svg-flatten: Add wasmtime support

7 files changed, 170 insertions, 82 deletions

diff --git a/svg-flatten/Makefile b/svg-flatten/Makefile
index fc5820f..94dab9b 100644
--- a/svg-flatten/Makefile
+++ b/svg-flatten/Makefile
@@ -6,10 +6,17 @@ PKG_CONFIG ?= pkg-config
 PYTHON3 ?= python3
 
 BUILDDIR ?= build
+CACHEDIR ?= cache
 PREFIX ?= /usr/local
-UPSTREAM_DIR ?= ../upstream
+UPSTREAM_DIR ?= upstream
 
-SOURCES := src/svg_color.cpp \
+WASI_SDK ?= wasi-sdk-11.0
+WASI_SDK_URL ?= https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-11/wasi-sdk-11.0-linux.tar.gz
+WASI_SDK_PATH ?= $(CACHEDIR)/$(WASI_SDK)
+WASI_CXX ?= $(WASI_SDK_PATH)/bin/clang++ --sysroot=$(WASI_SDK_PATH)/share/wasi-sysroot
+
+SOURCES := \
+	src/svg_color.cpp \
 	src/svg_doc.cpp \
 	src/svg_geom.cpp \
 	src/svg_import_util.cpp \
@@ -47,28 +54,47 @@ STB_INCLUDES		?= -isystem$(UPSTREAM_DIR)/stb
 INCLUDES := -Iinclude -Isrc $(CLIPPER_INCLUDES) $(VORONOI_INCLUDES) $(POISSON_INCLUDES) $(BASE64_INCLUDES) $(ARGAGG_INCLUDES) $(CAVC_INCLUDES) $(SUBPROCESS_INCLUDES) $(MINUNIT_INCLUDES) $(STB_INCLUDES)
 
 CXXFLAGS := -std=c++2a -g -Wall -Wextra -O2
-LDFLAGS := -lm -lstdc++ -lstdc++fs # for debian's ancient compilers
+LDFLAGS := -lm -lstdc++
 
-PKG_CONFIG_DEPS := 
 ifdef USE_SYSTEM_PUGIXML
-	CXXFLAGS += $(shell $(PKG_CONFIG) --cflags pugixml)
-	LDFLAGS += $(shell $(PKG_CONFIG) --libs pugixml)
+	HOST_CXXFLAGS := $(CXXFLAGS) $(shell $(PKG_CONFIG) --cflags pugixml)
+	HOST_LDFLAGS := $(LDFLAGS) $(shell $(PKG_CONFIG) --libs pugixml)
+	HOST_SOURCES := $(SOURCES)
+	HOST_INCLUDES := $(INCLUDES)
 else
-	SOURCES += $(PUGIXML_SOURCES)
-	INCLUDES += $(PUGIXML_INCLUDES)
+	HOST_CXXFLAGS := $(CXXFLAGS)
+	HOST_LDFLAGS := $(LDFLAGS)
+	HOST_SOURCES := $(SOURCES) $(PUGIXML_SOURCES)
+	HOST_INCLUDES := $(INCLUDES) $(PUGIXML_INCLUDES)
 endif
 
-TARGET := svg-flatten
+HOST_LDFLAGS += -lstdc++fs # for debian's ancient compilers
+
+WASI_CXXFLAGS ?= -DNOFORK -DNOTHROW -DWASI -DPUGIXML_NO_EXCEPTIONS -fno-exceptions $(CXXFLAGS)
+
+BINARY := svg-flatten
+
+all: $(BUILDDIR)/$(BINARY)
 
-all: $(BUILDDIR)/$(TARGET)
+$(CACHEDIR)/$(WASI_SDK):
+	mkdir -p $(dir $@)
+	cd $(dir $@); curl -L ${WASI_SDK_URL} | tar xzf -
 
-$(BUILDDIR)/%.o: %.cpp
+$(BUILDDIR)/wasi/%.o: %.cpp $(CACHEDIR)/$(WASI_SDK) 
 	@mkdir -p $(dir $@) 
-	$(CXX) -c $(CXXFLAGS) $(CXXFLAGS) $(INCLUDES) -o $@ $^
+	$(WASI_CXX) -c $(WASI_CXXFLAGS) $(INCLUDES) $(PUGIXML_INCLUDES) -o $@ $<
 
