From c20aefc10fed618ce5c083e885be2d7c3c89cafd Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@audacityteam.org>
Date: Mon, 16 Apr 2018 17:04:55 -0400
Subject: [PATCH] Save, later rethrow exceptions caught in callbacks from C
 libraries

---
 src/effects/SBSMSEffect.cpp     | 30 ++++++++++--------------------
 src/effects/nyquist/Nyquist.cpp | 27 +++++++++------------------
 src/effects/nyquist/Nyquist.h   |  3 +--
 3 files changed, 20 insertions(+), 40 deletions(-)

diff --git a/src/effects/SBSMSEffect.cpp b/src/effects/SBSMSEffect.cpp
index eb7336d49..6e1c3f895 100644
--- a/src/effects/SBSMSEffect.cpp
+++ b/src/effects/SBSMSEffect.cpp
@@ -62,8 +62,7 @@ public:
    std::unique_ptr<WaveTrack> outputLeftTrack;
    std::unique_ptr<WaveTrack> outputRightTrack;
 
-   wxFileName failedFileName;
-   bool error{ false };
+   std::exception_ptr mpException {};
 };
 
 class SBSMSEffectInterface final : public SBSMSInterfaceSliding {
@@ -100,23 +99,16 @@ long resampleCB(void *cb_data, SBSMSFrame *data)
    // I don't know if we can safely propagate errors through sbsms, and it
    // does not seem to let us report error codes, so use this roundabout to
    // stop the effect early.
-   // This would be easier with std::exception_ptr but we don't have that yet.
    try {
       r->leftTrack->Get(
          (samplePtr)(r->leftBuffer.get()), floatSample, r->offset, blockSize);
       r->rightTrack->Get(
          (samplePtr)(r->rightBuffer.get()), floatSample, r->offset, blockSize);
    }
-   catch ( const FileException& e ) {
-      if ( e.cause == FileException::Cause::Read )
-         r->failedFileName = e.fileName;
-      data->size = 0;
-      r->error = true;
-      return 0;
-   }
    catch ( ... ) {
+      // Save the exception object for re-throw when out of the library
+      r->mpException = std::current_exception();
       data->size = 0;
-      r->error = true;
       return 0;
    }
 
@@ -425,15 +417,13 @@ bool EffectSBSMS::Process()
                if (TrackProgress(nWhichTrack, frac))
                   return false;
             }
-            if (rb.failedFileName.IsOk())
-               // re-construct an exception
-               // I wish I had std::exception_ptr instead
-               // and could re-throw any AudacityException
-               throw FileException{
-                  FileException::Cause::Read, rb.failedFileName };
-            else if (rb.error)
-               // well, what?
-               bGoodResult = false;
+
+            {
+               auto pException = rb.mpException;
+               rb.mpException = {};
+               if (pException)
+                  std::rethrow_exception(pException);
+            }
 
             if (bGoodResult) {
                rb.outputLeftTrack->Flush();
diff --git a/src/effects/nyquist/Nyquist.cpp b/src/effects/nyquist/Nyquist.cpp
index ed522765b..1e3eddb03 100644
--- a/src/effects/nyquist/Nyquist.cpp
+++ b/src/effects/nyquist/Nyquist.cpp
@@ -967,8 +967,7 @@ bool NyquistEffect::TransferDataFromWindow()
 
 bool NyquistEffect::ProcessOne()
 {
-   mError = false;
-   mFailedFileName.Clear();
+   mpException = {};
 
    nyx_rval rval;
 
@@ -1393,15 +1392,12 @@ bool NyquistEffect::ProcessOne()
    }
 
    // See if GetCallback found read errors
-   if (mFailedFileName.IsOk())
-      // re-construct an exception
-      // I wish I had std::exception_ptr instead
-      // and could re-throw any AudacityException
-      throw FileException{
-         FileException::Cause::Read, mFailedFileName };
-   else if (mError)
-      // what, then?
-      success = false;
+   {
+      auto pException = mpException;
+      mpException = {};
+      if (pException)
+         std::rethrow_exception( pException );
+   }
 
    if (!success)
       return false;
@@ -2156,14 +2152,9 @@ int NyquistEffect::GetCallback(float *buffer, int ch,
             mCurBuffer[ch].ptr(), floatSample,
             mCurBufferStart[ch], mCurBufferLen[ch]);
       }
-      catch ( const FileException& e ) {
-         if ( e.cause == FileException::Cause::Read )
-            mFailedFileName = e.fileName;
-         mError = true;
-         return -1;
-      }
       catch ( ... ) {
-         mError = true;
+         // Save the exception object for re-throw when out of the library
+         mpException = std::current_exception();
          return -1;
       }
    }
diff --git a/src/effects/nyquist/Nyquist.h b/src/effects/nyquist/Nyquist.h
index da215f033..beaefe97a 100644
--- a/src/effects/nyquist/Nyquist.h
+++ b/src/effects/nyquist/Nyquist.h
@@ -275,8 +275,7 @@ private:
    wxTextCtrl *mCommandText;
    wxCheckBox *mVersionCheckBox;
 
-   bool              mError{ false };
-   wxFileName        mFailedFileName;
+   std::exception_ptr mpException {};
 
    DECLARE_EVENT_TABLE()