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libpng/pngwtran.c
John Bowler 82fa6aed0e [libpng17] Added byte, short and other overflow checking 
Added 'assert' based overflow checking for debug builds for char
and short assignments. Simply ignore the error in release builds
(a truncated value will be used without warning). Controlled by
PNG_RANGE_CHECK_SUPPORTED.
2015-03-22 15:57:53 -05:00

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/* pngwtran.c - transforms the data in a row for PNG writers
*
* Last changed in libpng 1.6.17 [(PENDING RELEASE)]
* Copyright (c) 1998-2015 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/
#include "pngpriv.h"
#define PNG_SRC_FILE PNG_SRC_FILE_pngwtran
#ifdef PNG_WRITE_SUPPORTED
#ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
/* This is here because png_row_info doesn't contain a png_ptr, so at present
* the transform routines can't signal an error. Instead we pass '0' as
* as png_ptr to png_check_byte in the non-release cases and do a hard cast
* in release.
*
* TODO: fix this.
*/
#ifdef PNG_RANGE_CHECK_SUPPORTED
# define CB(b) png_check_byte(0, b)
# define CU(u) png_check_u16(0, u)
#else
# define CB(b) ((png_byte)(b))
# define CU(u) ((png_uint_16)(u))
#endif
#ifdef PNG_WRITE_PACK_SUPPORTED
/* Pack pixels into bytes. Pass the true bit depth in bit_depth. The
* row_info bit depth should be 8 (one pixel per byte). The channels
* should be 1 (this only happens on grayscale and paletted images).
*/
static void
png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
{
png_debug(1, "in png_do_pack");
if (row_info->bit_depth == 8 &&
row_info->channels == 1)
{
switch ((int)bit_depth)
{
case 1:
{
png_bytep sp, dp;
int mask, v;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
sp = row;
dp = row;
mask = 0x80;
v = 0;
for (i = 0; i < row_width; i++)
{
if (*sp != 0)
v |= mask;
sp++;
if (mask > 1)
mask >>= 1;
else
{
mask = 0x80;
*dp = CB(v);
dp++;
v = 0;
}
}
if (mask != 0x80)
*dp = CB(v);
break;
}
case 2:
{
png_bytep sp, dp;
int shift, v;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
sp = row;
dp = row;
shift = 6;
v = 0;
for (i = 0; i < row_width; i++)
{
png_byte value;
value = PNG_BYTE(*sp & 0x03);
v |= (value << shift);
if (shift == 0)
{
shift = 6;
*dp = CB(v);
dp++;
v = 0;
}
else
shift -= 2;
sp++;
}
if (shift != 6)
*dp = CB(v);
break;
}
case 4:
{
png_bytep sp, dp;
int shift, v;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
sp = row;
dp = row;
shift = 4;
v = 0;
for (i = 0; i < row_width; i++)
{
png_byte value;
value = PNG_BYTE(*sp & 0x0f);
v |= (value << shift);
if (shift == 0)
{
shift = 4;
*dp = CB(v);
dp++;
v = 0;
}
else
shift -= 4;
sp++;
}
if (shift != 4)
*dp = CB(v);
break;
}
default:
break;
}
row_info->bit_depth = CB(bit_depth);
row_info->pixel_depth = CB(bit_depth * row_info->channels);
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
row_info->width);
}
}
#endif
#ifdef PNG_WRITE_SHIFT_SUPPORTED
/* Shift pixel values to take advantage of whole range. Pass the
* true number of bits in bit_depth. The row should be packed
* according to row_info->bit_depth. Thus, if you had a row of
* bit depth 4, but the pixels only had values from 0 to 7, you
* would pass 3 as bit_depth, and this routine would translate the
* data to 0 to 15.