-$(BUILDDIR)/$(TARGET): $(SOURCES:%.cpp=$(BUILDDIR)/%.o)
+$(BUILDDIR)/$(BINARY).wasm: $(patsubst %.cpp,$(BUILDDIR)/wasi/%.o,$(SOURCES) $(PUGIXML_SOURCES))
+	@mkdir -p $(dir $@)
+	$(WASI_CXX) $(WASI_CXXFLAGS) -o $@ $^ $(LDFLAGS)
+
+$(BUILDDIR)/host/%.o: %.cpp
+	@mkdir -p $(dir $@) 
+	$(CXX) -c $(HOST_CXXFLAGS) $(HOST_CXXFLAGS) $(HOST_INCLUDES) -o $@ $<
+
+$(BUILDDIR)/$(BINARY): $(HOST_SOURCES:%.cpp=$(BUILDDIR)/host/%.o)
 	@mkdir -p $(dir $@) 
-	$(CXX) $(CXXFLAGS) -o $@ $^ $(LDFLAGS)
+	$(CXX) $(HOST_CXXFLAGS) -o $@ $^ $(HOST_LDFLAGS)
 
 $(BUILDDIR)/nopencv-test: src/test/nopencv_test.cpp src/nopencv.cpp src/util.cpp
 	@mkdir -p $(dir $@) 
@@ -82,8 +108,12 @@ tests: $(BUILDDIR)/nopencv-test
 
 .PHONY: install
 install:
-	$(INSTALL) $(BUILDDIR)/$(TARGET) $(PREFIX)/bin
+	$(INSTALL) $(BUILDDIR)/$(BINARY) $(PREFIX)/bin
 	
 .PHONY: clean
 clean:
 	rm -rf $(BUILDDIR)
+
+.PHONY: mrproper
+mrproper: clean
+	rm -rf $(CACHEDIR)
diff --git a/svg-flatten/src/main.cpp b/svg-flatten/src/main.cpp
index 8512547..2ebcfe9 100644
--- a/svg-flatten/src/main.cpp
+++ b/svg-flatten/src/main.cpp
@@ -3,6 +3,7 @@
 #include <cstdio>
 #include <filesystem>
 #include <iostream>
+#include <iomanip>
 #include <fstream>
 #include <algorithm>
 #include <string>
@@ -17,6 +18,34 @@ using argagg::parser;
 using namespace std;
 using namespace gerbolyze;
 
+string temp_file_path(const char *suffix) {
+    ifstream rnd;
+    rnd.open("/dev/urandom", ios::in | ios::binary);
+
+    char fn_buf[8];
+    rnd.read(fn_buf, sizeof(fn_buf));
+
+    if (rnd.rdstate()) {
+        cerr << "Error getting random data for temporary file name" << endl;
+        abort();
+    }
+
+    ostringstream out;
+    out << "tmp_";
+    for (size_t i=0; i<sizeof(fn_buf); i++) {
+        out << setfill('0') << setw(2) << setbase(16) << static_cast<int>(fn_buf[i] & 0xff);
+    }
+    out << suffix;
+
+    cerr << "out \"" << out.str() << "\"" << endl;
+#ifndef WASI
+    filesystem::path base = filesystem::temp_directory_path();
+    return (base / out.str()).native();
+#else
+    return "/tmp/" + out.str();
+#endif
+}
+
 int main(int argc, char **argv) {
     parser argparser {{
             {"help", {"-h", "--help"},
@@ -114,15 +143,7 @@ int main(int argc, char **argv) {
         << endl;
 
     argagg::parser_results args;
-    try {
-        args = argparser.parse(argc, argv);
-    } catch (const std::exception& e) {
-        argagg::fmt_ostream fmt(cerr);
-        fmt << usage.str() << argparser << '\n'
-            << "Encountered exception while parsing arguments: " << e.what()
-            << '\n';
-        return EXIT_FAILURE;
-    }
+    args = argparser.parse(argc, argv);
 
     if (args["help"]) {
         argagg::fmt_ostream fmt(cerr);
@@ -267,8 +288,8 @@ int main(int argc, char **argv) {
         transform(ending.begin(), ending.end(), ending.begin(), [](unsigned char c){ return std::tolower(c); }); /* c++ yeah */
     }
     
-    filesystem::path barf = { filesystem::temp_directory_path() /= (std::tmpnam(nullptr) + string(".svg")) };
-    filesystem::path frob = { filesystem::temp_directory_path() /= (std::tmpnam(nullptr) + string(".svg")) };
+    string barf =  temp_file_path(".svg");
+    string frob = temp_file_path(".svg");
 
     bool is_svg = args["force_svg"] || (ending == ".svg" && !args["force_png"]);
     if (!is_svg) {
@@ -352,10 +373,15 @@ int main(int argc, char **argv) {
         }
         string dpi_str = to_string(dpi);
         
