/** @file
This contains some useful functions for accessing files.

Copyright (c) 2004 - 2018, Intel Corporation. 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 <assert.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include "CommonLib.h"
#include "MemoryFile.h"


//
// Local (static) function prototypes
//
STATIC
VOID
CheckMemoryFileState (
  IN EFI_HANDLE InputMemoryFile
  );

//
// Function implementations
//

EFI_STATUS
GetMemoryFile (
  IN CHAR8       *InputFileName,
  OUT EFI_HANDLE *OutputMemoryFile
  )
/*++

Routine Description:

  This opens a file, reads it into memory and returns a memory file
  object.

Arguments:

  InputFile          Memory file image.
  OutputMemoryFile   Handle to memory file

Returns:

  EFI_STATUS
  OutputMemoryFile is valid if !EFI_ERROR

--*/
{
  EFI_STATUS  Status;
  CHAR8       *InputFileImage;
  UINT32      BytesRead;
  MEMORY_FILE *NewMemoryFile;

  Status = GetFileImage (InputFileName, &InputFileImage, &BytesRead);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  NewMemoryFile = malloc (sizeof (*NewMemoryFile));
  if (NewMemoryFile == NULL) {
    free (InputFileImage);
    return EFI_OUT_OF_RESOURCES;
  }

  NewMemoryFile->FileImage           = InputFileImage;
  NewMemoryFile->CurrentFilePointer  = InputFileImage;
  NewMemoryFile->Eof                 = InputFileImage + BytesRead;

  *OutputMemoryFile = (EFI_HANDLE)NewMemoryFile;

  CheckMemoryFileState (*OutputMemoryFile);

  return EFI_SUCCESS;
}


EFI_STATUS
FreeMemoryFile (
  IN EFI_HANDLE InputMemoryFile
  )
/*++

Routine Description:

  Frees all memory associated with the input memory file.

Arguments:

  InputMemoryFile   Handle to memory file

Returns:

  EFI_STATUS

--*/
{
  MEMORY_FILE *MemoryFile;

  CheckMemoryFileState (InputMemoryFile);

  MemoryFile = (MEMORY_FILE*)InputMemoryFile;

  free (MemoryFile->FileImage);

  //
  // Invalidate state of MEMORY_FILE structure to catch invalid usage.
  //
  memset (MemoryFile, 0xcc, sizeof (*MemoryFile));
  MemoryFile->Eof -= 1;

  free (MemoryFile);

  return EFI_SUCCESS;
}


CHAR8 *
ReadMemoryFileLine (
  IN EFI_HANDLE     InputMemoryFile
  )
/*++

Routine Description:

  This function reads a line from the memory file.  The newline characters
  are stripped and a null terminated string is returned.

  If the string pointer returned is non-NULL, then the caller must free the
  memory associated with this string.

Arguments:

  InputMemoryFile   Handle to memory file

Returns:

  NULL if error or EOF
  NULL character termincated string otherwise (MUST BE FREED BY CALLER)

--*/
{
  CHAR8       *EndOfLine;
  UINTN       CharsToCopy;
  MEMORY_FILE *InputFile;
  UINTN       BytesToEof;
  CHAR8       *OutputString;

  //
  // Verify input parameters are not null
  //
  CheckMemoryFileState (InputMemoryFile);

  InputFile = (MEMORY_FILE*)InputMemoryFile;

  //
  // Check for end of file condition
  //
  if (InputFile->CurrentFilePointer >= InputFile->Eof) {
    return NULL;
  }

  //
  // Determine the number of bytes remaining until the EOF
  //
  BytesToEof = InputFile->Eof - InputFile->CurrentFilePointer;

  //
  // Find the next newline char
  //
  EndOfLine = memchr (InputFile->CurrentFilePointer, '\n', BytesToEof);

  //
  // Determine the number of characters to copy.
  //
  if (EndOfLine == 0) {
    //
    // If no newline found, copy to the end of the file.
    //
    CharsToCopy = InputFile->Eof - InputFile->CurrentFilePointer;
  } else {
    //
    // Newline found in the file.
    //
    CharsToCopy = EndOfLine - InputFile->CurrentFilePointer;
  }

  OutputString = malloc (CharsToCopy + 1);
  if (OutputString == NULL) {
    return NULL;
  }

  //
  // Copy the line.
  //
  memcpy (OutputString, InputFile->CurrentFilePointer, CharsToCopy);

  //
  // Add the null termination over the 0x0D
  //
  if (OutputString[CharsToCopy - 1] == '\r') {

    OutputString[CharsToCopy - 1] = '\0';

  } else {

    OutputString[CharsToCopy] = '\0';

  }

  //
  // Increment the current file pointer (include the 0x0A)
  //
  InputFile->CurrentFilePointer += CharsToCopy + 1;
  if (InputFile->CurrentFilePointer > InputFile->Eof) {
    InputFile->CurrentFilePointer = InputFile->Eof;
  }
  CheckMemoryFileState (InputMemoryFile);

  //
  // Return the string
  //
  return OutputString;
}


STATIC
VOID
CheckMemoryFileState (
  IN EFI_HANDLE InputMemoryFile
  )
{
  MEMORY_FILE *MemoryFile;

  assert (InputMemoryFile != NULL);

  MemoryFile = (MEMORY_FILE*)InputMemoryFile;

  assert (MemoryFile->FileImage != NULL);
  assert (MemoryFile->CurrentFilePointer != NULL);
  assert (MemoryFile->Eof != NULL);
  assert (MemoryFile->Eof >= MemoryFile->FileImage);
  assert (MemoryFile->CurrentFilePointer >= MemoryFile->FileImage);
  assert (MemoryFile->CurrentFilePointer <= MemoryFile->Eof);
}