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/* pngread.c - read a PNG file
*
* Copyright (c) 2018-2019 Cosmin Truta
* Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
* Copyright (c) 1996-1997 Andreas Dilger
* 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
*
* This file contains routines that an application calls directly to
* read a PNG file or stream.
*/
#include "pngpriv.h"
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
# include <errno.h>
#endif
#ifdef PNG_READ_SUPPORTED
/* Create a PNG structure for reading, and allocate any memory needed. */
PNG_FUNCTION(png_structp,PNGAPI
png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
{
#ifndef PNG_USER_MEM_SUPPORTED
png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
error_fn, warn_fn, NULL, NULL, NULL);
#else
return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
warn_fn, NULL, NULL, NULL);
}
/* Alternate create PNG structure for reading, and allocate any memory
* needed.
*/
PNG_FUNCTION(png_structp,PNGAPI
png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
{
png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
#endif /* USER_MEM */
if (png_ptr != NULL)
{
png_ptr->mode = PNG_IS_READ_STRUCT;
/* Added in libpng-1.6.0; this can be used to detect a read structure if
* required (it will be zero in a write structure.)
*/
# ifdef PNG_SEQUENTIAL_READ_SUPPORTED
png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE;
# endif
# ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED
png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
/* In stable builds only warn if an application error can be completely
* handled.
*/
# if PNG_RELEASE_BUILD
png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
# endif
# endif
/* TODO: delay this, it can be done in png_init_io (if the app doesn't
* do it itself) avoiding setting the default function if it is not
* required.
*/
png_set_read_fn(png_ptr, NULL, NULL);
}
return png_ptr;
}
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the information before the actual image data. This has been
* changed in v0.90 to allow reading a file that already has the magic
* bytes read from the stream. You can tell libpng how many bytes have
* been read from the beginning of the stream (up to the maximum of 8)
* via png_set_sig_bytes(), and we will only check the remaining bytes
* here. The application can then have access to the signature bytes we
* read if it is determined that this isn't a valid PNG file.
*/
void PNGAPI
png_read_info(png_structrp png_ptr, png_inforp info_ptr)
{
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
int keep;
#endif
png_debug(1, "in png_read_info");
if (png_ptr == NULL || info_ptr == NULL)
return;
/* Read and check the PNG file signature. */
png_read_sig(png_ptr, info_ptr);
for (;;)
{
png_uint_32 length = png_read_chunk_header(png_ptr);
png_uint_32 chunk_name = png_ptr->chunk_name;
/* IDAT logic needs to happen here to simplify getting the two flags
* right.
*/
if (chunk_name == png_IDAT)
{
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "Missing IHDR before IDAT");
else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
(png_ptr->mode & PNG_HAVE_PLTE) == 0)
png_chunk_error(png_ptr, "Missing PLTE before IDAT");
else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
png_chunk_benign_error(png_ptr, "Too many IDATs found");
png_ptr->mode |= PNG_HAVE_IDAT;
}
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
{
png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
png_ptr->mode |= PNG_AFTER_IDAT;
}
/* This should be a binary subdivision search or a hash for
* matching the chunk name rather than a linear search.
*/
if (chunk_name == png_IHDR)
png_handle_IHDR(png_ptr, info_ptr, length);
else if (chunk_name == png_IEND)
png_handle_IEND(png_ptr, info_ptr, length);
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
{
png_handle_unknown(png_ptr, info_ptr, length, keep);
if (chunk_name == png_PLTE)
png_ptr->mode |= PNG_HAVE_PLTE;
else if (chunk_name == png_IDAT)
{
png_ptr->idat_size = 0; /* It has been consumed */
break;
}
}
#endif
else if (chunk_name == png_PLTE)
png_handle_PLTE(png_ptr, info_ptr, length);
else if (chunk_name == png_IDAT)
{
#ifdef PNG_READ_APNG_SUPPORTED
png_have_info(png_ptr, info_ptr);
#endif
png_ptr->idat_size = length;
break;
}
#ifdef PNG_READ_bKGD_SUPPORTED
else if (chunk_name == png_bKGD)
png_handle_bKGD(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_cHRM_SUPPORTED
else if (chunk_name == png_cHRM)
png_handle_cHRM(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_eXIf_SUPPORTED
else if (chunk_name == png_eXIf)
png_handle_eXIf(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_gAMA_SUPPORTED
else if (chunk_name == png_gAMA)
png_handle_gAMA(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_hIST_SUPPORTED
else if (chunk_name == png_hIST)
png_handle_hIST(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_oFFs_SUPPORTED
else if (chunk_name == png_oFFs)
png_handle_oFFs(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_pCAL_SUPPORTED
else if (chunk_name == png_pCAL)
png_handle_pCAL(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sCAL_SUPPORTED
else if (chunk_name == png_sCAL)
png_handle_sCAL(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_pHYs_SUPPORTED
else if (chunk_name == png_pHYs)
png_handle_pHYs(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sBIT_SUPPORTED
else if (chunk_name == png_sBIT)
png_handle_sBIT(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sRGB_SUPPORTED
else if (chunk_name == png_sRGB)
png_handle_sRGB(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_iCCP_SUPPORTED
else if (chunk_name == png_iCCP)
png_handle_iCCP(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sPLT_SUPPORTED
else if (chunk_name == png_sPLT)
