file_sys: Move IPS patching code into separate source file

In anticipation of a new BPS patcher.

src/core/CMakeLists.txt

@@ -74,6 +74,8 @@ add_library(core STATIC
     file_sys/ivfc_archive.h
     file_sys/ncch_container.cpp
     file_sys/ncch_container.h
+    file_sys/patch.cpp
+    file_sys/patch.h
     file_sys/path_parser.cpp
     file_sys/path_parser.h
     file_sys/romfs_reader.cpp

src/core/file_sys/ncch_container.cpp

@@ -12,6 +12,7 @@
 #include "common/logging/log.h"
 #include "core/core.h"
 #include "core/file_sys/ncch_container.h"
+#include "core/file_sys/patch.h"
 #include "core/file_sys/seed_db.h"
 #include "core/hw/aes/key.h"
 #include "core/loader/loader.h"
@@ -24,53 +25,6 @@ namespace FileSys {
 static const int kMaxSections = 8;   ///< Maximum number of sections (files) in an ExeFs
 static const int kBlockSize = 0x200; ///< Size of ExeFS blocks (in bytes)
 
-/**
- * Attempts to patch a buffer using an IPS
- * @param ips Vector of the patches to apply
- * @param buffer Vector to patch data into
- */
-static void ApplyIPS(std::vector<u8>& ips, std::vector<u8>& buffer) {
-    u32 cursor = 5;
-    u32 patch_length = ips.size() - 3;
-    std::string ips_header(ips.begin(), ips.begin() + 5);
-
-    if (ips_header != "PATCH") {
-        LOG_INFO(Service_FS, "Attempted to load invalid IPS");
-        return;
-    }
-
-    while (cursor < patch_length) {
-        std::string eof_check(ips.begin() + cursor, ips.begin() + cursor + 3);
-
-        if (eof_check == "EOF")
-            return;
-
-        u32 offset = ips[cursor] << 16 | ips[cursor + 1] << 8 | ips[cursor + 2];
-        std::size_t length = ips[cursor + 3] << 8 | ips[cursor + 4];
-
-        // check for an rle record
-        if (length == 0) {
-            length = ips[cursor + 5] << 8 | ips[cursor + 6];
-
-            if (buffer.size() < offset + length)
-                return;
-
-            for (u32 i = 0; i < length; ++i)
-                buffer[offset + i] = ips[cursor + 7];
-
-            cursor += 8;
-
-            continue;
-        }
-
-        if (buffer.size() < offset + length)
-            return;
-
-        std::memcpy(&buffer[offset], &ips[cursor + 5], length);
-        cursor += length + 5;
-    }
-}
-
 /**
  * Get the decompressed size of an LZSS compressed ExeFS file
  * @param buffer Buffer of compressed file
@@ -553,7 +507,7 @@ Loader::ResultStatus NCCHContainer::LoadSectionExeFS(const char* name, std::vect
     return Loader::ResultStatus::ErrorNotUsed;
 }
 
-bool NCCHContainer::ApplyIPSPatch(std::vector<u8>& code) const {
+bool NCCHContainer::ApplyCodePatch(std::vector<u8>& code) const {
     const std::string override_ips = filepath + ".exefsdir/code.ips";
 
     FileUtil::IOFile ips_file{override_ips, "rb"};
@@ -565,7 +519,7 @@ bool NCCHContainer::ApplyIPSPatch(std::vector<u8>& code) const {
         return false;
 
     LOG_INFO(Service_FS, "File {} patching code.bin", override_ips);
-    ApplyIPS(ips, code);
+    Patch::ApplyIpsPatch(ips, code);
     return true;
 }
 

src/core/file_sys/ncch_container.h

@@ -272,11 +272,11 @@ public:
     Loader::ResultStatus ReadExtdataId(u64& extdata_id);
 
     /**
-     * Apply an IPS patch for .code (if it exists).
+     * Apply a patch for .code (if it exists).
      * This should only be called after allocating .bss.
      * @return bool true if a patch was applied, false otherwise
      */
-    bool ApplyIPSPatch(std::vector<u8>& code) const;
+    bool ApplyCodePatch(std::vector<u8>& code) const;
 
     /**
      * Checks whether the NCCH container contains an ExeFS

src/core/file_sys/patch.cpp

@@ -0,0 +1,55 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <cstring>
+#include <string>
+#include "common/logging/log.h"
+#include "core/file_sys/patch.h"
+
+namespace FileSys::Patch {
+
+bool ApplyIpsPatch(const std::vector<u8>& ips, std::vector<u8>& buffer) {
+    u32 cursor = 5;
+    u32 patch_length = ips.size() - 3;
+    std::string ips_header(ips.begin(), ips.begin() + 5);
+
+    if (ips_header != "PATCH") {
+        LOG_INFO(Service_FS, "Attempted to load invalid IPS");
+        return false;
+    }
+
+    while (cursor < patch_length) {
+        std::string eof_check(ips.begin() + cursor, ips.begin() + cursor + 3);
+
+        if (eof_check == "EOF")
+            return false;
+
+        u32 offset = ips[cursor] << 16 | ips[cursor + 1] << 8 | ips[cursor + 2];
+        std::size_t length = ips[cursor + 3] << 8 | ips[cursor + 4];
+
+        // check for an rle record
+        if (length == 0) {
+            length = ips[cursor + 5] << 8 | ips[cursor + 6];
+
+            if (buffer.size() < offset + length)
+                return false;
+
+            for (u32 i = 0; i < length; ++i)
+                buffer[offset + i] = ips[cursor + 7];
+
+            cursor += 8;
+
+            continue;
+        }
+
+        if (buffer.size() < offset + length)
+            return false;
+
+        std::memcpy(&buffer[offset], &ips[cursor + 5], length);
+        cursor += length + 5;
+    }
+    return true;
+}
+
+} // namespace FileSys::Patch

src/core/file_sys/patch.h

@@ -0,0 +1,15 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <vector>
+
+#include "common/common_types.h"
+
+namespace FileSys::Patch {
+
+bool ApplyIpsPatch(const std::vector<u8>& patch, std::vector<u8>& buffer);
+
+} // namespace FileSys::Patch

src/core/loader/ncch.cpp

@@ -101,7 +101,7 @@ ResultStatus AppLoader_NCCH::LoadExec(std::shared_ptr<Kernel::Process>& process)
             bss_page_size;
 
         // Apply any IPS patch now that the entire codeset (including .bss) has been allocated
-        overlay_ncch->ApplyIPSPatch(code);
+        overlay_ncch->ApplyCodePatch(code);
 
         codeset->entrypoint = codeset->CodeSegment().addr;
         codeset->memory = std::move(code);