/** @file
  OpenCore driver.

Copyright (c) 2019, vit9696. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution.  The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include <Base.h>

#include <Library/OcMainLib.h>

#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/OcAfterBootCompatLib.h>
#include <Library/OcAppleKernelLib.h>
#include <Library/OcMiscLib.h>
#include <Library/OcAppleImg4Lib.h>
#include <Library/OcStringLib.h>
#include <Library/OcVirtualFsLib.h>
#include <Library/PrintLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiRuntimeServicesTableLib.h>

STATIC OC_STORAGE_CONTEXT  *mOcStorage;
STATIC OC_GLOBAL_CONFIG    *mOcConfiguration;
STATIC OC_CPU_INFO         *mOcCpuInfo;
STATIC UINT8               mKernelDigest[SHA384_DIGEST_SIZE];

STATIC UINT32              mOcDarwinVersion;
STATIC BOOLEAN             mUse32BitKernel;

STATIC CACHELESS_CONTEXT   mOcCachelessContext;
STATIC BOOLEAN             mOcCachelessInProgress;

STATIC EFI_FILE_PROTOCOL   *mCustomKernelDirectory;
STATIC BOOLEAN             mCustomKernelDirectoryInProgress;

STATIC
VOID
OcKernelConfigureCapabilities (
  IN OUT EFI_LOADED_IMAGE_PROTOCOL  *LoadedImage,
  IN     UINT32                     Capabilities
  )
{
  CONST CHAR8  *KernelArch;
  CHAR8        *AppleArchValue;
  CONST CHAR8  *NewArguments[2];
  UINT32       ArgumentCount;
  UINT32       RequestedArch;
  BOOLEAN      HasAppleArch;
  UINT32       KernelVersion;
  BOOLEAN      IsSnowLeo;
  BOOLEAN      IsLion;

  DEBUG ((DEBUG_VERBOSE, "OC: Supported boot capabilities %u\n", Capabilities));

  //
  // Reset to the default value.
  // Capabilities will always have K64 stripped when compiled for IA32.
  //
  mUse32BitKernel = (Capabilities & OC_KERN_CAPABILITY_K64_U64) == 0;

  //
  // Skip if not Apple image.
  //
  if (LoadedImage->FilePath == NULL
    || (OcGetBootDevicePathType (LoadedImage->FilePath, NULL, NULL) & OC_BOOT_APPLE_ANY) == 0) {
    return;
  }

  //
  // arch boot argument overrides any compatibility checks.
  //
  HasAppleArch = OcCheckArgumentFromEnv (
    LoadedImage,
    gRT->GetVariable,
    "arch=",
    L_STR_LEN ("arch="),
    &AppleArchValue
    );

  if (HasAppleArch) {
    mUse32BitKernel = AsciiStrCmp (AppleArchValue, "i386") == 0;
    DEBUG ((DEBUG_INFO, "OC: Arch %a overrides capabilities %u\n", AppleArchValue, Capabilities));
    FreePool (AppleArchValue);
    return;
  }

  //
  // Determine the current operating system.
  //
  IsSnowLeo = FALSE;
  IsLion    = FALSE;

  if ((Capabilities & OC_KERN_CAPABILITY_ALL) == OC_KERN_CAPABILITY_ALL) {
    KernelVersion = KERNEL_VERSION_SNOW_LEOPARD_MIN;
    IsSnowLeo     = TRUE;
  } else if ((Capabilities & OC_KERN_CAPABILITY_ALL) == OC_KERN_CAPABILITY_K32_K64_U64) {
    KernelVersion = KERNEL_VERSION_LION_MIN;
    IsLion        = TRUE;
  } else if ((Capabilities & OC_KERN_CAPABILITY_ALL) == OC_KERN_CAPABILITY_K32_U32_U64) {
    KernelVersion = KERNEL_VERSION_LEOPARD_MIN;
  } else {
    KernelVersion = KERNEL_VERSION_MOUNTAIN_LION_MIN;
  }

  //
  // Determine requested arch.
  //
  // There are issues with booting with -legacy on 10.4 and 10.5, and EFI64.
  // We can only use this on 10.6, or on 10.4/10.5 if on EFI32.
  //
  // i386-user32 is not supported on 10.7, fallback to i386.
  //
  KernelArch = OC_BLOB_GET (&mOcConfiguration->Kernel.Scheme.KernelArch);
  if (AsciiStrCmp (KernelArch, "x86_64") == 0) {
    RequestedArch = OC_KERN_CAPABILITY_K64_U64;
  } else if (AsciiStrCmp (KernelArch, "i386") == 0) {
    RequestedArch = OC_KERN_CAPABILITY_K32_U64;
  } else if (AsciiStrCmp (KernelArch, "i386-user32") == 0
#if defined(MDE_CPU_X64)
    && (IsSnowLeo || IsLion)
#endif
    ) {
    if (!IsLion) {
      RequestedArch = OC_KERN_CAPABILITY_K32_U32;
    } else {
      DEBUG ((DEBUG_INFO, "OC: Requested arch i386-user32 is not supported on 10.7, falling back to i386\n"));
      RequestedArch = OC_KERN_CAPABILITY_K32_U64;
    }
  } else {
    RequestedArch = 0;
  }

  //
  // In automatic mode, if we do not support SSSE3 and can downgrade to U32, do it.
  // See also note above regarding 10.4 and 10.5.
  //
  if (RequestedArch == 0
#if defined(MDE_CPU_X64)
    && IsSnowLeo
#endif
    && (mOcCpuInfo->ExtFeatures & CPUID_EXTFEATURE_EM64T) != 0
    && (mOcCpuInfo->Features & CPUID_FEATURE_SSSE3) == 0
    && (Capabilities & OC_KERN_CAPABILITY_K32_U32) != 0) {
    //
    // Should be guaranteed that we support 32-bit kernel with a 64-bit userspace.
    //
    ASSERT ((Capabilities & OC_KERN_CAPABILITY_K32_U64) != 0);

    DEBUG ((DEBUG_INFO, "OC: Missing SSSE3 disables U64 capabilities %u\n", Capabilities));
    Capabilities = OC_KERN_CAPABILITY_K32_U32;
  }

  //
  // If we support K64 mode, check whether the board supports it.
  //
  if ((Capabilities & OC_KERN_CAPABILITY_K64_U64) != 0
    && !OcPlatformIs64BitSupported (KernelVersion)) {
    DEBUG ((DEBUG_INFO, "OC: K64 forbidden due to current platform on version %u\n", KernelVersion));
    Capabilities &= ~(OC_KERN_CAPABILITY_K64_U64);
  }

