During a discussion today I came across that there are checks in the VxWorks and in LynxOS which tells you that the address you assign for a pointer is from a valid range. This the first time I am hearing about this code like I assign int *i=&variable;.
I should get a warning or error which says that In my application I cannot assign the address value to the integer.
Like while I do a NULL check I am only checking the address 0x00000000. But there can be the case the address might be 0x00000001. Which is also an invalid case if its an unmapped area and might not be accessible. Is any one aware of some thing similar for Linux or can guide how its done in VxWorks or LynxOS.
Any ideas??
The function you seek in VxWorks is called vxMemProbe.
Basically the vxMemProbe libraries insert special exception handling code to catch a page fault or bus error. The vxMemProbe function is used to check if the address is valid for read or write. It also allows you to test if the particular address is accessible with a given data width (8,16,32,64 bits) and alignment.
The underlying mechanism of vxMemProbe is tied to the specific architectures exception handling mechanisms. The vxMemProbe libraries insert code into the exception handlers. When you probe an address that triggers an exception the handler checks to see if vxMemProbe triggered the exception. If so, then the handler restores the state processor prior to the exception and returns execution to where vxMemProbe was called while also returning value via the architectures given calling conventions.