Copy data into a new varying-length structure

This function performs the following steps:

1. Allocates a new varying-length structure.
   For the new varying-length structure, the mi_var_copy() function allocates a data portion whose size is that of the data in the existing varying-length structure.

   Server only: The mi_var_copy() function allocates the varying-length structure that it creates with the current memory duration.
2. Copies the data in the data portion of the existing varying-length structure to the data portion of the newly allocated varying-length structure.

   The mi_var_copy() function automatically copies the number of bytes that the data length in the existing varying-length descriptor specifies.

3. Returns a pointer to the newly allocated varying-length structure as a pointer to an mi_lvarchar value

Suppose you have the varying-length structure that Copying a null-terminated string into a varying-length structure shows. The following code fragment uses the mi_var_copy() function to create a copy of this varying-length structure:

mi_lvarchar *lvarch, *lvarch_copy;
...
lvarch_copy = mi_var_copy(lvarch);

After the call to mi_var_copy() completes successfully, the lvarch_copy variable points to a new varying-length structure, as The following figure shows. The varying-length structure that lvarch_copy references is a completely separate structure from the structure that lvarch references.