sendfile(2) returns a ssize_t.  The man page documents it as
returning an int.  Also unistd.h knows nothing about
sendfile, it needs only sys/sendfile.h.  Attached is a patch
that also cleans up some formatting errors.

--- sendfile.2.old      Tue Oct  5 15:22:36 1999
+++ sendfile.2  Tue Oct  5 15:25:32 1999
@@ -4,10 +4,12 @@
 .SH NAME
 sendfile \- transfer data between file descriptors
 .SH SYNOPSIS
-.B #include <unistd.h>
+.nf
+.B #include <sys/sendfile.h>
 .sp
-.BI int sendfile(int out_fd, int in_fd, off_t *offset,
size_t count)
-
+.BI "ssize_t sendfile(int " out_fd ", int " in_fd ", off_t
*" offset ,
+.BI "                 size_t " count );
+.fi
 .SH DESCRIPTION
 This call copies data between file descriptor and another
file descriptor
 or socket.
@@ -25,8 +27,8 @@
 is the number of bytes to copy between file descriptors.

 .SH NOTES
-Sendfile does not modify the current file pointer of
-in_fd, but does for out_fd.
+.RI "Sendfile does not modify the current file pointer of "
in_fd ,
+.RI "but does for " out_fd ".

 If you plan to use sendfile for sending files to a TCP
socket, but need
 to send some header data in front of the file contents,
please refer to
@@ -63,7 +65,9 @@
 .B sendfile
 is a new feature in Linux 2.2.

-Other Unixes often implement sendfile with different
semantics and prototypes. It should
-not be used in portable programs.
+Other Unixes often implement
+.B sendfile
+with different semantics and prototypes. It should not be
used in portable
+programs.
 .SH SEE ALSO
 .BR socket "(2), " open "(2)"