  //
  // If we are not choosing the architecture automatically, try to use the requested one.
  // Otherwise try best available.
  //
  if (RequestedArch != 0 && (Capabilities & RequestedArch) != 0) {
    Capabilities = RequestedArch;
  } else if ((Capabilities & OC_KERN_CAPABILITY_K64_U64) != 0) {
    Capabilities = OC_KERN_CAPABILITY_K64_U64;
  } else if ((Capabilities & OC_KERN_CAPABILITY_K32_U64) != 0) {
    Capabilities = OC_KERN_CAPABILITY_K32_U64;
  } else if ((Capabilities & OC_KERN_CAPABILITY_K32_U32) != 0) {
    Capabilities = OC_KERN_CAPABILITY_K32_U32;
  } else {
    ASSERT (FALSE);
  }

  //
  // Pass arch argument when we are:
  // - SnowLeo64 and try to boot x86_64.
  // - SnowLeo64 or Lion64 and try to boot i386.
  //
  ArgumentCount = 0;
  if (Capabilities == OC_KERN_CAPABILITY_K64_U64 && IsSnowLeo) {
    NewArguments[ArgumentCount++] = "arch=x86_64";
  } else if (Capabilities != OC_KERN_CAPABILITY_K64_U64 && (IsSnowLeo || IsLion)) {
    NewArguments[ArgumentCount++] = "arch=i386";
  }

  //
  // Pass legacy argument when we are booting i386.
  //
  if (Capabilities == OC_KERN_CAPABILITY_K32_U32
    && !OcCheckArgumentFromEnv (LoadedImage, gRT->GetVariable, "-legacy", L_STR_LEN ("-legacy"), NULL)) {
    NewArguments[ArgumentCount++] = "-legacy";
  }

  //
  // Update argument list.
  //
  if (ArgumentCount > 0) {
    OcAppendArgumentsToLoadedImage (
      LoadedImage,
      &NewArguments[0],
      ArgumentCount,
      FALSE
      );
  }

  //
  // If we do not support K64 for this target, force 32.
  //
  if ((Capabilities & OC_KERN_CAPABILITY_K64_U64) == 0) {
    mUse32BitKernel = TRUE;
  }
}

STATIC
VOID
OcKernelLoadAndReserveKext (
  IN     OC_KERNEL_ADD_ENTRY  *Kext,
  IN     UINT32               Index,
  IN     BOOLEAN              IsForced,
  IN     EFI_FILE_PROTOCOL    *RootFile,
  IN     OC_STORAGE_CONTEXT   *Storage,
  IN     OC_GLOBAL_CONFIG     *Config,
  IN     KERNEL_CACHE_TYPE    CacheType,
  IN     BOOLEAN              Is32Bit,
  IN OUT UINT32               *ReservedExeSize,
  IN OUT UINT32               *ReservedInfoSize,
  IN OUT UINT32               *NumReservedKexts
  )
{
  EFI_STATUS              Status;
  CHAR8                   *Identifier;
  CHAR8                   *BundlePath;
  CHAR8                   *Comment;
  CONST CHAR8             *Arch;
  CHAR8                   *PlistPath;
  CHAR8                   *ExecutablePath;
  CHAR16                  FullPath[OC_STORAGE_SAFE_PATH_MAX];

  if (!Kext->Enabled) {
    return;
  }

  //
  // Free existing data if present, but only for forced kexts.
  // Injected kexts will never change.
  //
  if (IsForced && Kext->PlistData != NULL) {
    FreePool (Kext->PlistData);
    Kext->PlistDataSize  = 0;
    Kext->PlistData      = NULL;

    if (Kext->ImageData != NULL) {
      FreePool (Kext->ImageData);
      Kext->ImageDataSize  = 0;
      Kext->ImageData      = NULL;
    }
  }

  Identifier    = OC_BLOB_GET (&Kext->Identifier);
  BundlePath    = OC_BLOB_GET (&Kext->BundlePath);
  Comment       = OC_BLOB_GET (&Kext->Comment);
  Arch          = OC_BLOB_GET (&Kext->Arch);
  PlistPath     = OC_BLOB_GET (&Kext->PlistPath);
  if (BundlePath[0] == '\0' || PlistPath[0] == '\0' || (IsForced && Identifier[0] == '\0')) {
    DEBUG ((
      DEBUG_ERROR,
      "OC: %s kext %u (%a) has invalid info\n",
      IsForced ? L"Forced" : L"Injected",
      Index,
      Comment
      ));
    Kext->Enabled = FALSE;
    return;
  }

  if (AsciiStrCmp (Arch, Is32Bit ? "x86_64" : "i386") == 0) {
    DEBUG ((
      DEBUG_INFO,
      "OC: %s kext %a (%a) at %u skipped due to arch %a != %a\n",
      IsForced ? L"Forced" : L"Injected",
      BundlePath,
      Comment,
      Index,
      Arch,
      Is32Bit ? "i386" : "x86_64"
      ));
    return;
  }

  //
  // Required for possible cacheless force injection later on.
  //
  AsciiUefiSlashes (BundlePath);

  //
  // Get plist path and data.
  //
  Status = OcUnicodeSafeSPrint (
    FullPath,
    sizeof (FullPath),
    IsForced ? L"%a\\%a" : OPEN_CORE_KEXT_PATH "%a\\%a",
    BundlePath,
    PlistPath
    );
  if (EFI_ERROR (Status)) {
    DEBUG ((
      DEBUG_WARN,
      "OC: Failed to fit %s kext path %s%a\\%a",
      IsForced ? L"forced" : L"injected",
      IsForced ? L"" : OPEN_CORE_KEXT_PATH,
      BundlePath,
      PlistPath
      ));
    Kext->Enabled = IsForced;
    return;
  }

  UnicodeUefiSlashes (FullPath);

  if (IsForced) {
    Kext->PlistData = OcReadFileFromDirectory (
      RootFile,
      FullPath,
      &Kext->PlistDataSize,
      0
      );
  } else {
    Kext->PlistData = OcStorageReadFileUnicode (
      Storage,
      FullPath,
      &Kext->PlistDataSize
      );
  }

  if (Kext->PlistData == NULL) {
    DEBUG ((
      IsForced ? DEBUG_INFO : DEBUG_ERROR,
      "OC: Plist %s is missing for %s kext %a (%a)\n",
      FullPath,
      IsForced ? L"forced" : L"injected",
      BundlePath,
      Comment
      ));
    Kext->Enabled = IsForced;
    return;
  }

