Add pidfile_fileno() to obtain the file descriptor for an open

pidfile.

3 files changed, 39 insertions, 2 deletions

diff --git a/lib/libutil/libutil.h b/lib/libutil/libutil.h
index 47896c1..25ac1db 100644
--- a/lib/libutil/libutil.h
+++ b/lib/libutil/libutil.h
@@ -170,6 +170,7 @@ struct pidfh *pidfile_open(const char *path, mode_t mode, pid_t *pidptr);
 int pidfile_write(struct pidfh *pfh);
 int pidfile_close(struct pidfh *pfh);
 int pidfile_remove(struct pidfh *pfh);
+int pidfile_fileno(struct pidfh *pfh);
 #endif
 
 #ifdef _UFS_UFS_QUOTA_H_
diff --git a/lib/libutil/pidfile.3 b/lib/libutil/pidfile.3
index c42b95b..7ab9857 100644
--- a/lib/libutil/pidfile.3
+++ b/lib/libutil/pidfile.3
@@ -46,6 +46,8 @@
 .Fn pidfile_close "struct pidfh *pfh"
 .Ft int
 .Fn pidfile_remove "struct pidfh *pfh"
+.Ft int
+.Fn pidfile_fileno "struct pidfh *pfh"
 .Sh DESCRIPTION
 The
 .Nm pidfile
@@ -92,6 +94,10 @@ to start a child process.
 The
 .Fn pidfile_remove
 function closes and removes a pidfile.
+.Pp
+The
+.Fn pidfile_fileno
+function returns the file descriptor for the open pid file.
 .Sh RETURN VALUES
 The
 .Fn pidfile_open
@@ -105,15 +111,25 @@ If an error occurs,
 will be set.
 .Pp
 .Rv -std pidfile_write pidfile_close pidfile_remove
+.Pp
+The
+.Fn pidfile_fileno
+function returns the low-level file descriptor.
+It returns -1 and sets
+.Va errno
+if a NULL
+.Vt pidfh
+is specified, or if the pidfile is no longer open.
 .Sh EXAMPLES
 The following example shows in which order these functions should be used.
 Note that it is safe to pass
 .Dv NULL
 to
 .Fn pidfile_write ,
-.Fn pidfile_remove
-and
+.Fn pidfile_remove ,
 .Fn pidfile_close
+and
+.Fn pidfile_fileno
 functions.
 .Bd -literal
 struct pidfh *pfh;
@@ -244,6 +260,16 @@ and
 system calls and the
 .Xr flopen 3
 library function.
+.Pp
+The
+.Fn pidfile_fileno
+function will fail if:
+.Bl -tag -width Er
+.It Bq Er EDOOFUS
+Improper function use.
+Probably called not from the process which used
+.Fn pidfile_open .
+.El
 .Sh SEE ALSO
 .Xr open 2 ,
 .Xr daemon 3 ,
diff --git a/lib/libutil/pidfile.c b/lib/libutil/pidfile.c
index fcd504c..cf5acce 100644
--- a/lib/libutil/pidfile.c
+++ b/lib/libutil/pidfile.c
@@ -266,3 +266,13 @@ pidfile_remove(struct pidfh *pfh)
 
 	return (_pidfile_remove(pfh, 1));
 }
+
+int
+pidfile_fileno(struct pidfh *pfh)
+{
+	if (pfh == NULL || pfh->pf_fd == -1) {
+		errno = EDOOFUS;
+		return (-1);
+	}
+	return (pfh->pf_fd);
+}