png_handle_sPLT(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tEXt_SUPPORTED
else if (chunk_name == png_tEXt)
png_handle_tEXt(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tIME_SUPPORTED
else if (chunk_name == png_tIME)
png_handle_tIME(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tRNS_SUPPORTED
else if (chunk_name == png_tRNS)
png_handle_tRNS(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_zTXt_SUPPORTED
else if (chunk_name == png_zTXt)
png_handle_zTXt(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_iTXt_SUPPORTED
else if (chunk_name == png_iTXt)
png_handle_iTXt(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_APNG_SUPPORTED
else if (chunk_name == png_acTL)
png_handle_acTL(png_ptr, info_ptr, length);
else if (chunk_name == png_fcTL)
png_handle_fcTL(png_ptr, info_ptr, length);
else if (chunk_name == png_fdAT)
png_handle_fdAT(png_ptr, info_ptr, length);
#endif
else
png_handle_unknown(png_ptr, info_ptr, length,
PNG_HANDLE_CHUNK_AS_DEFAULT);
}
}
#endif /* SEQUENTIAL_READ */
#ifdef PNG_READ_APNG_SUPPORTED
void PNGAPI
png_read_frame_head(png_structp png_ptr, png_infop info_ptr)
{
png_byte have_chunk_after_DAT; /* after IDAT or after fdAT */
png_debug(0, "Reading frame head");
if ((png_ptr->mode & PNG_HAVE_acTL) == 0)
png_error(png_ptr, "attempt to png_read_frame_head() but "
"no acTL present");
/* do nothing for the main IDAT */
if (png_ptr->num_frames_read == 0)
return;
png_read_reset(png_ptr);
png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
png_ptr->mode &= ~PNG_HAVE_fcTL;
have_chunk_after_DAT = 0;
for (;;)
{
png_uint_32 length = png_read_chunk_header(png_ptr);
if (png_ptr->chunk_name == png_IDAT)
{
/* discard trailing IDATs for the first frame */
if (have_chunk_after_DAT != 0 || png_ptr->num_frames_read > 1)
png_error(png_ptr, "png_read_frame_head(): out of place IDAT");
png_crc_finish(png_ptr, length);
}
else if (png_ptr->chunk_name == png_fcTL)
{
png_handle_fcTL(png_ptr, info_ptr, length);
have_chunk_after_DAT = 1;
}
else if (png_ptr->chunk_name == png_fdAT)
{
png_ensure_sequence_number(png_ptr, length);
/* discard trailing fdATs for frames other than the first */
if (have_chunk_after_DAT == 0 && png_ptr->num_frames_read > 1)
png_crc_finish(png_ptr, length - 4);
else if (png_ptr->mode & PNG_HAVE_fcTL)
{
png_ptr->idat_size = length - 4;
png_ptr->mode |= PNG_HAVE_IDAT;
break;
}
else
png_error(png_ptr, "png_read_frame_head(): out of place fdAT");
}
else
{
png_warning(png_ptr, "Skipped (ignored) a chunk "
"between APNG chunks");
png_crc_finish(png_ptr, length);
}
}
}
#endif /* READ_APNG */
/* Optional call to update the users info_ptr structure */
void PNGAPI
png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
{
png_debug(1, "in png_read_update_info");
if (png_ptr != NULL)
{
if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
{
png_read_start_row(png_ptr);
# ifdef PNG_READ_TRANSFORMS_SUPPORTED
png_read_transform_info(png_ptr, info_ptr);
# else
PNG_UNUSED(info_ptr)
# endif
}
/* New in 1.6.0 this avoids the bug of doing the initializations twice */
else
png_app_error(png_ptr,
"png_read_update_info/png_start_read_image: duplicate call");
}
}
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Initialize palette, background, etc, after transformations
* are set, but before any reading takes place. This allows
* the user to obtain a gamma-corrected palette, for example.
* If the user doesn't call this, we will do it ourselves.
*/
void PNGAPI
png_start_read_image(png_structrp png_ptr)
{
png_debug(1, "in png_start_read_image");
if (png_ptr != NULL)
{
if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
png_read_start_row(png_ptr);
/* New in 1.6.0 this avoids the bug of doing the initializations twice */
else
png_app_error(png_ptr,
"png_start_read_image/png_read_update_info: duplicate call");
}
}
#endif /* SEQUENTIAL_READ */
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
#ifdef PNG_MNG_FEATURES_SUPPORTED
/* Undoes intrapixel differencing,
* NOTE: this is apparently only supported in the 'sequential' reader.
*/
static void
png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
{
png_debug(1, "in png_do_read_intrapixel");
if (
(row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
{
int bytes_per_pixel;
png_uint_32 row_width = row_info->width;
if (row_info->bit_depth == 8)
{
png_bytep rp;
png_uint_32 i;
if (row_info->color_type == PNG_COLOR_TYPE_RGB)
bytes_per_pixel = 3;
else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
bytes_per_pixel = 4;
else
return;
for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
{
*(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
*(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
}
}
else if (row_info->bit_depth == 16)
{
png_bytep rp;
png_uint_32 i;
if (row_info->color_type == PNG_COLOR_TYPE_RGB)
bytes_per_pixel = 6;
else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
bytes_per_pixel = 8;
else
return;
for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
{
png_uint_32 s0 = (png_uint_32)(*(rp ) << 8) | *(rp + 1);
png_uint_32 s1 = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
png_uint_32 s2 = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5);
png_uint_32 red = (s0 + s1 + 65536) & 0xffff;
png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
*(rp ) = (png_byte)((red >> 8) & 0xff);
*(rp + 1) = (png_byte)(red & 0xff);
*(rp + 4) = (png_byte)((blue >> 8) & 0xff);
*(rp + 5) = (png_byte)(blue & 0xff);
}
}
}
}
#endif /* MNG_FEATURES */
void PNGAPI
png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
{
png_row_info row_info;
if (png_ptr == NULL)
return;
png_debug2(1, "in png_read_row (row %lu, pass %d)",
(unsigned long)png_ptr->row_number, png_ptr->pass);
/* png_read_start_row sets the information (in particular iwidth) for this
* interlace pass.