  //
  // Get executable path and data, if present.
  //
  ExecutablePath = OC_BLOB_GET (&Kext->ExecutablePath);
  if (ExecutablePath[0] != '\0') {
    Status = OcUnicodeSafeSPrint (
      FullPath,
      sizeof (FullPath),
      IsForced ? L"%a\\%a" : OPEN_CORE_KEXT_PATH "%a\\%a",
      BundlePath,
      ExecutablePath
      );
    if (EFI_ERROR (Status)) {
      DEBUG ((
        DEBUG_WARN,
        "OC: Failed to fit %s kext path %s%a\\%a",
        IsForced ? L"forced" : L"injected",
        IsForced ? L"" : OPEN_CORE_KEXT_PATH,
        BundlePath,
        ExecutablePath
        ));
      Kext->Enabled = IsForced;
      FreePool (Kext->PlistData);
      Kext->PlistData = NULL;
      return;
    }

    UnicodeUefiSlashes (FullPath);

    if (IsForced) {
      Kext->ImageData = OcReadFileFromDirectory (
        RootFile,
        FullPath,
        &Kext->ImageDataSize,
        0
        );
    } else {
      Kext->ImageData = OcStorageReadFileUnicode (
        Storage,
        FullPath,
        &Kext->ImageDataSize
        );
    }

    if (Kext->ImageData == NULL) {
      DEBUG ((
        IsForced ? DEBUG_INFO : DEBUG_ERROR,
        "OC: Image %s is missing for %s kext %a (%a)\n",
        FullPath,
        IsForced ? L"forced" : L"injected",
        BundlePath,
        Comment
        ));
      Kext->Enabled = IsForced;
      FreePool (Kext->PlistData);
      Kext->PlistData = NULL;
      return;
    }
  }

  if (CacheType == CacheTypeCacheless || CacheType == CacheTypeMkext) {
    Status = MkextReserveKextSize (
      ReservedInfoSize,
      ReservedExeSize,
      Kext->PlistDataSize,
      Kext->ImageData,
      Kext->ImageDataSize,
      Is32Bit
      );
  } else if (CacheType == CacheTypePrelinked) {
    Status = PrelinkedReserveKextSize (
      ReservedInfoSize,
      ReservedExeSize,
      Kext->PlistDataSize,
      Kext->ImageData,
      Kext->ImageDataSize,
      Is32Bit
      );
  }

  if (EFI_ERROR (Status)) {
    DEBUG ((
      DEBUG_INFO,
      "OC: Failed to fit %s kext %a (%a) - %r\n",
      Is32Bit ? L"32-bit" : L"64-bit",
      BundlePath,
      Comment,
      Status
      ));
    if (Kext->ImageData != NULL) {
      FreePool (Kext->ImageData);
      Kext->ImageData = NULL;
    }
    FreePool (Kext->PlistData);
    Kext->PlistData = NULL;
    return;
  }

  (*NumReservedKexts)++;
}

STATIC
EFI_STATUS
OcKernelLoadKextsAndReserve (
  IN  EFI_FILE_PROTOCOL   *RootFile,
  IN  OC_STORAGE_CONTEXT  *Storage,
  IN  OC_GLOBAL_CONFIG    *Config,
  IN  KERNEL_CACHE_TYPE   CacheType,
  IN  BOOLEAN             Is32Bit,
  OUT UINT32              *ReservedExeSize,
  OUT UINT32              *ReservedInfoSize,
  OUT UINT32              *NumReservedKexts
  )
{
  UINT32                  Index;
  OC_KERNEL_ADD_ENTRY     *Kext;

  *ReservedInfoSize = PRELINK_INFO_RESERVE_SIZE;
  *ReservedExeSize  = 0;
  *NumReservedKexts = 0;

  //
  // Process system kexts to be force injected.
  //
  for (Index = 0; Index < Config->Kernel.Force.Count; Index++) {
    Kext = Config->Kernel.Force.Values[Index];

    OcKernelLoadAndReserveKext (
      Kext,
      Index,
      TRUE,
      RootFile,
      Storage,
      Config,
      CacheType,
      Is32Bit,
      ReservedExeSize,
      ReservedInfoSize,
      NumReservedKexts
      );
  }

  //
  // Process kexts to be injected.
  //
  for (Index = 0; Index < Config->Kernel.Add.Count; Index++) {
    Kext = Config->Kernel.Add.Values[Index];

    OcKernelLoadAndReserveKext (
      Kext,
      Index,
      FALSE,
      RootFile,
      Storage,
      Config,
      CacheType,
      Is32Bit,
      ReservedExeSize,
      ReservedInfoSize,
      NumReservedKexts
      );
  }

  if (CacheType == CacheTypePrelinked) {
    if (*ReservedExeSize > PRELINKED_KEXTS_MAX_SIZE
      || *ReservedInfoSize + *ReservedExeSize < *ReservedExeSize) {
      return EFI_UNSUPPORTED;
    }
  }

  DEBUG ((
    DEBUG_INFO,
    "OC: Kext reservation size info %X exe %X\n",
    *ReservedInfoSize, *ReservedExeSize
    ));
  return EFI_SUCCESS;
}

STATIC
VOID
OcKernelInjectKext (
  IN OC_KERNEL_ADD_ENTRY  *Kext,
  IN UINT32               Index,
  IN BOOLEAN              IsForced,
  IN KERNEL_CACHE_TYPE    CacheType,
  IN VOID                 *Context,
  IN UINT32               DarwinVersion,
  IN BOOLEAN              Is32Bit
  )
{
  EFI_STATUS              Status;
  CONST CHAR8             *Identifier;
  CONST CHAR8             *BundlePath;
  CONST CHAR8             *ExecutablePath;
  CONST CHAR8             *Comment;
  CHAR8                   FullPath[OC_STORAGE_SAFE_PATH_MAX];
  UINT32                  MaxKernel;
  UINT32                  MinKernel;

  if (!Kext->Enabled || Kext->PlistData == NULL) {
    return;
  }

  Identifier  = OC_BLOB_GET (&Kext->Identifier);
  BundlePath  = OC_BLOB_GET (&Kext->BundlePath);
  Comment     = OC_BLOB_GET (&Kext->Comment);
  MaxKernel   = OcParseDarwinVersion (OC_BLOB_GET (&Kext->MaxKernel));
  MinKernel   = OcParseDarwinVersion (OC_BLOB_GET (&Kext->MinKernel));

  if (!OcMatchDarwinVersion (DarwinVersion, MinKernel, MaxKernel)) {
    DEBUG ((
      DEBUG_INFO,
      "OC: %a%a injection skips %a (%a) kext at %u due to version %u <= %u <= %u\n",
      PRINT_KERNEL_CACHE_TYPE (CacheType),
      IsForced ? " force" : "",
      BundlePath,
      Comment,
      Index,
      MinKernel,
      DarwinVersion,
      MaxKernel
      ));
    return;
  }

