how to get (segment offset) each different plane (IODeviceTree, IOService ....) to make a dump? - objective-c

Question

I want to read analyze a plane (IODeviceTree IOUSB IOService IOACPIPlane)
without using ioreg, by creating a pointer (segment offset) in memory, my question is how to get the address of a plane, that in C or Objective C. Thank you for your answers.

Answer 1

First of all, I'm not sure what you mean by "segment offset" in this context, but the rest of the question makes sense, so I'll just ignore that part for my answer.
Second, the source code for ioreg is available here so you can see exactly how that does it.
A quick summary of how I would do it:
The main function you need to call is IORegistryCreateIterator().
Do not set the options argument to kIORegistryIterateRecursively - otherwise it will be difficult to find the graph structure.
For the plane argument, specify e.g. kIOServicePlane.
Keep calling IOIteratorNext(), and every time you get a registry entry back, try to recurse using IORegistryIteratorEnterEntry() and every time you get IO_OBJECT_NULL back, step one level back out using IORegistryIteratorExitEntry().
Working example code:
#include <stdio.h>
#include <IOKit/IOKitLib.h>
int main(int argc, const char * argv[])
{
io_iterator_t iter = IO_OBJECT_NULL;
unsigned recursion_level = 0;
kern_return_t result = IORegistryCreateIterator(kIOMasterPortDefault, kIOServicePlane, 0, &iter);
if (result == 0 && iter != IO_OBJECT_NULL)
{
while (true)
{
io_object_t entry = IOIteratorNext(iter);
if (entry != IO_OBJECT_NULL)
{
io_name_t name = "";
IORegistryEntryGetName(entry, name);
printf("%*s+ %s\n", recursion_level * 2, "", name);
++recursion_level;
result = IORegistryIteratorEnterEntry(iter);
assert(result == KERN_SUCCESS);
}
else
{
if (recursion_level == 0)
break;
result = IORegistryIteratorExitEntry(iter);
assert(result == KERN_SUCCESS);
--recursion_level;
}
}
}
return 0;
}
(Make sure to link against the IOKit.framework)
Of course, you can do much more interesting things than call IORegistryEntryGetName() on each registry entry.