Import macOS userland

adv_cmds-176
basic_cmds-55
bootstrap_cmds-116.100.1
developer_cmds-66
diskdev_cmds-667.40.1
doc_cmds-53.60.1
file_cmds-321.40.3
mail_cmds-35
misc_cmds-34
network_cmds-606.40.1
patch_cmds-17
remote_cmds-63
shell_cmds-216.60.1
system_cmds-880.60.2
text_cmds-106

7 files changed, 1753 insertions, 0 deletions

diff --git a/text_cmds/tail/extern.h b/text_cmds/tail/extern.h
new file mode 100644
index 0000000..d956680
--- /dev/null
+++ b/text_cmds/tail/extern.h
@@ -0,0 +1,76 @@
+/*-
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 THE REGENTS 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.
+ *
+ *	@(#)extern.h	8.1 (Berkeley) 6/6/93
+ *
+ * $FreeBSD$
+ */
+
+#define	WR(p, size) do { \
+	if (write(STDOUT_FILENO, p, size) != (ssize_t)size) \
+		oerr(); \
+	} while(0)
+
+#define TAILMAPLEN (4<<20)
+
+struct mapinfo {
+	off_t	mapoff;
+	off_t	maxoff;
+	size_t	maplen;
+	char	*start;
+	int	fd;
+};
+
+struct file_info {
+	FILE *fp;
+	char *file_name;
+	struct stat st;
+};
+
+typedef struct file_info file_info_t;
+
+enum STYLE { NOTSET = 0, FBYTES, FLINES, RBYTES, RLINES, REVERSE };
+
+void follow(file_info_t *, enum STYLE, off_t);
+void forward(FILE *, enum STYLE, off_t, struct stat *);
+void reverse(FILE *, enum STYLE, off_t, struct stat *);
+
+int bytes(FILE *, off_t);
+int lines(FILE *, off_t);
+
+void ierr(void);
+void oerr(void);
+int mapprint(struct mapinfo *, off_t, off_t);
+int maparound(struct mapinfo *, off_t);
+
+extern int Fflag, fflag, qflag, rflag, rval, no_files;
+extern const char *fname;
diff --git a/text_cmds/tail/forward.c b/text_cmds/tail/forward.c
new file mode 100644
index 0000000..172898a
--- /dev/null
+++ b/text_cmds/tail/forward.c
@@ -0,0 +1,520 @@
+/*-
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Edward Sze-Tyan Wang.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 THE REGENTS 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.
+ */
+
+#include <sys/cdefs.h>
+
+__FBSDID("$FreeBSD$");
+
+#ifndef lint
+static const char sccsid[] = "@(#)forward.c	8.1 (Berkeley) 6/6/93";
+#endif
+
+#include <sys/param.h>
+#include <sys/mount.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/mman.h>
+#include <sys/event.h>
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "extern.h"
+
+static void rlines(FILE *, off_t, struct stat *);
+static void show(file_info_t *);
+static void set_events(file_info_t *files);
+
+/* defines for inner loop actions */
+#define USE_SLEEP	0
+#define USE_KQUEUE	1
+#define ADD_EVENTS	2
+
+struct kevent *ev;
+int action = USE_SLEEP;
+int kq;
+
+static const file_info_t *last;
+
+/*
+ * forward -- display the file, from an offset, forward.
+ *
+ * There are eight separate cases for this -- regular and non-regular
+ * files, by bytes or lines and from the beginning or end of the file.
+ *
+ * FBYTES	byte offset from the beginning of the file
+ *	REG	seek
+ *	NOREG	read, counting bytes
+ *
+ * FLINES	line offset from the beginning of the file
+ *	REG	read, counting lines
+ *	NOREG	read, counting lines
+ *
+ * RBYTES	byte offset from the end of the file
+ *	REG	seek
+ *	NOREG	cyclically read characters into a wrap-around buffer
+ *
+ * RLINES
+ *	REG	mmap the file and step back until reach the correct offset.
