From 92691d84853875ee9bc8296309e5172210044c61 Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@audacityteam.org>
Date: Mon, 20 Nov 2017 21:25:46 -0500
Subject: [PATCH] Bug1784: Changed conditions for exceptions from Sequence...

... That for SetSamples was too strict, making needless errors in case of
harmless zero-length clips.

The one for Get was analogous to SetSamples.

That for Delete was too lax.  But reexamination shows the stricter condition
to be satisfied in all calls.  Sequence::Delete() can be reached only from
WaveClip::Clear and WaveClip::ClearAndAddCutLine(), and all calls to those
are in WaveTrack.cpp.
---
 src/Sequence.cpp | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/Sequence.cpp b/src/Sequence.cpp
index 9b2964ddc..2eafed2fc 100644
--- a/src/Sequence.cpp
+++ b/src/Sequence.cpp
@@ -1123,8 +1123,7 @@ bool Sequence::Get(samplePtr buffer, sampleFormat format,
       return len == 0;
    }
 
-   if (start < 0 || start > mNumSamples ||
-       start + len > mNumSamples) {
+   if (start < 0 || start + len > mNumSamples) {
       if (mayThrow)
          THROW_INCONSISTENCY_EXCEPTION;
       ClearSamples( buffer, floatSample, 0, len );
@@ -1164,8 +1163,7 @@ void Sequence::SetSamples(samplePtr buffer, sampleFormat format,
 {
    const auto size = mBlock.size();
 
-   if (start < 0 || start >= mNumSamples ||
-       start + len > mNumSamples)
+   if (start < 0 || start + len > mNumSamples)
       THROW_INCONSISTENCY_EXCEPTION;
 
    size_t tempSize = mMaxSamples;
@@ -1660,7 +1658,7 @@ void Sequence::Delete(sampleCount start, sampleCount len)
    if (len == 0)
       return;
 
-   if (len < 0 || start < 0 || start >= mNumSamples)
+   if (len < 0 || start < 0 || start + len > mNumSamples)
       THROW_INCONSISTENCY_EXCEPTION;
 
    //TODO: add a ref-deref mechanism to SeqBlock/BlockArray so we don't have to make this a critical section.