예제 #1
0
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
%   S i g n a t u r e I m a g e                                               %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  SignatureImage() computes a message digest from an image pixel stream with
%  an implementation of the NIST SHA-256 Message Digest algorithm.  This
%  signature uniquely identifies the image and is convenient for determining
%  if an image has been modified or whether two images are identical.
%
%  The format of the SignatureImage method is:
%
%      MagickBooleanType SignatureImage(Image *image,ExceptionInfo *exception)
%
%  A description of each parameter follows:
%
%    o image: the image.
%
%    o exception: return any errors or warnings in this structure.
%
*/
MagickExport MagickBooleanType SignatureImage(Image *image,
  ExceptionInfo *exception)
{
  CacheView
    *image_view;

  char
    *hex_signature;

  double
    pixel;

  register const Quantum
    *p;

  SignatureInfo
    *signature_info;

  ssize_t
    y;

  StringInfo
    *signature;

  unsigned char
    *pixels;

  /*
    Compute image digital signature.
  */
  assert(image != (Image *) NULL);
  assert(image->signature == MagickSignature);
  if (image->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
  signature_info=AcquireSignatureInfo();
  signature=AcquireStringInfo(image->columns*GetPixelChannels(image)*
    sizeof(pixel));
  image_view=AcquireVirtualCacheView(image,exception);
  for (y=0; y < (ssize_t) image->rows; y++)
  {
    register ssize_t
      x;

    register unsigned char
      *q;

    p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
    if (p == (const Quantum *) NULL)
      break;
    SetStringInfoLength(signature,image->columns*GetPixelChannels(image)*
      sizeof(pixel));
    pixels=GetStringInfoDatum(signature);
    q=pixels;
    for (x=0; x < (ssize_t) image->columns; x++)
    {
      register ssize_t
        i;

      if (GetPixelReadMask(image,p) == 0)
        {
          p+=GetPixelChannels(image);
          continue;
        }
      for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
      {
        register ssize_t
          j;

        PixelChannel channel=GetPixelChannelChannel(image,i);
        PixelTrait traits=GetPixelChannelTraits(image,channel);
        if (traits == UndefinedPixelTrait)
          continue;
        pixel=QuantumScale*p[i];
        for (j=0; j < (ssize_t) sizeof(pixel); j++)
          *q++=(unsigned char) ((unsigned char *) &pixel)[j];
      }
      p+=GetPixelChannels(image);
    }
    SetStringInfoLength(signature,(size_t) (q-pixels));
    UpdateSignature(signature_info,signature);
  }
  image_view=DestroyCacheView(image_view);
  FinalizeSignature(signature_info);
  hex_signature=StringInfoToHexString(GetSignatureDigest(signature_info));
  (void) DeleteImageProperty(image,"signature");
  (void) SetImageProperty(image,"signature",hex_signature,exception);
  /*
    Free resources.
  */
  hex_signature=DestroyString(hex_signature);
  signature=DestroyStringInfo(signature);
  signature_info=DestroySignatureInfo(signature_info);
  return(MagickTrue);
}
예제 #2
0
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
%   S i g n a t u r e I m a g e                                               %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  SignatureImage() computes a message digest from an image pixel stream with
%  an implementation of the NIST SHA-256 Message Digest algorithm.  This
%  signature uniquely identifies the image and is convenient for determining
%  if an image has been modified or whether two images are identical.
%
%  The format of the SignatureImage method is:
%
%      MagickBooleanType SignatureImage(Image *image)
%
%  A description of each parameter follows:
%
%    o image: the image.
%
*/
MagickExport MagickBooleanType SignatureImage(Image *image)
{
  CacheView
    *image_view;

  char
    *hex_signature;

  ExceptionInfo
    *exception;

  QuantumInfo
    *quantum_info;

  QuantumType
    quantum_type;

  register const PixelPacket
    *p;

  SignatureInfo
    *signature_info;

  size_t
    length;

  ssize_t
    y;

  StringInfo
    *signature;

  unsigned char
    *pixels;

  /*
    Compute image digital signature.
  */
  assert(image != (Image *) NULL);
  assert(image->signature == MagickSignature);
  if (image->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
  quantum_info=AcquireQuantumInfo((const ImageInfo *) NULL,image);
  if (quantum_info == (QuantumInfo *) NULL)
    ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
      image->filename);
  quantum_type=RGBQuantum;
  if (image->matte != MagickFalse)
    quantum_type=RGBAQuantum;
  if (image->colorspace == CMYKColorspace)
    {
      quantum_type=CMYKQuantum;
      if (image->matte != MagickFalse)
        quantum_type=CMYKAQuantum;
    }
  signature_info=AcquireSignatureInfo();
  signature=AcquireStringInfo(quantum_info->extent);
  pixels=GetQuantumPixels(quantum_info);
  exception=(&image->exception);
  image_view=AcquireCacheView(image);
  for (y=0; y < (ssize_t) image->rows; y++)
  {
    p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
    if (p == (const PixelPacket *) NULL)
      break;
    length=ExportQuantumPixels(image,image_view,quantum_info,quantum_type,
      pixels,&image->exception);
    SetStringInfoLength(signature,length);
    SetStringInfoDatum(signature,pixels);
    UpdateSignature(signature_info,signature);
  }
  image_view=DestroyCacheView(image_view);
  quantum_info=DestroyQuantumInfo(quantum_info);
  FinalizeSignature(signature_info);
  hex_signature=StringInfoToHexString(GetSignatureDigest(signature_info));
  (void) DeleteImageProperty(image,"signature");
  (void) SetImageProperty(image,"signature",hex_signature);
  /*
    Free resources.
  */
  hex_signature=DestroyString(hex_signature);
  signature=DestroyStringInfo(signature);
  signature_info=DestroySignatureInfo(signature_info);
  return(MagickTrue);
}