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Fix PNG predictor 12, 14, and 15.

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This commit is contained in:
Michael R Sweet 2021-06-01 17:48:36 -04:00
parent 2856b440d1
commit 3efb4f800b
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GPG Key ID: 999559A027815955
2 changed files with 57 additions and 58 deletions
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4
pdfio-private.h
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@ -262,11 +262,11 @@ struct _pdfio_stream_s // Stream
*bufend; // End of buffer
z_stream flate; // Flate filter state
_pdfio_predictor_t predictor; // Predictor function, if any
int pbcurrent; // Current predictor line (0 or 1)
size_t pbpixel, // Size of a pixel in bytes
pbsize; // Predictor buffer size, if any
unsigned char cbuffer[4096], // Compressed data buffer
*pbuffers[2]; // Predictor buffers, as needed
*prbuffer, // Raw buffer (previous line), as needed
*psbuffer; // PNG filter buffer, as needed
};

111
pdfio-stream.c
View File

@ -119,8 +119,8 @@ pdfioStreamClose(pdfio_stream_t *st) // I - Stream
done:
free(st->pbuffers[0]);
free(st->pbuffers[1]);
free(st->prbuffer);
free(st->psbuffer);
free(st);
return (ret);
@ -216,11 +216,11 @@ _pdfioStreamCreate(
if (predictor >= 10)
st->pbsize ++; // Add PNG predictor byte
if ((st->pbuffers[0] = calloc(1, st->pbsize)) == NULL || (st->pbuffers[1] = calloc(1, st->pbsize)) == NULL)
if ((st->prbuffer = calloc(1, st->pbsize - 1)) == NULL || (st->psbuffer = calloc(1, st->pbsize)) == NULL)
{
_pdfioFileError(st->pdf, "Unable to allocate %lu bytes for Predictor buffers.", (unsigned long)st->pbsize);
free(st->pbuffers[0]);
free(st->pbuffers[1]);
free(st->prbuffer);
free(st->psbuffer);
free(st);
return (NULL);
}
@ -234,8 +234,8 @@ _pdfioStreamCreate(
if (deflateInit(&(st->flate), 9) != Z_OK)
{
_pdfioFileError(st->pdf, "Unable to start Flate filter.");
free(st->pbuffers[0]);
free(st->pbuffers[1]);
free(st->prbuffer);
free(st->psbuffer);
free(st);
return (NULL);
}
@ -429,11 +429,11 @@ _pdfioStreamOpen(pdfio_obj_t *obj, // I - Object
if (predictor >= 10)
st->pbsize ++; // Add PNG predictor byte
if ((st->pbuffers[0] = calloc(1, st->pbsize)) == NULL || (st->pbuffers[1] = calloc(1, st->pbsize)) == NULL)
if ((st->prbuffer = calloc(1, st->pbsize - 1)) == NULL || (st->psbuffer = calloc(1, st->pbsize)) == NULL)
{
_pdfioFileError(st->pdf, "Unable to allocate %lu bytes for Predictor buffers.", (unsigned long)st->pbsize);
free(st->pbuffers[0]);
free(st->pbuffers[1]);
free(st->prbuffer);
free(st->psbuffer);
free(st);
return (NULL);
}
@ -447,8 +447,8 @@ _pdfioStreamOpen(pdfio_obj_t *obj, // I - Object
if (inflateInit(&(st->flate)) != Z_OK)
{
_pdfioFileError(st->pdf, "Unable to start Flate filter.");
free(st->pbuffers[0]);
free(st->pbuffers[1]);
free(st->prbuffer);
free(st->psbuffer);
free(st);
return (NULL);
}
@ -649,8 +649,8 @@ pdfioStreamWrite(
// First column bytes remaining
const unsigned char *bufptr = (const unsigned char *)buffer;
// Pointer into buffer
unsigned char *thisptr, // Current raw buffer
*prevptr; // Previous raw buffer
unsigned char *sptr, // Pointer into sbuffer
*pptr; // Previous raw buffer
PDFIO_DEBUG("pdfioStreamWrite(st=%p, buffer=%p, bytes=%lu)\n", st, buffer, (unsigned long)bytes);
@ -681,13 +681,13 @@ pdfioStreamWrite(
{
// Store the PNG predictor in the first byte of the buffer...
