From 052f746c68b3821573e6cb5be567a7dfd239f4ce Mon Sep 17 00:00:00 2001
From: Peter Johnson <peter@tortall.net>
Date: Sat, 10 Sep 2016 21:30:39 -0700
Subject: [PATCH] Use StringRef and ArrayRef return values when buf passed.

For functions where a SmallVector is passed to be used as a stack buffer for
the return value, have the return value be the appropriate StringRef or
ArrayRef type.  This allows for both more natural usage and enables directly
returning (rather than copying) a permanently stored or constant string.
---
 include/cameraserver_cpp.h    | 48 ++++++++++--------
 include/cameraserver_oo.h     |  2 +-
 include/cameraserver_oo.inl   |  5 +-
 java/lib/CameraServerJNI.cpp  | 40 +++++++--------
 src/HTTPSinkImpl.cpp          |  6 +--
 src/HTTPSinkImpl.h            |  3 +-
 src/SinkImpl.h                |  3 +-
 src/SourceImpl.h              | 16 +++---
 src/UnlimitedHandleResource.h | 11 +++--
 src/cameraserver_c.cpp        | 40 +++++++--------
 src/cameraserver_cpp.cpp      | 92 ++++++++++++++++++-----------------
 11 files changed, 141 insertions(+), 125 deletions(-)

diff --git a/include/cameraserver_cpp.h b/include/cameraserver_cpp.h
index 7caf5d8373..7691c42b91 100644
--- a/include/cameraserver_cpp.h
+++ b/include/cameraserver_cpp.h
@@ -14,6 +14,7 @@
 #include <string>
 #include <vector>
 
+#include "llvm/ArrayRef.h"
 #include "llvm/SmallVector.h"
 #include "llvm/StringRef.h"
 
@@ -50,8 +51,9 @@ struct USBCameraInfo {
 
 CS_PropertyType GetPropertyType(CS_Property property, CS_Status* status);
 std::string GetPropertyName(CS_Property property, CS_Status* status);
-void GetPropertyName(CS_Property property, llvm::SmallVectorImpl<char>& name,
-                     CS_Status* status);
+llvm::StringRef GetPropertyName(CS_Property property,
+                                llvm::SmallVectorImpl<char>& buf,
+                                CS_Status* status);
 bool GetBooleanProperty(CS_Property property, CS_Status* status);
 void SetBooleanProperty(CS_Property property, bool value, CS_Status* status);
 double GetDoubleProperty(CS_Property property, CS_Status* status);
@@ -59,8 +61,9 @@ void SetDoubleProperty(CS_Property property, double value, CS_Status* status);
 double GetDoublePropertyMin(CS_Property property, CS_Status* status);
 double GetDoublePropertyMax(CS_Property property, CS_Status* status);
 std::string GetStringProperty(CS_Property property, CS_Status* status);
-void GetStringProperty(CS_Property property, llvm::SmallVectorImpl<char>& value,
-                       CS_Status* status);
+llvm::StringRef GetStringProperty(CS_Property property,
+                                  llvm::SmallVectorImpl<char>& buf,
+                                  CS_Status* status);
 void SetStringProperty(CS_Property property, llvm::StringRef value,
                        CS_Status* status);
 int GetEnumProperty(CS_Property property, CS_Status* status);
@@ -83,19 +86,21 @@ CS_Source CreateCvSource(llvm::StringRef name, int numChannels,
 // Source Functions
 //
 std::string GetSourceName(CS_Source source, CS_Status* status);
-void GetSourceName(CS_Source source, llvm::SmallVectorImpl<char>& name,
-                   CS_Status* status);
+llvm::StringRef GetSourceName(CS_Source source,
+                              llvm::SmallVectorImpl<char>& buf,
+                              CS_Status* status);
 std::string GetSourceDescription(CS_Source source, CS_Status* status);
-void GetSourceDescription(CS_Source source, llvm::SmallVectorImpl<char>& desc,
-                          CS_Status* status);
+llvm::StringRef GetSourceDescription(CS_Source source,
+                                     llvm::SmallVectorImpl<char>& buf,
+                                     CS_Status* status);
 uint64_t GetSourceLastFrameTime(CS_Source source, CS_Status* status);
 int GetSourceNumChannels(CS_Source source, CS_Status* status);
 bool IsSourceConnected(CS_Source source, CS_Status* status);
 CS_Property GetSourceProperty(CS_Source source, llvm::StringRef name,
                               CS_Status* status);
-void EnumerateSourceProperties(CS_Source source,
-                               llvm::SmallVectorImpl<CS_Property>& properties,
-                               CS_Status* status);
+llvm::ArrayRef<CS_Property> EnumerateSourceProperties(
+    CS_Source source, llvm::SmallVectorImpl<CS_Property>& vec,
+    CS_Status* status);
 CS_Source CopySource(CS_Source source, CS_Status* status);
 void ReleaseSource(CS_Source source, CS_Status* status);
 