*/
if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
png_read_start_row(png_ptr);
/* 1.5.6: row_info moved out of png_struct to a local here. */
row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
row_info.color_type = png_ptr->color_type;
row_info.bit_depth = png_ptr->bit_depth;
row_info.channels = png_ptr->channels;
row_info.pixel_depth = png_ptr->pixel_depth;
row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
#ifdef PNG_WARNINGS_SUPPORTED
if (png_ptr->row_number == 0 && png_ptr->pass == 0)
{
/* Check for transforms that have been set but were defined out */
#if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
#endif
#if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
if ((png_ptr->transformations & PNG_FILLER) != 0)
png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
#endif
#if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
!defined(PNG_READ_PACKSWAP_SUPPORTED)
if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
#endif
#if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
if ((png_ptr->transformations & PNG_PACK) != 0)
png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
#endif
#if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
if ((png_ptr->transformations & PNG_SHIFT) != 0)
png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
#endif
#if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
if ((png_ptr->transformations & PNG_BGR) != 0)
png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
#endif
#if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
#endif
}
#endif /* WARNINGS */
#ifdef PNG_READ_INTERLACING_SUPPORTED
/* If interlaced and we do not need a new row, combine row and return.
* Notice that the pixels we have from previous rows have been transformed
* already; we can only combine like with like (transformed or
* untransformed) and, because of the libpng API for interlaced images, this
* means we must transform before de-interlacing.
*/
if (png_ptr->interlaced != 0 &&
(png_ptr->transformations & PNG_INTERLACE) != 0)
{
switch (png_ptr->pass)
{
case 0:
if (png_ptr->row_number & 0x07)
{
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, 1/*display*/);
png_read_finish_row(png_ptr);
return;
}
break;
case 1:
if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
{
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, 1/*display*/);
png_read_finish_row(png_ptr);
return;
}
break;
case 2:
if ((png_ptr->row_number & 0x07) != 4)
{
if (dsp_row != NULL && (png_ptr->row_number & 4))
png_combine_row(png_ptr, dsp_row, 1/*display*/);
png_read_finish_row(png_ptr);
return;
}
break;
case 3:
if ((png_ptr->row_number & 3) || png_ptr->width < 3)
{
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, 1/*display*/);
png_read_finish_row(png_ptr);
return;
}
break;
case 4:
if ((png_ptr->row_number & 3) != 2)
{
if (dsp_row != NULL && (png_ptr->row_number & 2))
png_combine_row(png_ptr, dsp_row, 1/*display*/);
png_read_finish_row(png_ptr);
return;
}
break;
case 5:
if ((png_ptr->row_number & 1) || png_ptr->width < 2)
{
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, 1/*display*/);
png_read_finish_row(png_ptr);
return;
}
break;
default:
case 6:
if ((png_ptr->row_number & 1) == 0)
{
png_read_finish_row(png_ptr);
return;
}
break;
}
}
#endif
if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
png_error(png_ptr, "Invalid attempt to read row data");
/* Fill the row with IDAT data: */
png_ptr->row_buf[0]=255; /* to force error if no data was found */
png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
{
if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
png_ptr->prev_row + 1, png_ptr->row_buf[0]);
else
png_error(png_ptr, "bad adaptive filter value");
}
/* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
* 1.5.6, while the buffer really is this big in current versions of libpng
* it may not be in the future, so this was changed just to copy the
* interlaced count:
*/
memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
#ifdef PNG_MNG_FEATURES_SUPPORTED
if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
(png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
{
/* Intrapixel differencing */
png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
}
#endif
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
if (png_ptr->transformations)
png_do_read_transformations(png_ptr, &row_info);
#endif
/* The transformed pixel depth should match the depth now in row_info. */
if (png_ptr->transformed_pixel_depth == 0)
{
png_ptr->transformed_pixel_depth = row_info.pixel_depth;
if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
png_error(png_ptr, "sequential row overflow");
}
else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
png_error(png_ptr, "internal sequential row size calculation error");
#ifdef PNG_READ_INTERLACING_SUPPORTED
/* Expand interlaced rows to full size */
if (png_ptr->interlaced != 0 &&
(png_ptr->transformations & PNG_INTERLACE) != 0)
{
if (png_ptr->pass < 6)
png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
png_ptr->transformations);
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, 1/*display*/);
if (row != NULL)
png_combine_row(png_ptr, row, 0/*row*/);
}
else
#endif
{
if (row != NULL)
png_combine_row(png_ptr, row, -1/*ignored*/);
if (dsp_row != NULL)
png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
}
png_read_finish_row(png_ptr);
if (png_ptr->read_row_fn != NULL)
(*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
}
#endif /* SEQUENTIAL_READ */
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read one or more rows of image data. If the image is interlaced,
* and png_set_interlace_handling() has been called, the rows need to
* contain the contents of the rows from the previous pass. If the
* image has alpha or transparency, and png_handle_alpha()[*] has been
* called, the rows contents must be initialized to the contents of the
* screen.
