From 147b4aa7e5278287e235cad1849e0d9dd0d5a0f0 Mon Sep 17 00:00:00 2001
From: Ladislav Zezula <zezula@volny.cz>
Date: Tue, 5 May 2020 09:48:39 +0200
Subject: Added option to open named section

---
 src/FileStream.cpp | 122 +++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 91 insertions(+), 31 deletions(-)

(limited to 'src')

diff --git a/src/FileStream.cpp b/src/FileStream.cpp
index 43a5f4f..a492e66 100644
--- a/src/FileStream.cpp
+++ b/src/FileStream.cpp
@@ -434,54 +434,114 @@ static void BaseFile_Init(TFileStream * pStream)
 //-----------------------------------------------------------------------------
 // Local functions - base memory-mapped file support
 
-static bool BaseMap_Open(TFileStream * pStream, const TCHAR * szFileName, DWORD dwStreamFlags)
+#ifdef PLATFORM_WINDOWS
+
+typedef struct _SECTION_BASIC_INFORMATION
+{
+    PVOID BaseAddress;
+    ULONG Attributes;
+    LARGE_INTEGER Size;
+} SECTION_BASIC_INFORMATION, *PSECTION_BASIC_INFORMATION;
+
+typedef ULONG (WINAPI * NTQUERYSECTION)(
+    IN  HANDLE SectionHandle,
+    IN  ULONG SectionInformationClass,
+    OUT PVOID SectionInformation,
+    IN  SIZE_T Length,
+    OUT PSIZE_T ResultLength);
+
+static bool RetrieveFileMappingSize(HANDLE hSection, ULARGE_INTEGER & RefFileSize)
+{
+    SECTION_BASIC_INFORMATION BasicInfo = {0};
+    NTQUERYSECTION PfnQuerySection;
+    HMODULE hNtdll;
+    SIZE_T ReturnLength = 0;
+    
+    if((hNtdll = GetModuleHandle(_T("ntdll.dll"))) != NULL)
+    {
+        PfnQuerySection = (NTQUERYSECTION)GetProcAddress(hNtdll, "NtQuerySection");
+        if(PfnQuerySection != NULL)
+        {
+            if(PfnQuerySection(hSection, 0, &BasicInfo, sizeof(SECTION_BASIC_INFORMATION), &ReturnLength) == 0)
+            {
+                RefFileSize.HighPart = BasicInfo.Size.HighPart;
+                RefFileSize.LowPart = BasicInfo.Size.LowPart;
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+#endif
+
+static bool BaseMap_Open(TFileStream * pStream, LPCTSTR szFileName, DWORD dwStreamFlags)
 {
 #ifdef PLATFORM_WINDOWS
 
-    ULARGE_INTEGER FileSize;
-    HANDLE hFile;
-    HANDLE hMap;
+    ULARGE_INTEGER FileSize = {0};
+    HANDLE hFile = INVALID_HANDLE_VALUE;
+    HANDLE hMap = NULL;
     bool bResult = false;
 
     // Keep compiler happy
     dwStreamFlags = dwStreamFlags;
 
-    // Open the file for read access
-    hFile = CreateFile(szFileName, FILE_READ_DATA, FILE_SHARE_READ, NULL, OPEN_EXISTING, 0, NULL);
-    if(hFile != INVALID_HANDLE_VALUE)
+    // 1) Try to treat "szFileName" as a section name
+    hMap = OpenFileMapping(SECTION_QUERY | FILE_MAP_READ, FALSE, szFileName);
+    if(hMap != NULL)
     {
-        // Retrieve file size. Don't allow mapping file of a zero size.
-        FileSize.LowPart = GetFileSize(hFile, &FileSize.HighPart);
-        if(FileSize.QuadPart != 0)
+        // Try to retrieve the size of the mapping
+        if(!RetrieveFileMappingSize(hMap, FileSize))
         {
-            // Now create mapping object
-            hMap = CreateFileMapping(hFile, NULL, PAGE_READONLY, 0, 0, NULL);
-            if(hMap != NULL)
+            CloseHandle(hMap);
+            hMap = NULL;
+        }
+    }
+
+    // 2) Treat the name as file name
+    else
+    {
+        hFile = CreateFile(szFileName, FILE_READ_DATA, FILE_SHARE_READ, NULL, OPEN_EXISTING, 0, NULL);
+        if(hFile != INVALID_HANDLE_VALUE)
+        {
+            // Retrieve file size. Don't allow mapping file of a zero size.
+            FileSize.LowPart = GetFileSize(hFile, &FileSize.HighPart);
+            if(FileSize.QuadPart != 0)
             {
-                // Map the entire view into memory
-                // Note that this operation will fail if the file can't fit
-                // into usermode address space
-                pStream->Base.Map.pbFile = (LPBYTE)MapViewOfFile(hMap, FILE_MAP_READ, 0, 0, 0);
-                if(pStream->Base.Map.pbFile != NULL)
-                {
-                    // Retrieve file time
-                    GetFileTime(hFile, NULL, NULL, (LPFILETIME)&pStream->Base.Map.FileTime);
+                // Now create file mapping over the file
+                hMap = CreateFileMapping(hFile, NULL, PAGE_READONLY, 0, 0, NULL);
+            }
+        }
+    }
 
-                    // Retrieve file size and position
-                    pStream->Base.Map.FileSize = FileSize.QuadPart;
-                    pStream->Base.Map.FilePos = 0;
-                    bResult = true;
-                }
+    // Did it succeed?
+    if(hMap != NULL)
+    {
+        // Map the entire view into memory
+        // Note that this operation will fail if the file can't fit
+        // into usermode address space
+        pStream->Base.Map.pbFile = (LPBYTE)MapViewOfFile(hMap, FILE_MAP_READ, 0, 0, 0);
+        if(pStream->Base.Map.pbFile != NULL)
+        {
+            // Retrieve file time. If it's named section, put 0
+            if(hFile != INVALID_HANDLE_VALUE)
+                GetFileTime(hFile, NULL, NULL, (LPFILETIME)&pStream->Base.Map.FileTime);
 
-                // Close the map handle
-                CloseHandle(hMap);
-            }
+            // Retrieve file size and position
+            pStream->Base.Map.FileSize = FileSize.QuadPart;
+            pStream->Base.Map.FilePos = 0;
+            bResult = true;
         }
 
-        // Close the file handle
-        CloseHandle(hFile);
+        // Close the map handle
+        CloseHandle(hMap);
     }
 
+    // Close the file handle
+    if(hFile != INVALID_HANDLE_VALUE)
+        CloseHandle(hFile);
+
     // If the file is not there and is not available for random access,
     // report error
     if(bResult == false)
-- 
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