@@ -133,11 +138,12 @@ CS_Sink CreateCvSinkCallback(llvm::StringRef name,
 // Sink Functions
 //
 std::string GetSinkName(CS_Sink sink, CS_Status* status);
-void GetSinkName(CS_Sink sink, llvm::SmallVectorImpl<char>& name,
-                 CS_Status* status);
+llvm::StringRef GetSinkName(CS_Sink sink, llvm::SmallVectorImpl<char>& buf,
+                            CS_Status* status);
 std::string GetSinkDescription(CS_Sink sink, CS_Status* status);
-void GetSinkDescription(CS_Sink sink, llvm::SmallVectorImpl<char>& desc,
-                        CS_Status* status);
+llvm::StringRef GetSinkDescription(CS_Sink sink,
+                                   llvm::SmallVectorImpl<char>& buf,
+                                   CS_Status* status);
 void SetSinkSource(CS_Sink sink, CS_Source source, CS_Status* status);
 CS_Property GetSinkSourceProperty(CS_Sink sink, llvm::StringRef name,
                                   CS_Status* status);
@@ -157,8 +163,8 @@ uint64_t SinkWaitForFrame(CS_Sink sink, CS_Status* status);
 bool GetSinkImage(CS_Sink sink, int channel, cv::Mat* image, CS_Status* status);
 uint64_t GrabSinkFrame(CS_Sink sink, cv::Mat* image, CS_Status* status);
 std::string GetSinkError(CS_Sink sink, CS_Status* status);
-void GetSinkError(CS_Sink sink, llvm::SmallVectorImpl<char>& msg,
-                  CS_Status* status);
+llvm::StringRef GetSinkError(CS_Sink sink, llvm::SmallVectorImpl<char>& buf,
+                             CS_Status* status);
 void SetSinkEnabled(CS_Sink sink, bool enabled, CS_Status* status);
 
 //
@@ -182,10 +188,10 @@ void RemoveSinkListener(CS_Listener handle, CS_Status* status);
 //
 std::vector<USBCameraInfo> EnumerateUSBCameras(CS_Status* status);
 
-void EnumerateSourceHandles(llvm::SmallVectorImpl<CS_Source>& handles,
-                            CS_Status* status);
-void EnumerateSinkHandles(llvm::SmallVectorImpl<CS_Sink>& handles,
-                          CS_Status* status);
+llvm::ArrayRef<CS_Source> EnumerateSourceHandles(
+    llvm::SmallVectorImpl<CS_Source>& vec, CS_Status* status);
+llvm::ArrayRef<CS_Sink> EnumerateSinkHandles(
+    llvm::SmallVectorImpl<CS_Sink>& vec, CS_Status* status);
 
 }  // namespace cs
 
diff --git a/include/cameraserver_oo.h b/include/cameraserver_oo.h
index f81370fc58..93eaf6fe57 100644
--- a/include/cameraserver_oo.h
+++ b/include/cameraserver_oo.h
@@ -63,7 +63,7 @@ class VideoProperty {
 
   // String-specific functions
   std::string GetString() const;
-  void GetString(llvm::SmallVectorImpl<char>& value) const;
+  llvm::StringRef GetString(llvm::SmallVectorImpl<char>& buf) const;
   void SetString(llvm::StringRef value);
 
   // Enum-specific functions
diff --git a/include/cameraserver_oo.inl b/include/cameraserver_oo.inl
index 55a6c7fee2..66aef29e40 100644
--- a/include/cameraserver_oo.inl
+++ b/include/cameraserver_oo.inl
@@ -50,9 +50,10 @@ inline std::string VideoProperty::GetString() const {
   return GetStringProperty(m_handle, &m_status);
 }
 