*
* "row" holds the actual image, and pixels are placed in it
* as they arrive. If the image is displayed after each pass, it will
* appear to "sparkle" in. "display_row" can be used to display a
* "chunky" progressive image, with finer detail added as it becomes
* available. If you do not want this "chunky" display, you may pass
* NULL for display_row. If you do not want the sparkle display, and
* you have not called png_handle_alpha(), you may pass NULL for rows.
* If you have called png_handle_alpha(), and the image has either an
* alpha channel or a transparency chunk, you must provide a buffer for
* rows. In this case, you do not have to provide a display_row buffer
* also, but you may. If the image is not interlaced, or if you have
* not called png_set_interlace_handling(), the display_row buffer will
* be ignored, so pass NULL to it.
*
* [*] png_handle_alpha() does not exist yet, as of this version of libpng
*/
void PNGAPI
png_read_rows(png_structrp png_ptr, png_bytepp row,
png_bytepp display_row, png_uint_32 num_rows)
{
png_uint_32 i;
png_bytepp rp;
png_bytepp dp;
png_debug(1, "in png_read_rows");
if (png_ptr == NULL)
return;
rp = row;
dp = display_row;
if (rp != NULL && dp != NULL)
for (i = 0; i < num_rows; i++)
{
png_bytep rptr = *rp++;
png_bytep dptr = *dp++;
png_read_row(png_ptr, rptr, dptr);
}
else if (rp != NULL)
for (i = 0; i < num_rows; i++)
{
png_bytep rptr = *rp;
png_read_row(png_ptr, rptr, NULL);
rp++;
}
else if (dp != NULL)
for (i = 0; i < num_rows; i++)
{
png_bytep dptr = *dp;
png_read_row(png_ptr, NULL, dptr);
dp++;
}
}
#endif /* SEQUENTIAL_READ */
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the entire image. If the image has an alpha channel or a tRNS
* chunk, and you have called png_handle_alpha()[*], you will need to
* initialize the image to the current image that PNG will be overlaying.
* We set the num_rows again here, in case it was incorrectly set in
* png_read_start_row() by a call to png_read_update_info() or
* png_start_read_image() if png_set_interlace_handling() wasn't called
* prior to either of these functions like it should have been. You can
* only call this function once. If you desire to have an image for
* each pass of a interlaced image, use png_read_rows() instead.
*
* [*] png_handle_alpha() does not exist yet, as of this version of libpng
*/
void PNGAPI
png_read_image(png_structrp png_ptr, png_bytepp image)
{
png_uint_32 i, image_height;
int pass, j;
png_bytepp rp;
png_debug(1, "in png_read_image");
if (png_ptr == NULL)
return;
#ifdef PNG_READ_INTERLACING_SUPPORTED
if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
{
pass = png_set_interlace_handling(png_ptr);
/* And make sure transforms are initialized. */
png_start_read_image(png_ptr);
}
else
{
if (png_ptr->interlaced != 0 &&
(png_ptr->transformations & PNG_INTERLACE) == 0)
{
/* Caller called png_start_read_image or png_read_update_info without
* first turning on the PNG_INTERLACE transform. We can fix this here,
* but the caller should do it!
*/
png_warning(png_ptr, "Interlace handling should be turned on when "
"using png_read_image");
/* Make sure this is set correctly */
png_ptr->num_rows = png_ptr->height;
}
/* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
* the above error case.
*/
pass = png_set_interlace_handling(png_ptr);
}
#else
if (png_ptr->interlaced)
png_error(png_ptr,
"Cannot read interlaced image -- interlace handler disabled");
pass = 1;
#endif
image_height=png_ptr->height;
for (j = 0; j < pass; j++)
{
rp = image;
for (i = 0; i < image_height; i++)
{
png_read_row(png_ptr, *rp, NULL);
rp++;
}
}
}
#endif /* SEQUENTIAL_READ */
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the end of the PNG file. Will not read past the end of the
* file, will verify the end is accurate, and will read any comments
* or time information at the end of the file, if info is not NULL.
*/
void PNGAPI
png_read_end(png_structrp png_ptr, png_inforp info_ptr)
{
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
int keep;
#endif
png_debug(1, "in png_read_end");
if (png_ptr == NULL)
return;
/* If png_read_end is called in the middle of reading the rows there may
* still be pending IDAT data and an owned zstream. Deal with this here.
