From 28aa04312c9aed0be6eac8940a1b0b0d7ab35868 Mon Sep 17 00:00:00 2001
From: JosJuice <josjuice@gmail.com>
Date: Wed, 4 Nov 2020 20:59:34 +0100
Subject: [PATCH] Common/LinearDiskCache: Replace std::fstream with
 File::IOFile

File::IOFile is better suited to this type of task.
Split out from a future PR.
---
 Source/Core/Common/LinearDiskCache.h          | 65 ++++++-------------
 .../Core/VideoBackends/Vulkan/ObjectCache.cpp |  1 +
 Source/Core/VideoCommon/VideoBackendBase.cpp  |  1 +
 3 files changed, 22 insertions(+), 45 deletions(-)

diff --git a/Source/Core/Common/LinearDiskCache.h b/Source/Core/Common/LinearDiskCache.h
index 81c146ec9a..77feb0f473 100644
--- a/Source/Core/Common/LinearDiskCache.h
+++ b/Source/Core/Common/LinearDiskCache.h
@@ -6,12 +6,11 @@
 
 #include <algorithm>
 #include <cstring>
-#include <fstream>
 #include <string>
 #include <type_traits>
 
 #include "Common/CommonTypes.h"
-#include "Common/FileUtil.h"
+#include "Common/File.h"
 #include "Common/Version.h"
 
 // On disk format:
@@ -54,8 +53,6 @@ public:
   // return number of read entries
   u32 OpenAndRead(const std::string& filename, LinearDiskCacheReader<K, V>& reader)
   {
-    using std::ios_base;
-
     // Since we're reading/writing directly to the storage of K instances,
     // K must be trivially copyable.
     static_assert(std::is_trivially_copyable<K>::value, "K must be a trivially copyable type");
@@ -65,16 +62,12 @@ public:
     m_num_entries = 0;
 
     // try opening for reading/writing
-    File::OpenFStream(m_file, filename, ios_base::in | ios_base::out | ios_base::binary);
+    m_file.Open(filename, "r+b");
 
-    m_file.seekg(0, std::ios::end);
-    std::fstream::pos_type end_pos = m_file.tellg();
-    m_file.seekg(0, std::ios::beg);
-    std::fstream::pos_type start_pos = m_file.tellg();
-    std::streamoff file_size = end_pos - start_pos;
+    const u64 file_size = m_file.GetSize();
 
     m_header.Init();
-    if (m_file.is_open() && ValidateHeader())
+    if (m_file.IsOpen() && ValidateHeader())
     {
       // good header, read some key/value pairs
       K key;
@@ -83,11 +76,9 @@ public:
       u32 value_size = 0;
       u32 entry_number = 0;
 
-      std::fstream::pos_type last_pos = m_file.tellg();
-
-      while (Read(&value_size))
+      while (m_file.ReadArray(&value_size, 1))
       {
-        std::streamoff next_extent = (last_pos - start_pos) + sizeof(value_size) + value_size;
+        const u64 next_extent = m_file.Tell() + sizeof(value_size) + value_size;
         if (next_extent > file_size)
           break;
 
@@ -95,8 +86,8 @@ public:
         value = new V[value_size];
 
         // read key/value and pass to reader
-        if (Read(&key) && Read(value, value_size) && Read(&entry_number) &&
-            entry_number == m_num_entries + 1)
+        if (m_file.ReadArray(&key, 1) && m_file.ReadArray(value, value_size) &&
+            m_file.ReadArray(&entry_number, 1) && entry_number == m_num_entries + 1)
         {
           reader.Read(key, value, value_size);
         }
@@ -106,10 +97,8 @@ public:
         }
 
         m_num_entries++;
-        last_pos = m_file.tellg();
       }
-      m_file.seekp(last_pos);
-      m_file.clear();
+      m_file.Clear();
 
       delete[] value;
       return m_num_entries;
@@ -118,18 +107,16 @@ public:
     // failed to open file for reading or bad header
     // close and recreate file
     Close();
-    File::OpenFStream(m_file, filename, ios_base::out | ios_base::trunc | ios_base::binary);
+    m_file.Open(filename, "wb");
     WriteHeader();
     return 0;
   }
 
-  void Sync() { m_file.flush(); }
+  void Sync() { m_file.Flush(); }
   void Close()
   {
-    if (m_file.is_open())
-      m_file.close();
-    // clear any error flags
-    m_file.clear();
+    if (m_file.IsOpen())
+      m_file.Close();
   }
 
   // Appends a key-value pair to the store.
@@ -137,35 +124,23 @@ public:
   {
     // TODO: Should do a check that we don't already have "key"? (I think each caller does that
     // already.)
-    Write(&value_size);
-    Write(&key);
-    Write(value, value_size);
+    m_file.WriteArray(&value_size, 1);
+    m_file.WriteArray(&key, 1);
+    m_file.WriteArray(value, value_size);
     m_num_entries++;
-    Write(&m_num_entries);
+    m_file.WriteArray(&m_num_entries, 1);
   }
 
 private:
-  void WriteHeader() { Write(&m_header); }
+  void WriteHeader() { m_file.WriteArray(&m_header, 1); }
   bool ValidateHeader()
   {
     char file_header[sizeof(Header)];
 
-    return (Read(file_header, sizeof(Header)) &&
+    return (m_file.ReadArray(file_header, sizeof(Header)) &&
             !memcmp((const char*)&m_header, file_header, sizeof(Header)));
   }
 
-  template <typename D>
-  bool Write(const D* data, u32 count = 1)
-  {
-    return m_file.write(reinterpret_cast<const char*>(data), count * sizeof(D)).good();
-  }
-
-  template <typename D>
-  bool Read(D* data, u32 count = 1)
-  {
-    return m_file.read(reinterpret_cast<char*>(data), count * sizeof(D)).good();
-  }
-
   struct Header
   {
     void Init()
@@ -183,6 +158,6 @@ private:
 
   } m_header;
 
-  std::fstream m_file;
+  File::IOFile m_file;
   u32 m_num_entries;
 };
diff --git a/Source/Core/VideoBackends/Vulkan/ObjectCache.cpp b/Source/Core/VideoBackends/Vulkan/ObjectCache.cpp
index 85609ec48e..93b2144338 100644
--- a/Source/Core/VideoBackends/Vulkan/ObjectCache.cpp
+++ b/Source/Core/VideoBackends/Vulkan/ObjectCache.cpp
@@ -10,6 +10,7 @@
 
 #include "Common/Assert.h"
 #include "Common/CommonFuncs.h"
+#include "Common/FileUtil.h"
 #include "Common/LinearDiskCache.h"
 #include "Common/MsgHandler.h"
 
diff --git a/Source/Core/VideoCommon/VideoBackendBase.cpp b/Source/Core/VideoCommon/VideoBackendBase.cpp
index c4c26ed6a3..d90064bae3 100644
--- a/Source/Core/VideoCommon/VideoBackendBase.cpp
+++ b/Source/Core/VideoCommon/VideoBackendBase.cpp
@@ -16,6 +16,7 @@
 #include "Common/CommonTypes.h"
 #include "Common/Config/Config.h"
 #include "Common/Event.h"
+#include "Common/FileUtil.h"
 #include "Common/Logging/Log.h"
 
 #include "Core/Config/MainSettings.h"