*/
static void
png_do_shift(png_row_infop row_info, png_bytep row,
png_const_color_8p bit_depth)
{
png_debug(1, "in png_do_shift");
if (row_info->color_type != PNG_COLOR_TYPE_PALETTE)
{
int shift_start[4], shift_dec[4];
int channels = 0;
if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
{
shift_start[channels] = row_info->bit_depth - bit_depth->red;
shift_dec[channels] = bit_depth->red;
channels++;
shift_start[channels] = row_info->bit_depth - bit_depth->green;
shift_dec[channels] = bit_depth->green;
channels++;
shift_start[channels] = row_info->bit_depth - bit_depth->blue;
shift_dec[channels] = bit_depth->blue;
channels++;
}
else
{
shift_start[channels] = row_info->bit_depth - bit_depth->gray;
shift_dec[channels] = bit_depth->gray;
channels++;
}
if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
{
shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
shift_dec[channels] = bit_depth->alpha;
channels++;
}
/* With low row depths, could only be grayscale, so one channel */
if (row_info->bit_depth < 8)
{
png_bytep bp = row;
png_size_t i;
unsigned int mask;
png_size_t row_bytes = row_info->rowbytes;
if (bit_depth->gray == 1 && row_info->bit_depth == 2)
mask = 0x55;
else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
mask = 0x11;
else
mask = 0xff;
for (i = 0; i < row_bytes; i++, bp++)
{
int j;
unsigned int v, out;
v = *bp;
out = 0;
for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
{
if (j > 0)
out |= v << j;
else
out |= (v >> (-j)) & mask;
}
*bp = CB(out);
}
}
else if (row_info->bit_depth == 8)
{
png_bytep bp = row;
png_uint_32 i;
png_uint_32 istop = channels * row_info->width;
for (i = 0; i < istop; i++, bp++)
{
const unsigned int c = i%channels;
int j;
unsigned int v, out;
v = *bp;
out = 0;
for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
{
if (j > 0)
out |= v << j;
else
out |= v >> (-j);
}
*bp = CB(out);
}
}
else
{
png_bytep bp;
png_uint_32 i;
png_uint_32 istop = channels * row_info->width;
for (bp = row, i = 0; i < istop; i++)
{
const unsigned int c = i%channels;
int j;
unsigned int value, v;
v = png_get_uint_16(bp);
value = 0;
for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
{
if (j > 0)
value |= v << j;
else
value |= v >> (-j);
}
*bp++ = CB(value >> 8);
*bp++ = PNG_BYTE(value);
}
}
}
}
#endif
#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
static void
png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
{
png_debug(1, "in png_do_write_swap_alpha");
{
if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
{
if (row_info->bit_depth == 8)
{
/* This converts from ARGB to RGBA */
png_bytep sp, dp;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
for (i = 0, sp = dp = row; i < row_width; i++)
{
png_byte save = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = save;
}
}
#ifdef PNG_WRITE_16BIT_SUPPORTED
else
{
/* This converts from AARRGGBB to RRGGBBAA */
png_bytep sp, dp;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
for (i = 0, sp = dp = row; i < row_width; i++)
{
png_byte save[2];
save[0] = *(sp++);
save[1] = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = save[0];
*(dp++) = save[1];
}
}
#endif /* WRITE_16BIT */
}
else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
{
if (row_info->bit_depth == 8)
{
/* This converts from AG to GA */
png_bytep sp, dp;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
for (i = 0, sp = dp = row; i < row_width; i++)
{
png_byte save = *(sp++);
*(dp++) = *(sp++);
*(dp++) = save;
}
}
#ifdef PNG_WRITE_16BIT_SUPPORTED
else
{
/* This converts from AAGG to GGAA */
png_bytep sp, dp;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
for (i = 0, sp = dp = row; i < row_width; i++)
{
png_byte save[2];
save[0] = *(sp++);
save[1] = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = save[0];
*(dp++) = save[1];
}
}
#endif /* WRITE_16BIT */