*/
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0)
#endif
png_read_finish_IDAT(png_ptr);
#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
/* Report invalid palette index; added at libng-1.5.10 */
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
png_ptr->num_palette_max > png_ptr->num_palette)
png_benign_error(png_ptr, "Read palette index exceeding num_palette");
#endif
do
{
png_uint_32 length = png_read_chunk_header(png_ptr);
png_uint_32 chunk_name = png_ptr->chunk_name;
if (chunk_name != png_IDAT)
png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
if (chunk_name == png_IEND)
png_handle_IEND(png_ptr, info_ptr, length);
else if (chunk_name == png_IHDR)
png_handle_IHDR(png_ptr, info_ptr, length);
else if (info_ptr == NULL)
png_crc_finish(png_ptr, length);
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
{
if (chunk_name == png_IDAT)
{
if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
|| (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
png_benign_error(png_ptr, ".Too many IDATs found");
}
png_handle_unknown(png_ptr, info_ptr, length, keep);
if (chunk_name == png_PLTE)
png_ptr->mode |= PNG_HAVE_PLTE;
}
#endif
else if (chunk_name == png_IDAT)
{
/* Zero length IDATs are legal after the last IDAT has been
* read, but not after other chunks have been read. 1.6 does not
* always read all the deflate data; specifically it cannot be relied
* upon to read the Adler32 at the end. If it doesn't ignore IDAT
* chunks which are longer than zero as well:
*/
if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
|| (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
png_benign_error(png_ptr, "..Too many IDATs found");
png_crc_finish(png_ptr, length);
}
else if (chunk_name == png_PLTE)
png_handle_PLTE(png_ptr, info_ptr, length);
#ifdef PNG_READ_bKGD_SUPPORTED
else if (chunk_name == png_bKGD)
png_handle_bKGD(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_cHRM_SUPPORTED
else if (chunk_name == png_cHRM)
png_handle_cHRM(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_eXIf_SUPPORTED
else if (chunk_name == png_eXIf)
png_handle_eXIf(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_gAMA_SUPPORTED
else if (chunk_name == png_gAMA)
png_handle_gAMA(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_hIST_SUPPORTED
else if (chunk_name == png_hIST)
png_handle_hIST(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_oFFs_SUPPORTED
else if (chunk_name == png_oFFs)
png_handle_oFFs(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_pCAL_SUPPORTED
else if (chunk_name == png_pCAL)
png_handle_pCAL(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sCAL_SUPPORTED
else if (chunk_name == png_sCAL)
png_handle_sCAL(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_pHYs_SUPPORTED
else if (chunk_name == png_pHYs)
png_handle_pHYs(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sBIT_SUPPORTED
else if (chunk_name == png_sBIT)
png_handle_sBIT(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sRGB_SUPPORTED
else if (chunk_name == png_sRGB)
png_handle_sRGB(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_iCCP_SUPPORTED
else if (chunk_name == png_iCCP)
png_handle_iCCP(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_sPLT_SUPPORTED
else if (chunk_name == png_sPLT)
png_handle_sPLT(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tEXt_SUPPORTED
else if (chunk_name == png_tEXt)
png_handle_tEXt(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tIME_SUPPORTED
else if (chunk_name == png_tIME)
png_handle_tIME(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_tRNS_SUPPORTED
else if (chunk_name == png_tRNS)
png_handle_tRNS(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_zTXt_SUPPORTED
else if (chunk_name == png_zTXt)
png_handle_zTXt(png_ptr, info_ptr, length);
#endif
#ifdef PNG_READ_iTXt_SUPPORTED
else if (chunk_name == png_iTXt)
png_handle_iTXt(png_ptr, info_ptr, length);
#endif
else
png_handle_unknown(png_ptr, info_ptr, length,
PNG_HANDLE_CHUNK_AS_DEFAULT);
} while ((png_ptr->mode & PNG_HAVE_IEND) == 0);
}
#endif /* SEQUENTIAL_READ */
/* Free all memory used in the read struct */
static void
png_read_destroy(png_structrp png_ptr)
{
png_debug(1, "in png_read_destroy");
#ifdef PNG_READ_GAMMA_SUPPORTED
png_destroy_gamma_table(png_ptr);
#endif
png_free(png_ptr, png_ptr->big_row_buf);
png_ptr->big_row_buf = NULL;
png_free(png_ptr, png_ptr->big_prev_row);
png_ptr->big_prev_row = NULL;
png_free(png_ptr, png_ptr->read_buffer);
png_ptr->read_buffer = NULL;
#ifdef PNG_READ_QUANTIZE_SUPPORTED
png_free(png_ptr, png_ptr->palette_lookup);
png_ptr->palette_lookup = NULL;
png_free(png_ptr, png_ptr->quantize_index);
png_ptr->quantize_index = NULL;
#endif
if ((png_ptr->free_me & PNG_FREE_PLTE) != 0)
{
png_zfree(png_ptr, png_ptr->palette);
png_ptr->palette = NULL;
}
png_ptr->free_me &= ~PNG_FREE_PLTE;
#if defined(PNG_tRNS_SUPPORTED) || \
defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
if ((png_ptr->free_me & PNG_FREE_TRNS) != 0)
{
png_free(png_ptr, png_ptr->trans_alpha);
png_ptr->trans_alpha = NULL;
}
png_ptr->free_me &= ~PNG_FREE_TRNS;
#endif
inflateEnd(&png_ptr->zstream);
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
png_free(png_ptr, png_ptr->save_buffer);
png_ptr->save_buffer = NULL;
#endif
#if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \
defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
png_free(png_ptr, png_ptr->unknown_chunk.data);
png_ptr->unknown_chunk.data = NULL;
#endif
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
png_free(png_ptr, png_ptr->chunk_list);
png_ptr->chunk_list = NULL;
#endif
#if defined(PNG_READ_EXPAND_SUPPORTED) && \
defined(PNG_ARM_NEON_IMPLEMENTATION)
png_free(png_ptr, png_ptr->riffled_palette);
png_ptr->riffled_palette = NULL;
#endif
/* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
* callbacks are still set at this point. They are required to complete the
* destruction of the png_struct itself.
*/
}
/* Free all memory used by the read */
void PNGAPI
png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
png_infopp end_info_ptr_ptr)
{
png_structrp png_ptr = NULL;
png_debug(1, "in png_destroy_read_struct");
if (png_ptr_ptr != NULL)
png_ptr = *png_ptr_ptr;
if (png_ptr == NULL)
return;
/* libpng 1.6.0: use the API to destroy info structs to ensure consistent
* behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API.