+ *	NOREG	cyclically read lines into a wrap-around array of buffers
+ */
+void
+forward(FILE *fp, enum STYLE style, off_t off, struct stat *sbp)
+{
+	int ch;
+
+	switch(style) {
+	case FBYTES:
+		if (off == 0)
+			break;
+		if (S_ISREG(sbp->st_mode)) {
+			if (sbp->st_size < off)
+				off = sbp->st_size;
+			if (fseeko(fp, off, SEEK_SET) == -1) {
+				ierr();
+				return;
+			}
+		} else while (off--)
+			if ((ch = getc(fp)) == EOF) {
+				if (ferror(fp)) {
+					ierr();
+					return;
+				}
+				break;
+			}
+		break;
+	case FLINES:
+		if (off == 0)
+			break;
+		for (;;) {
+			if ((ch = getc(fp)) == EOF) {
+				if (ferror(fp)) {
+					ierr();
+					return;
+				}
+				break;
+			}
+			if (ch == '\n' && !--off)
+				break;
+		}
+		break;
+	case RBYTES:
+		if (S_ISREG(sbp->st_mode)) {
+			if (sbp->st_size >= off &&
+			    fseeko(fp, -off, SEEK_END) == -1) {
+				ierr();
+				return;
+			}
+		} else if (off == 0) {
+			while (getc(fp) != EOF);
+			if (ferror(fp)) {
+				ierr();
+				return;
+			}
+		} else
+			if (bytes(fp, off))
+				return;
+		break;
+	case RLINES:
+		if (S_ISREG(sbp->st_mode))
+			if (!off) {
+				if (fseeko(fp, (off_t)0, SEEK_END) == -1) {
+					ierr();
+					return;
+				}
+			} else
+				rlines(fp, off, sbp);
+		else if (off == 0) {
+			while (getc(fp) != EOF);
+			if (ferror(fp)) {
+				ierr();
+				return;
+			}
+		} else
+			if (lines(fp, off))
+				return;
+		break;
+	default:
+		break;
+	}
+
+	while ((ch = getc(fp)) != EOF)
+		if (putchar(ch) == EOF)
+			oerr();
+	if (ferror(fp)) {
+		ierr();
+		return;
+	}
+	(void)fflush(stdout);
+}
+
+/*
+ * rlines -- display the last offset lines of the file.
+ */
+static void
+rlines(fp, off, sbp)
+	FILE *fp;
+	off_t off;
+	struct stat *sbp;
+{
+#ifdef __APPLE__
+	/* Using mmap on network filesystems can frequently lead
+	to distress, and even on local file systems other processes
+	truncating the file can also lead to upset. */
+
+	/* Seek to sbp->st_blksize before the end of the file, find
+	all the newlines.   If there are enough, print the last off
+	lines.  Otherwise go back another sbp->st_blksize bytes,
+	and count newlines.  Avoid re-reading blocks when possible. */
+
+	// +1 because we capture line ends and we want off line _starts_,
+	// +1 because the first line might be partial when try_at != 0
+	off_t search_for = off +2;
+	off_t try_at = sbp->st_size;
+	off_t last_try = sbp->st_size;
+	off_t found_this_pass = 0;
+	off_t found_total = 0;
+	off_t *found_at = calloc(search_for, sizeof(off_t));
+
+	flockfile(fp);
+
+	if (found_at == NULL) {
+		ierr();
+		goto done;
+	}
+
+	if (off == 0 || sbp->st_size == 0) {
+		goto done;
+	}
+
+	/* The last character is special.  Check to make sure that it is a \n,
+	 * and if not, subtract one from the number of \n we need to search for.
+	 */
+	if (0 != fseeko(fp, sbp->st_size - 1, SEEK_SET)) {
+		ierr();
+		goto done;
+	}
+	if ('\n' != getc_unlocked(fp)) {
+		search_for--;
+	}
+
+	while(try_at != 0) {
+		found_this_pass = 0;
+
+		if (try_at < sbp->st_blksize) {
+			found_at[found_this_pass++] = 0;
+			try_at = 0;
+		} else {
+			last_try = try_at;
+			try_at -= sbp->st_blksize;
+		}
+
+		if (0 != fseeko(fp, try_at, SEEK_SET)) {
+			ierr();
+			goto done;
+		}
+
+		char ch;
+		while(EOF != (ch = getc_unlocked(fp))) {
+			if (ch == '\n') {
+				found_at[found_this_pass++ % search_for] = ftello(fp);
+				found_total++;
+			}
+			if (ftello(fp) == last_try && found_total < search_for) {
+				// We just reached the last block we scanned,
+				// and we know there arn't enough lines found
+				// so far to be happy, so we don't have to
+				// read it again.
