Re: Solution to catching signals without using Lua hooks

[eugeny gladkih <john@...>]

>>>>> "PD" == Patrick Donnelly <batrick.donnelly@gmail.com> writes:

 PD> lua_newthread(). I haven't run into any issues yet, but I wonder if
 PD> this solution has any problems or side effects I don't see?

yep, the first and most important is that malloc() must not be
called in signal handler nor any others libc
functions. furthermore, not all syscalls may be used,
too. please read following:

   Async-signal-safe functions
       A signal handling routine established by sigaction(2) or signal(2) must
       be  very careful, since processing elsewhere may be interrupted at some
       arbitrary point in the execution of the program.  POSIX has the concept
       of  "safe function".  If a signal interrupts the execution of an unsafe
       function, and handler calls an unsafe function, then  the  behavior  of
       the  program  is undefined.  POSIX.1-2003 requires an implementation to
       guarantee that the following functions can be safely  called  inside  a
       signal handler:

       _Exit(),   _exit(),  abort(),  accept(),  access(),  aio_error(),  aio-
       _return(),  aio_suspend(),  alarm(),  bind(),   cfgetispeed(),   cfget-
       ospeed(),  cfsetispeed(),  cfsetospeed(),  chdir(),  chmod(),  chown(),
       clock_gettime(), close(), connect(), creat(), dup(), dup2(),  execle(),
       execve(),  fchmod(),  fchown(),  fcntl(),  fdatasync(),  fork(), fpath-
       conf(), fstat(), fsync(), ftruncate(), getegid(), geteuid(),  getgid(),
       getgroups(),   getpeername(),   getpgrp(),  getpid(),  getppid(),  get-
       sockname(), getsockopt(), getuid(), kill(), link(), listen(),  lseek(),
       lstat(),   mkdir(),  mkfifo(),  open(),  pathconf(),  pause(),  pipe(),
       poll(), posix_trace_event(), pselect(),  raise(),  read(),  readlink(),
       recv(), recvfrom(), recvmsg(), rename(), rmdir(), select(), sem_post(),
       send(), sendmsg(), sendto(), setgid(),  setpgid(),  setsid(),  setsock-
       opt(),  setuid(),  shutdown(),  sigaction(),  sigaddset(), sigdelset(),
       sigemptyset(), sigfillset(), sigismember(), signal(), sigpause(),  sig-
       pending(),  sigprocmask(), sigqueue(), sigset(), sigsuspend(), sleep(),
       socket(),  socketpair(),  stat(),  symlink(),   sysconf(),   tcdrain(),
       tcflow(),  tcflush(),  tcgetattr(),  tcgetpgrp(), tcsendbreak(), tcset-
       attr(),  tcsetpgrp(),  time(),   timer_getoverrun(),   timer_gettime(),
       timer_settime(),  times(), umask(), uname(), unlink(), utime(), wait(),
       waitpid(), write().

-- 
Yours sincerely, Eugeny.
Doctor Web, Ltd. http://www.drweb.com
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