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gif.c
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gif.c
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/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% %
% %
% GGGG IIIII FFFFF %
% G I F %
% G GG I FFF %
% G G I F %
% GGG IIIII F %
% %
% %
% Read/Write Compuserv Graphics Interchange Format %
% %
% Software Design %
% Cristy %
% July 1992 %
% %
% %
% Copyright 1999-2020 ImageMagick Studio LLC, a non-profit organization %
% dedicated to making software imaging solutions freely available. %
% %
% You may not use this file except in compliance with the License. You may %
% obtain a copy of the License at %
% %
% https://imagemagick.org/script/license.php %
% %
% Unless required by applicable law or agreed to in writing, software %
% distributed under the License is distributed on an "AS IS" BASIS, %
% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. %
% See the License for the specific language governing permissions and %
% limitations under the License. %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%
*/
/*
Include declarations.
*/
#include "MagickCore/studio.h"
#include "MagickCore/attribute.h"
#include "MagickCore/blob.h"
#include "MagickCore/blob-private.h"
#include "MagickCore/cache.h"
#include "MagickCore/color.h"
#include "MagickCore/color-private.h"
#include "MagickCore/colormap.h"
#include "MagickCore/colormap-private.h"
#include "MagickCore/colorspace.h"
#include "MagickCore/colorspace-private.h"
#include "MagickCore/exception.h"
#include "MagickCore/exception-private.h"
#include "MagickCore/image.h"
#include "MagickCore/image-private.h"
#include "MagickCore/list.h"
#include "MagickCore/profile.h"
#include "MagickCore/magick.h"
#include "MagickCore/memory_.h"
#include "MagickCore/monitor.h"
#include "MagickCore/monitor-private.h"
#include "MagickCore/option.h"
#include "MagickCore/pixel.h"
#include "MagickCore/pixel-accessor.h"
#include "MagickCore/property.h"
#include "MagickCore/quantize.h"
#include "MagickCore/quantum-private.h"
#include "MagickCore/resource_.h"
#include "MagickCore/static.h"
#include "MagickCore/string_.h"
#include "MagickCore/string-private.h"
#include "MagickCore/module.h"
/*
Define declarations.
*/
#define MaximumLZWBits 12
#define MaximumLZWCode (1UL << MaximumLZWBits)
/*
Typdef declarations.
*/
typedef struct _LZWCodeInfo
{
unsigned char
buffer[280];
size_t
count,
bit;
MagickBooleanType
eof;
} LZWCodeInfo;
typedef struct _LZWStack
{
size_t
*codes,
*index,
*top;
} LZWStack;
typedef struct _LZWInfo
{
Image
*image;
LZWStack
*stack;
MagickBooleanType
genesis;
size_t
data_size,
maximum_data_value,
clear_code,
end_code,
bits,
first_code,
last_code,
maximum_code,
slot,
*table[2];
LZWCodeInfo
code_info;
} LZWInfo;
/*
Forward declarations.
*/
static inline int
GetNextLZWCode(LZWInfo *,const size_t);
static MagickBooleanType
WriteGIFImage(const ImageInfo *,Image *,ExceptionInfo *);
static ssize_t
ReadBlobBlock(Image *,unsigned char *);
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% %
% %
% D e c o d e I m a g e %
% %
% %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% DecodeImage uncompresses an image via GIF-coding.
%
% The format of the DecodeImage method is:
%
% MagickBooleanType DecodeImage(Image *image,const ssize_t opacity)
%
% A description of each parameter follows:
%
% o image: the address of a structure of type Image.
%
% o opacity: The colormap index associated with the transparent color.