-inline void VideoProperty::GetString(llvm::SmallVectorImpl<char>& value) const {
+inline llvm::StringRef VideoProperty::GetString(
+    llvm::SmallVectorImpl<char>& buf) const {
   m_status = 0;
-  GetStringProperty(m_handle, value, &m_status);
+  return GetStringProperty(m_handle, buf, &m_status);
 }
 
 inline void VideoProperty::SetString(llvm::StringRef value) {
diff --git a/java/lib/CameraServerJNI.cpp b/java/lib/CameraServerJNI.cpp
index 2e3c365d63..21acad92e9 100644
--- a/java/lib/CameraServerJNI.cpp
+++ b/java/lib/CameraServerJNI.cpp
@@ -99,8 +99,8 @@ JNIEXPORT jstring JNICALL Java_edu_wpi_cameraserver_CameraServerJNI_getPropertyN
   (JNIEnv *env, jclass, jint property)
 {
   CS_Status status;
-  llvm::SmallString<128> str;
-  cs::GetPropertyName(property, str, &status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetPropertyName(property, buf, &status);
   if (!CheckStatus(env, status)) return nullptr;
   return MakeJString(env, str);
 }
@@ -196,8 +196,8 @@ JNIEXPORT jstring JNICALL Java_edu_wpi_cameraserver_CameraServerJNI_getStringPro
   (JNIEnv *env, jclass, jint property)
 {
   CS_Status status;
-  llvm::SmallString<128> str;
-  cs::GetStringProperty(property, str, &status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetStringProperty(property, buf, &status);
   if (!CheckStatus(env, status)) return nullptr;
   return MakeJString(env, str);
 }
@@ -323,8 +323,8 @@ JNIEXPORT jstring JNICALL Java_edu_wpi_cameraserver_CameraServerJNI_getSourceNam
   (JNIEnv *env, jclass, jint source)
 {
   CS_Status status;
-  llvm::SmallString<128> str;
-  cs::GetSourceName(source, str, &status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetSourceName(source, buf, &status);
   if (!CheckStatus(env, status)) return nullptr;
   return MakeJString(env, str);
 }
@@ -338,8 +338,8 @@ JNIEXPORT jstring JNICALL Java_edu_wpi_cameraserver_CameraServerJNI_getSourceDes
   (JNIEnv *env, jclass, jint source)
 {
   CS_Status status;
-  llvm::SmallString<128> str;
-  cs::GetSourceDescription(source, str, &status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetSourceDescription(source, buf, &status);
   if (!CheckStatus(env, status)) return nullptr;
   return MakeJString(env, str);
 }
@@ -409,8 +409,8 @@ JNIEXPORT jintArray JNICALL Java_edu_wpi_cameraserver_CameraServerJNI_enumerateS
   (JNIEnv *env, jclass, jint source)
 {
   CS_Status status;
-  llvm::SmallVector<CS_Property, 32> arr;
-  cs::EnumerateSourceProperties(source, arr, &status);
+  llvm::SmallVector<CS_Property, 32> buf;
+  auto arr = cs::EnumerateSourceProperties(source, buf, &status);
   if (!CheckStatus(env, status)) return nullptr;
   return MakeJIntArray(env, arr);
 }
@@ -562,8 +562,8 @@ JNIEXPORT jstring JNICALL Java_edu_wpi_cameraserver_CameraServerJNI_getSinkName
   (JNIEnv *env, jclass, jint sink)
 {
   CS_Status status;
-  llvm::SmallString<128> str;
-  cs::GetSinkName(sink, str, &status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetSinkName(sink, buf, &status);
   if (!CheckStatus(env, status)) return nullptr;
   return MakeJString(env, str);
 }
@@ -577,8 +577,8 @@ JNIEXPORT jstring JNICALL Java_edu_wpi_cameraserver_CameraServerJNI_getSinkDescr
   (JNIEnv *env, jclass, jint sink)
 {
   CS_Status status;
-  llvm::SmallString<128> str;
-  cs::GetSinkDescription(sink, str, &status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetSinkDescription(sink, buf, &status);
   if (!CheckStatus(env, status)) return nullptr;
   return MakeJString(env, str);
 }
@@ -687,8 +687,8 @@ JNIEXPORT jstring JNICALL Java_edu_wpi_cameraserver_CameraServerJNI_getSinkError
   (JNIEnv *env, jclass, jint sink)
 {
   CS_Status status;
-  llvm::SmallString<128> str;
-  cs::GetSinkError(sink, str, &status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetSinkError(sink, buf, &status);
   if (!CheckStatus(env, status)) return nullptr;
   return MakeJString(env, str);
 }
@@ -762,8 +762,8 @@ JNIEXPORT jintArray JNICALL Java_edu_wpi_cameraserver_CameraServerJNI_enumerateS
   (JNIEnv *env, jclass)
 {
   CS_Status status;
-  llvm::SmallVector<CS_Source, 16> arr;
-  cs::EnumerateSourceHandles(arr, &status);
+  llvm::SmallVector<CS_Source, 16> buf;
+  auto arr = cs::EnumerateSourceHandles(buf, &status);
   if (!CheckStatus(env, status)) return nullptr;
   return MakeJIntArray(env, arr);
 }
@@ -777,8 +777,8 @@ JNIEXPORT jintArray JNICALL Java_edu_wpi_cameraserver_CameraServerJNI_enumerateS
   (JNIEnv *env, jclass)
 {
   CS_Status status;
-  llvm::SmallVector<CS_Sink, 16> arr;
-  cs::EnumerateSinkHandles(arr, &status);
+  llvm::SmallVector<CS_Sink, 16> buf;
+  auto arr = cs::EnumerateSinkHandles(buf, &status);
   if (!CheckStatus(env, status)) return nullptr;
   return MakeJIntArray(env, arr);
 }
diff --git a/src/HTTPSinkImpl.cpp b/src/HTTPSinkImpl.cpp
index 75dd4129c0..1df78435c3 100644
--- a/src/HTTPSinkImpl.cpp
+++ b/src/HTTPSinkImpl.cpp
@@ -258,9 +258,9 @@ HTTPSinkImpl::HTTPSinkImpl(llvm::StringRef name, llvm::StringRef description,
 