  if (Kext->ImageData != NULL) {
    ExecutablePath = OC_BLOB_GET (&Kext->ExecutablePath);
  } else {
    ExecutablePath = NULL;
  }

  if (!IsForced) {
    Status = OcAsciiSafeSPrint (FullPath, sizeof (FullPath), "/Library/Extensions/%a", BundlePath);
    if (EFI_ERROR (Status)) {
      DEBUG ((DEBUG_WARN, "OC: Failed to fit kext path /Library/Extensions/%a", BundlePath));
      return;
    }
  }

  if (CacheType == CacheTypeCacheless) {
    if (IsForced
      && AsciiStrnCmp (BundlePath, "System\\Library\\Extensions", L_STR_LEN ("System\\Library\\Extensions")) == 0) {
      Status = CachelessContextForceKext (Context, Identifier);
    } else {
      Status = CachelessContextAddKext (
        Context,
        Kext->PlistData,
        Kext->PlistDataSize,
        Kext->ImageData,
        Kext->ImageDataSize
        );
    }
  } else if (CacheType == CacheTypeMkext) {
    Status = MkextInjectKext (
      Context,
      IsForced ? Identifier : NULL,
      IsForced ? BundlePath : FullPath,
      Kext->PlistData,
      Kext->PlistDataSize,
      Kext->ImageData,
      Kext->ImageDataSize
      );
  } else if (CacheType == CacheTypePrelinked) {
    Status = PrelinkedInjectKext (
      Context,
      IsForced ? Identifier : NULL,
      IsForced ? BundlePath : FullPath,
      Kext->PlistData,
      Kext->PlistDataSize,
      ExecutablePath,
      Kext->ImageData,
      Kext->ImageDataSize
      );
  } else {
    Status = EFI_UNSUPPORTED;
  }

  DEBUG ((
    !IsForced && EFI_ERROR (Status) ? DEBUG_WARN : DEBUG_INFO,
    "OC: %a%a injection %a (%a) - %r\n",
    PRINT_KERNEL_CACHE_TYPE (CacheType),
    IsForced ? " force" : "",
    BundlePath,
    Comment,
    Status
    ));
}

STATIC
VOID
OcKernelInjectKexts (
  IN OC_GLOBAL_CONFIG   *Config,
  IN KERNEL_CACHE_TYPE  CacheType,
  IN VOID               *Context,
  IN UINT32             DarwinVersion,
  IN BOOLEAN            Is32Bit,
  IN UINT32             LinkedExpansion,
  IN UINT32             ReservedExeSize
  )
{
  EFI_STATUS      Status;
  UINT32          Index;

  if (CacheType == CacheTypePrelinked) {
    Status = PrelinkedInjectPrepare (
      Context,
      LinkedExpansion,
      ReservedExeSize
      );
    if (EFI_ERROR (Status)) {
      DEBUG ((DEBUG_WARN, "OC: Prelink inject prepare error - %r\n", Status));
      return;
    }
  }

  //
  // Process system kexts to be force injected.
  //
  for (Index = 0; Index < Config->Kernel.Force.Count; Index++) {
    OcKernelInjectKext (
      Config->Kernel.Force.Values[Index],
      Index,
      TRUE,
      CacheType,
      Context,
      DarwinVersion,
      Is32Bit
      );
  }

  //
  // Process kexts to be injected.
  //
  for (Index = 0; Index < Config->Kernel.Add.Count; Index++) {
    OcKernelInjectKext (
      Config->Kernel.Add.Values[Index],
      Index,
      FALSE,
      CacheType,
      Context,
      DarwinVersion,
      Is32Bit
      );
  }

  if (CacheType == CacheTypeCacheless || CacheType == CacheTypeMkext) {
    Status = EFI_SUCCESS;
  } else if (CacheType == CacheTypePrelinked) {
    DEBUG ((
      DEBUG_INFO,
      "OC: Prelink size %u kext offset %u reserved %u\n",
      ((PRELINKED_CONTEXT *) Context)->PrelinkedSize,
      ((PRELINKED_CONTEXT *) Context)->KextsFileOffset,
      ReservedExeSize
      ));

    ASSERT (
      ((PRELINKED_CONTEXT *) Context)->PrelinkedSize -
      ((PRELINKED_CONTEXT *) Context)->KextsFileOffset <= ReservedExeSize
      );
    
    Status = PrelinkedInjectComplete (Context);
  } else {
    Status = EFI_UNSUPPORTED;
  }

  if (EFI_ERROR (Status)) {
    DEBUG ((DEBUG_WARN, "OC: %a insertion error - %r\n", PRINT_KERNEL_CACHE_TYPE (CacheType), Status));
  }
}

STATIC
EFI_STATUS
OcKernelProcessPrelinked (
  IN     OC_GLOBAL_CONFIG  *Config,
  IN     UINT32            DarwinVersion,
  IN     BOOLEAN           Is32Bit,
  IN OUT UINT8             *Kernel,
  IN     UINT32            *KernelSize,
  IN     UINT32            AllocatedSize,
  IN     UINT32            LinkedExpansion,
  IN     UINT32            ReservedExeSize
  )
{
  EFI_STATUS           Status;
  PRELINKED_CONTEXT    Context;

  Status = PrelinkedContextInit (&Context, Kernel, *KernelSize, AllocatedSize, Is32Bit);

  if (!EFI_ERROR (Status)) {
    OcKernelInjectKexts (Config, CacheTypePrelinked, &Context, DarwinVersion, Is32Bit, LinkedExpansion, ReservedExeSize);

    OcKernelApplyPatches (Config, mOcCpuInfo, DarwinVersion, Is32Bit, CacheTypePrelinked, &Context, NULL, 0);

    OcKernelBlockKexts (Config, DarwinVersion, Is32Bit, CacheTypePrelinked, &Context);

    *KernelSize = Context.PrelinkedSize;

    PrelinkedContextFree (&Context);
  }

  return Status;
}

STATIC
EFI_STATUS
OcKernelProcessMkext (
  IN     OC_GLOBAL_CONFIG  *Config,
  IN     UINT32            DarwinVersion,
  IN     BOOLEAN           Is32Bit,
  IN OUT UINT8             *Mkext,
  IN OUT UINT32            *MkextSize,
  IN     UINT32            AllocatedSize
  )
{
  EFI_STATUS            Status;
  MKEXT_CONTEXT         Context;

  Status = MkextContextInit (&Context, Mkext, *MkextSize, AllocatedSize);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  OcKernelInjectKexts (Config, CacheTypeMkext, &Context, DarwinVersion, Is32Bit, 0, 0);

