Hi all, As we all know, from a signal handler it is only safe to call functions that are "async signal safe". I have a couple of questions (three, actually), if anyone happens to know the answer to:
First, why the name? The list contains functions that are obviously not async. Does that mean these functions are only safe in non-blocking mode? (make sense, but you'd expect it to be better documented) The second is why isn't mmap and munmap on this list? These are functions that are handled entirely by the kernel, and will, therefor, never block on something that is up to the program that is currently halted by the signal. Mmap is, in fact, marked as async-signal-safe on Solaris[1]. And yet, Posix decided not to include it in its list. On a related note - is mmap async-signal-safe on Linux? And, lastly, what is the signal delivery flow in the kernel? What happens when a signal arrives in the middle of a blocking system call? Is the signal handler really called before the system call code has finished? The prospect seems so absurd to me that it defies all logic, as well as my understanding of the process, but that is the only explanation I have for why mmap should not be signal handler safe. Thanks, Shachar 1- http://docs.oracle.com/cd/E19963-01/html/821-1463/mmap-2.html
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