filesystem.h

#include <efi.h>
#include <efilib.h>
// #include "memory.h"

UINT64 FileSize(EFI_FILE_HANDLE FileHandle)
{
  UINT64 ret;
  EFI_FILE_INFO *FileInfo; /* file information structure */
  /* get the file's size */
  FileInfo = LibFileInfo(FileHandle);
  ret = FileInfo->FileSize;
  FreePool(FileInfo);
  return ret;
}

EFI_FILE_HANDLE GetVolume(EFI_HANDLE image)
{
  EFI_LOADED_IMAGE *loaded_image = NULL;                  /* image interface */
  EFI_GUID lipGuid = EFI_LOADED_IMAGE_PROTOCOL_GUID;      /* image interface GUID */
  EFI_FILE_IO_INTERFACE *IOVolume;                        /* file system interface */
  EFI_GUID fsGuid = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID; /* file system interface GUID */
  EFI_FILE_HANDLE Volume;                                 /* the volume's interface */

  /* get the loaded image protocol interface for our "image" */
  uefi_call_wrapper(BS->HandleProtocol, 3, image, &lipGuid, (void **)&loaded_image);
  /* get the volume handle */
  uefi_call_wrapper(BS->HandleProtocol, 3, loaded_image->DeviceHandle, &fsGuid, (VOID *)&IOVolume);
  uefi_call_wrapper(IOVolume->OpenVolume, 2, IOVolume, &Volume);
  return Volume;
}

void *ReadFileTooBuffer(CHAR16 *FileName, EFI_FILE_HANDLE Volume)
{
  EFI_FILE_HANDLE FileHandle;

  /* open the file */
  uefi_call_wrapper(Volume->Open, 5, Volume, &FileHandle, FileName, EFI_FILE_MODE_READ, EFI_FILE_READ_ONLY | EFI_FILE_HIDDEN | EFI_FILE_SYSTEM);

  UINT64 ReadSize = FileSize(FileHandle);
  UINT8 *Buffer = uefi_malloc(ReadSize);

  uefi_call_wrapper(FileHandle->Read, 3, FileHandle, &ReadSize, Buffer);

  /* close the file */
  uefi_call_wrapper(FileHandle->Close, 1, FileHandle);

  return Buffer;
}

BOOLEAN FileExists(CHAR16 *FileName, EFI_FILE_HANDLE Volume)
{
  char *buffer = ReadFileTooBuffer(FileName, Volume);

  if (buffer[0] == '\0') {
    return 1;
  } else {
    return 0;
  }
}