%
*/
static LZWInfo *RelinquishLZWInfo(LZWInfo *lzw_info)
{
if (lzw_info->table[0] != (size_t *) NULL)
lzw_info->table[0]=(size_t *) RelinquishMagickMemory(
lzw_info->table[0]);
if (lzw_info->table[1] != (size_t *) NULL)
lzw_info->table[1]=(size_t *) RelinquishMagickMemory(
lzw_info->table[1]);
if (lzw_info->stack != (LZWStack *) NULL)
{
if (lzw_info->stack->codes != (size_t *) NULL)
lzw_info->stack->codes=(size_t *) RelinquishMagickMemory(
lzw_info->stack->codes);
lzw_info->stack=(LZWStack *) RelinquishMagickMemory(lzw_info->stack);
}
lzw_info=(LZWInfo *) RelinquishMagickMemory(lzw_info);
return((LZWInfo *) NULL);
}
static inline void ResetLZWInfo(LZWInfo *lzw_info)
{
size_t
one;
lzw_info->bits=lzw_info->data_size+1;
one=1;
lzw_info->maximum_code=one << lzw_info->bits;
lzw_info->slot=lzw_info->maximum_data_value+3;
lzw_info->genesis=MagickTrue;
}
static LZWInfo *AcquireLZWInfo(Image *image,const size_t data_size)
{
LZWInfo
*lzw_info;
register ssize_t
i;
size_t
one;
lzw_info=(LZWInfo *) AcquireMagickMemory(sizeof(*lzw_info));
if (lzw_info == (LZWInfo *) NULL)
return((LZWInfo *) NULL);
(void) memset(lzw_info,0,sizeof(*lzw_info));
lzw_info->image=image;
lzw_info->data_size=data_size;
one=1;
lzw_info->maximum_data_value=(one << data_size)-1;
lzw_info->clear_code=lzw_info->maximum_data_value+1;
lzw_info->end_code=lzw_info->maximum_data_value+2;
lzw_info->table[0]=(size_t *) AcquireQuantumMemory(MaximumLZWCode,
sizeof(**lzw_info->table));
lzw_info->table[1]=(size_t *) AcquireQuantumMemory(MaximumLZWCode,
sizeof(**lzw_info->table));
if ((lzw_info->table[0] == (size_t *) NULL) ||
(lzw_info->table[1] == (size_t *) NULL))
{
lzw_info=RelinquishLZWInfo(lzw_info);
return((LZWInfo *) NULL);
}
(void) memset(lzw_info->table[0],0,MaximumLZWCode*
sizeof(**lzw_info->table));
(void) memset(lzw_info->table[1],0,MaximumLZWCode*
sizeof(**lzw_info->table));
for (i=0; i <= (ssize_t) lzw_info->maximum_data_value; i++)
{
lzw_info->table[0][i]=0;
lzw_info->table[1][i]=(size_t) i;
}
ResetLZWInfo(lzw_info);
lzw_info->code_info.buffer[0]='\0';
lzw_info->code_info.buffer[1]='\0';
lzw_info->code_info.count=2;
lzw_info->code_info.bit=8*lzw_info->code_info.count;
lzw_info->code_info.eof=MagickFalse;
lzw_info->genesis=MagickTrue;
lzw_info->stack=(LZWStack *) AcquireMagickMemory(sizeof(*lzw_info->stack));
if (lzw_info->stack == (LZWStack *) NULL)
{
lzw_info=RelinquishLZWInfo(lzw_info);
return((LZWInfo *) NULL);
}
lzw_info->stack->codes=(size_t *) AcquireQuantumMemory(2UL*
MaximumLZWCode,sizeof(*lzw_info->stack->codes));
if (lzw_info->stack->codes == (size_t *) NULL)
{
lzw_info=RelinquishLZWInfo(lzw_info);
return((LZWInfo *) NULL);
}
lzw_info->stack->index=lzw_info->stack->codes;
lzw_info->stack->top=lzw_info->stack->codes+2*MaximumLZWCode;
return(lzw_info);
}
static inline int GetNextLZWCode(LZWInfo *lzw_info,const size_t bits)
{
int
code;
register ssize_t
i;
size_t
one;
while (((lzw_info->code_info.bit+bits) > (8*lzw_info->code_info.count)) &&
