Fix various undefined behaviours detected by UBSan

src/array_view.hh

@@ -34,7 +34,7 @@ public:
     template<typename Alloc, typename U,
              typename = typename std::enable_if<sizeof(U) == sizeof(T)>::type>
     constexpr ArrayView(const std::vector<U, Alloc>& v)
-        : m_pointer(&v[0]), m_size(v.size()) {}
+        : m_pointer(v.data()), m_size(v.size()) {}
 
     constexpr ArrayView(const std::initializer_list<T>& v)
         : m_pointer(v.begin()), m_size(v.size()) {}

src/hash.cc

@@ -1,6 +1,7 @@
 #include "hash.hh"
 
 #include <cstdint>
+#include <cstring>
 
 namespace Kakoune
 {
@@ -32,11 +33,12 @@ size_t hash_data(const char* input, size_t len)
     constexpr uint32_t c2 = 0x1b873593;
 
     const int nblocks = len / 4;
-    const uint32_t* blocks = reinterpret_cast<const uint32_t*>(data + nblocks*4);
+    const uint8_t* blocks = data + nblocks*4;
 
     for (int i = -nblocks; i; ++i)
     {
-        uint32_t key = blocks[i];
+        uint32_t key;
+        memcpy(&key, blocks + 4*i, 4);
         key *= c1;
         key = rotl(key, 15);
         key *= c2;

src/highlighters.cc

@@ -1014,7 +1014,7 @@ struct LineNumbersHighlighter : Highlighter
     }
 
 private:
-    void do_highlight(const Context& context, HighlightPass, DisplayBuffer& display_buffer, BufferRange)
+    void do_highlight(const Context& context, HighlightPass, DisplayBuffer& display_buffer, BufferRange) override
     {
         const Face face = get_face("LineNumbers");
         const Face face_wrapped = get_face("LineNumbersWrapped");

src/remote.cc

@@ -23,7 +23,7 @@
 namespace Kakoune
 {
 
-enum class MessageType : char
+enum class MessageType : uint8_t
 {
     Unknown,
     Connect,
@@ -54,7 +54,7 @@ public:
     ~MsgWriter() noexcept(false)
     {
         uint32_t count = (uint32_t)m_buffer.size() - m_start;
-        *reinterpret_cast<uint32_t*>(m_buffer.data() + m_start + 1) = count;
+        memcpy(m_buffer.data() + m_start + sizeof(MessageType), &count, sizeof(uint32_t));
     }
 
     void write(const char* val, size_t size)
@@ -172,7 +172,9 @@ public:
     uint32_t size() const
     {
         kak_assert(m_write_pos >= header_size); 
-        return *reinterpret_cast<const uint32_t*>(m_stream.data()+1);
+        uint32_t res;
+        memcpy(&res, m_stream.data() + sizeof(MessageType), sizeof(uint32_t));
+        return res;
     }
 
     MessageType type() const

src/string.cc

@@ -22,7 +22,8 @@ String::Data::Data(const char* data, size_t size, size_t capacity)
         l.size = size;
         l.capacity = capacity;
 
-        memcpy(l.ptr, data, size);
+        if (data != nullptr)
+            memcpy(l.ptr, data, size);
         l.ptr[size] = 0;
     }
     else
@@ -101,6 +102,9 @@ void String::Data::force_size(size_t new_size)
 
 void String::Data::append(const char* str, size_t len)
 {
+    if (len == 0)
+        return;
+
     const size_t new_size = size() + len;
     reserve(new_size);
 
@@ -147,7 +151,8 @@ void String::Data::set_size(size_t size)
 void String::Data::set_short(const char* data, size_t size)
 {
     s.size = (size << 1) | 1;
-    memcpy(s.string, data, size);
+    if (data != nullptr)
+        memcpy(s.string, data, size);
     s.string[size] = 0;
 }
 
@@ -308,7 +313,7 @@ Optional<int> str_to_int_ifp(StringView str)
             return {};
         res = res * 10 + c - '0';
     }
-    return negative ? -(int)res : (int)res;
+    return negative ? -res : res;
 }
 
 int str_to_int(StringView str)

src/utils.hh

@@ -21,8 +21,8 @@ public:
 
     static T& instance()
     {
-        kak_assert (ms_instance);
-        return *ms_instance;
+        kak_assert(ms_instance);
+        return *static_cast<T*>(ms_instance);
     }
 
     static bool has_instance()
@@ -33,8 +33,8 @@ public:
 protected:
     Singleton()
     {
-        kak_assert(not ms_instance);
-        ms_instance = static_cast<T*>(this);
+        kak_assert(ms_instance == nullptr);
+        ms_instance = this;
     }
 
     ~Singleton()
@@ -44,11 +44,11 @@ protected:
     }
 
 private:
-    static T* ms_instance;
+    static Singleton* ms_instance;
 };
 
 template<typename T>
-T* Singleton<T>::ms_instance = nullptr;
+Singleton<T>* Singleton<T>::ms_instance = nullptr;
 
 // *** On scope end ***
 //