fix undefined behavior in unit tests

3 files changed, 26 insertions, 8 deletions

diff --git a/vespalib/src/vespa/vespalib/data/databuffer.cpp b/vespalib/src/vespa/vespalib/data/databuffer.cpp
index 8640a369267..313fbe58fab 100644
--- a/vespalib/src/vespa/vespalib/data/databuffer.cpp
+++ b/vespalib/src/vespa/vespalib/data/databuffer.cpp
@@ -77,7 +77,9 @@ DataBuffer::shrink(size_t newsize)
     if (newsize != 0) {
         newbuf = static_cast<char *>(newBuf.get());
         newdata = newbuf + padbefore(_alignment, newbuf);
-        memcpy(newdata, _datapt, getDataLen());
+        if (getDataLen() > 0) {
+            memcpy(newdata, _datapt, getDataLen());
+        }
     }
     _buffer.swap(newBuf);
     _bufstart = newbuf;
@@ -101,7 +103,9 @@ DataBuffer::pack(size_t needbytes)
         Alloc newBuf(_buffer.create(bufsize));
         char *newbuf = static_cast<char *>(newBuf.get());
         char *newdata = newbuf + padbefore(_alignment, newbuf);
-        memcpy(newdata, _datapt, dataLen);
+        if (dataLen > 0) {
+            memcpy(newdata, _datapt, dataLen);
+        }
         _bufstart = newbuf;
         _datapt   = newdata;
         _freept   = newdata + dataLen;
@@ -109,7 +113,9 @@ DataBuffer::pack(size_t needbytes)
         _buffer.swap(newBuf);
     } else {
         char *datapt = _bufstart + padbefore(_alignment, _bufstart);
-        memmove(datapt, _datapt, dataLen);
+        if (dataLen > 0) {
+            memmove(datapt, _datapt, dataLen);
+        }
         _datapt = datapt;
         _freept = _datapt + dataLen;
     }
@@ -119,8 +125,12 @@ DataBuffer::pack(size_t needbytes)
 bool
 DataBuffer::equals(DataBuffer *other)
 {
-    if (getDataLen() != other->getDataLen())
+    if (getDataLen() != other->getDataLen()) {
         return false;
+    }
+    if (getDataLen() == 0) {
+        return true;
+    }
     return memcmp(getData(), other->getData(), getDataLen()) == 0;
 }
 
diff --git a/vespalib/src/vespa/vespalib/objects/nbostream.cpp b/vespalib/src/vespa/vespalib/objects/nbostream.cpp
index c4af25efcac..a369bd21c56 100644
--- a/vespalib/src/vespa/vespalib/objects/nbostream.cpp
+++ b/vespalib/src/vespa/vespalib/objects/nbostream.cpp
@@ -60,7 +60,9 @@ nbostream::nbostream(const nbostream & rhs) :
 {
     extend(rhs.size());
     _wp = rhs.size();
-    memcpy(_wbuf.data(), &rhs._rbuf[rhs._rp], _wp);
+    if (_wp > 0) {
+        memcpy(_wbuf.data(), &rhs._rbuf[rhs._rp], _wp);
+    }
 }
 
 nbostream::nbostream(nbostream && rhs) noexcept
@@ -76,7 +78,9 @@ nbostream::nbostream(nbostream && rhs) noexcept
     rhs._rbuf = ConstBufferRef();
     if (!_longLivedBuffer && (_wbuf.capacity() == 0)) {
         _wbuf.resize(roundUp2inN(_rbuf.size()));
-        memcpy(_wbuf.data(), &_rbuf[_rp], size());
+        if (size() > 0) {
+            memcpy(_wbuf.data(), &_rbuf[_rp], size());
+        }
         _wp = size();
         _rp = 0;
         _rbuf = ConstBufferRef(_wbuf.data(), _wbuf.capacity());
@@ -120,7 +124,9 @@ void nbostream::reserve(size_t sz)
 
 void nbostream::compact()
 {
-    memmove(_wbuf.data(), &_rbuf[_rp], left());
+    if (left() > 0) {
+        memmove(_wbuf.data(), &_rbuf[_rp], left());
+    }
     _wp = left();
     _rp = 0;
 }
diff --git a/vespalib/src/vespa/vespalib/objects/nbostream.h b/vespalib/src/vespa/vespalib/objects/nbostream.h
index e7bed8d59ff..12d4fac04cc 100644
--- a/vespalib/src/vespa/vespalib/objects/nbostream.h
+++ b/vespalib/src/vespa/vespalib/objects/nbostream.h
@@ -159,7 +159,9 @@ public:
         if (__builtin_expect(space() < sz, false)) {
             extend(sz);
         }
-        memcpy(&_wbuf[_wp], v, sz);
+        if (sz > 0) {
+            memcpy(&_wbuf[_wp], v, sz);
+        }
         _wp += sz;
     }
     void read(void *v, size_t sz) {