(lzw_info->code_info.eof == MagickFalse))
{
ssize_t
count;
lzw_info->code_info.buffer[0]=lzw_info->code_info.buffer[
lzw_info->code_info.count-2];
lzw_info->code_info.buffer[1]=lzw_info->code_info.buffer[
lzw_info->code_info.count-1];
lzw_info->code_info.bit-=8*(lzw_info->code_info.count-2);
lzw_info->code_info.count=2;
count=ReadBlobBlock(lzw_info->image,&lzw_info->code_info.buffer[
lzw_info->code_info.count]);
if (count > 0)
lzw_info->code_info.count+=count;
else
lzw_info->code_info.eof=MagickTrue;
}
if ((lzw_info->code_info.bit+bits) > (8*lzw_info->code_info.count))
return(-1);
code=0;
one=1;
for (i=0; i < (ssize_t) bits; i++)
{
code|=((lzw_info->code_info.buffer[lzw_info->code_info.bit/8] &
(one << (lzw_info->code_info.bit % 8))) != 0) << i;
lzw_info->code_info.bit++;
}
return(code);
}
static inline int PopLZWStack(LZWStack *stack_info)
{
if (stack_info->index <= stack_info->codes)
return(-1);
stack_info->index--;
return((int) *stack_info->index);
}
static inline void PushLZWStack(LZWStack *stack_info,const size_t value)
{
if (stack_info->index >= stack_info->top)
return;
*stack_info->index=value;
stack_info->index++;
}
static int ReadBlobLZWByte(LZWInfo *lzw_info)
{
int
code;
size_t
one,
value;
ssize_t
count;
if (lzw_info->stack->index != lzw_info->stack->codes)
return(PopLZWStack(lzw_info->stack));
if (lzw_info->genesis != MagickFalse)
{
lzw_info->genesis=MagickFalse;
do
{
lzw_info->first_code=(size_t) GetNextLZWCode(lzw_info,lzw_info->bits);
lzw_info->last_code=lzw_info->first_code;
} while (lzw_info->first_code == lzw_info->clear_code);
return((int) lzw_info->first_code);
}
code=GetNextLZWCode(lzw_info,lzw_info->bits);
if (code < 0)
return(code);
if ((size_t) code == lzw_info->clear_code)
{
ResetLZWInfo(lzw_info);
return(ReadBlobLZWByte(lzw_info));
}
if ((size_t) code == lzw_info->end_code)
return(-1);
if ((size_t) code < lzw_info->slot)
value=(size_t) code;
else
{
PushLZWStack(lzw_info->stack,lzw_info->first_code);
value=lzw_info->last_code;
}
count=0;
while (value > lzw_info->maximum_data_value)
{
if ((size_t) count > MaximumLZWCode)
return(-1);
count++;
if ((size_t) value > MaximumLZWCode)
return(-1);
PushLZWStack(lzw_info->stack,lzw_info->table[1][value]);
value=lzw_info->table[0][value];
}
lzw_info->first_code=lzw_info->table[1][value];
PushLZWStack(lzw_info->stack,lzw_info->first_code);
one=1;
if (lzw_info->slot < MaximumLZWCode)
{
lzw_info->table[0][lzw_info->slot]=lzw_info->last_code;
lzw_info->table[1][lzw_info->slot]=lzw_info->first_code;
lzw_info->slot++;
if ((lzw_info->slot >= lzw_info->maximum_code) &&
(lzw_info->bits < MaximumLZWBits))
{
lzw_info->bits++;
lzw_info->maximum_code=one << lzw_info->bits;
}
}
lzw_info->last_code=(size_t) code;
return(PopLZWStack(lzw_info->stack));
}
static MagickBooleanType DecodeImage(Image *image,const ssize_t opacity,
ExceptionInfo *exception)
{
int
c;
LZWInfo
*lzw_info;
size_t
pass;
ssize_t
index,
offset,
y;
unsigned char
data_size;
/*
Allocate decoder tables.