 HTTPSinkImpl::~HTTPSinkImpl() { Stop(); }
 
-void HTTPSinkImpl::GetDescription(llvm::SmallVectorImpl<char>& desc) const {
-  llvm::raw_svector_ostream oss{desc};
-  oss << m_description;
+llvm::StringRef HTTPSinkImpl::GetDescription(
+    llvm::SmallVectorImpl<char>& buf) const {
+  return m_description;
 }
 
 void HTTPSinkImpl::Stop() {
diff --git a/src/HTTPSinkImpl.h b/src/HTTPSinkImpl.h
index 1f7ca94003..ab9e995e01 100644
--- a/src/HTTPSinkImpl.h
+++ b/src/HTTPSinkImpl.h
@@ -35,7 +35,8 @@ class HTTPSinkImpl : public SinkImpl {
                std::unique_ptr<wpi::NetworkAcceptor> acceptor);
   ~HTTPSinkImpl() override;
 
-  void GetDescription(llvm::SmallVectorImpl<char>& desc) const override;
+  llvm::StringRef GetDescription(
+      llvm::SmallVectorImpl<char>& buf) const override;
 
   void SetSourceChannel(int channel) { m_sourceChannel.store(channel); }
 
diff --git a/src/SinkImpl.h b/src/SinkImpl.h
index 77dd34cfad..716be983cd 100644
--- a/src/SinkImpl.h
+++ b/src/SinkImpl.h
@@ -28,7 +28,8 @@ class SinkImpl {
   SinkImpl& operator=(const SinkImpl& queue) = delete;
 
   llvm::StringRef GetName() const { return m_name; }
-  virtual void GetDescription(llvm::SmallVectorImpl<char>& desc) const = 0;
+  virtual llvm::StringRef GetDescription(
+      llvm::SmallVectorImpl<char>& buf) const = 0;
 
   void Enable() {
     std::lock_guard<std::mutex> lock(m_mutex);
diff --git a/src/SourceImpl.h b/src/SourceImpl.h
index c44b582e75..cade571e50 100644
--- a/src/SourceImpl.h
+++ b/src/SourceImpl.h
@@ -15,6 +15,7 @@
 #include <string>
 #include <vector>
 