  OcKernelApplyPatches (Config, mOcCpuInfo, DarwinVersion, Is32Bit, CacheTypeMkext, &Context, NULL, 0);

  OcKernelBlockKexts (Config, DarwinVersion, Is32Bit, CacheTypeMkext, &Context);

  MkextInjectPatchComplete (&Context);

  *MkextSize = Context.MkextSize;

  MkextContextFree (&Context);
  return Status;
}

STATIC
EFI_STATUS
OcKernelInitCacheless (
  IN     OC_GLOBAL_CONFIG       *Config,
  IN     CACHELESS_CONTEXT      *Context,
  IN     UINT32                 DarwinVersion,
  IN     BOOLEAN                Is32Bit,
  IN     CHAR16                 *FileName,
  IN     EFI_FILE_PROTOCOL      *ExtensionsDir,
     OUT EFI_FILE_PROTOCOL      **File
  )
{
  EFI_STATUS            Status;

  Status = CachelessContextInit (
    Context,
    FileName,
    ExtensionsDir,
    DarwinVersion,
    Is32Bit
    );
  if (EFI_ERROR (Status)) {
    return Status;
  }

  OcKernelInjectKexts (Config, CacheTypeCacheless, Context, DarwinVersion, Is32Bit, 0, 0);

  OcKernelApplyPatches (Config, mOcCpuInfo, DarwinVersion, Is32Bit, CacheTypeCacheless, Context, NULL, 0);

  OcKernelBlockKexts (Config, DarwinVersion, Is32Bit, CacheTypeCacheless, Context);

  return CachelessContextOverlayExtensionsDir (Context, File);
}

STATIC
EFI_STATUS
OcKernelReadAppleKernel (
  IN     EFI_FILE_PROTOCOL  *RootFile,
  IN     EFI_FILE_PROTOCOL  *KernelFile,
  IN     CHAR16             *FileName,
  IN     BOOLEAN            Is32Bit,
  IN OUT UINT32             *DarwinVersion,
     OUT UINT8              **Kernel,
     OUT UINT32             *KernelSize,
     OUT UINT32             *AllocatedSize,
     OUT UINT32             *ReservedExeSize,
     OUT UINT32             *LinkedExpansion,
     OUT UINT8              *Digest  OPTIONAL
  )
{
  EFI_STATUS         Status;
  BOOLEAN            Result;
  UINT32             DarwinVersionNew;
  BOOLEAN            IsKernel32Bit;

  UINT32             ReservedInfoSize;
  UINT32             NumReservedKexts;
  UINT32             ReservedFullSize;

  OcKernelLoadKextsAndReserve (
    RootFile,
    mOcStorage,
    mOcConfiguration,
    CacheTypePrelinked,
    Is32Bit,
    ReservedExeSize,
    &ReservedInfoSize,
    &NumReservedKexts
    );

  *LinkedExpansion = KcGetSegmentFixupChainsSize (*ReservedExeSize);
  if (*LinkedExpansion == 0) {
    return EFI_UNSUPPORTED;
  }

  Result = OcOverflowTriAddU32 (
    ReservedInfoSize,
    *ReservedExeSize,
    *LinkedExpansion,
    &ReservedFullSize
    );
  if (Result) {
    return EFI_UNSUPPORTED;
  }

  //
  // Read last requested architecture for kernel.
  //
  DEBUG ((DEBUG_INFO, "OC: Trying %a XNU hook on %s\n", Is32Bit ? "32-bit" : "64-bit", FileName));
  Status = ReadAppleKernel (
    KernelFile,
    Is32Bit,
    &IsKernel32Bit,
    Kernel,
    KernelSize,
    AllocatedSize,
    ReservedFullSize,
    Digest
    );
  DEBUG ((
    DEBUG_INFO,
    "OC: Result of %a XNU hook on %s (%02X%02X%02X%02X) is %r\n",
    IsKernel32Bit ? "32-bit" : "64-bit",
    FileName,
    Digest != NULL ? Digest[0] : 0,
    Digest != NULL ? Digest[1] : 0,
    Digest != NULL ? Digest[2] : 0,
    Digest != NULL ? Digest[3] : 0,
    Status
    ));

  if (!EFI_ERROR (Status)) {
    //
    // 10.6 and below may keep older prelinkedkernels around, do not load those.
    //
    DarwinVersionNew = OcKernelReadDarwinVersion (*Kernel, *KernelSize);
    if (DarwinVersionNew < *DarwinVersion) {
      FreePool (*Kernel);
      *Kernel = NULL;

      return EFI_INVALID_PARAMETER;
    }

    //
    // If we failed to obtain the requested bitness for the platform, abort.
    //
    if (Is32Bit != IsKernel32Bit) {
      DEBUG ((DEBUG_WARN, "OC: %a kernel architecture is not available, aborting.\n", Is32Bit ? "32-bit" : "64-bit"));
      FreePool (*Kernel);
      *Kernel = NULL;
      return EFI_NOT_FOUND;
    }

    *DarwinVersion = DarwinVersionNew;
  }

  return Status;
}

STATIC
EFI_STATUS
OcKernelFuzzyMatch (
  IN     EFI_FILE_PROTOCOL  *RootFile,
  IN     CHAR16             *FileName,
  IN     UINT64             OpenMode,
  IN     UINT64             Attributes,
  IN     BOOLEAN            Is32Bit,
  IN OUT UINT32             *DarwinVersion,
     OUT EFI_FILE_PROTOCOL  **KernelFile,
     OUT UINT8              **Kernel,
     OUT UINT32             *KernelSize,
     OUT UINT32             *AllocatedSize,
     OUT UINT32             *ReservedExeSize,
     OUT UINT32             *LinkedExpansion,
     OUT UINT8              *Digest  OPTIONAL
  )
{
  EFI_STATUS          Status;
  EFI_FILE_PROTOCOL   *FileDirectory;
  CHAR16              *FileNameDir;
  UINTN               FileNameDirLength;

  EFI_FILE_INFO       *FileInfo;
  EFI_FILE_INFO       *FileInfoNext;
  CHAR16              *FileNameCacheNew;
  UINTN               FileNameCacheNewLength;
  UINTN               FileNameCacheNewSize;

  DIRECTORY_SEARCH_CONTEXT Context;

  FileInfo          = NULL;
  FileNameCacheNew  = NULL;

  //
  // Open parent directory.
  //
  FileNameDirLength = OcStriStr (FileName, L"\\kernelcache") - FileName;
  FileNameDir = AllocateZeroPool (StrnSizeS (FileName, FileNameDirLength));
  if (FileNameDir == NULL) {
    return EFI_OUT_OF_RESOURCES;
  }
  CopyMem (FileNameDir, FileName, StrnSizeS (FileName, FileNameDirLength) - sizeof (*FileName));

