various: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

17 files changed, 124 insertions, 0 deletions

diff --git a/pw/bitmap.c b/pw/bitmap.c
index 8e96bff..be82b2c 100644
--- a/pw/bitmap.c
+++ b/pw/bitmap.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/bitmap.h b/pw/bitmap.h
new file mode 100644
index 0000000..570c678
--- /dev/null
+++ b/pw/bitmap.h
@@ -0,0 +1,52 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (C) 1996
+ *	David L. Nugent.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY DAVID L. NUGENT AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL DAVID L. NUGENT OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _BITMAP_H_
+#define _BITMAP_H_
+
+#include <sys/cdefs.h>
+
+struct bitmap
+{
+	int	      size;
+	unsigned char *map;
+};
+
+__BEGIN_DECLS
+struct bitmap bm_alloc(int size);
+void bm_dealloc(struct bitmap * bm);
+void bm_setbit(struct bitmap * bm, int pos);
+void bm_clrbit(struct bitmap * bm, int pos);
+int bm_isset(struct bitmap * bm, int pos);
+int bm_firstunset(struct bitmap * bm);
+int bm_lastset(struct bitmap * bm);
+__END_DECLS
+
+#endif				/* !_BITMAP_H */
diff --git a/pw/cpdir.c b/pw/cpdir.c
index 679758b..4e6ca88 100644
--- a/pw/cpdir.c
+++ b/pw/cpdir.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/grupd.c b/pw/grupd.c
index 5d0df02..e98dd29 100644
--- a/pw/grupd.c
+++ b/pw/grupd.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/psdate.c b/pw/psdate.c
index b63d882..94d2a34 100644
--- a/pw/psdate.c
+++ b/pw/psdate.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/psdate.h b/pw/psdate.h
new file mode 100644
index 0000000..bb71da3
--- /dev/null
+++ b/pw/psdate.h
@@ -0,0 +1,42 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (C) 1996
+ *	David L. Nugent.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY DAVID L. NUGENT AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL DAVID L. NUGENT OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _PSDATE_H_
+#define _PSDATE_H_
+
+#include <time.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+time_t parse_date(time_t dt, char const * str);
+void print_date(char *buf, time_t t, int dotime);
+__END_DECLS
+
+#endif				/* !_PSDATE_H_ */
diff --git a/pw/pw.c b/pw/pw.c
index 700a7b2..5f02a15 100644
--- a/pw/pw.c
+++ b/pw/pw.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/pw.h b/pw/pw.h
index 592d592..816c755 100644
--- a/pw/pw.h
+++ b/pw/pw.h
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/pw_conf.c b/pw/pw_conf.c
index a3bd0bd..e1dc682 100644
--- a/pw/pw_conf.c
+++ b/pw/pw_conf.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/pw_group.c b/pw/pw_group.c
index 0a2b1eb..dd65062 100644
--- a/pw/pw_group.c
+++ b/pw/pw_group.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/pw_log.c b/pw/pw_log.c
index fe8d803..17e14d1 100644
--- a/pw/pw_log.c
+++ b/pw/pw_log.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/pw_nis.c b/pw/pw_nis.c
index 087c946..4b70bc1 100644
--- a/pw/pw_nis.c
+++ b/pw/pw_nis.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/pw_user.c b/pw/pw_user.c
index 92d5c6c..395564d 100644
--- a/pw/pw_user.c
+++ b/pw/pw_user.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/pw_vpw.c b/pw/pw_vpw.c
index 58e5294..ea87f71 100644
--- a/pw/pw_vpw.c
+++ b/pw/pw_vpw.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/pwupd.c b/pw/pwupd.c
index 87c3c99..ac91c9e 100644
--- a/pw/pwupd.c
+++ b/pw/pwupd.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/pwupd.h b/pw/pwupd.h
index daca487..b6f268b 100644
--- a/pw/pwupd.h
+++ b/pw/pwupd.h
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *
diff --git a/pw/rm_r.c b/pw/rm_r.c
index 45fc5d1..940266d 100644
--- a/pw/rm_r.c
+++ b/pw/rm_r.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
  * Copyright (C) 1996
  *	David L. Nugent.  All rights reserved.
  *