Signals and library functions
This questions stems from a discussion on error handling in recursive functions on another forum. And I quote
How does signal/raise have the advantage that the invoked routine is able to access the library functions? Can someone give me an example?
>On May 30, 10:17=A0am, David Resnick <lndresn...@gmail.com> wrote:
>> Sure, and a fourth is to pass down a pointer to a variable to use for
>> error reporting.
>Yet another one is to use signal()/raise().
If the routine so invoked does not terminate with longjump
(and longjump was already proffered earlier in the list) then
when the routine returns, execution will resume with the return
of raise() (which will have a value of 0 if successful, non-zero
signal()/raise() does have the advantage that the invoked routine
is able to access library functions, and is able to access static storage
that is not volatile sig_atomic_t (undefined behaviour if the
invocation of the signal'd routine does not come from raise()).
Effectively, signal()/raise() becomes a method for storing a hidden
global pointer to a subroutine that gets called when raise() is used...
nothing you couldn't easily duplicate. Hmmm, I bet there has already
been an IOCC entry (or five) that relied upon this...