  Status = OcSafeFileOpen (RootFile, &FileDirectory, FileNameDir, EFI_FILE_MODE_READ, 0);
  if (EFI_ERROR (Status)) {
    FreePool (FileNameDir);
    return Status;
  }

  //
  // Search for kernelcache files, trying each one.
  //
  OcDirectorySeachContextInit (&Context);
  do {
    Status = OcGetNewestFileFromDirectory (
      &Context,
      FileDirectory,
      L"kernelcache",
      &FileInfoNext
      );

    if (EFI_ERROR (Status)) {
      break;
    }
        
    if (FileInfo != NULL) {
      FreePool (FileInfo);
    }
    if (FileNameCacheNew != NULL) {
      FreePool (FileNameCacheNew);
    }
    FileInfo = FileInfoNext;

    FileNameCacheNewLength = FileNameDirLength + L_STR_LEN ("\\") + StrLen (FileInfo->FileName);
    FileNameCacheNewSize = (FileNameCacheNewLength + 1) * sizeof (*FileNameCacheNew);
    FileNameCacheNew = AllocateZeroPool (FileNameCacheNewSize);
    if (FileNameCacheNew == NULL) {
      Status = EFI_OUT_OF_RESOURCES;
      break;
    }

    Status = OcUnicodeSafeSPrint (FileNameCacheNew, FileNameCacheNewSize, L"%s\\%s", FileNameDir, FileInfo->FileName);
    if (EFI_ERROR (Status)) {
      break;
    }

    Status = OcSafeFileOpen (RootFile, KernelFile, FileNameCacheNew, OpenMode, Attributes);
    if (EFI_ERROR (Status)) {
      continue;
    }

    Status = OcKernelReadAppleKernel (
      RootFile,
      *KernelFile,
      FileNameCacheNew,
      Is32Bit,
      DarwinVersion,
      Kernel,
      KernelSize,
      AllocatedSize,
      ReservedExeSize,
      LinkedExpansion,
      Digest
      );
  } while (EFI_ERROR (Status));

  if (FileInfo != NULL) {
    FreePool (FileInfo);
  }
  if (FileNameCacheNew != NULL) {
    FreePool (FileNameCacheNew);
  }
  FreePool (FileNameDir);

  return Status;
}

STATIC
EFI_STATUS
EFIAPI
OcKernelFileOpen (
  IN  EFI_FILE_PROTOCOL       *This,
  OUT EFI_FILE_PROTOCOL       **NewHandle,
  IN  CHAR16                  *FileName,
  IN  UINT64                  OpenMode,
  IN  UINT64                  Attributes
  )
{
  EFI_STATUS         Status;
  BOOLEAN            Result;
  CONST CHAR8        *ForceCacheType;
  CONST CHAR8        *SecureBootModel;
  KERNEL_CACHE_TYPE  MaxCacheTypeAllowed;
  BOOLEAN            UseSecureBoot;

  UINT8              *Kernel;
  UINT32             KernelSize;
  UINT32             AllocatedSize;
  EFI_FILE_PROTOCOL  *VirtualFileHandle;
  EFI_STATUS         PrelinkedStatus;
  EFI_TIME           ModificationTime;
  UINT32             ReservedInfoSize;
  UINT32             ReservedExeSize;
  UINT32             NumReservedKexts;
  UINT32             LinkedExpansion;
  UINT32             ReservedFullSize;
  CHAR16             *NewFileName;
  EFI_FILE_PROTOCOL  *EspNewHandle;

  if (mCustomKernelDirectoryInProgress) {
    DEBUG ((DEBUG_INFO, "OC: Skipping OpenFile hooking on ESP Kernels directory\n"));
    return OcSafeFileOpen (This, NewHandle, FileName, OpenMode, Attributes);
  }

  //
  // Prevent access to cache files depending on maximum cache type allowed.
  //
  ForceCacheType = OC_BLOB_GET (&mOcConfiguration->Kernel.Scheme.KernelCache);
  if (AsciiStrCmp (ForceCacheType, "Cacheless") == 0) {
    MaxCacheTypeAllowed = CacheTypeCacheless;
  } else if (AsciiStrCmp (ForceCacheType, "Mkext") == 0) {
    MaxCacheTypeAllowed = CacheTypeMkext;
  } else if (AsciiStrCmp (ForceCacheType, "Prelinked") == 0) {
    MaxCacheTypeAllowed = CacheTypePrelinked;
  } else {
    MaxCacheTypeAllowed = CacheTypeNone;
  }

  //
  // We only want to calculate kernel hashes if secure boot is enabled.
  //
  SecureBootModel = OC_BLOB_GET (&mOcConfiguration->Misc.Security.SecureBootModel);
  UseSecureBoot   = AsciiStrCmp (SecureBootModel, OC_SB_MODEL_DISABLED) != 0;

  //
  // Hook injected OcXXXXXXXX.kext reads from /S/L/E.
  //
  if (mOcCachelessInProgress
    && OpenMode == EFI_FILE_MODE_READ
    && StrnCmp (FileName, L"System\\Library\\Extensions\\Oc", L_STR_LEN (L"System\\Library\\Extensions\\Oc")) == 0) {
    Status = CachelessContextPerformInject (&mOcCachelessContext, FileName, NewHandle);
    DEBUG ((
      DEBUG_INFO,
      "OC: Hooking SLE injected file %s with %u mode gave - %r\n",
      FileName,
      (UINT32) OpenMode,
      Status
      ));

    return Status;
  }

  Status = OcSafeFileOpen (This, NewHandle, FileName, OpenMode, Attributes);

  DEBUG ((
    DEBUG_VERBOSE,
    "OC: Opening file %s with %u mode gave - %r\n",
    FileName,
    (UINT32) OpenMode,
    Status
    ));

  //
  // Hook kernelcache read attempts for fuzzy kernelcache matching.
  // Only hook if the desired kernelcache file does not exist.
  //
  Kernel = NULL;
  if (mOcConfiguration->Kernel.Scheme.FuzzyMatch
    && Status == EFI_NOT_FOUND
    && OpenMode == EFI_FILE_MODE_READ
    && (StrStr (FileName, L"\\kernelcache") != NULL)) {
    //
    // Change the target to the custom one if requested CustomKernel.
    //
    if (mCustomKernelDirectory != NULL) {
      DEBUG ((DEBUG_INFO, "OC: Redirecting %s to the custom one on ESP\n", FileName));
      NewFileName = OcStrrChr (FileName, L'\\');
      if (NewFileName == NULL) {
        NewFileName = FileName;
      }
      DEBUG ((DEBUG_INFO, "OC: Filename after redirection: %s\n", NewFileName));

