memory: xstrchrnul and xmemscan.

src/nvim/memory.c

@@ -222,6 +222,35 @@ void *xmemdupz(const void *data, size_t len)
   return memcpy(xmallocz(len), data, len);
 }
 
+/// A version of strchr() that returns a pointer to the terminating NUL if it
+/// doesn't find `c`.
+///
+/// @param str The string to search.
+/// @param c   The char to look for.
+/// @returns a pointer to the first instance of `c`, or to the NUL terminator
+///          if not found.
+char *xstrchrnul(const char *str, char c)
+  FUNC_ATTR_NONNULL_RET FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE
+{
+  char *p = strchr(str, c);
+  return p ? p : (char *)(str + strlen(str));
+}
+
+/// A version of memchr() that returns a pointer one past the end
+/// if it doesn't find `c`.
+///
+/// @param addr The address of the memory object.
+/// @param c    The char to look for.
+/// @param size The size of the memory object.
+/// @returns a pointer to the first instance of `c`, or one past the end if not
+///          found.
+void *xmemscan(const void *addr, char c, size_t size)
+  FUNC_ATTR_NONNULL_RET FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE
+{
+  char *p = memchr(addr, c, size);
+  return p ? p : (char *)addr + size;
+}
+
 /// The xstpcpy() function shall copy the string pointed to by src (including
 /// the terminating NUL character) into the array pointed to by dst.
 ///