Appendix A Functions Callable from Signal Handlers

POSIX 1.b Migration Guide

Functions Callable from Signal Handlers

Because of their asynchronous nature, signals can interrupt any library function, and many system calls. If the signal handler calls the active function again, it may corrupt the state of the library, or fail in some subtle way.

POSIX.1 (POSIX.1b and POSIX.1c) specifies a list of functions that are required to be callable by signal handlers. The following is a list POSIX.1b-specific functions required to be callable by signal handlers.

Table A-1: List of Callable Functions

access()

fdatasync()

read()

tcdrain()

aio_error()

fork()

rename()

tcflow()

aio_return()

fstat()

rmdir()

tcflush()

aio_suspend()

fsync()

sem_post()

tcgetattr()

alarm()

getegid()

setgid()

tcgetpgrp()

cfgetispeed()

geteuid()

setpgid()

tcsendbreak()

cfgetospeed()

getgid()

setsid()

tcsetattr()

cfsetispeed()

getgroups()

setuid()

tcsetpgrp()

cfgetospeed()

getpgrp()

sigaction()

time()

chdir()

getpid()

sigaddset()

timer_getoverrun()

chmod()

getppid()

sigdelset()

timer_gettime()

chown()

getuid()

sigemptyset()

timer_settime()

clock_gettime()

kill()

sigfillset()

times()

close()

link()

sigismember()

umask()

creat()

lseek()

sigpending()

uname()

dup()

mkdir()

sigprocmask()

unlink()

dup2()

mkfifo()

sigqueue()

utime()

execle()

open()

sigsuspend()

wait()

execve()

pathconf()

sleep()

waitpid()

_exit()

pause()

stat()

write()

fcntl()

pipe()

sysconf()

Table A-1: List of Callable Functions
access()	fdatasync()	read()	tcdrain()
aio_error()	fork()	rename()	tcflow()
aio_return()	fstat()	rmdir()	tcflush()
aio_suspend()	fsync()	sem_post()	tcgetattr()
alarm()	getegid()	setgid()	tcgetpgrp()
cfgetispeed()	geteuid()	setpgid()	tcsendbreak()
cfgetospeed()	getgid()	setsid()	tcsetattr()
cfsetispeed()	getgroups()	setuid()	tcsetpgrp()
cfgetospeed()	getpgrp()	sigaction()	time()
chdir()	getpid()	sigaddset()	timer_getoverrun()
chmod()	getppid()	sigdelset()	timer_gettime()
chown()	getuid()	sigemptyset()	timer_settime()
clock_gettime()	kill()	sigfillset()	times()
close()	link()	sigismember()	umask()
creat()	lseek()	sigpending()	uname()
dup()	mkdir()	sigprocmask()	unlink()
dup2()	mkfifo()	sigqueue()	utime()
execle()	open()	sigsuspend()	wait()
execve()	pathconf()	sleep()	waitpid()
_exit()	pause()	stat()	write()
fcntl()	pipe()	sysconf()

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