c - How to pass two parameter to sa_sigaction? they are FILE* and PID of child process -

when capture signal, want send message 'end' child process , if still live use kill pid kill it. no global variable

i think have use sa_sigaction, confuse how send file* of pipe , pid of child it. can can give em example this??

i'd pass pip , pid hdl how change code?? i'd capture signal can captured, first parameter of sigaction(sigint, &act, pip) ?? instead of sigint in advance

static void hdl (int sig, siginfo_t *siginfo, void *pip) {     xxxxxxx }  int main() {     file** pip;     int* pid;     struct sigaction act;     memset (&act, '\0', sizeof(act));     act.sa_sigaction = &hdl;     act.sa_flags = sa_siginfo;     sigaction(sigint, &act, pip);       sleep (10);        return 0; } 

this not possible (to pass more arguments signal handler). need use global or static variable.

^{you cannot add parameter signal handler, simple pid_t or file* or void*}

signals delivered kernel, , kernel (with some low-level, machine , abi specific, trampoline-like code in libc) pushes call frame signal handler (and 1 sigreturn(2)). signature of handlers fixed, documented in signal(7)

besides, have small number of signals. consider having global variable array of data related signal.

with sigaction(2) (using sa_siginfo) int signal number, siginfo_t , ucontext_t pointers handler. can use them appropriately. instance, sigio can use si_fd file descriptor causing signal.

beware signal handlers allowed call (even indirectly) small set of functions (the so-called async-signal-safe functions, subset of syscalls). in particular calling fputs or <stdio.h> function; or malloc forbidden inside signal handlers. hence, thru global variables, should not use file* inside signal handler (that undefined behavior, if might apparently work want sometimes).

a common habit (see posix documentation signal.h) only set global volatile sig_atomic_t flags in signal handler, , test (and reset) flag outside handler. you'll able typically call poll(2) -probably using fileno(3)- or waitpid(2) (outside of yous signal handler, e.g. in loop inside main code).

you need reads books on advanced linux programming , or advanced posix programming