+#ifndef NOFORK
         const char *command_line[] = {nullptr, "--keep-named-groups", "--dpi", dpi_str.c_str(), barf.c_str(), frob.c_str(), nullptr};
         if (run_cargo_command("usvg", command_line, "USVG")) {
             return EXIT_FAILURE;
         }
+#else
+        cerr << "Error: The caller of svg-flatten (you?) must use --no-usvg and run usvg externally since wasi does not yet support fork/exec." << endl;
+        return EXIT_FAILURE;
+#endif
     }
 
     VectorizerSelectorizer vec_sel(vectorizer, args["vectorizer_map"] ? args["vectorizer_map"].as<string>() : "");
diff --git a/svg-flatten/src/svg_import_util.cpp b/svg-flatten/src/svg_import_util.cpp
index cb60482..85db3ad 100644
--- a/svg-flatten/src/svg_import_util.cpp
+++ b/svg-flatten/src/svg_import_util.cpp
@@ -61,6 +61,11 @@ string gerbolyze::parse_data_iri(const string &data_url) {
     size_t b64_begin = data_url.find_first_not_of(" ", foo + strlen("base64,"));
     assert(b64_begin != string::npos);
 
-    return base64_decode(data_url.substr(b64_begin));
+    bool err_out;
+    string out = base64_decode(data_url.substr(b64_begin), false, &err_out);
+
+    if (err_out)
+      return "";
+    return out;
 }
 
diff --git a/svg-flatten/src/util.cpp b/svg-flatten/src/util.cpp
index e88f4e9..d9a5a09 100644
--- a/svg-flatten/src/util.cpp
+++ b/svg-flatten/src/util.cpp
@@ -1,16 +1,19 @@
 
-#include <pwd.h>
 #include <sys/types.h>
 #include <string>
 #include <iostream>
 
+#ifndef NOFORK
+#include <pwd.h>
 #include <subprocess.h>
+#endif
 #include <filesystem>
 
 #include "util.h"
 
 using namespace std;
 
+#ifndef NOFORK
 int gerbolyze::run_cargo_command(const char *cmd_name, const char *cmdline[], const char *envvar) {
     const char *homedir;
     if ((homedir = getenv("HOME")) == NULL) {
@@ -81,4 +84,11 @@ int gerbolyze::run_cargo_command(const char *cmd_name, const char *cmdline[], co
 
     return 0;
 }
+#else
+int gerbolyze::run_cargo_command(const char *cmd_name, const char *cmdline[], const char *envvar) {
+    (void) cmd_name, (void) cmdline, (void) envvar;
+    cerr << "Error: Cannot spawn " << cmd_name << " subprocess since binary was built with fork/exec disabled (-DNOFORK=1)" << endl;
+    return EXIT_FAILURE;
+}
+#endif
 
diff --git a/svg-flatten/upstream b/svg-flatten/upstream
new file mode 120000
index 0000000..f84a283
--- /dev/null
+++ b/svg-flatten/upstream
@@ -0,0 +1 @@
+../upstream
\ No newline at end of file
diff --git a/upstream/clipper-6.4.2/cpp/clipper.cpp b/upstream/clipper-6.4.2/cpp/clipper.cpp
index d0e5ba2..42aaec7 100644
--- a/upstream/clipper-6.4.2/cpp/clipper.cpp
+++ b/upstream/clipper-6.4.2/cpp/clipper.cpp
@@ -39,6 +39,9 @@
 *******************************************************************************/

 

 #include "clipper.hpp"

+#ifdef NOTHROW

+#include <iostream>

+#endif

 #include <cmath>

 #include <vector>

 #include <algorithm>

@@ -133,6 +136,18 @@ struct LocMinSorter
 //------------------------------------------------------------------------------

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

 

+inline void panic(const char *msg);

+inline void panic(const char *msg) {

+#ifdef NOTHROW

+    std::cerr << "Fatal clipper exception: " << msg << std::endl;

+    abort();

+#else

+    throw clipperException(msg);

+#endif

+}

+

+//------------------------------------------------------------------------------

+

 inline cInt Round(double val)

 {

   if ((val < 0)) return static_cast<cInt>(val - 0.5); 

