Re: [Libguestfs] [PATCH libguestfs] launch: Implement a safer getumask.

> + mask = umask (0); > + if (mask == -1) { > + perror ("umask"); perror() is NOT async-safe (it manipulates stdio, and could permanently wedgelock the child if you happened to fork() while some other thread was also using stdio). Safe error reporting in a fork()d child is basically impossible; the best you can do is write() something back to the parent and let the parent do the error reporting. :(