AP_Common: added strncpy_noterm

used to suppress string termination warnings

libraries/AP_Common/AP_Common.cpp

@@ -70,3 +70,16 @@ bool hex_to_uint8(uint8_t a, uint8_t &res)
     }
     return true;
 }
+
+/*
+  strncpy without the warning for not leaving room for nul termination
+ */
+void strncpy_noterm(char *dest, const char *src, size_t n)
+{
+    size_t len = strnlen(src, n);
+    if (len < n) {
+        // include nul term if it fits
+        len++;
+    }
+    memcpy(dest, src, len);
+}

libraries/AP_Common/AP_Common.h

@@ -138,3 +138,8 @@ template<typename s, size_t t> struct assert_storage_size {
 bool is_bounded_int32(int32_t value, int32_t lower_bound, int32_t upper_bound);
 
 bool hex_to_uint8(uint8_t a, uint8_t &res);  // return the uint8 value of an ascii hex character
+
+/*
+  strncpy without the warning for not leaving room for nul termination
+ */
+void strncpy_noterm(char *dest, const char *src, size_t n);