@@ -898,7 +913,7 @@ void RangeTest(const IntPoint& Pt, bool& useFullRange)
   if (useFullRange)

   {

     if (Pt.X > hiRange || Pt.Y > hiRange || -Pt.X > hiRange || -Pt.Y > hiRange) 

-      throw clipperException("Coordinate outside allowed range");

+      panic("Coordinate outside allowed range");

   }

   else if (Pt.X > loRange|| Pt.Y > loRange || -Pt.X > loRange || -Pt.Y > loRange) 

   {

@@ -1046,10 +1061,10 @@ bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
 {

 #ifdef use_lines

   if (!Closed && PolyTyp == ptClip)

-    throw clipperException("AddPath: Open paths must be subject.");

+    panic("AddPath: Open paths must be subject.");

 #else

   if (!Closed)

-    throw clipperException("AddPath: Open paths have been disabled.");

+    panic("AddPath: Open paths have been disabled.");

 #endif

 

   int highI = (int)pg.size() -1;

@@ -1062,8 +1077,10 @@ bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
 

   bool IsFlat = true;

   //1. Basic (first) edge initialization ...

+#ifndef NOTHROW

   try

   {

+#endif

     edges[1].Curr = pg[1];

     RangeTest(pg[0], m_UseFullRange);

     RangeTest(pg[highI], m_UseFullRange);

@@ -1074,12 +1091,14 @@ bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
       RangeTest(pg[i], m_UseFullRange);

       InitEdge(&edges[i], &edges[i+1], &edges[i-1], pg[i]);

     }

+#ifndef NOTHROW

   }

   catch(...)

   {

     delete [] edges;

     throw; //range test fails

   }

+#endif

   TEdge *eStart = &edges[0];

 

   //2. Remove duplicate vertices, and (when closed) collinear edges ...

@@ -1439,10 +1458,10 @@ void ClipperBase::SwapPositionsInAEL(TEdge *Edge1, TEdge *Edge2)
 }

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

 

-void ClipperBase::UpdateEdgeIntoAEL(TEdge *&e)

+void ClipperBase::UpdateEdgeIntoAEL(TEdge *&e, bool *err_out)

 {

   if (!e->NextInLML) 

-    throw clipperException("UpdateEdgeIntoAEL: invalid call");

+    *err_out = true;

 

   e->NextInLML->OutIdx = e->OutIdx;

   TEdge* AelPrev = e->PrevInAEL;

@@ -1510,7 +1529,7 @@ bool Clipper::Execute(ClipType clipType, Paths &solution,
 {

   if( m_ExecuteLocked ) return false;

   if (m_HasOpenPaths)

-    throw clipperException("Error: PolyTree struct is needed for open path clipping.");

+    panic("Error: PolyTree struct is needed for open path clipping.");

   m_ExecuteLocked = true;

   solution.resize(0);

   m_SubjFillType = subjFillType;

@@ -1559,36 +1578,30 @@ void Clipper::FixHoleLinkage(OutRec &outrec)
 

 bool Clipper::ExecuteInternal()

 {

-  bool succeeded = true;

-  try {

-    Reset();

-    m_Maxima = MaximaList();

-    m_SortedEdges = 0;

+  bool error = false;

+  Reset();

+  m_Maxima = MaximaList();

+  m_SortedEdges = 0;

 

-    succeeded = true;

-    cInt botY, topY;

-    if (!PopScanbeam(botY)) return false;

-    InsertLocalMinimaIntoAEL(botY);

-    while (PopScanbeam(topY) || LocalMinimaPending())

+  error = false;

+  cInt botY, topY;

+  if (!PopScanbeam(botY)) return false;

+  InsertLocalMinimaIntoAEL(botY);

+  while (PopScanbeam(topY) || LocalMinimaPending())

+  {

+    ProcessHorizontals(&error);

+      ClearGhostJoins();

+    if (!ProcessIntersections(topY, &error))

     {

-      ProcessHorizontals();

-	    ClearGhostJoins();

-      if (!ProcessIntersections(topY))

-      {

-        succeeded = false;

-        break;

-      }

-      ProcessEdgesAtTopOfScanbeam(topY);

-      botY = topY;

-      InsertLocalMinimaIntoAEL(botY);

+      error = true;

+      break;

     }

-  }

-  catch(...) 

