1 files changed, 184 insertions, 0 deletions
diff --git a/roms/edk2/FatPkg/EnhancedFatDxe/DirectoryCache.c b/roms/edk2/FatPkg/EnhancedFatDxe/DirectoryCache.c
new file mode 100644
index 000000000..2333016d1
--- /dev/null
+++ b/roms/edk2/FatPkg/EnhancedFatDxe/DirectoryCache.c
@@ -0,0 +1,184 @@
+/** @file
+  Functions for directory cache operation.
+
+Copyright (c) 2005, Intel Corporation. All rights reserved.<BR>
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+
+**/
+
+#include "Fat.h"
+
+/**
+
+  Free the directory structure and release the memory.
+
+  @param  ODir                  - The directory to be freed.
+
+**/
+STATIC
+VOID
+FatFreeODir (
+  IN FAT_ODIR    *ODir
+  )
+{
+  FAT_DIRENT  *DirEnt;
+
+  //
+  // Release Directory Entry Nodes
+  //
+  while (!IsListEmpty (&ODir->ChildList)) {
+    DirEnt = DIRENT_FROM_LINK (ODir->ChildList.ForwardLink);
+    RemoveEntryList (&DirEnt->Link);
+    //
+    // Make sure the OFile has been closed
+    //
+    ASSERT (DirEnt->OFile == NULL);
+    FatFreeDirEnt (DirEnt);
+  }
+
+  FreePool (ODir);
+}
+
+/**
+
+  Allocate the directory structure.
+
+  @param  OFile                   - The corresponding OFile.
+
+**/
+STATIC
+FAT_ODIR *
+FatAllocateODir (
+  IN FAT_OFILE   *OFile
+  )
+{
+  FAT_ODIR  *ODir;
+
+  ODir = AllocateZeroPool (sizeof (FAT_ODIR));
+  if (ODir != NULL) {
+    //
+    // Initialize the directory entry list
+    //
+    ODir->Signature = FAT_ODIR_SIGNATURE;
+    InitializeListHead (&ODir->ChildList);
+    ODir->CurrentCursor = &ODir->ChildList;
+  }
+
+  return ODir;
+}
+
+/**
+
+  Discard the directory structure when an OFile will be freed.
+  Volume will cache this directory if the OFile does not represent a deleted file.
+
+  @param  OFile                 - The OFile whose directory structure is to be discarded.
+
+**/
+VOID
+FatDiscardODir (
+  IN FAT_OFILE    *OFile
+  )
+{
+  FAT_ODIR    *ODir;
+  FAT_VOLUME  *Volume;
+
+  Volume  = OFile->Volume;
+  ODir    = OFile->ODir;
+  if (!OFile->DirEnt->Invalid) {
+    //
+    // If OFile does not represent a deleted file, then we will cache the directory
+    // We use OFile's first cluster as the directory's tag
+    //
+    ODir->DirCacheTag = OFile->FileCluster;
+    InsertHeadList (&Volume->DirCacheList, &ODir->DirCacheLink);
+    if (Volume->DirCacheCount == FAT_MAX_DIR_CACHE_COUNT) {
+      //
+      // Replace the least recent used directory
+      //
+      ODir = ODIR_FROM_DIRCACHELINK (Volume->DirCacheList.BackLink);
+      RemoveEntryList (&ODir->DirCacheLink);
+    } else {
+      //
+      // No need to find a replace
+      //
+      Volume->DirCacheCount++;
+      ODir = NULL;
+    }
+  }
+  //
+  // Release ODir Structure
+  //
+  if (ODir != NULL) {
+    FatFreeODir (ODir);
+  }
+}
+
+/**
+
+
+  Request the directory structure when an OFile is newly generated.
+  If the directory structure is cached by volume, then just return this directory;
+  Otherwise, allocate a new one for OFile.
+
+  @param  OFile                 - The OFile which requests directory structure.
+
+**/
+VOID
+FatRequestODir (
+  IN FAT_OFILE    *OFile
+  )
+{
+  UINTN           DirCacheTag;
+  FAT_VOLUME      *Volume;
+  FAT_ODIR        *ODir;
+  FAT_ODIR        *CurrentODir;
+  LIST_ENTRY      *CurrentODirLink;
+
+  Volume      = OFile->Volume;
+  ODir        = NULL;
+  DirCacheTag = OFile->FileCluster;
+  for (CurrentODirLink  = Volume->DirCacheList.ForwardLink;
+       CurrentODirLink != &Volume->DirCacheList;
+       CurrentODirLink  = CurrentODirLink->ForwardLink
+      ) {
+    CurrentODir = ODIR_FROM_DIRCACHELINK (CurrentODirLink);
+    if (CurrentODir->DirCacheTag == DirCacheTag) {
+      RemoveEntryList (&CurrentODir->DirCacheLink);
+      Volume->DirCacheCount--;
+      ODir = CurrentODir;
+      break;
+    }
+  }
+
+  if (ODir == NULL) {
+    //
+    // This directory is not cached, then allocate a new one
+    //
+    ODir = FatAllocateODir (OFile);
+  }
+
+  OFile->ODir = ODir;
+}
+
+/**
+
+  Clean up all the cached directory structures when the volume is going to be abandoned.
+
+  @param  Volume                - FAT file system volume.
+
+**/
+VOID
+FatCleanupODirCache (
+  IN FAT_VOLUME         *Volume
+  )
+{
+  FAT_ODIR  *ODir;
+  while (Volume->DirCacheCount > 0) {
+    ODir = ODIR_FROM_DIRCACHELINK (Volume->DirCacheList.BackLink);
+    RemoveEntryList (&ODir->DirCacheLink);
+    FatFreeODir (ODir);
+    Volume->DirCacheCount--;
+  }
+}