 @@ calculateSectionOffsets(ElfFile &file)
    auto offset = file.header.shoff;
    offset += align_up(static_cast<uint32_t>((file.sections.size() - file.num_discarded_sections) * sizeof(elf::SectionHeader)), 64);
 
+   // Set all offsets to 0, so we can detect sections we didn't relocate
+   for (auto &section : file.sections) {
+      section->header.offset = 0u;
+   }
+
    for (auto &section : file.sections) {
       if (section->header.type == elf::SHT_NOBITS ||
           section->header.type == elf::SHT_NULL) {
@@ -764,35 +769,20 @@ calculateSectionOffsets(ElfFile &file)
    }
 
    // Next the "readMin / readMax" sections, which are:
-   // - !(flags & SHF_EXECINSTR) || type == SHT_RPL_EXPORTS
-   // - !(flags & SHF_WRITE)
+   // - type == SHT_RPL_EXPORTS || SHT_RPL_IMPORTS
+   // - !(flags & (SHF_EXECINSTR | SHF_WRITE))
    // - flags & SHF_ALLOC
-   for (auto &section : file.sections) {
-      if (section->header.size == 0 ||
-          section->header.type == elf::SHT_RPL_FILEINFO ||
-          section->header.type == elf::SHT_RPL_IMPORTS ||
-          section->header.type == elf::SHT_RPL_CRCS ||
-          section->header.type == elf::SHT_NOBITS) {
-         continue;
-      }
-
-      if ((!(section->header.flags & elf::SHF_EXECINSTR) ||
-             section->header.type == elf::SHT_RPL_EXPORTS) &&
-          !(section->header.flags & elf::SHF_WRITE) &&
-           (section->header.flags & elf::SHF_ALLOC)) {
-         section->header.offset = offset;
-         section->header.size = static_cast<uint32_t>(section->data.size());
-         offset += section->header.size;
-      }
-   }
-
-   // Import sections are part of the read sections, but have execinstr flag set
-   // so let's insert them here to avoid complicating the above logic.
-   for (auto &section : file.sections) {
-      if (section->header.type == elf::SHT_RPL_IMPORTS) {
-         section->header.offset = offset;
-         section->header.size = static_cast<uint32_t>(section->data.size());
-         offset += section->header.size;
+   // See: https://github.com/decaf-emu/decaf-emu/blob/e6c528a20a41c34e0f9eb91dd3da40f119db2dee/src/libdecaf/src/cafe/loader/cafe_loader_setup.cpp#L575
+   for (auto &section: file.sections) {
+      if (section->header.size > 0 &&
+          (section->header.flags & elf::SHF_ALLOC)) {
+         if (section->header.type == elf::SHT_RPL_EXPORTS ||
+             section->header.type == elf::SHT_RPL_IMPORTS ||
+             !(section->header.flags & (elf::SHF_EXECINSTR | elf::SHF_WRITE))) {
+            section->header.offset = offset;
+            section->header.size = static_cast<uint32_t>(section->data.size());
+            offset += section->header.size;
+         }
       }
    }
 
@@ -840,7 +830,7 @@ calculateSectionOffsets(ElfFile &file)
       if (section->header.offset == 0 &&
           section->header.type != elf::SHT_NULL &&
           section->header.type != elf::SHT_NOBITS) {
-         fmt::print("Failed to calculate offset for section {}\n", section->index);
+         fmt::print("Failed to calculate offset for section {} ({})\n", section->name, section->index);
          return false;
       }