# SIOL - Simple IO Layer

## Top-Down-View of siol

```
+==================+
| Write-Mask       |
+==================+
| Buffer           | <--- maybe this could be deprecated, I see no usecase for the buffer
+==================+
| Cache (V)        |
+==================+      +========================+
| Maps             | <=== | Sections (transformed) |
+==================+      +========================+
| Descs            |
|      +===========+
|      | Cache (P) |
+======+===========+
| Plugin           |
+==================+
```

## Maps

Every map has a mapid which is a unique identifier. Code from the outside of RIO shall use this id instead of a pointer. This may cost performance, but pointers can hurt you.

Mapping information in the map:

* from
* to
* delta
* fd

## Section Transformation

At the moment there are 3 different transformation-targets:

* Hexeditor
* Analysis
* Emulation

Mapping information in the section:

* addr
* size
* vaddr
* vsize
* fd

A section can be related to 2 maps:

* memmap
* filemap

Hexeditor-Transformation:

* check if addr != vaddr, if so continue
* create a map with the size of min (size, vsize), that maps the to fd corresponding desc to vaddr, starting at addr
* filemap is set to the id of the map
* memmap stays 0

Analysis-Transformation:

* when vsize <= size perform Hexeditor-Transformation, and you're done
* create a map with the size of size, that the to fd corresponding vaddr, starting at addr
* filemap is set to the id of the map
* open a new desc, using the null-plugin, with the size of vsize - size
* create another map with the size of vsize - size, that maps the new desc to vaddr + size, starting at 0x0
* memmap is set to the id of the second map

Emulation-Transformation:

* when the section does not allow write-access perform Analysis-Transformation, and you're done
* open a new desc with write-permissions, using the malloc-plugin, with the size of vsize
* copy min (size, vsize) bytes fram the desc, that fd refers to, starting at addr, to the new desc, starting at 0x0
* create a map with the size of vsize, that maps the new desc to vaddr, starting at 0x0