*/
assert(image != (Image *) NULL);
assert(image->signature == MagickCoreSignature);
if (image->debug != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
data_size=(unsigned char) ReadBlobByte(image);
if (data_size > MaximumLZWBits)
ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
lzw_info=AcquireLZWInfo(image,data_size);
if (lzw_info == (LZWInfo *) NULL)
ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
image->filename);
pass=0;
offset=0;
for (y=0; y < (ssize_t) image->rows; y++)
{
register ssize_t
x;
register Quantum
*magick_restrict q;
q=QueueAuthenticPixels(image,0,offset,image->columns,1,exception);
if (q == (Quantum *) NULL)
break;
for (x=0; x < (ssize_t) image->columns; )
{
c=ReadBlobLZWByte(lzw_info);
if (c < 0)
break;
index=ConstrainColormapIndex(image,(ssize_t) c,exception);
SetPixelIndex(image,(Quantum) index,q);
SetPixelViaPixelInfo(image,image->colormap+index,q);
SetPixelAlpha(image,index == opacity ? TransparentAlpha : OpaqueAlpha,q);
x++;
q+=GetPixelChannels(image);
}
if (SyncAuthenticPixels(image,exception) == MagickFalse)
break;
if (x < (ssize_t) image->columns)
break;
if (image->interlace == NoInterlace)
offset++;
else
{
switch (pass)
{
case 0:
default:
{
offset+=8;
break;
}
case 1:
{
offset+=8;
break;
}
case 2:
{
offset+=4;
break;
}
case 3:
{
offset+=2;
break;
}
}
if ((pass == 0) && (offset >= (ssize_t) image->rows))
{
pass++;
offset=4;
}
if ((pass == 1) && (offset >= (ssize_t) image->rows))
{
pass++;
offset=2;
}
if ((pass == 2) && (offset >= (ssize_t) image->rows))
{
pass++;
offset=1;
}
}
}
lzw_info=RelinquishLZWInfo(lzw_info);
if (y < (ssize_t) image->rows)
ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
return(MagickTrue);
}
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% %
% %
% E n c o d e I m a g e %
% %
% %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% EncodeImage compresses an image via GIF-coding.
%
% The format of the EncodeImage method is:
%
% MagickBooleanType EncodeImage(const ImageInfo *image_info,Image *image,
% const size_t data_size)
%
% A description of each parameter follows:
%
% o image_info: the image info.
%
% o image: the address of a structure of type Image.
%
% o data_size: The number of bits in the compressed packet.
%
*/
static MagickBooleanType EncodeImage(const ImageInfo *image_info,Image *image,
const size_t data_size,ExceptionInfo *exception)
{
#define MaxCode(number_bits) ((one << (number_bits))-1)
#define MaxHashTable 5003
#define MaxGIFBits 12UL
#define MaxGIFTable (1UL << MaxGIFBits)
#define GIFOutputCode(code) \
{ \
/* \
Emit a code. \
*/ \
if (bits > 0) \
datum|=(size_t) (code) << bits; \
else \
datum=(size_t) (code); \
bits+=number_bits; \
while (bits >= 8) \
{ \
/* \
Add a character to current packet. \
*/ \
packet[length++]=(unsigned char) (datum & 0xff); \
if (length >= 254) \
{ \
(void) WriteBlobByte(image,(unsigned char) length); \
(void) WriteBlob(image,length,packet); \
length=0; \
} \
datum>>=8; \
bits-=8; \
} \
if (free_code > max_code) \
{ \
number_bits++; \
if (number_bits == MaxGIFBits) \
max_code=MaxGIFTable; \
else \
max_code=MaxCode(number_bits); \
} \
}
Quantum
index;
short
*hash_code,
*hash_prefix,
waiting_code;
size_t
bits,
clear_code,
datum,
end_of_information_code,
free_code,
length,
max_code,
next_pixel,
number_bits,
one,
pass;
ssize_t
displacement,
offset,
k,
y;
unsigned char
*packet,
*hash_suffix;
/*
Allocate encoder tables.
*/
assert(image != (Image *) NULL);
one=1;
packet=(unsigned char *) AcquireQuantumMemory(256,sizeof(*packet));
hash_code=(short *) AcquireQuantumMemory(MaxHashTable,sizeof(*hash_code));
hash_prefix=(short *) AcquireQuantumMemory(MaxHashTable,sizeof(*hash_prefix));
hash_suffix=(unsigned char *) AcquireQuantumMemory(MaxHashTable,
sizeof(*hash_suffix));
if ((packet == (unsigned char *) NULL) || (hash_code == (short *) NULL) ||
(hash_prefix == (short *) NULL) ||
(hash_suffix == (unsigned char *) NULL))
{
if (packet != (unsigned char *) NULL)
packet=(unsigned char *) RelinquishMagickMemory(packet);
if (hash_code != (short *) NULL)
hash_code=(short *) RelinquishMagickMemory(hash_code);
if (hash_prefix != (short *) NULL)
hash_prefix=(short *) RelinquishMagickMemory(hash_prefix);
if (hash_suffix != (unsigned char *) NULL)
hash_suffix=(unsigned char *) RelinquishMagickMemory(hash_suffix);
return(MagickFalse);
}
/*
Initialize GIF encoder.