      This     = mCustomKernelDirectory;
      FileName = NewFileName;
    }

    DEBUG ((DEBUG_INFO, "OC: Trying kernelcache fuzzy matching on %s\n", FileName));

    Status = OcKernelFuzzyMatch (
      This,
      FileName,
      OpenMode,
      Attributes,
      mUse32BitKernel,
      &mOcDarwinVersion,
      NewHandle,
      &Kernel,
      &KernelSize,
      &AllocatedSize,
      &ReservedExeSize,
      &LinkedExpansion,
      UseSecureBoot ? mKernelDigest : NULL
      );
  }

  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // boot.efi uses /S/L/K/kernel as is to determine valid filesystem.
  // Just skip it to speedup the boot process.
  // On 10.9 mach_kernel is loaded for manual linking aferwards, so we cannot skip it.
  // We also want to skip files named "kernel" that are part of kext bundles, and im4m.
  //
  if (OpenMode == EFI_FILE_MODE_READ
    && OcStriStr (FileName, L"kernel") != NULL
    && StrCmp (FileName, L"System\\Library\\Kernels\\kernel") != 0
    && OcStriStr (FileName, L".kext\\") == NULL
    && OcStriStr (FileName, L".im4m") == NULL) {
    //
    // Change the target to the custom one if requested CustomKernel.
    //
    if (mCustomKernelDirectory != NULL) {
      DEBUG ((DEBUG_INFO, "OC: Redirecting %s to the custom one on ESP\n", FileName));
      NewFileName = OcStrrChr (FileName, L'\\');
      if (NewFileName == NULL) {
        NewFileName = FileName;
      }

      DEBUG ((DEBUG_INFO, "OC: Filename after redirection: %s\n", NewFileName));

      mCustomKernelDirectoryInProgress = TRUE;
      Status = OcSafeFileOpen (mCustomKernelDirectory, &EspNewHandle, NewFileName, OpenMode, Attributes);
      mCustomKernelDirectoryInProgress = FALSE;
      if (!EFI_ERROR (Status)) {
        (*NewHandle)->Close (*NewHandle);

        This = mCustomKernelDirectory;
        *NewHandle = EspNewHandle;
        FileName = NewFileName;
      }
    }

    //
    // Kernel loading for fuzzy kernelcache is performed earlier.
    //
    if (Kernel == NULL) {
      Status = OcKernelReadAppleKernel (
        This,
        *NewHandle,
        FileName,
        mUse32BitKernel,
        &mOcDarwinVersion,
        &Kernel,
        &KernelSize,
        &AllocatedSize,
        &ReservedExeSize,
        &LinkedExpansion,
        UseSecureBoot ? mKernelDigest : NULL
        );

      if (Status == EFI_NOT_FOUND) {
        (*NewHandle)->Close (*NewHandle);
        *NewHandle = NULL;

        return Status;
      }
    }

    if (!EFI_ERROR (Status)) {
      //
      // Disable prelinked if forcing mkext or cacheless, but only on appropriate versions.
      // We also disable prelinked on 10.5 or older due to prelinked on those versions being unsupported.
      //
      if ((OcStriStr (FileName, L"kernelcache") != NULL || OcStriStr (FileName, L"prelinkedkernel") != NULL)
        && ((MaxCacheTypeAllowed == CacheTypeNone && mOcDarwinVersion <= KERNEL_VERSION_LEOPARD_MAX)
        || (MaxCacheTypeAllowed == CacheTypeMkext && mOcDarwinVersion <= KERNEL_VERSION_SNOW_LEOPARD_MAX)
        || (MaxCacheTypeAllowed == CacheTypeCacheless && mOcDarwinVersion <= KERNEL_VERSION_MAVERICKS_MAX))) {
        DEBUG ((DEBUG_INFO, "OC: Blocking prelinked due to ForceKernelCache=%a: %s\n", ForceCacheType, FileName));

        FreePool (Kernel);
        (*NewHandle)->Close (*NewHandle);
        *NewHandle = NULL;

        return EFI_NOT_FOUND;
      }

      //
      // Apply patches to kernel itself, and then process prelinked.
      //
      OcKernelApplyPatches (
        mOcConfiguration,
        mOcCpuInfo,
        mOcDarwinVersion,
        mUse32BitKernel,
        CacheTypeNone,
        NULL,
        Kernel,
        KernelSize
        );

      PrelinkedStatus = OcKernelProcessPrelinked (
        mOcConfiguration,
        mOcDarwinVersion,
        mUse32BitKernel,
        Kernel,
        &KernelSize,
        AllocatedSize,
        LinkedExpansion,
        ReservedExeSize
        );

      DEBUG ((DEBUG_INFO, "OC: Prelinked status - %r\n", PrelinkedStatus));

      Status = OcGetFileModificationTime (*NewHandle, &ModificationTime);
      if (EFI_ERROR (Status)) {
        ZeroMem (&ModificationTime, sizeof (ModificationTime));
      }

      (*NewHandle)->Close (*NewHandle);

      //
      // Virtualise newly created kernel.
      //
      Status = CreateVirtualFileFileNameCopy (FileName, Kernel, KernelSize, &ModificationTime, &VirtualFileHandle);
      if (EFI_ERROR (Status)) {
        DEBUG ((DEBUG_WARN, "OC: Failed to virtualise kernel file (%s) - %r\n", FileName, Status));
        FreePool (Kernel);
        return EFI_OUT_OF_RESOURCES;
      }

      if (UseSecureBoot) {
        OcAppleImg4RegisterOverride (mKernelDigest, Kernel, KernelSize);
      }

      //
      // Return our handle.
      //
      *NewHandle = VirtualFileHandle;
      return EFI_SUCCESS;
    }
  }

  if (OpenMode == EFI_FILE_MODE_READ
    && OcStriStr (FileName, L"Extensions.mkext") != NULL) {

    //
    // Disable mkext booting if forcing cacheless.
    //
    if (MaxCacheTypeAllowed == CacheTypeCacheless) {
      DEBUG ((DEBUG_INFO, "OC: Blocking mkext due to ForceKernelCache=%a: %s\n", ForceCacheType, FileName));
      (*NewHandle)->Close (*NewHandle);
      *NewHandle = NULL;

      return EFI_NOT_FOUND;
    }
    
    OcKernelLoadKextsAndReserve (
      This,
      mOcStorage,
      mOcConfiguration,
      CacheTypeMkext,
      mUse32BitKernel,
      &ReservedExeSize,
      &ReservedInfoSize,
      &NumReservedKexts
      );

