chromium/third_party/libwebp/src/imageio/pngdec.c

// Copyright 2012 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// PNG decode.

#include "./pngdec.h"

#ifdef HAVE_CONFIG_H
#include "webp/config.h"
#endif

#include <stdio.h>

#ifdef WEBP_HAVE_PNG
#ifndef PNG_USER_MEM_SUPPORTED
#define PNG_USER_MEM_SUPPORTED …
#endif
#include <png.h>
#include <setjmp.h>   // note: this must be included *after* png.h
#include <stdlib.h>
#include <string.h>

#include "webp/encode.h"
#include "./imageio_util.h"
#include "./metadata.h"

#define LOCAL_PNG_VERSION …
#define LOCAL_PNG_PREREQ(maj, min) …

static void PNGAPI error_function(png_structp png, png_const_charp error) { … }

#if LOCAL_PNG_PREREQ(1,4)
LocalPngAllocSize;
#else
typedef png_size_t LocalPngAllocSize;
#endif

static png_voidp MallocFunc(png_structp png_ptr, LocalPngAllocSize size) { … }

static void FreeFunc(png_structp png_ptr, png_voidp ptr) { … }

// Converts the NULL terminated 'hexstring' which contains 2-byte character
// representations of hex values to raw data.
// 'hexstring' may contain values consisting of [A-F][a-f][0-9] in pairs,
// e.g., 7af2..., separated by any number of newlines.
// 'expected_length' is the anticipated processed size.
// On success the raw buffer is returned with its length equivalent to
// 'expected_length'. NULL is returned if the processed length is less than
// 'expected_length' or any character aside from those above is encountered.
// The returned buffer must be freed by the caller.
static uint8_t* HexStringToBytes(const char* hexstring,
                                 size_t expected_length) { … }

static int ProcessRawProfile(const char* profile, size_t profile_len,
                             MetadataPayload* const payload) { … }

static const struct { … } kPNGMetadataMap[] = …;

// Looks for metadata at both the beginning and end of the PNG file, giving
// preference to the head.
// Returns true on success. The caller must use MetadataFree() on 'metadata' in
// all cases.
static int ExtractMetadataFromPNG(png_structp png,
                                  png_infop const head_info,
                                  png_infop const end_info,
                                  Metadata* const metadata) { … }

PNGReadContext;

static void ReadFunc(png_structp png_ptr, png_bytep data, png_size_t length) { … }

int ReadPNG(const uint8_t* const data, size_t data_size,
            struct WebPPicture* const pic,
            int keep_alpha, struct Metadata* const metadata) { … }
#else  // !WEBP_HAVE_PNG
int ReadPNG(const uint8_t* const data, size_t data_size,
            struct WebPPicture* const pic,
            int keep_alpha, struct Metadata* const metadata) {
  (void)data;
  (void)data_size;
  (void)pic;
  (void)keep_alpha;
  (void)metadata;
  fprintf(stderr, "PNG support not compiled. Please install the libpng "
          "development package before building.\n");
  return 0;
}
#endif  // WEBP_HAVE_PNG

// -----------------------------------------------------------------------------