5.7. Other Inputs
Programs must ensure that all inputs are controlled; this is particularly
difficult for setuid/setgid programs because they have so many such inputs.
Other inputs programs must consider include the current directory,
signals, memory maps (mmaps), System V IPC, pending timers,
resource limits, the scheduling priority, and the umask (which determines
the default permissions of newly-created files).
Consider explicitly changing directories (using chdir(2)) to an appropriately
fully named directory at program startup.