if (st->predictor == _PDFIO_PREDICTOR_PNG_AUTO)
st->pbuffers[st->pbcurrent][0] = 4; // Use Paeth predictor for auto...
st->psbuffer[0] = 4; // Use Paeth predictor for auto...
else
st->pbuffers[st->pbcurrent][0] = (unsigned char)(st->predictor - 10);
st->psbuffer[0] = (unsigned char)(st->predictor - 10);
// Then process the current line using the specified PNG predictor...
thisptr = st->pbuffers[st->pbcurrent] + 1;
prevptr = st->pbuffers[!st->pbcurrent] + 1;
sptr = st->psbuffer + 1;
pptr = st->prbuffer;
switch (st->predictor)
{
@ -697,58 +697,58 @@ pdfioStreamWrite(
case _PDFIO_PREDICTOR_PNG_NONE :
// No PNG predictor...
memcpy(thisptr, buffer, pbline);
memcpy(sptr, buffer, pbline);
break;
case _PDFIO_PREDICTOR_PNG_SUB :
// Encode the difference from the previous column
for (remaining = pbline; remaining > 0; remaining --, bufptr ++, thisptr ++)
for (remaining = pbline; remaining > 0; remaining --, bufptr ++, sptr ++)
{
if (remaining < firstcol)
*thisptr = *bufptr - thisptr[-pbpixel];
*sptr = *bufptr - bufptr[-pbpixel];
else
*thisptr = *bufptr;
*sptr = *bufptr;
}
break;
case _PDFIO_PREDICTOR_PNG_UP :
// Encode the difference from the previous line
for (remaining = pbline; remaining > 0; remaining --, bufptr ++, thisptr ++, prevptr ++)
for (remaining = pbline; remaining > 0; remaining --, bufptr ++, sptr ++, pptr ++)
{
*thisptr = *bufptr - *prevptr;
*sptr = *bufptr - *pptr;
}
break;
case _PDFIO_PREDICTOR_PNG_AVERAGE :
// Encode the difference with the average of the previous column and line
for (remaining = pbline; remaining > 0; remaining --, bufptr ++, thisptr ++, prevptr ++)
for (remaining = pbline; remaining > 0; remaining --, bufptr ++, sptr ++, pptr ++)
{
if (remaining < firstcol)
*thisptr = *bufptr - (thisptr[-pbpixel] + *prevptr) / 2;
*sptr = *bufptr - (bufptr[-pbpixel] + *pptr) / 2;
else
*thisptr = *bufptr - *prevptr / 2;
*sptr = *bufptr - *pptr / 2;
}
break;
case _PDFIO_PREDICTOR_PNG_PAETH :
case _PDFIO_PREDICTOR_PNG_AUTO :
// Encode the difference with a linear transform function
for (remaining = pbline; remaining > 0; remaining --, bufptr ++, thisptr ++, prevptr ++)
for (remaining = pbline; remaining > 0; remaining --, bufptr ++, sptr ++, pptr ++)
{
if (remaining < firstcol)
*thisptr = *bufptr - stream_paeth(thisptr[-pbpixel], *prevptr, prevptr[-pbpixel]);
*sptr = *bufptr - stream_paeth(bufptr[-pbpixel], *pptr, pptr[-pbpixel]);
else
*thisptr = *bufptr - stream_paeth(0, *prevptr, 0);
*sptr = *bufptr - stream_paeth(0, *pptr, 0);
}
break;
}
// Write the encoded line...