}
}
}
#endif
#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
static void
png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
{
png_debug(1, "in png_do_write_invert_alpha");
{
if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
{
if (row_info->bit_depth == 8)
{
/* This inverts the alpha channel in RGBA */
png_bytep sp, dp;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
for (i = 0, sp = dp = row; i < row_width; i++)
{
/* Does nothing
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*/
sp+=3; dp = sp;
*(dp++) = CB(255 - *(sp++));
}
}
#ifdef PNG_WRITE_16BIT_SUPPORTED
else
{
/* This inverts the alpha channel in RRGGBBAA */
png_bytep sp, dp;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
for (i = 0, sp = dp = row; i < row_width; i++)
{
/* Does nothing
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*/
sp+=6; dp = sp;
*(dp++) = CB(255 - *(sp++));
*(dp++) = CB(255 - *(sp++));
}
}
#endif /* WRITE_16BIT */
}
else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
{
if (row_info->bit_depth == 8)
{
/* This inverts the alpha channel in GA */
png_bytep sp, dp;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
for (i = 0, sp = dp = row; i < row_width; i++)
{
*(dp++) = *(sp++);
*(dp++) = CB(255 - *(sp++));
}
}
#ifdef PNG_WRITE_16BIT_SUPPORTED
else
{
/* This inverts the alpha channel in GGAA */
png_bytep sp, dp;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
for (i = 0, sp = dp = row; i < row_width; i++)
{
/* Does nothing
*(dp++) = *(sp++);
*(dp++) = *(sp++);
*/
sp+=2; dp = sp;
*(dp++) = CB(255 - *(sp++));
*(dp++) = CB(255 - *(sp++));
}
}
#endif /* WRITE_16BIT */
}
}
}
#endif
/* Transform the data according to the user's wishes. The order of
* transformations is significant.
*/
void /* PRIVATE */
png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
{
png_debug(1, "in png_do_write_transformations");
if (png_ptr == NULL)
return;
#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
if (png_ptr->write_user_transform_fn != NULL)
(*(png_ptr->write_user_transform_fn)) /* User write transform
function */
(png_ptr, /* png_ptr */
row_info, /* row_info: */
/* png_uint_32 width; width of row */
/* png_size_t rowbytes; number of bytes in row */
/* png_byte color_type; color type of pixels */
/* png_byte bit_depth; bit depth of samples */
/* png_byte channels; number of channels (1-4) */
/* png_byte pixel_depth; bits per pixel (depth*channels) */
png_ptr->row_buf + 1); /* start of pixel data for row */
#endif
#ifdef PNG_WRITE_FILLER_SUPPORTED
if ((png_ptr->transformations & PNG_FILLER) != 0)
png_do_strip_channel(row_info, png_ptr->row_buf + 1,
!(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
#endif
#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
png_do_packswap(row_info, png_ptr->row_buf + 1);
#endif
#ifdef PNG_WRITE_PACK_SUPPORTED
if ((png_ptr->transformations & PNG_PACK) != 0)
png_do_pack(row_info, png_ptr->row_buf + 1,
(png_uint_32)png_ptr->bit_depth);
#endif
#ifdef PNG_WRITE_SWAP_SUPPORTED
# ifdef PNG_16BIT_SUPPORTED
if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
png_do_swap(row_info, png_ptr->row_buf + 1);
# endif
#endif
#ifdef PNG_WRITE_SHIFT_SUPPORTED
if ((png_ptr->transformations & PNG_SHIFT) != 0)
png_do_shift(row_info, png_ptr->row_buf + 1,
&(png_ptr->shift));
#endif
#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1);
#endif
#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1);
#endif
#ifdef PNG_WRITE_BGR_SUPPORTED
if ((png_ptr->transformations & PNG_BGR) != 0)
png_do_bgr(row_info, png_ptr->row_buf + 1);
#endif
#ifdef PNG_WRITE_INVERT_SUPPORTED
if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
png_do_invert(row_info, png_ptr->row_buf + 1);
#endif
}
#endif /* WRITE_TRANSFORMS */
#endif /* WRITE */
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