* The extra was, apparently, unnecessary yet this hides memory leak bugs.
*/
png_destroy_info_struct(png_ptr, end_info_ptr_ptr);
png_destroy_info_struct(png_ptr, info_ptr_ptr);
*png_ptr_ptr = NULL;
png_read_destroy(png_ptr);
png_destroy_png_struct(png_ptr);
}
void PNGAPI
png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
{
if (png_ptr == NULL)
return;
png_ptr->read_row_fn = read_row_fn;
}
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
#ifdef PNG_INFO_IMAGE_SUPPORTED
void PNGAPI
png_read_png(png_structrp png_ptr, png_inforp info_ptr,
int transforms, voidp params)
{
if (png_ptr == NULL || info_ptr == NULL)
return;
/* png_read_info() gives us all of the information from the
* PNG file before the first IDAT (image data chunk).
*/
png_read_info(png_ptr, info_ptr);
if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
png_error(png_ptr, "Image is too high to process with png_read_png()");
/* -------------- image transformations start here ------------------- */
/* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
* is not implemented. This will only happen in de-configured (non-default)
* libpng builds. The results can be unexpected - png_read_png may return
* short or mal-formed rows because the transform is skipped.
*/
/* Tell libpng to strip 16-bit/color files down to 8 bits per color.
*/
if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
/* Added at libpng-1.5.4. "strip_16" produces the same result that it
* did in earlier versions, while "scale_16" is now more accurate.
*/
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
png_set_scale_16(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
#endif
/* If both SCALE and STRIP are required pngrtran will effectively cancel the
* latter by doing SCALE first. This is ok and allows apps not to check for
* which is supported to get the right answer.
*/
if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
png_set_strip_16(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
#endif
/* Strip alpha bytes from the input data without combining with
* the background (not recommended).
*/
if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
png_set_strip_alpha(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
#endif
/* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
* byte into separate bytes (useful for paletted and grayscale images).
*/
if ((transforms & PNG_TRANSFORM_PACKING) != 0)
#ifdef PNG_READ_PACK_SUPPORTED
png_set_packing(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
#endif
/* Change the order of packed pixels to least significant bit first
* (not useful if you are using png_set_packing).
*/
if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
#ifdef PNG_READ_PACKSWAP_SUPPORTED
png_set_packswap(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
#endif
/* Expand paletted colors into true RGB triplets
* Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
* Expand paletted or RGB images with transparency to full alpha
* channels so the data will be available as RGBA quartets.
*/
if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
#ifdef PNG_READ_EXPAND_SUPPORTED
png_set_expand(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
#endif
/* We don't handle background color or gamma transformation or quantizing.
*/
/* Invert monochrome files to have 0 as white and 1 as black
*/
if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
#ifdef PNG_READ_INVERT_SUPPORTED
png_set_invert_mono(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
#endif
/* If you want to shift the pixel values from the range [0,255] or
* [0,65535] to the original [0,7] or [0,31], or whatever range the
* colors were originally in:
*/
if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
#ifdef PNG_READ_SHIFT_SUPPORTED
if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
png_set_shift(png_ptr, &info_ptr->sig_bit);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
#endif
/* Flip the RGB pixels to BGR (or RGBA to BGRA) */
if ((transforms & PNG_TRANSFORM_BGR) != 0)
#ifdef PNG_READ_BGR_SUPPORTED
png_set_bgr(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
#endif
/* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
png_set_swap_alpha(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
#endif
/* Swap bytes of 16-bit files to least significant byte first */
if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
#ifdef PNG_READ_SWAP_SUPPORTED
png_set_swap(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
#endif
/* Added at libpng-1.2.41 */
/* Invert the alpha channel from opacity to transparency */
if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
png_set_invert_alpha(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
#endif
/* Added at libpng-1.2.41 */
/* Expand grayscale image to RGB */
if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
png_set_gray_to_rgb(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
#endif
/* Added at libpng-1.5.4 */
if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
#ifdef PNG_READ_EXPAND_16_SUPPORTED
png_set_expand_16(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
#endif
/* We don't handle adding filler bytes */
/* We use png_read_image and rely on that for interlace handling, but we also
* call png_read_update_info therefore must turn on interlace handling now:
*/
(void)png_set_interlace_handling(png_ptr);
/* Optional call to gamma correct and add the background to the palette
* and update info structure. REQUIRED if you are expecting libpng to
* update the palette for you (i.e., you selected such a transform above).
*/
png_read_update_info(png_ptr, info_ptr);
/* -------------- image transformations end here ------------------- */
png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
if (info_ptr->row_pointers == NULL)
{
png_uint_32 iptr;
info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
info_ptr->height * (sizeof (png_bytep))));
for (iptr=0; iptr<info_ptr->height; iptr++)
info_ptr->row_pointers[iptr] = NULL;
info_ptr->free_me |= PNG_FREE_ROWS;
for (iptr = 0; iptr < info_ptr->height; iptr++)
info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
png_malloc(png_ptr, info_ptr->rowbytes));
}
png_read_image(png_ptr, info_ptr->row_pointers);
info_ptr->valid |= PNG_INFO_IDAT;
/* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
png_read_end(png_ptr, info_ptr);
PNG_UNUSED(params)
}
#endif /* INFO_IMAGE */
#endif /* SEQUENTIAL_READ */
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
/* SIMPLIFIED READ
*
* This code currently relies on the sequential reader, though it could easily
* be made to work with the progressive one.
