clean up UNO available() implementations

There seems to be some confusion here. available() is actually the
number of bytes that can be read without blocking, but most
implementations seems to be just returning the number of bytes remaining
in the stream. Since we're doing that, let's do it properly.

(*) some of them were just casting, instead of clamping, which will
return wrong values sometimes.
(*) FileStreamWrapper_Impl/OInputStreamWrapper/OTempFileService were
doing unnecessary work, instead of just asking the underlying SvStream
for it's remaining size

Change-Id: I3ef26e0363e989ed3e00be0fdb993e1cdeb7819f
Reviewed-on: https://gerrit.libreoffice.org/57264
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

2 files changed, 2 insertions, 3 deletions

diff --git a/comphelper/source/streaming/memorystream.cxx b/comphelper/source/streaming/memorystream.cxx
index b85701c30321..39b2fa0a63c5 100644
--- a/comphelper/source/streaming/memorystream.cxx
+++ b/comphelper/source/streaming/memorystream.cxx
@@ -150,7 +150,7 @@ void SAL_CALL UNOMemoryStream::skipBytes( sal_Int32 nBytesToSkip )
 
 sal_Int32 SAL_CALL UNOMemoryStream::available()
 {
-    return static_cast< sal_Int32 >( maData.size() ) - mnCursor;
+    return std::min<sal_Int64>( SAL_MAX_INT32, maData.size() - mnCursor);
 }
 
 void SAL_CALL UNOMemoryStream::closeInput()
diff --git a/comphelper/source/streaming/oslfile2streamwrap.cxx b/comphelper/source/streaming/oslfile2streamwrap.cxx
index 342c4a907e08..198ff1ecea12 100644
--- a/comphelper/source/streaming/oslfile2streamwrap.cxx
+++ b/comphelper/source/streaming/oslfile2streamwrap.cxx
@@ -120,8 +120,7 @@ sal_Int32 SAL_CALL OSLInputStreamWrapper::available()
     eError = m_pFile->setPos(osl_Pos_Absolut, nPos);
     if (eError != FileBase::E_None)
        throw css::io::NotConnectedException(OUString(),static_cast<css::uno::XWeak*>(this));
-    return sal::static_int_cast< sal_Int32 >(
-        std::max(nAvailable, sal::static_int_cast< sal_uInt64 >(SAL_MAX_INT32)));
+    return std::min<sal_Int64>(nAvailable, SAL_MAX_INT32);
 }