gcc and aligning

[Grzegorz Kulewski]

Hi,

I am trying to experiment with real Linux kernel programming. And I have 
this question.

I have:

struct tree_node {
	struct tree_node *left, *right;
	...
};

struct some1 {
	struct tree_node n;
	...
};

struct some2 {
	struct tree_node n;
	...
};


And I want to write universal function that searches tree of structs some1 
or some2 (but one kind of struct per one tree). Like this:

struct tree_node *search(struct tree_node *root, struct tree_node *key, 
size_t size_of_the_struct);

And in this function I want to compare the _rest_ of some1 or some2 (the 
key) against other nodes. But gcc can insert some alignment between n and 
the rest of some1 or some2. Can I assume that the alignment fill is the 
same in all instances of this struct (for example 0 bytes) and use memcmp 
to compare bytes from begin_of_the_struct + sizeof(struct tree_node) to 
begin_of_the_struct + size_of_the_struct? 

Or is there some better solution?


Thanks,

Grzegorz Kulewski

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