allow optionally ignoring a few more recoverable errors

6 files changed, 68 insertions, 25 deletions

diff --git a/lodepng.cpp b/lodepng.cpp
index 37b0562..6998910 100644
--- a/lodepng.cpp
+++ b/lodepng.cpp
@@ -1,7 +1,7 @@
 /*
-LodePNG version 20170917
+LodePNG version 20180114
 
-Copyright (c) 2005-2017 Lode Vandevenne
+Copyright (c) 2005-2018 Lode Vandevenne
 
 This software is provided 'as-is', without any express or implied
 warranty. In no event will the authors be held liable for any damages
@@ -39,7 +39,7 @@ Rename this file to lodepng.cpp to use it for C++, or to lodepng.c to use it for
 #pragma warning( disable : 4996 ) /*VS does not like fopen, but fopen_s is not standard C so unusable here*/
 #endif /*_MSC_VER */
 
-const char* LODEPNG_VERSION_STRING = "20170917";
+const char* LODEPNG_VERSION_STRING = "20180114";
 
 /*
 This source file is built up in the following large parts. The code sections
@@ -4565,12 +4565,20 @@ static void decodeGeneric(unsigned char** out, unsigned* w, unsigned* h,
     const unsigned char* data; /*the data in the chunk*/
 
     /*error: size of the in buffer too small to contain next chunk*/
-    if((size_t)((chunk - in) + 12) > insize || chunk < in) CERROR_BREAK(state->error, 30);
+    if((size_t)((chunk - in) + 12) > insize || chunk < in)
+    {
+      if(state->decoder.ignore_end) break; /*other errors may still happen though*/
+      CERROR_BREAK(state->error, 30);
+    }
 
     /*length of the data of the chunk, excluding the length bytes, chunk type and CRC bytes*/
     chunkLength = lodepng_chunk_length(chunk);
     /*error: chunk length larger than the max PNG chunk size*/
-    if(chunkLength > 2147483647) CERROR_BREAK(state->error, 63);
+    if(chunkLength > 2147483647)
+    {
+      if(state->decoder.ignore_end) break; /*other errors may still happen though*/
+      CERROR_BREAK(state->error, 63);
+    }
 
     if((size_t)((chunk - in) + chunkLength + 12) > insize || (chunk + chunkLength + 12) < in)
     {
@@ -4657,7 +4665,10 @@ static void decodeGeneric(unsigned char** out, unsigned* w, unsigned* h,
     else /*it's not an implemented chunk type, so ignore it: skip over the data*/
     {
       /*error: unknown critical chunk (5th bit of first byte of chunk type is 0)*/
-      if(!lodepng_chunk_ancillary(chunk)) CERROR_BREAK(state->error, 69);
+      if(!state->decoder.ignore_critical && !lodepng_chunk_ancillary(chunk))
+      {
+        CERROR_BREAK(state->error, 69);
+      }
 
       unknown = 1;
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
@@ -4822,6 +4833,8 @@ void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings)
   settings->remember_unknown_chunks = 0;
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
   settings->ignore_crc = 0;
+  settings->ignore_critical = 0;
+  settings->ignore_end = 0;
   lodepng_decompress_settings_init(&settings->zlibsettings);
 }
 
diff --git a/lodepng.h b/lodepng.h
index d633bfa..cf6667c 100644
--- a/lodepng.h
+++ b/lodepng.h
@@ -1,7 +1,7 @@
 /*
-LodePNG version 20170917
+LodePNG version 20180114
 
-Copyright (c) 2005-2017 Lode Vandevenne
+Copyright (c) 2005-2018 Lode Vandevenne
 
 This software is provided 'as-is', without any express or implied
 warranty. In no event will the authors be held liable for any damages
@@ -255,6 +255,7 @@ const char* lodepng_error_text(unsigned code);
 typedef struct LodePNGDecompressSettings LodePNGDecompressSettings;
 struct LodePNGDecompressSettings
 {
+  /* Check LodePNGDecoderSettings for more ignorable errors */
   unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/
 
   /*use custom zlib decoder instead of built in one (default: null)*/
@@ -520,7 +521,10 @@ typedef struct LodePNGDecoderSettings
 {
   LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/
 
+  /* Check LodePNGDecompressSettings for more ignorable errors */
   unsigned ignore_crc; /*ignore CRC checksums*/
+  unsigned ignore_critical; /*ignore unknown critical chunks*/
+  unsigned ignore_end; /*ignore issues at end of file if possible (missing IEND chunk, too large chunk, ...)*/
 
   unsigned color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/
 
@@ -1567,6 +1571,8 @@ For decoding:
 state.decoder.zlibsettings.ignore_adler32: ignore ADLER32 checksums
 state.decoder.zlibsettings.custom_...: use custom inflate function
 state.decoder.ignore_crc: ignore CRC checksums
+state.decoder.ignore_critical: ignore unknown critical chunks
+state.decoder.ignore_end: ignore missing IEND chunk. May fail if this corruption causes other errors
 state.decoder.color_convert: convert internal PNG color to chosen one
 state.decoder.read_text_chunks: whether to read in text metadata chunks
 state.decoder.remember_unknown_chunks: whether to read in unknown chunks
@@ -1608,6 +1614,7 @@ yyyymmdd.
 Some changes aren't backwards compatible. Those are indicated with a (!)
 symbol.
 
