RE: Check_isVirtualWorld. Newbie's questions

[Adar D. <ad...@vm...>]

> The first question is:
> what aspect of Virtualization does it test? Something about signals?

VmCheck_GetVersion makes the BDOOR_CMD_GETVERSION backdoor call, which, if called within a VMware guest, will cause the vmm to place a "magic" number in register EAX and return control to the guest.

> The second question is:
> why can't we limit ourselves to only checking the Vmware version by
> VmCheck_GetVersion and exit if it returns false?

The signal handling code is there because if we're not on a VMware platform, performing the backdoor call will likely trigger a SIGSEGV. We want to handle such cases gracefully so we set up a custom SIGSEGV handler that will jump to just after the call to sigsetjmp if a SIGSEGV is indeed triggered. That lets us correctly report that we're not running under a VMware platform instead of crashing the program using this code.