Can you eXecute code on the heap?
The problem is that the heap is in a data segment, and CPU’s/operating systems nowadays have measures to prevent exactly this kind of behavior (it’s called the NX bit, or No-eXecute bit for x86 CPUs). If a segement is marked as NX, you can’t execute code from it.
Why does an executable file not have a stack or heap?
The answer is that execution occurs in the code section, which is neither stack nor heap. In a typical paged memory system, the code from a program file (e.g., a .exe in Windows) is loaded into executable but read-only pages.
What are the three levels of security in Unix?
A UNIX file has permissions or modes that define who can do what to it. There are three access types (read, write, execute) and three accessors: the user who owns it, the group that may have access to it, and all “other” users.
Is there a way to increase Java heap space in the code itself?
The reason it cannot be increased is that it allocated on start up. It can only get set before the JVM starts. What you can do is relauch the application with a higher maximum. e.g. on start you check the maximum and if it not high enough you run the same program except with a higher maximum.
How to execute function code in heap / stack memory?
With the default setting, you are copying a JMP instruction that cannot work at another location. The linker generates these JMPs so it can easily reorganize code segments without having to completely relink the entire image. Hans Passant. I would suggest adding of static keyword to MyFunction and using a constant number (try 50) for size.
What’s the difference between a stack and heap?
A stack is not flexible, the memory size allotted cannot be changed whereas a heap is flexible, and the allotted memory can be altered. Accessing time of heap takes is more than a stack. Memory is allocated in a contiguous block. Memory is allocated in any random order.
Which is more thread safe heap or stack memory?
Heap-memory is also not threaded-safe as Stack-memory because data stored in Heap-memory are visible to all threads. Size of Heap-memory is quite larger as compared to the Stack-memory. Heap-memory is accessible or exists as long as the whole application (or java program) runs.