+#include "llvm/ArrayRef.h"
 #include "llvm/StringRef.h"
 #include "cameraserver_c.h"
 #include "Frame.h"
@@ -31,7 +32,8 @@ class SourceImpl {
   SourceImpl& operator=(const SourceImpl& queue) = delete;
 
   llvm::StringRef GetName() const { return m_name; }
-  virtual void GetDescription(llvm::SmallVectorImpl<char>& desc) const = 0;
+  virtual llvm::StringRef GetDescription(
+      llvm::SmallVectorImpl<char>& buf) const = 0;
   int GetNumChannels() const { return m_numChannels; }
   bool IsConnected() const { return m_connected; }
 
@@ -78,19 +80,19 @@ class SourceImpl {
 
   // Property functions
   virtual int GetProperty(llvm::StringRef name) const = 0;
-  virtual void EnumerateProperties(
-      llvm::SmallVectorImpl<int>& properties) const = 0;
+  virtual llvm::ArrayRef<int> EnumerateProperties(
+      llvm::SmallVectorImpl<int>& vec) const = 0;
   virtual CS_PropertyType GetPropertyType(int property) const = 0;
-  virtual void GetPropertyName(int property,
-                               llvm::SmallVectorImpl<char>& name) const = 0;
+  virtual llvm::StringRef GetPropertyName(
+      int property, llvm::SmallVectorImpl<char>& buf) const = 0;
   virtual bool GetBooleanProperty(int property) const = 0;
   virtual void SetBooleanProperty(int property, bool value) = 0;
   virtual double GetDoubleProperty(int property) const = 0;
   virtual void SetDoubleProperty(int property, double value) = 0;
   virtual double GetPropertyMin(int property) const = 0;
   virtual double GetPropertyMax(int property) const = 0;
-  virtual void GetStringProperty(int property,
-                                 llvm::SmallVectorImpl<char>& value) const = 0;
+  virtual llvm::StringRef GetStringProperty(
+      int property, llvm::SmallVectorImpl<char>& buf) const = 0;
   virtual void SetStringProperty(int property, llvm::StringRef value) = 0;
   virtual int GetEnumProperty(int property) const = 0;
   virtual void SetEnumProperty(int property, int value) = 0;
diff --git a/src/UnlimitedHandleResource.h b/src/UnlimitedHandleResource.h
index 403998f5e1..219bbe618a 100644
--- a/src/UnlimitedHandleResource.h
+++ b/src/UnlimitedHandleResource.h
@@ -12,6 +12,7 @@
 #include <mutex>
 #include <vector>
 
+#include "llvm/ArrayRef.h"
 #include "llvm/SmallVector.h"
 #include "support/atomic_static.h"
 
@@ -52,7 +53,7 @@ class UnlimitedHandleResource {
   void Free(THandle handle);
 
   template <typename T>
-  void GetAll(llvm::SmallVectorImpl<T>& handles);
+  llvm::ArrayRef<T> GetAll(llvm::SmallVectorImpl<T>& vec);
 
  private:
   THandle MakeHandle(size_t i) {
@@ -124,13 +125,15 @@ void UnlimitedHandleResource<THandle, TStruct, typeValue, TMutex>::Free(
 
 template <typename THandle, typename TStruct, int typeValue, typename TMutex>
 template <typename T>
-void UnlimitedHandleResource<THandle, TStruct, typeValue, TMutex>::GetAll(
-    llvm::SmallVectorImpl<T>& handles) {
+llvm::ArrayRef<T>
+UnlimitedHandleResource<THandle, TStruct, typeValue, TMutex>::GetAll(
+    llvm::SmallVectorImpl<T>& vec) {
   std::lock_guard<TMutex> sync(m_handleMutex);
   size_t i;
   for (i = 0; i < m_structures.size(); i++) {
-    if (m_structures[i] != nullptr) handles.push_back(MakeHandle(i));
+    if (m_structures[i] != nullptr) vec.push_back(MakeHandle(i));
   }
+  return vec;
 }
 
 template <typename THandle, typename TStruct, int typeValue,
diff --git a/src/cameraserver_c.cpp b/src/cameraserver_c.cpp
index 336c0abdeb..a9a5bc95ca 100644
--- a/src/cameraserver_c.cpp
+++ b/src/cameraserver_c.cpp
@@ -32,8 +32,8 @@ CS_PropertyType CS_GetPropertyType(CS_Property property, CS_Status* status) {
 }
 
