/** @file
*
*  Copyright (c) 2012-2014, ARM Limited. All rights reserved.
*
*  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 <Protocol/SimpleFileSystem.h>
#include <Library/UefiLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/DebugLib.h>

#include "BootMonFsInternal.h"

/**
  Read data from an open file.

  @param[in]      This        A pointer to the EFI_FILE_PROTOCOL instance that
                              is the file handle to read data from.
  @param[in out]  BufferSize  On input, the size of the Buffer. On output, the
                              amount of data returned in Buffer. In both cases,
                              the size is measured in bytes.
  @param[out]     Buffer      The buffer into which the data is read.

  @retval  EFI_SUCCESS            The data was read.
  @retval  EFI_DEVICE_ERROR       On entry, the current file position is
                                  beyond the end of the file, or the device
                                  reported an error while performing the read
                                  operation.
  @retval  EFI_INVALID_PARAMETER  At least one of the parameters is invalid.

**/
EFIAPI
EFI_STATUS
BootMonFsReadFile (
  IN EFI_FILE_PROTOCOL  *This,
  IN OUT UINTN          *BufferSize,
  OUT VOID              *Buffer
  )
{
  BOOTMON_FS_INSTANCE   *Instance;
  BOOTMON_FS_FILE       *File;
  EFI_DISK_IO_PROTOCOL  *DiskIo;
  EFI_BLOCK_IO_MEDIA    *Media;
  UINT64                FileStart;
  EFI_STATUS            Status;
  UINTN                 RemainingFileSize;

  if ((This == NULL)       ||
      (BufferSize == NULL) ||
      (Buffer == NULL)        ) {
    return EFI_INVALID_PARAMETER;
  }
  File = BOOTMON_FS_FILE_FROM_FILE_THIS (This);
  if (File->Info == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  // Ensure the file has been written in Flash before reading it.
  // This keeps the code simple and avoids having to manage a non-flushed file.
  BootMonFsFlushFile (This);

  Instance  = File->Instance;
  DiskIo    = Instance->DiskIo;
  Media     = Instance->Media;
  FileStart = (Media->LowestAlignedLba + File->HwDescription.BlockStart) * Media->BlockSize;

  if (File->Position >= File->Info->FileSize) {
    // The entire file has been read or the position has been
    // set past the end of the file.
    *BufferSize = 0;
    if (File->Position > File->Info->FileSize) {
      return EFI_DEVICE_ERROR;
    } else {
      return EFI_SUCCESS;
    }
  }

  // This driver assumes that the entire file is in region 0.
  RemainingFileSize = File->Info->FileSize - File->Position;

  // If read would go past end of file, truncate the read
  if (*BufferSize > RemainingFileSize) {
    *BufferSize = RemainingFileSize;
  }

  Status = DiskIo->ReadDisk (
                    DiskIo,
                    Media->MediaId,
                    FileStart + File->Position,
                    *BufferSize,
                    Buffer
                    );
  if (EFI_ERROR (Status)) {
    *BufferSize = 0;
  }

  File->Position += *BufferSize;

  return Status;
}

/**
  Write data to an open file.

  The data is not written to the flash yet. It will be written when the file
  will be either read, closed or flushed.

  @param[in]      This        A pointer to the EFI_FILE_PROTOCOL instance that
                              is the file handle to write data to.
  @param[in out]  BufferSize  On input, the size of the Buffer. On output, the
                              size of the data actually written. In both cases,
                              the size is measured in bytes.
  @param[in]      Buffer      The buffer of data to write.

  @retval  EFI_SUCCESS            The data was written.
  @retval  EFI_ACCESS_DENIED      The file was opened read only.
  @retval  EFI_OUT_OF_RESOURCES   Unable to allocate the buffer to store the
                                  data to write.
  @retval  EFI_INVALID_PARAMETER  At least one of the parameters is invalid.

**/
EFIAPI
EFI_STATUS
BootMonFsWriteFile (
  IN EFI_FILE_PROTOCOL  *This,
  IN OUT UINTN          *BufferSize,
  IN VOID               *Buffer
  )
{
  BOOTMON_FS_FILE         *File;
  BOOTMON_FS_FILE_REGION  *Region;

  if (This == NULL) {
    return EFI_INVALID_PARAMETER;
  }
  File = BOOTMON_FS_FILE_FROM_FILE_THIS (This);
  if (File->Info == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  if (File->OpenMode == EFI_FILE_MODE_READ) {
    return EFI_ACCESS_DENIED;
  }

  // Allocate and initialize the memory region
  Region = (BOOTMON_FS_FILE_REGION*)AllocateZeroPool (sizeof (BOOTMON_FS_FILE_REGION));
  if (Region == NULL) {
    *BufferSize = 0;
    return EFI_OUT_OF_RESOURCES;
  }

  Region->Buffer = AllocateCopyPool (*BufferSize, Buffer);
  if (Region->Buffer == NULL) {
    *BufferSize = 0;
    FreePool (Region);
    return EFI_OUT_OF_RESOURCES;
  }

  Region->Size   = *BufferSize;
  Region->Offset = File->Position;

  InsertTailList (&File->RegionToFlushLink, &Region->Link);

  File->Position += *BufferSize;

  if (File->Position > File->Info->FileSize) {
    File->Info->FileSize = File->Position;
  }

  return EFI_SUCCESS;
}

/**
  Set a file's current position.

  @param[in]  This      A pointer to the EFI_FILE_PROTOCOL instance that is
                        the file handle to set the requested position on.
  @param[in]  Position  The byte position from the start of the file to set.

  @retval  EFI_SUCCESS            The position was set.
  @retval  EFI_INVALID_PARAMETER  At least one of the parameters is invalid.

**/
EFIAPI
EFI_STATUS
BootMonFsSetPosition (
  IN EFI_FILE_PROTOCOL  *This,
  IN UINT64             Position
  )
{
  BOOTMON_FS_FILE  *File;

  if (This == NULL) {
    return EFI_INVALID_PARAMETER;
  }
  File = BOOTMON_FS_FILE_FROM_FILE_THIS (This);
  if (File->Info == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // UEFI Spec section 12.5:
  // "Seeking to position 0xFFFFFFFFFFFFFFFF causes the current position to
  // be set to the end of the file."
  //
  if (Position == 0xFFFFFFFFFFFFFFFF) {
    Position = File->Info->FileSize;
  }

  File->Position = Position;

  return EFI_SUCCESS;
}

/**
  Return a file's current position.

  @param[in]   This      A pointer to the EFI_FILE_PROTOCOL instance that is
                         the file handle to get the current position on.
  @param[out]  Position  The address to return the file's current position value.

  @retval  EFI_SUCCESS            The position was returned.
  @retval  EFI_INVALID_PARAMETER  At least one of the parameters is invalid.

**/
EFIAPI
EFI_STATUS
BootMonFsGetPosition (
  IN  EFI_FILE_PROTOCOL *This,
  OUT UINT64            *Position
  )
{
  BOOTMON_FS_FILE         *File;

  if (This == NULL) {
    return EFI_INVALID_PARAMETER;
  }
  File = BOOTMON_FS_FILE_FROM_FILE_THIS (This);
  if (File->Info == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  if (Position == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  *Position = File->Position;

  return EFI_SUCCESS;
}