+*) 14 jan 2018: allow optionally ignoring a few more recoverable errors
 *) 17 sep 2017: fix memory leak for some encoder input error cases
 *) 27 nov 2016: grey+alpha auto color model detection bugfix
 *) 18 apr 2016: Changed qsort to custom stable sort (for platforms w/o qsort).
diff --git a/lodepng_unittest.cpp b/lodepng_unittest.cpp
index 5d11b2d..975f2b4 100644
--- a/lodepng_unittest.cpp
+++ b/lodepng_unittest.cpp
@@ -28,7 +28,7 @@ freely, subject to the following restrictions:
 /*
 Testing instructions:
 
-*) Ensure no tests commented out below
+*) Ensure no tests commented out below or early return in doMain
 
 *) Compile with g++ with all warnings and run the unit test
 g++ lodepng.cpp lodepng_util.cpp lodepng_unittest.cpp -Wall -Wextra -Wshadow -pedantic -ansi -O3 && ./a.out
diff --git a/lodepng_util.cpp b/lodepng_util.cpp
index 76efdea..9d86686 100644
--- a/lodepng_util.cpp
+++ b/lodepng_util.cpp
@@ -1,7 +1,7 @@
 /*
 LodePNG Utils
 
-Copyright (c) 2005-2014 Lode Vandevenne
+Copyright (c) 2005-2018 Lode Vandevenne
 
 This software is provided 'as-is', without any express or implied
 warranty. In no event will the authors be held liable for any damages
@@ -52,9 +52,9 @@ unsigned getChunkInfo(std::vector<std::string>& names, std::vector<size_t>& size
     if(std::string(type).size() != 4) return 1;
 
     unsigned length = lodepng_chunk_length(chunk);
-    if(chunk + length + 12 > end) return 1;
     names.push_back(type);
     sizes.push_back(length);
+    if(chunk + length + 12 > end) return 1;
 
     next = lodepng_chunk_next_const(chunk);
     if (next <= chunk) return 1; // integer overflow
diff --git a/lodepng_util.h b/lodepng_util.h
index 236ad46..19fcbcb 100644
--- a/lodepng_util.h
+++ b/lodepng_util.h
@@ -1,7 +1,7 @@
 /*
 LodePNG Utils
 
-Copyright (c) 2005-2014 Lode Vandevenne
+Copyright (c) 2005-2018 Lode Vandevenne
 
 This software is provided 'as-is', without any express or implied
 warranty. In no event will the authors be held liable for any damages
diff --git a/pngdetail.cpp b/pngdetail.cpp
index f0a5158..00aa9dd 100644
--- a/pngdetail.cpp
+++ b/pngdetail.cpp
@@ -1,7 +1,7 @@
 /*
 LodePNG pngdetail
 
-Copyright (c) 2005-2015 Lode Vandevenne
+Copyright (c) 2005-2018 Lode Vandevenne
 
 This software is provided 'as-is', without any express or implied
 warranty. In no event will the authors be held liable for any damages
@@ -797,6 +797,11 @@ unsigned showFileInfo(const std::string& filename, const Options& options)
   std::vector<unsigned char> image;
   unsigned w, h;
 
+  if(options.show_png_info)
+  {
+    std::cout << "pngdetail version: " << LODEPNG_VERSION_STRING << std::endl;
+  }
+
   unsigned error = lodepng::load_file(buffer, filename); //load the image file with given filename
 
   if(error)
@@ -810,27 +815,45 @@ unsigned showFileInfo(const std::string& filename, const Options& options)
   state.info_raw.bitdepth = 16;
   error = lodepng::decode(image, w, h, state, buffer);
 
-  // In case of checksum errors, disable checksums
-  while (error == 57 || error == 58) {
+  // In case of checksum errors and some other ignorable errors, report it but ignore it and retry
+  while (error) {
+    std::cerr << "Decoder error " << error << ": " << lodepng_error_text(error) << std::endl;
+    unsigned error2 = error;
     if(error == 57)
     {
-      std::cout << "Error: invalid CRC checksum" << std::endl;
+      std::cerr << "Ignoring the error: enabling ignore_crc" << std::endl;
       state.decoder.ignore_crc = 1;
       error = lodepng::decode(image, w, h, state, buffer);
     }
-
-    if(error == 58)
+    else if(error == 58)
     {
-      std::cout << "Error: invalid Adler32 checksum" << std::endl;
+      std::cerr << "Ignoring the error: enabling ignore_adler32" << std::endl;
       state.decoder.zlibsettings.ignore_adler32 = 1;
       error = lodepng::decode(image, w, h, state, buffer);
     }
-  }
-
-  if(error)
-  {
-    std::cout << "Decoder error " << error << ": " << lodepng_error_text(error) << std::endl;
-    // Do not return: some sections may still show partial info about a corrupted PNG.
+    else if(error == 69)
+    {
+      std::cerr << "Ignoring the error: enabling ignore_critical" << std::endl;
+      state.decoder.ignore_critical = 1;
+      error = lodepng::decode(image, w, h, state, buffer);
+    }
+    else if(error == 30 || error == 63)
+    {
+      std::cerr << "Ignoring the error: enabling ignore_end" << std::endl;
+      state.decoder.ignore_end = 1;
+      error = lodepng::decode(image, w, h, state, buffer);
+    }
+    else
+    {
+      if(error == 0) std::cerr << "This error is unrecoverable" << std::endl;
+      break;  // other error that we cannot ignore
+    }
+    if(error == 0) std::cerr << "Successfully ignored the error" << std::endl;
+    if(error == error2)
+    {
+      std::cerr << "Failed to ignore the error" << std::endl;
+      break; // avoid infinite loop if ignoring did not fix the error code
+    }
   }
 
   bool extra_newlines = false;