-  {

-    succeeded = false;

+    ProcessEdgesAtTopOfScanbeam(topY, &error);

+    botY = topY;

+    InsertLocalMinimaIntoAEL(botY);

   }

 

-  if (succeeded)

+  if (!error)

   {

     //fix orientations ...

     for (PolyOutList::size_type i = 0; i < m_PolyOuts.size(); ++i)

@@ -1617,7 +1630,7 @@ bool Clipper::ExecuteInternal()
 

   ClearJoins();

   ClearGhostJoins();

-  return succeeded;

+  return !error;

 }

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

 

@@ -2509,11 +2522,11 @@ OutPt* Clipper::GetLastOutPt(TEdge *e)
 }

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

 

-void Clipper::ProcessHorizontals()

+void Clipper::ProcessHorizontals(bool *err_out)

 {

   TEdge* horzEdge;

   while (PopEdgeFromSEL(horzEdge))

-    ProcessHorizontal(horzEdge);

+    ProcessHorizontal(horzEdge, err_out);

 }

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

 

@@ -2633,7 +2646,7 @@ void GetHorzDirection(TEdge& HorzEdge, Direction& Dir, cInt& Left, cInt& Right)
 * the AEL. These 'promoted' edges may in turn intersect [%] with other HEs.    *

 *******************************************************************************/

 

-void Clipper::ProcessHorizontal(TEdge *horzEdge)

+void Clipper::ProcessHorizontal(TEdge *horzEdge, bool *err_out)

 {

   Direction dir;

   cInt horzLeft, horzRight;

@@ -2762,7 +2775,7 @@ void Clipper::ProcessHorizontal(TEdge *horzEdge)
 	//Break out of loop if HorzEdge.NextInLML is not also horizontal ...

 	if (!horzEdge->NextInLML || !IsHorizontal(*horzEdge->NextInLML)) break;

 

-	UpdateEdgeIntoAEL(horzEdge);

+	UpdateEdgeIntoAEL(horzEdge, err_out);

     if (horzEdge->OutIdx >= 0) AddOutPt(horzEdge, horzEdge->Bot);

     GetHorzDirection(*horzEdge, dir, horzLeft, horzRight);

 

@@ -2791,7 +2804,7 @@ void Clipper::ProcessHorizontal(TEdge *horzEdge)
     if(horzEdge->OutIdx >= 0)

     {

       op1 = AddOutPt( horzEdge, horzEdge->Top);

-      UpdateEdgeIntoAEL(horzEdge);

+      UpdateEdgeIntoAEL(horzEdge, err_out);

       if (horzEdge->WindDelta == 0) return;

       //nb: HorzEdge is no longer horizontal here

       TEdge* ePrev = horzEdge->PrevInAEL;

@@ -2814,7 +2827,7 @@ void Clipper::ProcessHorizontal(TEdge *horzEdge)
       }

     }

     else

-      UpdateEdgeIntoAEL(horzEdge); 

+      UpdateEdgeIntoAEL(horzEdge, err_out); 

   }

   else

   {

@@ -2824,22 +2837,25 @@ void Clipper::ProcessHorizontal(TEdge *horzEdge)
 }

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

 

-bool Clipper::ProcessIntersections(const cInt topY)

+bool Clipper::ProcessIntersections(const cInt topY, bool *err_out)

 {

+  (void) err_out;

   if( !m_ActiveEdges ) return true;

-  try {

+  //try {

     BuildIntersectList(topY);

     size_t IlSize = m_IntersectList.size();

     if (IlSize == 0) return true;

     if (IlSize == 1 || FixupIntersectionOrder()) ProcessIntersectList();

     else return false;

+    /*

   }

   catch(...) 

   {

     m_SortedEdges = 0;

     DisposeIntersectNodes();

-    throw clipperException("ProcessIntersections error");

+    *err_out = true;

   }

+  */

   m_SortedEdges = 0;

   return true;

 }

@@ -2954,7 +2970,7 @@ bool Clipper::FixupIntersectionOrder()
 }

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

 

-void Clipper::DoMaxima(TEdge *e)

+void Clipper::DoMaxima(TEdge *e, bool *err_out)

 {

   TEdge* eMaxPair = GetMaximaPairEx(e);

   if (!eMaxPair)

@@ -3002,11 +3018,11 @@ void Clipper::DoMaxima(TEdge *e)
     DeleteFromAEL(eMaxPair);

   } 

 #endif

-  else throw clipperException("DoMaxima error");

+  else *err_out = true;

 }

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

 

-void Clipper::ProcessEdgesAtTopOfScanbeam(const cInt topY)

+void Clipper::ProcessEdgesAtTopOfScanbeam(const cInt topY, bool *err_out)

