[Crash-utility] Adding a new command rbtree

[qiaonuohan]

At 2012-5-22 23:15, Dave Anderson wrote:
> Doing it that way really confuses two different "offset" issues that are associated
> with this command:
>
>   (1) the offset of an rb_root or radix_tree_node within a containing
>       data structure, and
>   (2) the offset of an rb_node within a containing data structure.
>

>
> And in both cases, forget trying to implement the "the -o is not necessary" and
> "the -o is only necessary..." optimizations, because it would be almost impossible
> to do.

Hello Dave,

I will list all the situations I was concerning.

First red-black tree:
1. rb_node is embedded in a structure. Address is the address of the 
structure, and -o shows the offset of rb_node to the structure.

2. same as 1., but the address is the address of rb_node when using -N 
in command line.

rb_root was not concering. I will recall the reason. I can get the root 
node from rb_root. And then the offspring of the root node. Then I still 
need a offset that shows the offset of the offspring node to its related 
structure to get the structure's information.

Then radix tree:
3. radix_tree_root's address is specified.

4. radix_tree_node's address is specified.

According to your reply, "-r offset" indicates rb_root and 
radix_tree_root, and "-n offset" indicates rb_node and radix_tree_node. 
And if I use "-r offset", then I need another option to show the offset 
of rb_node. And when using "-n offset" together with an address, which 
can only be one of rb_node's address and address of the structure 
rb_node embedded in, I may need another option to indicate the address's 
type.

So I think "tree -t type -r offset -n offset -m addr..." is a good 
choice. "-r offset" indicates the rb_root or radix_tree_root's offset, 
and "-n offset" indicates the rb_node or radix_tree_node's offset. When 
only using "-n offset" indicates the addr is related to rb_node or 
radix_tree_node, but if "-r offset" is also specified, the addr is 
related to rb_root or radix_tree_root. When "-m" is specified, the addr 
is the address of the root(when specified "-r offset") or the node. If 
"-m" is not specified, the addr is the address of the structure that 
containing the root(when specified "-r offset") or the node.

Do you think it's OK?

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Regards
Qiao Nuohan