*/
/* Arguments to png_image_finish_read: */
/* Encoding of PNG data (used by the color-map code) */
# define P_NOTSET 0 /* File encoding not yet known */
# define P_sRGB 1 /* 8-bit encoded to sRGB gamma */
# define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
# define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */
# define P_LINEAR8 4 /* 8-bit linear: only from a file value */
/* Color-map processing: after libpng has run on the PNG image further
* processing may be needed to convert the data to color-map indices.
*/
#define PNG_CMAP_NONE 0
#define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */
#define PNG_CMAP_TRANS 2 /* Process GA data to a background index */
#define PNG_CMAP_RGB 3 /* Process RGB data */
#define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
/* The following document where the background is for each processing case. */
#define PNG_CMAP_NONE_BACKGROUND 256
#define PNG_CMAP_GA_BACKGROUND 231
#define PNG_CMAP_TRANS_BACKGROUND 254
#define PNG_CMAP_RGB_BACKGROUND 256
#define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
typedef struct
{
/* Arguments: */
png_imagep image;
png_voidp buffer;
png_int_32 row_stride;
png_voidp colormap;
png_const_colorp background;
/* Local variables: */
png_voidp local_row;
png_voidp first_row;
ptrdiff_t row_bytes; /* step between rows */
int file_encoding; /* E_ values above */
png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */
int colormap_processing; /* PNG_CMAP_ values above */
} png_image_read_control;
/* Do all the *safe* initialization - 'safe' means that png_error won't be
* called, so setting up the jmp_buf is not required. This means that anything
* called from here must *not* call png_malloc - it has to call png_malloc_warn
* instead so that control is returned safely back to this routine.
*/
static int
png_image_read_init(png_imagep image)
{
if (image->opaque == NULL)
{
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
png_safe_error, png_safe_warning);
/* And set the rest of the structure to NULL to ensure that the various
* fields are consistent.
*/
memset(image, 0, (sizeof *image));
image->version = PNG_IMAGE_VERSION;
if (png_ptr != NULL)
{
png_infop info_ptr = png_create_info_struct(png_ptr);
if (info_ptr != NULL)
{
png_controlp control = png_voidcast(png_controlp,
png_malloc_warn(png_ptr, (sizeof *control)));
if (control != NULL)
{
memset(control, 0, (sizeof *control));
control->png_ptr = png_ptr;
control->info_ptr = info_ptr;
control->for_write = 0;
image->opaque = control;
return 1;
}
/* Error clean up */
png_destroy_info_struct(png_ptr, &info_ptr);
}
png_destroy_read_struct(&png_ptr, NULL, NULL);
}
return png_image_error(image, "png_image_read: out of memory");
}
return png_image_error(image, "png_image_read: opaque pointer not NULL");
}
/* Utility to find the base format of a PNG file from a png_struct. */
static png_uint_32
png_image_format(png_structrp png_ptr)
{
png_uint_32 format = 0;
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
format |= PNG_FORMAT_FLAG_COLOR;
if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
format |= PNG_FORMAT_FLAG_ALPHA;
/* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
* sets the png_struct fields; that's all we are interested in here. The
* precise interaction with an app call to png_set_tRNS and PNG file reading
* is unclear.
*/
else if (png_ptr->num_trans > 0)
format |= PNG_FORMAT_FLAG_ALPHA;
if (png_ptr->bit_depth == 16)
format |= PNG_FORMAT_FLAG_LINEAR;
if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
format |= PNG_FORMAT_FLAG_COLORMAP;
return format;
}
/* Is the given gamma significantly different from sRGB? The test is the same
* one used in pngrtran.c when deciding whether to do gamma correction. The
* arithmetic optimizes the division by using the fact that the inverse of the
* file sRGB gamma is 2.2
*/
static int
png_gamma_not_sRGB(png_fixed_point g)
{
if (g < PNG_FP_1)
{
/* An uninitialized gamma is assumed to be sRGB for the simplified API. */
if (g == 0)
return 0;
return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */);
}
return 1;
}
/* Do the main body of a 'png_image_begin_read' function; read the PNG file
* header and fill in all the information. This is executed in a safe context,
* unlike the init routine above.
*/
static int
png_image_read_header(png_voidp argument)
{
png_imagep image = png_voidcast(png_imagep, argument);
png_structrp png_ptr = image->opaque->png_ptr;
png_inforp info_ptr = image->opaque->info_ptr;
#ifdef PNG_BENIGN_ERRORS_SUPPORTED
png_set_benign_errors(png_ptr, 1/*warn*/);
#endif
png_read_info(png_ptr, info_ptr);
/* Do this the fast way; just read directly out of png_struct. */
image->width = png_ptr->width;
image->height = png_ptr->height;
{
png_uint_32 format = png_image_format(png_ptr);
image->format = format;
#ifdef PNG_COLORSPACE_SUPPORTED
/* Does the colorspace match sRGB? If there is no color endpoint
* (colorant) information assume yes, otherwise require the
* 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the
* colorspace has been determined to be invalid ignore it.
*/
if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
& (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
#endif
}
/* We need the maximum number of entries regardless of the format the
* application sets here.