 char* CS_GetPropertyName(CS_Property property, CS_Status* status) {
-  llvm::SmallString<128> str;
-  cs::GetPropertyName(property, str, status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetPropertyName(property, buf, status);
   if (*status != 0) return nullptr;
   return ConvertToC(str);
 }
@@ -65,8 +65,8 @@ double CS_GetDoublePropertyMax(CS_Property property, CS_Status* status) {
 }
 
 char* CS_GetStringProperty(CS_Property property, CS_Status* status) {
-  llvm::SmallString<128> str;
-  cs::GetStringProperty(property, str, status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetStringProperty(property, buf, status);
   if (*status != 0) return nullptr;
   return ConvertToC(str);
 }
@@ -114,15 +114,15 @@ CS_Source CS_CreateCvSource(const char* name, int numChannels,
 }
 
 char* CS_GetSourceName(CS_Source source, CS_Status* status) {
-  llvm::SmallString<128> str;
-  cs::GetSourceName(source, str, status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetSourceName(source, buf, status);
   if (*status != 0) return nullptr;
   return ConvertToC(str);
 }
 
 char* CS_GetSourceDescription(CS_Source source, CS_Status* status) {
-  llvm::SmallString<128> str;
-  cs::GetSourceDescription(source, str, status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetSourceDescription(source, buf, status);
   if (*status != 0) return nullptr;
   return ConvertToC(str);
 }
@@ -146,8 +146,8 @@ CS_Property CS_GetSourceProperty(CS_Source source, const char* name,
 
 CS_Property* CS_EnumerateSourceProperties(CS_Source source, int* count,
                                           CS_Status* status) {
-  llvm::SmallVector<CS_Property, 32> vec;
-  cs::EnumerateSourceProperties(source, vec, status);
+  llvm::SmallVector<CS_Property, 32> buf;
+  auto vec = cs::EnumerateSourceProperties(source, buf, status);
   CS_Property* out =
       static_cast<CS_Property*>(std::malloc(vec.size() * sizeof(CS_Property)));
   *count = vec.size();
@@ -224,15 +224,15 @@ CS_Sink CS_CreateCvSinkCallback(const char* name, void* data,
 }
 
 char* CS_GetSinkName(CS_Sink sink, CS_Status* status) {
-  llvm::SmallString<128> str;
-  cs::GetSinkName(sink, str, status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetSinkName(sink, buf, status);
   if (*status != 0) return nullptr;
   return ConvertToC(str);
 }
 
 char* CS_GetSinkDescription(CS_Sink sink, CS_Status* status) {
-  llvm::SmallString<128> str;
-  cs::GetSinkDescription(sink, str, status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetSinkDescription(sink, buf, status);
   if (*status != 0) return nullptr;
   return ConvertToC(str);
 }
@@ -273,8 +273,8 @@ uint64_t CS_GrabSinkFrame(CS_Sink sink, struct CvMat* image,
 }
 
 char* CS_GetSinkError(CS_Sink sink, CS_Status* status) {
-  llvm::SmallString<128> str;
-  cs::GetSinkError(sink, str, status);
+  llvm::SmallString<128> buf;
+  auto str = cs::GetSinkError(sink, buf, status);
   if (*status != 0) return nullptr;
   return ConvertToC(str);
 }
@@ -349,8 +349,8 @@ void CS_FreeEnumeratedUSBCameras(CS_USBCameraInfo* cameras, int count) {
 }
 
 CS_Source* CS_EnumerateSources(int* count, CS_Status* status) {
-  llvm::SmallVector<CS_Source, 32> handles;
-  cs::EnumerateSourceHandles(handles, status);
+  llvm::SmallVector<CS_Source, 32> buf;
+  auto handles = cs::EnumerateSourceHandles(buf, status);
   CS_Source* sources =
       static_cast<CS_Source*>(std::malloc(handles.size() * sizeof(CS_Source)));
   *count = handles.size();
@@ -368,8 +368,8 @@ void CS_ReleaseEnumeratedSources(CS_Source* sources, int count) {
 }
 
