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The current implementation of getumask involves writing a file with mode 0777 and then testing what mode was created by the kernel. This doesn't work properly if the user set a per-mount umask (or fmask/ dmask). This alternative method was suggested by Josh Stone. By forking, we can use the thread-unsafe method (calling umask) and pass the result back over a pipe. This change also fixes

...} > + if (pid == 0) { > + /* The child process must ONLY call async-safe functions. */ > + close (fd[0]); > + > + 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. :( > + _exit (EXIT_FAILURE); > +...