On 04 Jan 2012, at 14:14, ik wrote:
As I understand (I hope I'm wrong), memory allocations inside a signal
handler is unsafe. Is that true ?
Yes. The reason is that signals could be raised at any point during
the execution, including e.g. while a heap manager routine was already
being executed.
Further-more, I wish to reload configuration under SIGHUP (it's a
daemon
application). What is the safest way in your opinion to do so ?
The only safe way to do almost anything using a signal handler is to
set a global variable in the handler and return, and in your program
regularly check this global variable to see whether you have to do
anything.
For example let's say we have a configuration files regarding database
access.
How safe will it be to re-read the settings and close and reopen the
connection on SIGHUP ?
About as unsafe as you can get.
Another question, is it possible to use exitproc if SIGKILL is sent,
or
there is nothing I can do at all ?
SIGKILL and SIGSTOP cannot be caught in any way.
And last question for now, is there a more FPC way to handle such
issues ?
Unix signals are unix signals. There is no FPC wrapper over them.
Adding one wouldn't help much, since as mentioned above you can do
almost nothing from a signal handler.
Jonas
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