*/
(void) memset(packet,0,256*sizeof(*packet));
(void) memset(hash_code,0,MaxHashTable*sizeof(*hash_code));
(void) memset(hash_prefix,0,MaxHashTable*sizeof(*hash_prefix));
(void) memset(hash_suffix,0,MaxHashTable*sizeof(*hash_suffix));
number_bits=data_size;
max_code=MaxCode(number_bits);
clear_code=((short) one << (data_size-1));
end_of_information_code=clear_code+1;
free_code=clear_code+2;
length=0;
datum=0;
bits=0;
GIFOutputCode(clear_code);
/*
Encode pixels.
*/
offset=0;
pass=0;
waiting_code=0;
for (y=0; y < (ssize_t) image->rows; y++)
{
register const Quantum
*magick_restrict p;
register ssize_t
x;
p=GetVirtualPixels(image,0,offset,image->columns,1,exception);
if (p == (const Quantum *) NULL)
break;
if (y == 0)
{
waiting_code=(short) GetPixelIndex(image,p);
p+=GetPixelChannels(image);
}
for (x=(ssize_t) (y == 0 ? 1 : 0); x < (ssize_t) image->columns; x++)
{
/*
Probe hash table.
*/
next_pixel=MagickFalse;
displacement=1;
index=(Quantum) ((size_t) GetPixelIndex(image,p) & 0xff);
p+=GetPixelChannels(image);
k=(ssize_t) (((size_t) index << (MaxGIFBits-8))+waiting_code);
if (k >= MaxHashTable)
k-=MaxHashTable;
if (k < 0)
continue;
if (hash_code[k] > 0)
{
if ((hash_prefix[k] == waiting_code) &&
(hash_suffix[k] == (unsigned char) index))
{
waiting_code=hash_code[k];
continue;
}
if (k != 0)
displacement=MaxHashTable-k;
for ( ; ; )
{
k-=displacement;
if (k < 0)
k+=MaxHashTable;
if (hash_code[k] == 0)
break;
if ((hash_prefix[k] == waiting_code) &&
(hash_suffix[k] == (unsigned char) index))
{
waiting_code=hash_code[k];
next_pixel=MagickTrue;
break;
}
}
if (next_pixel != MagickFalse)
continue;
}
GIFOutputCode(waiting_code);
if (free_code < MaxGIFTable)
{
hash_code[k]=(short) free_code++;
hash_prefix[k]=waiting_code;
hash_suffix[k]=(unsigned char) index;
}
else
{
/*
Fill the hash table with empty entries.
*/
for (k=0; k < MaxHashTable; k++)
hash_code[k]=0;
/*
Reset compressor and issue a clear code.
*/
free_code=clear_code+2;
GIFOutputCode(clear_code);
number_bits=data_size;
max_code=MaxCode(number_bits);
}
waiting_code=(short) index;
}
if (image_info->interlace == NoInterlace)
offset++;
else
switch (pass)
{
case 0:
default:
{
offset+=8;
if (offset >= (ssize_t) image->rows)
{
pass++;
offset=4;
}
break;
}
case 1:
{
offset+=8;
if (offset >= (ssize_t) image->rows)
{
pass++;
offset=2;
}
break;
}
case 2:
{
offset+=4;
if (offset >= (ssize_t) image->rows)
{
pass++;
offset=1;
}
break;
}
case 3:
{
offset+=2;
break;
}
}
}
/*
Flush out the buffered code.
*/
GIFOutputCode(waiting_code);
GIFOutputCode(end_of_information_code);
if (bits > 0)
{
/*
Add a character to current packet.
*/
packet[length++]=(unsigned char) (datum & 0xff);
if (length >= 254)
{
(void) WriteBlobByte(image,(unsigned char) length);
(void) WriteBlob(image,length,packet);
length=0;
}
}
/*
Flush accumulated data.
*/
if (length > 0)
{
(void) WriteBlobByte(image,(unsigned char) length);
(void) WriteBlob(image,length,packet);
}
/*
Free encoder memory.