 CS_Sink* CS_EnumerateSinks(int* count, CS_Status* status) {
-  llvm::SmallVector<CS_Sink, 32> handles;
-  cs::EnumerateSinkHandles(handles, status);
+  llvm::SmallVector<CS_Sink, 32> buf;
+  auto handles = cs::EnumerateSinkHandles(buf, status);
   CS_Sink* sinks =
       static_cast<CS_Sink*>(std::malloc(handles.size() * sizeof(CS_Sink)));
   *count = handles.size();
diff --git a/src/cameraserver_cpp.cpp b/src/cameraserver_cpp.cpp
index fd80c1cece..063f465e2e 100644
--- a/src/cameraserver_cpp.cpp
+++ b/src/cameraserver_cpp.cpp
@@ -55,12 +55,13 @@ std::string GetPropertyName(CS_Property property, CS_Status* status) {
   return name.str();
 }
 
-void GetPropertyName(CS_Property property, llvm::SmallVectorImpl<char>& name,
-                     CS_Status* status) {
+llvm::StringRef GetPropertyName(CS_Property property,
+                                llvm::SmallVectorImpl<char>& buf,
+                                CS_Status* status) {
   int propertyIndex;
   auto source = GetPropertySource(property, &propertyIndex, status);
-  if (!source) return;
-  source->GetPropertyName(propertyIndex, name);
+  if (!source) return llvm::StringRef{};
+  return source->GetPropertyName(propertyIndex, buf);
 }
 
 bool GetBooleanProperty(CS_Property property, CS_Status* status) {
@@ -114,12 +115,13 @@ std::string GetStringProperty(CS_Property property, CS_Status* status) {
   return value.str();
 }
 
-void GetStringProperty(CS_Property property, llvm::SmallVectorImpl<char>& value,
-                       CS_Status* status) {
+llvm::StringRef GetStringProperty(CS_Property property,
+                                  llvm::SmallVectorImpl<char>& buf,
+                                  CS_Status* status) {
   int propertyIndex;
   auto source = GetPropertySource(property, &propertyIndex, status);
-  if (!source) return;
-  source->GetStringProperty(propertyIndex, value);
+  if (!source) return llvm::StringRef{};
+  return source->GetStringProperty(propertyIndex, buf);
 }
 
 void SetStringProperty(CS_Property property, llvm::StringRef value,
@@ -188,36 +190,36 @@ std::string GetSourceName(CS_Source source, CS_Status* status) {
   return data->source->GetName();
 }
 
-void GetSourceName(CS_Source source, llvm::SmallVectorImpl<char>& name,
-                   CS_Status* status) {
+llvm::StringRef GetSourceName(CS_Source source,
+                              llvm::SmallVectorImpl<char>& buf,
+                              CS_Status* status) {
   auto data = Sources::GetInstance().Get(source);
   if (!data) {
     *status = CS_INVALID_HANDLE;
-    return;
+    return llvm::StringRef{};
   }
-  auto str = data->source->GetName();
-  name.append(str.begin(), str.end());
+  return data->source->GetName();
 }
 
 std::string GetSourceDescription(CS_Source source, CS_Status* status) {
-  llvm::SmallString<128> desc;
   auto data = Sources::GetInstance().Get(source);
   if (!data) {
     *status = CS_INVALID_HANDLE;
     return std::string{};
   }
-  data->source->GetDescription(desc);
-  return desc.str();
+  llvm::SmallString<128> buf;
+  return data->source->GetDescription(buf);
 }
 
-void GetSourceDescription(CS_Source source, llvm::SmallVectorImpl<char>& desc,
-                          CS_Status* status) {
+llvm::StringRef GetSourceDescription(CS_Source source,
+                                     llvm::SmallVectorImpl<char>& buf,
+                                     CS_Status* status) {
   auto data = Sources::GetInstance().Get(source);
   if (!data) {
     *status = CS_INVALID_HANDLE;
-    return;
+    return llvm::StringRef{};
   }
-  data->source->GetDescription(desc);
+  return data->source->GetDescription(buf);
 }
 
 uint64_t GetSourceLastFrameTime(CS_Source source, CS_Status* status) {
@@ -257,10 +259,11 @@ CS_Property GetSourceProperty(CS_Source source, llvm::StringRef name,
   return Handle{source, property, Handle::kProperty};
 }
 