    Result = OcOverflowAddU32 (
      ReservedInfoSize,
      ReservedExeSize,
      &ReservedFullSize
      );
    if (Result) {
      return EFI_UNSUPPORTED;
    }

    DEBUG ((DEBUG_INFO, "OC: Trying %a mkext hook on %s\n", mUse32BitKernel ? "32-bit" : "64-bit", FileName));
    Status = ReadAppleMkext (
      *NewHandle,
      mUse32BitKernel,
      &Kernel,
      &KernelSize,
      &AllocatedSize,
      ReservedFullSize,
      NumReservedKexts
      );
    DEBUG ((DEBUG_INFO, "OC: Result of mkext hook on %s is %r\n", FileName, Status));

    if (!EFI_ERROR (Status)) {
      //
      // Process mkext.
      //
      Status = OcKernelProcessMkext (
        mOcConfiguration,
        mOcDarwinVersion,
        mUse32BitKernel,
        Kernel,
        &KernelSize,
        AllocatedSize
        );
      DEBUG ((DEBUG_INFO, "OC: Mkext status - %r\n", Status));
      if (!EFI_ERROR (Status)) {
        Status = OcGetFileModificationTime (*NewHandle, &ModificationTime);
        if (EFI_ERROR (Status)) {
          ZeroMem (&ModificationTime, sizeof (ModificationTime));
        }

        (*NewHandle)->Close (*NewHandle);

        //
        // Virtualise newly created mkext.
        //
        Status = CreateVirtualFileFileNameCopy (FileName, Kernel, KernelSize, &ModificationTime, &VirtualFileHandle);
        if (EFI_ERROR (Status)) {
          DEBUG ((DEBUG_WARN, "OC: Failed to virtualise mkext file (%s) - %r\n", FileName, Status));
          FreePool (Kernel);
          return EFI_OUT_OF_RESOURCES;
        }

        *NewHandle = VirtualFileHandle;
        return EFI_SUCCESS;
      } else {
        FreePool (Kernel);
      }
    }
  }

  //
  // Hook /S/L/E for cacheless boots.
  //
  if (OpenMode == EFI_FILE_MODE_READ
    && StrCmp (FileName, L"System\\Library\\Extensions") == 0) {

    //
    // Free existing context if we are re-opening Extensions directory.
    //
    if (mOcCachelessInProgress) {
      CachelessContextFree (&mOcCachelessContext);
    }
    mOcCachelessInProgress = FALSE;

    OcKernelLoadKextsAndReserve (
      This,
      mOcStorage,
      mOcConfiguration,
      CacheTypeCacheless,
      mUse32BitKernel,
      &ReservedExeSize,
      &ReservedInfoSize,
      &NumReservedKexts
      );

    //
    // Initialize Extensions directory overlay for cacheless injection.
    //
    Status = OcKernelInitCacheless (
      mOcConfiguration,
      &mOcCachelessContext,
      mOcDarwinVersion,
      mUse32BitKernel,
      FileName,
      *NewHandle,
      &VirtualFileHandle
      );
    
    DEBUG ((DEBUG_INFO, "OC: Result of SLE hook on %s is %r\n", FileName, Status));

    if (!EFI_ERROR (Status)) {
      mOcCachelessInProgress  = TRUE;
      *NewHandle              = VirtualFileHandle;
      return EFI_SUCCESS;
    }
  }

  //
  // Hook /S/L/E contents for processing during cacheless boots.
  //
  if (mOcCachelessInProgress
    && OpenMode == EFI_FILE_MODE_READ
    && StrnCmp (FileName, L"System\\Library\\Extensions\\", L_STR_LEN (L"System\\Library\\Extensions\\")) == 0) {
      Status = CachelessContextHookBuiltin (
        &mOcCachelessContext,
        FileName,
        *NewHandle,
        &VirtualFileHandle
        );

      if (EFI_ERROR (Status)) {
        DEBUG ((DEBUG_INFO, "OC: Error SLE hooking %s - %r\n", FileName, Status));
      }

      if (!EFI_ERROR (Status) && VirtualFileHandle != NULL) {
        *NewHandle = VirtualFileHandle;
        return EFI_SUCCESS;
      }
  }

  //
  // This is not Apple kernel, just return the original file.
  // We recurse the filtering to additionally catch com.apple.boot.[RPS] directories.
  //
  return CreateRealFile (*NewHandle, OcKernelFileOpen, TRUE, NewHandle);
}

VOID
OcLoadKernelSupport (
  IN OC_STORAGE_CONTEXT  *Storage,
  IN OC_GLOBAL_CONFIG    *Config,
  IN OC_CPU_INFO         *CpuInfo
  )
{
  EFI_STATUS         Status;
  EFI_FILE_PROTOCOL  *Root;

  Status = EnableVirtualFs (gBS, OcKernelFileOpen);

  if (!EFI_ERROR (Status)) {
    mOcStorage                        = Storage;
    mOcConfiguration                  = Config;
    mOcCpuInfo                        = CpuInfo;
    mOcDarwinVersion                  = 0;
    mOcCachelessInProgress            = FALSE;
    mCustomKernelDirectoryInProgress  = FALSE;
    //
    // Open customised Kernels if needed.
    //
    mCustomKernelDirectory = NULL;
    if (mOcConfiguration->Kernel.Scheme.CustomKernel) {
      Status = OcFindWritableOcFileSystem (&Root);
      if (!EFI_ERROR (Status)) {
        //
        // Open Kernels directory.
        //
        Status = Root->Open (
          Root,
          &mCustomKernelDirectory,
          L"Kernels",
          EFI_FILE_MODE_READ,
          EFI_FILE_DIRECTORY
          );
        if (EFI_ERROR (Status)) {
          DEBUG ((DEBUG_INFO, "OC: Unable to open Kernels folder for custom kernel - %r, falling back to normal one\n", Status));
          mCustomKernelDirectory = NULL;
        }
      } else {
        DEBUG ((DEBUG_INFO, "OC: Unable to find root writable filesystem for custom kernel - %r, falling back to normal one\n", Status));
      }
    }

    OcImageLoaderRegisterConfigure (OcKernelConfigureCapabilities);
  } else {
    DEBUG ((DEBUG_ERROR, "OC: Failed to enable vfs - %r\n", Status));
  }
}

VOID
OcUnloadKernelSupport (
  VOID
  )
{
  EFI_STATUS  Status;

  if (mOcStorage != NULL) {
    OcImageLoaderRegisterConfigure (NULL);
    Status = DisableVirtualFs (gBS);
    if (EFI_ERROR (Status)) {
      DEBUG ((DEBUG_ERROR, "OC: Failed to disable vfs - %r\n", Status));
    }
    mOcStorage       = NULL;
    mOcConfiguration = NULL;
  }
}