*/
hash_suffix=(unsigned char *) RelinquishMagickMemory(hash_suffix);
hash_prefix=(short *) RelinquishMagickMemory(hash_prefix);
hash_code=(short *) RelinquishMagickMemory(hash_code);
packet=(unsigned char *) RelinquishMagickMemory(packet);
return(MagickTrue);
}
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% %
% %
% I s G I F %
% %
% %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% IsGIF() returns MagickTrue if the image format type, identified by the
% magick string, is GIF.
%
% The format of the IsGIF method is:
%
% MagickBooleanType IsGIF(const unsigned char *magick,const size_t length)
%
% A description of each parameter follows:
%
% o magick: compare image format pattern against these bytes.
%
% o length: Specifies the length of the magick string.
%
*/
static MagickBooleanType IsGIF(const unsigned char *magick,const size_t length)
{
if (length < 4)
return(MagickFalse);
if (LocaleNCompare((char *) magick,"GIF8",4) == 0)
return(MagickTrue);
return(MagickFalse);
}
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% %
% %
+ R e a d B l o b B l o c k %
% %
% %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% ReadBlobBlock() reads data from the image file and returns it. The
% amount of data is determined by first reading a count byte. The number
% of bytes read is returned.
%
% The format of the ReadBlobBlock method is:
%
% ssize_t ReadBlobBlock(Image *image,unsigned char *data)
%
% A description of each parameter follows:
%
% o image: the image.
%
% o data: Specifies an area to place the information requested from
% the file.
%
*/
static ssize_t ReadBlobBlock(Image *image,unsigned char *data)
{
ssize_t
count;
unsigned char
block_count;
assert(image != (Image *) NULL);
assert(image->signature == MagickCoreSignature);
assert(data != (unsigned char *) NULL);
count=ReadBlob(image,1,&block_count);
if (count != 1)
return(0);
count=ReadBlob(image,(size_t) block_count,data);
if (count != (ssize_t) block_count)
return(0);
return(count);
}
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% %
% %
% R e a d G I F I m a g e %
% %
% %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% ReadGIFImage() reads a Compuserve Graphics image file and returns it.
% It allocates the memory necessary for the new Image structure and returns a
% pointer to the new image.
%
% The format of the ReadGIFImage method is:
%
% Image *ReadGIFImage(const ImageInfo *image_info,ExceptionInfo *exception)
%
% A description of each parameter follows:
%
% o image_info: the image info.
%
% o exception: return any errors or warnings in this structure.
%
*/
static void *DestroyGIFProfile(void *profile)
{
return((void *) DestroyStringInfo((StringInfo *) profile));
}
static MagickBooleanType PingGIFImage(Image *image,ExceptionInfo *exception)
{
unsigned char
buffer[256],
length,
data_size;
assert(image != (Image *) NULL);
assert(image->signature == MagickCoreSignature);
if (image->debug != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
if (ReadBlob(image,1,&data_size) != 1)
ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
if (data_size > MaximumLZWBits)
ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
if (ReadBlob(image,1,&length) != 1)
ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
while (length != 0)
{
if (ReadBlob(image,length,buffer) != (ssize_t) length)
ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
if (ReadBlob(image,1,&length) != 1)
ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
}
return(MagickTrue);
}
static Image *ReadGIFImage(const ImageInfo *image_info,ExceptionInfo *exception)
{
#define BitSet(byte,bit) (((byte) & (bit)) == (bit))
#define LSBFirstOrder(x,y) (((y) << 8) | (x))
#define ThrowGIFException(exception,message) \
{ \
if (profiles != (LinkedListInfo *) NULL) \
profiles=DestroyLinkedList(profiles,DestroyGIFProfile); \
if (global_colormap != (unsigned char *) NULL) \
global_colormap=(unsigned char *) RelinquishMagickMemory(global_colormap); \
if (meta_image != (Image *) NULL) \
meta_image=DestroyImage(meta_image); \
ThrowReaderException((exception),(message)); \
}
Image
*image,
*meta_image;
LinkedListInfo
*profiles;
MagickBooleanType
status;
register ssize_t
i;
register unsigned char
*p;
size_t
duration,
global_colors,
image_count,
local_colors,
one;
ssize_t
count,
opacity;
unsigned char
background,
buffer[257],