-void EnumerateSourceProperties(CS_Source source,
-                               llvm::SmallVectorImpl<CS_Property>& properties,
-                               CS_Status* status) {
+llvm::ArrayRef<CS_Property> EnumerateSourceProperties(
+    CS_Source source, llvm::SmallVectorImpl<CS_Property>& vec,
+    CS_Status* status) {
   // TODO
+  return llvm::ArrayRef<CS_Property>{};
 }
 
 CS_Source CopySource(CS_Source source, CS_Status* status) {
@@ -358,36 +361,35 @@ std::string GetSinkName(CS_Sink sink, CS_Status* status) {
   return data->sink->GetName();
 }
 
-void GetSinkName(CS_Sink sink, llvm::SmallVectorImpl<char>& name,
-                 CS_Status* status) {
+llvm::StringRef GetSinkName(CS_Sink sink, llvm::SmallVectorImpl<char>& buf,
+                            CS_Status* status) {
   auto data = Sinks::GetInstance().Get(sink);
   if (!data) {
     *status = CS_INVALID_HANDLE;
-    return;
+    return llvm::StringRef{};
   }
-  auto str = data->sink->GetName();
-  name.append(str.begin(), str.end());
+  return data->sink->GetName();
 }
 
 std::string GetSinkDescription(CS_Sink sink, CS_Status* status) {
-  llvm::SmallString<128> desc;
   auto data = Sinks::GetInstance().Get(sink);
   if (!data) {
     *status = CS_INVALID_HANDLE;
     return std::string{};
   }
-  data->sink->GetDescription(desc);
-  return desc.str();
+  llvm::SmallString<128> buf;
+  return data->sink->GetDescription(buf);
 }
 
-void GetSinkDescription(CS_Sink sink, llvm::SmallVectorImpl<char>& desc,
-                        CS_Status* status) {
+llvm::StringRef GetSinkDescription(CS_Sink sink,
+                                   llvm::SmallVectorImpl<char>& buf,
+                                   CS_Status* status) {
   auto data = Sinks::GetInstance().Get(sink);
   if (!data) {
     *status = CS_INVALID_HANDLE;
-    return;
+    return llvm::StringRef{};
   }
-  data->sink->GetDescription(desc);
+  return data->sink->GetDescription(buf);
 }
 
 void SetSinkSource(CS_Sink sink, CS_Source source, CS_Status* status) {
@@ -464,12 +466,12 @@ uint64_t GrabSinkFrame(CS_Sink sink, cv::Mat* image, CS_Status* status) {
 }
 
 std::string GetSinkError(CS_Sink sink, CS_Status* status) {
-  return "";  // TODO
+  return std::string{};  // TODO
 }
 
-void GetSinkError(CS_Sink sink, llvm::SmallVectorImpl<char>& msg,
-                  CS_Status* status) {
-  // TODO
+llvm::StringRef GetSinkError(CS_Sink sink, llvm::SmallVectorImpl<char>& buf,
+                             CS_Status* status) {
+  return llvm::StringRef{};  // TODO
 }
 
 void SetSinkEnabled(CS_Sink sink, bool enabled, CS_Status* status) {
@@ -509,14 +511,14 @@ std::vector<USBCameraInfo> EnumerateUSBCameras(CS_Status* status) {
   return std::vector<USBCameraInfo>{};  // TODO
 }
 
-void EnumerateSourceHandles(llvm::SmallVectorImpl<CS_Source>& handles,
-                            CS_Status* status) {
-  Sources::GetInstance().GetAll(handles);
+llvm::ArrayRef<CS_Source> EnumerateSourceHandles(
+    llvm::SmallVectorImpl<CS_Source>& vec, CS_Status* status) {
+  return Sources::GetInstance().GetAll(vec);
 }
 
-void EnumerateSinkHandles(llvm::SmallVectorImpl<CS_Sink>& handles,
-                          CS_Status* status) {
-  Sinks::GetInstance().GetAll(handles);
+llvm::ArrayRef<CS_Sink> EnumerateSinkHandles(
+    llvm::SmallVectorImpl<CS_Sink>& vec, CS_Status* status) {
+  return Sinks::GetInstance().GetAll(vec);
 }
 
 }  // namespace cs