if (!stream_write(st, st->pbuffers[st->pbcurrent], st->pbsize))
if (!stream_write(st, st->psbuffer, st->pbsize))
return (false);
st->pbcurrent = !st->pbcurrent;
bytes -= pbline;
memcpy(st->prbuffer, buffer, pbline);
bytes -= pbline;
}
return (true);
@ -850,9 +850,9 @@ stream_read(pdfio_stream_t *st, // I - Stream
// First column bytes remaining
unsigned char *bufptr = (unsigned char *)buffer,
// Pointer into buffer
*thisptr = st->pbuffers[st->pbcurrent] + 1,
*sptr = st->psbuffer + 1,
// Current (raw) line
*prevptr = st->pbuffers[!st->pbcurrent] + 1;
*pptr = st->prbuffer;
// Previous (raw) line
PDFIO_DEBUG("stream_read: PNG predictor.\n");
@ -864,7 +864,7 @@ stream_read(pdfio_stream_t *st, // I - Stream
return (-1);
}
st->flate.next_out = (Bytef *)thisptr - 1;
st->flate.next_out = (Bytef *)sptr - 1;
st->flate.avail_out = (uInt)st->pbsize;
while (st->flate.avail_out > 0)
@ -898,44 +898,43 @@ stream_read(pdfio_stream_t *st, // I - Stream
return (-1); // Early end of stream
// Apply predictor for this line
PDFIO_DEBUG("stream_read: Line %02X %02X %02X %02X %02X.\n", thisptr[-1], thisptr[0], thisptr[0], thisptr[2], thisptr[3]);
PDFIO_DEBUG("stream_read: Line %02X %02X %02X %02X %02X.\n", sptr[-1], sptr[0], sptr[0], sptr[2], sptr[3]);
switch (thisptr[-1])
switch (sptr[-1])
{
case 0 : // None
memcpy(buffer, thisptr, remaining);
memcpy(buffer, sptr, remaining);
break;
case 1 : // Sub
for (; remaining > firstcol; remaining --, thisptr ++)
*bufptr++ = *thisptr;
for (; remaining > 0; remaining --, thisptr ++)
*bufptr++ = *thisptr + thisptr[-pbpixel];
for (; remaining > firstcol; remaining --, sptr ++)
*bufptr++ = *sptr;
for (; remaining > 0; remaining --, sptr ++, bufptr ++)
*bufptr = *sptr + bufptr[-pbpixel];
break;
case 2 : // Up
for (; remaining > 0; remaining --, thisptr ++, prevptr ++)
*bufptr++ = *thisptr + *prevptr;
for (; remaining > 0; remaining --, sptr ++, pptr ++)
*bufptr++ = *sptr + *pptr;
break;
case 3 : // Average
for (; remaining > firstcol; remaining --, thisptr ++, prevptr ++)
*bufptr++ = *thisptr + *prevptr / 2;
for (; remaining > 0; remaining --, thisptr ++, prevptr ++)
*bufptr++ = *thisptr + (thisptr[-pbpixel] + *prevptr) / 2;
for (; remaining > firstcol; remaining --, sptr ++, pptr ++)
*bufptr++ = *sptr + *pptr / 2;
for (; remaining > 0; remaining --, sptr ++, pptr ++, bufptr ++)
*bufptr = *sptr + (bufptr[-pbpixel] + *pptr) / 2;
break;
case 4 : // Paeth
for (; remaining > firstcol; remaining --, thisptr ++, prevptr ++)
*bufptr++ = *thisptr + stream_paeth(0, *prevptr, 0);
for (; remaining > 0; remaining --, thisptr ++, prevptr ++)
*bufptr++ = *thisptr + stream_paeth(thisptr[-pbpixel], *prevptr, prevptr[-pbpixel]);
for (; remaining > firstcol; remaining --, sptr ++, pptr ++)
*bufptr++ = *sptr + stream_paeth(0, *pptr, 0);
for (; remaining > 0; remaining --, sptr ++, pptr ++, bufptr ++)
*bufptr = *sptr + stream_paeth(bufptr[-pbpixel], *pptr, pptr[-pbpixel]);
break;
default :
_pdfioFileError(st->pdf, "Bad PNG filter %d in data stream.", thisptr[-1]);
_pdfioFileError(st->pdf, "Bad PNG filter %d in data stream.", sptr[-1]);
return (-1);
}
// Copy the computed line and swap buffers...
memcpy(st->pbuffers[st->pbcurrent] + 1, buffer, st->pbsize - 1);
st->pbcurrent = !st->pbcurrent;
memcpy(st->prbuffer, buffer, st->pbsize - 1);
// Return the number of bytes we copied for this line...
return ((ssize_t)(st->pbsize - 1));