On 11 July 2017 at 20:35, Thomas Dineen wrote: > Gentle People: > > Some questions on program exits and exit error handlers. > > I am developing a multi-platform application using Gnu/Gcc tools. Your question has nothing to do with GCC, it's about general C programming in a UNIX environment. There are hundreds of resources for that on the web. > When you Cntrl-C a program is an exit handler of function called? > Is it possible to attach a user supplied Exit Handler to do some > cleanup like close sockets? A SIGINT signal will be raised by Ctrl-C, so you can set a signal handler for that signal, which can set a flag to say the program has been interrupted. On return from the signal handler the main program can check for that flag (e.g. in your main event loop) and exit cleanly. > When I Cntrl-C my program it appears the a socket may be left open > causing errors when I restart the program. So I am thinking about exit > handlers to close sockets, close files, and release memory. The sockets are not still held open by the process, because the process no longer exists. But they will be in a TIME_WAIT state if it wasn't cleanly shutdown, and so won't be reusable until that times out. Read about the SO_REUSEADDR socket option, and maybe SO_LINGER. You don't need to close files or release memory when a process exits, that happens automatically. A process that doesn't exist can't still be using memory. > If a program crashes on a common error like divide by zero, or bad > pointer is it possible to add an error handler to catch and process these > errors? You generally don't want to. Again, none of this is about GCC, so this is not the right list to ask.
