PathCopy | Small Windows utility for copying file

Your question seems to be about single-linked list. This function inserts nodes in to single-linked list.

It allocates pathNode, assigns it as head.

strtok breaks the strings in to tokens, the first token is for head.

If the next token is successful, it allocates another node, that node becomes the new head. pathNode->next = head indicates that the next element is head. It then assigns head = pathNode, and continues in the loop.

"pathNode is a NULL value, I mean, how could that be possible if the "Node" type variable is fixed (at least initially)"

pathNode can be NULL if there is not enough memory and malloc fails.

"However, there's again the use of pathNode = malloc(sizeof(Node));"

There is a malloc at the beginning for head and malloc inside the loop for the following nodes.

Also, there a couple of problems. The function uses pathCopy to duplicate the source string. This is the right approach because strtok will modify its source. But pathCopy should be freed at the end. It is of little use to return it to the caller.

Overall this function is more complicated than it needs to be. Here is a simpler example:

You need to trigger a UI update...