*/
{
png_uint_32 cmap_entries;
switch (png_ptr->color_type)
{
case PNG_COLOR_TYPE_GRAY:
cmap_entries = 1U << png_ptr->bit_depth;
break;
case PNG_COLOR_TYPE_PALETTE:
cmap_entries = (png_uint_32)png_ptr->num_palette;
break;
default:
cmap_entries = 256;
break;
}
if (cmap_entries > 256)
cmap_entries = 256;
image->colormap_entries = cmap_entries;
}
return 1;
}
#ifdef PNG_STDIO_SUPPORTED
int PNGAPI
png_image_begin_read_from_stdio(png_imagep image, FILE* file)
{
if (image != NULL && image->version == PNG_IMAGE_VERSION)
{
if (file != NULL)
{
if (png_image_read_init(image) != 0)
{
/* This is slightly evil, but png_init_io doesn't do anything other
* than this and we haven't changed the standard IO functions so
* this saves a 'safe' function.
*/
image->opaque->png_ptr->io_ptr = file;
return png_safe_execute(image, png_image_read_header, image);
}
}
else
return png_image_error(image,
"png_image_begin_read_from_stdio: invalid argument");
}
else if (image != NULL)
return png_image_error(image,
"png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
return 0;
}
int PNGAPI
png_image_begin_read_from_file(png_imagep image, const char *file_name)
{
if (image != NULL && image->version == PNG_IMAGE_VERSION)
{
if (file_name != NULL)
{
FILE *fp = fopen(file_name, "rb");
if (fp != NULL)
{
if (png_image_read_init(image) != 0)
{
image->opaque->png_ptr->io_ptr = fp;
image->opaque->owned_file = 1;
return png_safe_execute(image, png_image_read_header, image);
}
/* Clean up: just the opened file. */
(void)fclose(fp);
}
else
return png_image_error(image, strerror(errno));
}
else
return png_image_error(image,
"png_image_begin_read_from_file: invalid argument");
}
else if (image != NULL)
return png_image_error(image,
"png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
return 0;
}
#endif /* STDIO */
static void PNGCBAPI
png_image_memory_read(png_structp png_ptr, png_bytep out, size_t need)
{
if (png_ptr != NULL)
{
png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
if (image != NULL)
{
png_controlp cp = image->opaque;
if (cp != NULL)
{
png_const_bytep memory = cp->memory;
size_t size = cp->size;
if (memory != NULL && size >= need)
{
memcpy(out, memory, need);
cp->memory = memory + need;
cp->size = size - need;
return;
}
png_error(png_ptr, "read beyond end of data");
}
}
png_error(png_ptr, "invalid memory read");
}
}
int PNGAPI png_image_begin_read_from_memory(png_imagep image,
png_const_voidp memory, size_t size)
{
if (image != NULL && image->version == PNG_IMAGE_VERSION)
{
if (memory != NULL && size > 0)
{
if (png_image_read_init(image) != 0)
{
/* Now set the IO functions to read from the memory buffer and
* store it into io_ptr. Again do this in-place to avoid calling a
* libpng function that requires error handling.
*/
image->opaque->memory = png_voidcast(png_const_bytep, memory);
image->opaque->size = size;
image->opaque->png_ptr->io_ptr = image;
image->opaque->png_ptr->read_data_fn = png_image_memory_read;
return png_safe_execute(image, png_image_read_header, image);
}
}
else
return png_image_error(image,
"png_image_begin_read_from_memory: invalid argument");
}
else if (image != NULL)
return png_image_error(image,
"png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
return 0;
}
/* Utility function to skip chunks that are not used by the simplified image
* read functions and an appropriate macro to call it.
*/
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
static void
png_image_skip_unused_chunks(png_structrp png_ptr)
{
/* Prepare the reader to ignore all recognized chunks whose data will not
* be used, i.e., all chunks recognized by libpng except for those
* involved in basic image reading:
*
* IHDR, PLTE, IDAT, IEND
*
* Or image data handling:
*
* tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
*
* This provides a small performance improvement and eliminates any
* potential vulnerability to security problems in the unused chunks.
*
* At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
* too. This allows the simplified API to be compiled without iCCP support,
* however if the support is there the chunk is still checked to detect
* errors (which are unfortunately quite common.)
*/
{
static const png_byte chunks_to_process[] = {
98, 75, 71, 68, '\0', /* bKGD */
99, 72, 82, 77, '\0', /* cHRM */
103, 65, 77, 65, '\0', /* gAMA */
# ifdef PNG_READ_iCCP_SUPPORTED
105, 67, 67, 80, '\0', /* iCCP */
# endif
115, 66, 73, 84, '\0', /* sBIT */
115, 82, 71, 66, '\0', /* sRGB */
};
/* Ignore unknown chunks and all other chunks except for the
* IHDR, PLTE, tRNS, IDAT, and IEND chunks.
*/
png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
NULL, -1);
/* But do not ignore image data handling chunks */
png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
}
}
# define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
#else
# define PNG_SKIP_CHUNKS(p) ((void)0)
#endif /* HANDLE_AS_UNKNOWN */
/* The following macro gives the exact rounded answer for all values in the
* range 0..255 (it actually divides by 51.2, but the rounding still generates
* the correct numbers 0..5
*/
#define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
/* Utility functions to make particular color-maps */
static void
set_file_encoding(png_image_read_control *display)
{
png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
if (png_gamma_significant(g) != 0)
{
if (png_gamma_not_sRGB(g) != 0)
{
display->file_encoding = P_FILE;
display->gamma_to_linear = png_reciprocal(g);
}
else
display->file_encoding = P_sRGB;
}
else
display->file_encoding = P_LINEAR8;
}
static unsigned int
decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
{
if (encoding == P_FILE) /* double check */
encoding = display->file_encoding;