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clinuxsignals

what is the use of SA_ONSTACK in sigaction?

When the signal is delivered, the signal handler is executed on the stack of the process. If SA_ONSTACK is used in sigaction(), then a different stack is used.

What is the use of using different stack? Any use case example?

Solution

  • One use of an alternate stack is to try and handle SIGSEGV properly.

    If your process just received a SIGSEGV because it exceeded its stack limit, you can't run the signal handler on the process's stack - it's full already. Having an alternate stack allows you to (carefully) run some more or less graceful shutdown in that case.