+				break;
+			}
+		}
+
+		if (found_this_pass >= search_for || try_at == 0) {
+			off_t min = found_at[0];
+			int min_i = 0;
+			int i;
+			int lim = (found_this_pass < search_for) ? found_this_pass : search_for;
+			for(i = 1; i < lim; i++) {
+				if (found_at[i] < min) {
+					min = found_at[i];
+					min_i = i;
+				}
+			}
+
+			off_t target = min;
+
+			if (found_this_pass >= search_for) {
+				// min_i might be a partial line (unless
+				// try_at is 0).   If we  found search_for
+				// lines, min_i+1 is the first known full line
+				// _and_ because we look for an extra line we
+				// don't need to show it.
+				target = found_at[(min_i + 1) % search_for];
+			}
+
+			if (0 != fseeko(fp, target, SEEK_SET)) {
+				ierr();
+				goto done;
+			}
+
+			flockfile(stdout);
+			while(EOF != (ch = getc_unlocked(fp))) {
+				if (EOF == putchar_unlocked(ch)) {
+					funlockfile(stdout);
+					oerr();
+					goto done;
+				}
+			}
+			funlockfile(stdout);
+			goto done;
+		}
+	}
+
+done:
+	funlockfile(fp);
+	free(found_at);
+	return;
+#else
+	struct mapinfo map;
+	off_t curoff, size;
+	int i;
+
+	if (!(size = sbp->st_size))
+		return;
+	map.start = NULL;
+	map.fd = fileno(fp);
+	map.mapoff = map.maxoff = size;
+
+	/*
+	 * Last char is special, ignore whether newline or not. Note that
+	 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
+	 */
+	curoff = size - 2;
+	while (curoff >= 0) {
+		if (curoff < map.mapoff && maparound(&map, curoff) != 0) {
+			ierr();
+			return;
+		}
+		for (i = curoff - map.mapoff; i >= 0; i--)
+			if (map.start[i] == '\n' && --off == 0)
+				break;
+		/* `i' is either the map offset of a '\n', or -1. */
+		curoff = map.mapoff + i;
+		if (i >= 0)
+			break;
+	}
+	curoff++;
+	if (mapprint(&map, curoff, size - curoff) != 0) {
+		ierr();
+		exit(1);
+	}
+
+	/* Set the file pointer to reflect the length displayed. */
+	if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) {
+		ierr();
+		return;
+	}
+	if (map.start != NULL && munmap(map.start, map.maplen)) {
+		ierr();
+		return;
+	}
+#endif
+}
+
+static void
+show(file_info_t *file)
+{
+    int ch;
+
+    while ((ch = getc(file->fp)) != EOF) {
+	if (last != file && no_files > 1) {
+		if (!qflag)
+			(void)printf("\n==> %s <==\n", file->file_name);
+		last = file;
+	}
+	if (putchar(ch) == EOF)
+		oerr();
+    }
+    (void)fflush(stdout);
+    if (ferror(file->fp)) {
+	    file->fp = NULL;
+	    fname = file->file_name;
+	    ierr();
+	    fname = NULL;
+    } else
+	    clearerr(file->fp);
+}
+
+static void
+set_events(file_info_t *files)
+{
+	int i, n = 0;
+	file_info_t *file;
+	struct timespec ts;
+	struct statfs sf;
+
+	ts.tv_sec = 0;
+	ts.tv_nsec = 0;
+
+	action = USE_KQUEUE;
+	for (i = 0, file = files; i < no_files; i++, file++) {
+		if (! file->fp)
+			continue;
+
+		if (fstatfs(fileno(file->fp), &sf) == 0 &&
+		    (sf.f_flags & MNT_LOCAL) == 0) {
+			action = USE_SLEEP;
+			return;
+		}
+
+		if (Fflag && fileno(file->fp) != STDIN_FILENO) {
+			EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE,
+			    EV_ADD | EV_ENABLE | EV_CLEAR,
+			    NOTE_DELETE | NOTE_RENAME, 0, 0);
+			n++;
+		}
+		EV_SET(&ev[n], fileno(file->fp), EVFILT_READ,
+		    EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0);
+		n++;
+	}
+
+	if (kevent(kq, ev, n, NULL, 0, &ts) < 0) {
+		action = USE_SLEEP;
+	}
+}
+
+/*
+ * follow -- display the file, from an offset, forward.
