radare2/doc/siol.md

SIOL - Simple IO Layer

Top-Down-View of siol

+==================+
| Write-Mask       |
+==================+
| Buffer           | <--- maybe this could be deprectated, 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

atm there are 3 diffent 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 referes 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