 {

   TEdge* e = m_ActiveEdges;

   while( e )

@@ -3025,7 +3041,7 @@ void Clipper::ProcessEdgesAtTopOfScanbeam(const cInt topY)
     {

       if (m_StrictSimple) m_Maxima.push_back(e->Top.X);

       TEdge* ePrev = e->PrevInAEL;

-      DoMaxima(e);

+      DoMaxima(e, err_out);

       if( !ePrev ) e = m_ActiveEdges;

       else e = ePrev->NextInAEL;

     }

@@ -3034,7 +3050,7 @@ void Clipper::ProcessEdgesAtTopOfScanbeam(const cInt topY)
       //2. promote horizontal edges, otherwise update Curr.X and Curr.Y ...

       if (IsIntermediate(e, topY) && IsHorizontal(*e->NextInLML))

       {

-        UpdateEdgeIntoAEL(e);

+        UpdateEdgeIntoAEL(e, err_out);

         if (e->OutIdx >= 0)

           AddOutPt(e, e->Bot);

         AddEdgeToSEL(e);

@@ -3072,7 +3088,7 @@ void Clipper::ProcessEdgesAtTopOfScanbeam(const cInt topY)
 

   //3. Process horizontals at the Top of the scanbeam ...

   m_Maxima.sort();

-  ProcessHorizontals();

+  ProcessHorizontals(err_out);

   m_Maxima.clear();

 

   //4. Promote intermediate vertices ...

@@ -3084,7 +3100,7 @@ void Clipper::ProcessEdgesAtTopOfScanbeam(const cInt topY)
       OutPt* op = 0;

       if( e->OutIdx >= 0 ) 

         op = AddOutPt(e, e->Top);

-      UpdateEdgeIntoAEL(e);

+      UpdateEdgeIntoAEL(e, err_out);

 

       //if output polygons share an edge, they'll need joining later ...

       TEdge* ePrev = e->PrevInAEL;

diff --git a/upstream/clipper-6.4.2/cpp/clipper.hpp b/upstream/clipper-6.4.2/cpp/clipper.hpp
index df1f813..8e91e81 100644
--- a/upstream/clipper-6.4.2/cpp/clipper.hpp
+++ b/upstream/clipper-6.4.2/cpp/clipper.hpp
@@ -242,7 +242,7 @@ protected:
   void DisposeOutRec(PolyOutList::size_type index);

   void SwapPositionsInAEL(TEdge *edge1, TEdge *edge2);

   void DeleteFromAEL(TEdge *e);

-  void UpdateEdgeIntoAEL(TEdge *&e);

+  void UpdateEdgeIntoAEL(TEdge *&e, bool *err_out);

 

   typedef std::vector<LocalMinimum> MinimaList;

   MinimaList::iterator m_CurrentLM;

@@ -317,9 +317,9 @@ private:
   void SwapPositionsInSEL(TEdge *edge1, TEdge *edge2);

   bool IsContributing(const TEdge& edge) const;

   bool IsTopHorz(const cInt XPos);

-  void DoMaxima(TEdge *e);

-  void ProcessHorizontals();

-  void ProcessHorizontal(TEdge *horzEdge);

+  void DoMaxima(TEdge *e, bool *err_out);

+  void ProcessHorizontals(bool *err_out);

+  void ProcessHorizontal(TEdge *horzEdge, bool *err_out);

   void AddLocalMaxPoly(TEdge *e1, TEdge *e2, const IntPoint &pt);

   OutPt* AddLocalMinPoly(TEdge *e1, TEdge *e2, const IntPoint &pt);

   OutRec* GetOutRec(int idx);

@@ -327,10 +327,10 @@ private:
   void IntersectEdges(TEdge *e1, TEdge *e2, IntPoint &pt);

   OutPt* AddOutPt(TEdge *e, const IntPoint &pt);

   OutPt* GetLastOutPt(TEdge *e);

-  bool ProcessIntersections(const cInt topY);

+  bool ProcessIntersections(const cInt topY, bool *err_out);

   void BuildIntersectList(const cInt topY);

   void ProcessIntersectList();

-  void ProcessEdgesAtTopOfScanbeam(const cInt topY);

+  void ProcessEdgesAtTopOfScanbeam(const cInt topY, bool *err_out);

   void BuildResult(Paths& polys);

   void BuildResult2(PolyTree& polytree);

   void SetHoleState(TEdge *e, OutRec *outrec);