+ *
+ */
+void
+follow(file_info_t *files, enum STYLE style, off_t off)
+{
+	int active, i, n = -1;
+	struct stat sb2;
+	file_info_t *file;
+	struct timespec ts;
+
+	/* Position each of the files */
+
+	file = files;
+	active = 0;
+	n = 0;
+	for (i = 0; i < no_files; i++, file++) {
+		if (file->fp) {
+			active = 1;
+			n++;
+			if (no_files > 1 && !qflag)
+				(void)printf("\n==> %s <==\n", file->file_name);
+			fname = file->file_name;
+			forward(file->fp, style, off, &file->st);
+			fname = NULL;
+			if (Fflag && fileno(file->fp) != STDIN_FILENO)
+			    n++;
+		}
+	}
+	if (! active)
+		return;
+
+	last = --file;
+
+	kq = kqueue();
+	if (kq < 0)
+		err(1, "kqueue");
+	ev = malloc(n * sizeof(struct kevent));
+	if (! ev)
+	    err(1, "Couldn't allocate memory for kevents.");
+	set_events(files);
+
+	for (;;) {
+		for (i = 0, file = files; i < no_files; i++, file++) {
+			if (! file->fp)
+				continue;
+			if (Fflag && file->fp && fileno(file->fp) != STDIN_FILENO) {
+				if (stat(file->file_name, &sb2) == 0 &&
+				    (sb2.st_ino != file->st.st_ino ||
+				     sb2.st_dev != file->st.st_dev ||
+				     sb2.st_nlink == 0)) {
+					show(file);
+					file->fp = freopen(file->file_name, "r", file->fp);
+					if (file->fp == NULL) {
+						ierr();
+						continue;
+					} else {
+						memcpy(&file->st, &sb2, sizeof(struct stat));
+						set_events(files);
+					}
+				}
+			}
+			show(file);
+		}
+
+		switch (action) {
+		case USE_KQUEUE:
+			ts.tv_sec = 1;
+			ts.tv_nsec = 0;
+			/*
+			 * In the -F case we set a timeout to ensure that
+			 * we re-stat the file at least once every second.
+			 */
+			n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL);
+			if (n < 0)
+				err(1, "kevent");
+			if (n == 0) {
+				/* timeout */
+				break;
+			} else if (ev->filter == EVFILT_READ && ev->data < 0) {
+				 /* file shrank, reposition to end */
+				if (lseek(ev->ident, (off_t)0, SEEK_END) == -1) {
+					ierr();
+					continue;
+				}
+			}
+			break;
+
+		case USE_SLEEP:
+			(void) usleep(250000);
+			break;
+		}
+	}
+}
diff --git a/text_cmds/tail/misc.c b/text_cmds/tail/misc.c
new file mode 100644
index 0000000..584e3d1
--- /dev/null
+++ b/text_cmds/tail/misc.c
@@ -0,0 +1,119 @@
+/*-
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Edward Sze-Tyan Wang.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 THE REGENTS 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.
+ */
+
+#include <sys/cdefs.h>
+
+__FBSDID("$FreeBSD$");
+
+#ifndef lint
+static const char sccsid[] = "@(#)misc.c	8.1 (Berkeley) 6/6/93";
+#endif
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+
+#include <err.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "extern.h"
+
+void
+ierr()
+{
+	warn("%s", fname);
+	rval = 1;
+}
+
+void
+oerr()
+{
+	err(1, "stdout");
+}
+
+/*
+ * Print `len' bytes from the file associated with `mip', starting at
+ * absolute file offset `startoff'. May move map window.
