Finds specific constructs in signal handler functions that can cause undefined behavior. The rules for what is allowed differ between C++ language versions.

Checked signal handler rules for C:

Checked signal handler rules for up to and including C++14:

The check is disabled on C++17 and later.

Asynchronous-safety is determined by comparing the function’s name against a set of known functions. In addition, the function must come from a system header include and in a global namespace. The (possible) arguments passed to the function are not checked. Any function that cannot be determined to be asynchronous-safe is assumed to be non-asynchronous-safe by the check, including user functions for which only the declaration is visible. Calls to user-defined functions with visible definitions are checked recursively.

This check implements the CERT C Coding Standard rule SIG30-C. Call only asynchronous-safe functions within signal handlers and the rule MSC54-CPP. A signal handler must be a plain old function. It has the alias names cert-sig30-c and cert-msc54-cpp.



Selects which set of functions is considered as asynchronous-safe (and therefore allowed in signal handlers). It can be set to the following values:


Selects a minimal set that is defined in the CERT SIG30-C rule. and includes functions abort(), _Exit(), quick_exit() and signal().


Selects a larger set of functions that is listed in POSIX.1-2017 (see this link for more information). The following functions are included: _Exit, _exit, abort, accept, access, aio_error, aio_return, aio_suspend, alarm, bind, cfgetispeed, cfgetospeed, cfsetispeed, cfsetospeed, chdir, chmod, chown, clock_gettime, close, connect, creat, dup, dup2, execl, execle, execv, execve, faccessat, fchdir, fchmod, fchmodat, fchown, fchownat, fcntl, fdatasync, fexecve, ffs, fork, fstat, fstatat, fsync, ftruncate, futimens, getegid, geteuid, getgid, getgroups, getpeername, getpgrp, getpid, getppid, getsockname, getsockopt, getuid, htonl, htons, kill, link, linkat, listen, longjmp, lseek, lstat, memccpy, memchr, memcmp, memcpy, memmove, memset, mkdir, mkdirat, mkfifo, mkfifoat, mknod, mknodat, ntohl, ntohs, open, openat, pause, pipe, poll, posix_trace_event, pselect, pthread_kill, pthread_self, pthread_sigmask, quick_exit, raise, read, readlink, readlinkat, recv, recvfrom, recvmsg, rename, renameat, rmdir, select, sem_post, send, sendmsg, sendto, setgid, setpgid, setsid, setsockopt, setuid, shutdown, sigaction, sigaddset, sigdelset, sigemptyset, sigfillset, sigismember, siglongjmp, signal, sigpause, sigpending, sigprocmask, sigqueue, sigset, sigsuspend, sleep, sockatmark, socket, socketpair, stat, stpcpy, stpncpy, strcat, strchr, strcmp, strcpy, strcspn, strlen, strncat, strncmp, strncpy, strnlen, strpbrk, strrchr, strspn, strstr, strtok_r, symlink, symlinkat, tcdrain, tcflow, tcflush, tcgetattr, tcgetpgrp, tcsendbreak, tcsetattr, tcsetpgrp, time, timer_getoverrun, timer_gettime, timer_settime, times, umask, uname, unlink, unlinkat, utime, utimensat, utimes, wait, waitpid, wcpcpy, wcpncpy, wcscat, wcschr, wcscmp, wcscpy, wcscspn, wcslen, wcsncat, wcsncmp, wcsncpy, wcsnlen, wcspbrk, wcsrchr, wcsspn, wcsstr, wcstok, wmemchr, wmemcmp, wmemcpy, wmemmove, wmemset, write

The function quick_exit is not included in the POSIX list but it is included here in the set of safe functions.

The default value is POSIX.