Patch #839038: Add getsid(2).
diff --git a/Doc/lib/libos.tex b/Doc/lib/libos.tex
index b93ce77..624fbf8 100644
--- a/Doc/lib/libos.tex
+++ b/Doc/lib/libos.tex
@@ -254,6 +254,12 @@
 Availability: \UNIX.
 \end{funcdesc}
 
+\begin{funcdesc}{getsid}{pid}
+Calls the system call \cfunction{getsid()}.  See the \UNIX{} manual
+for the semantics.
+Availability: \UNIX.
+\end{funcdesc}
+
 \begin{funcdesc}{setsid}{}
 Calls the system call \cfunction{setsid()}.  See the \UNIX{} manual
 for the semantics.