Check FS feature flags instead of checking for NTFS (microsoft#1859)

sba923 · Jan 19, 2022 · 52a3e7d · 52a3e7d
1 parent 8ea9ef2
commit 52a3e7d
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Showing 3 changed files with 46 additions and 27 deletions.
diff --git a/src/AppInstallerCommonCore/Downloader.cpp b/src/AppInstallerCommonCore/Downloader.cpp
@@ -248,14 +248,19 @@ namespace AppInstaller::Utility
 
         return false;
     }
+
+    static inline bool FileSupportsMotw(const std::filesystem::path& path)
+    {
+        return SupportsNamedStreams(path);
+    }
 
     void ApplyMotwIfApplicable(const std::filesystem::path& filePath, URLZONE zone)
     {
         AICLI_LOG(Core, Info, << "Started applying motw to " << filePath << " with zone: " << zone);
 
-        if (!IsNTFS(filePath))
+        if (!FileSupportsMotw(filePath))
         {
-            AICLI_LOG(Core, Info, << "File system is not NTFS. Skipped applying motw");
+            AICLI_LOG(Core, Info, << "File system does not support ADS. Skipped applying motw");
             return;
         }
 
@@ -274,9 +279,9 @@ namespace AppInstaller::Utility
     {
         AICLI_LOG(Core, Info, << "Started removing motw to " << filePath);
 
-        if (!IsNTFS(filePath))
+        if (!FileSupportsMotw(filePath))
         {
-            AICLI_LOG(Core, Info, << "File system is not NTFS. Skipped removing motw");
+            AICLI_LOG(Core, Info, << "File system does not support ADS. Skipped removing motw");
             return;
         }
 
@@ -307,9 +312,9 @@ namespace AppInstaller::Utility
     {
         AICLI_LOG(Core, Info, << "Started applying motw using IAttachmentExecute to " << filePath);
 
-        if (!IsNTFS(filePath))
+        if (!FileSupportsMotw(filePath))
         {
-            AICLI_LOG(Core, Info, << "File system is not NTFS. Skipped applying motw");
+            AICLI_LOG(Core, Info, << "File system does not support ADS. Skipped applying motw");
             return S_OK;
         }
 

diff --git a/src/AppInstallerCommonCore/Public/AppInstallerRuntime.h b/src/AppInstallerCommonCore/Public/AppInstallerRuntime.h
@@ -58,8 +58,8 @@ namespace AppInstaller::Runtime
     // Determines whether the process is running with administrator privileges.
     bool IsRunningAsAdmin();
 
-    // Checks if the file system is NTFS
-    bool IsNTFS(const std::filesystem::path& filePath);
+    // Checks if the file system at path supports named streams/ADS
+    bool SupportsNamedStreams(const std::filesystem::path& path);
 
     // Checks if the file system at path supports hard links
     bool SupportsHardLinks(const std::filesystem::path& path);

diff --git a/src/AppInstallerCommonCore/Runtime.cpp b/src/AppInstallerCommonCore/Runtime.cpp
@@ -415,39 +415,53 @@ namespace AppInstaller::Runtime
         return wil::test_token_membership(nullptr, SECURITY_NT_AUTHORITY, SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_ADMINS);
     }
 
-    // TODO: Replace this function with proper checks for supported functionality rather
-    //       than simply relying on "is it NTFS?", even if those functions delegate to
-    //       this one for the answer.
-    bool IsNTFS(const std::filesystem::path& filePath)
+    DWORD GetVolumeInformationFlagsByHandle(HANDLE anyFileHandle)
     {
-        wil::unique_hfile fileHandle{ CreateFileW(
-            filePath.c_str(), /*lpFileName*/
-            FILE_READ_ATTRIBUTES, /*dwDesiredAccess*/
-            0, /*dwShareMode*/
-            NULL, /*lpSecurityAttributes*/
-            OPEN_EXISTING, /*dwCreationDisposition*/
-            FILE_ATTRIBUTE_NORMAL, /*dwFlagsAndAttributes*/
-            NULL /*hTemplateFile*/) };
-
-        THROW_LAST_ERROR_IF(fileHandle.get() == INVALID_HANDLE_VALUE);
-
+        DWORD flags = 0;
         wchar_t fileSystemName[MAX_PATH];
         THROW_LAST_ERROR_IF(!GetVolumeInformationByHandleW(
-            fileHandle.get(), /*hFile*/
+            anyFileHandle, /*hFile*/
             NULL, /*lpVolumeNameBuffer*/
             0, /*nVolumeNameSize*/
             NULL, /*lpVolumeSerialNumber*/
             NULL, /*lpMaximumComponentLength*/
-            NULL, /*lpFileSystemFlags*/
+            &flags, /*lpFileSystemFlags*/
             fileSystemName, /*lpFileSystemNameBuffer*/
             MAX_PATH /*nFileSystemNameSize*/));
 
-        return _wcsicmp(fileSystemName, L"NTFS") == 0;
+        // Vista and older does not report all flags, fix them up here
+        if (!(flags & FILE_SUPPORTS_HARD_LINKS) && !_wcsicmp(fileSystemName, L"NTFS"))
+        {
+            flags |= FILE_SUPPORTS_HARD_LINKS|FILE_SUPPORTS_EXTENDED_ATTRIBUTES|FILE_SUPPORTS_OPEN_BY_FILE_ID|FILE_SUPPORTS_USN_JOURNAL;
+        }
+
+        return flags;
+    }
+
+    DWORD GetVolumeInformationFlags(const std::filesystem::path& anyPath)
+    {
+        wil::unique_hfile fileHandle{ CreateFileW(
+            anyPath.c_str(), /*lpFileName*/
+            0, /*dwDesiredAccess*/
+            FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE, /*dwShareMode*/
+            NULL, /*lpSecurityAttributes*/
+            OPEN_EXISTING, /*dwCreationDisposition*/
+            FILE_ATTRIBUTE_NORMAL, /*dwFlagsAndAttributes*/
+            NULL /*hTemplateFile*/) };
+
+        THROW_LAST_ERROR_IF(fileHandle.get() == INVALID_HANDLE_VALUE);
+
+        return GetVolumeInformationFlagsByHandle(fileHandle.get());
+    }
+
+    bool SupportsNamedStreams(const std::filesystem::path& path)
+    {
+        return (GetVolumeInformationFlags(path) & FILE_NAMED_STREAMS) != 0;
     }
 
     bool SupportsHardLinks(const std::filesystem::path& path)
     {
-        return IsNTFS(path);
+        return (GetVolumeInformationFlags(path) & FILE_SUPPORTS_HARD_LINKS) != 0;
     }
 
     constexpr bool IsReleaseBuild()