+ */
+int
+mapprint(struct mapinfo *mip, off_t startoff, off_t len)
+{
+	int n;
+
+	while (len > 0) {
+		if (startoff < mip->mapoff || startoff >= mip->mapoff +
+		    (off_t)mip->maplen) {
+			if (maparound(mip, startoff) != 0)
+				return (1);
+		}
+		n = (mip->mapoff + mip->maplen) - startoff;
+		if (n > len)
+			n = len;
+		WR(mip->start + (startoff - mip->mapoff), n);
+		startoff += n;
+		len -= n;
+	}
+	return (0);
+}
+
+/*
+ * Move the map window so that it contains the byte at absolute file
+ * offset `offset'. The start of the map window will be TAILMAPLEN
+ * aligned.
+ */
+int
+maparound(struct mapinfo *mip, off_t offset)
+{
+
+	if (mip->start != NULL && munmap(mip->start, mip->maplen) != 0)
+		return (1);
+
+	mip->mapoff = offset & ~((off_t)TAILMAPLEN - 1);
+	mip->maplen = TAILMAPLEN;
+	if ((off_t)mip->maplen > mip->maxoff - mip->mapoff)
+		mip->maplen = mip->maxoff - mip->mapoff;
+	if (mip->maplen <= 0)
+		abort();
+	if ((mip->start = mmap(NULL, mip->maplen, PROT_READ, MAP_SHARED,
+	     mip->fd, mip->mapoff)) == MAP_FAILED)
+		return (1);
+
+	return (0);
+}
diff --git a/text_cmds/tail/read.c b/text_cmds/tail/read.c
new file mode 100644
index 0000000..85d4d6e
--- /dev/null
+++ b/text_cmds/tail/read.c
@@ -0,0 +1,214 @@
+/*-
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Edward Sze-Tyan Wang.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 THE REGENTS 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.
+ */
+
+#include <sys/cdefs.h>
+
+__FBSDID("$FreeBSD$");
+
+#ifndef lint
+static const char sccsid[] = "@(#)read.c	8.1 (Berkeley) 6/6/93";
+#endif
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "extern.h"
+
+/*
+ * bytes -- read bytes to an offset from the end and display.
+ *
+ * This is the function that reads to a byte offset from the end of the input,
+ * storing the data in a wrap-around buffer which is then displayed.  If the
+ * rflag is set, the data is displayed in lines in reverse order, and this
+ * routine has the usual nastiness of trying to find the newlines.  Otherwise,
+ * it is displayed from the character closest to the beginning of the input to
+ * the end.
+ */
+int
+bytes(FILE *fp, off_t off)
+{
+	int ch, len, tlen;
+	char *ep, *p, *t;
+	int wrap;
+	char *sp;
+
+	if ((sp = p = malloc(off)) == NULL)
+		err(1, "malloc");
+
+	for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) {
+		*p = ch;
+		if (++p == ep) {
+			wrap = 1;
+			p = sp;
+		}
+	}
+	if (ferror(fp)) {
+		ierr();
+		free(sp);
+		return 1;
+	}
+
+	if (rflag) {
+		for (t = p - 1, len = 0; t >= sp; --t, ++len)
+			if (*t == '\n' && len) {
+				WR(t + 1, len);
+				len = 0;
+		}
+		if (wrap) {
+			tlen = len;
+			for (t = ep - 1, len = 0; t >= p; --t, ++len)
+				if (*t == '\n') {
+					if (len) {
+						WR(t + 1, len);
+						len = 0;
+					}
+					if (tlen) {
+						WR(sp, tlen);
+						tlen = 0;
+					}
+				}
+			if (len)
+				WR(t + 1, len);
+			if (tlen)
+				WR(sp, tlen);
+		}
+	} else {
+		if (wrap && (len = ep - p))
+			WR(p, len);
+		len = p - sp;
+		if (len)
+			WR(sp, len);
+	}
+
+	free(sp);
+	return 0;
+}
+
+/*
+ * lines -- read lines to an offset from the end and display.
+ *
+ * This is the function that reads to a line offset from the end of the input,
+ * storing the data in an array of buffers which is then displayed.  If the
+ * rflag is set, the data is displayed in lines in reverse order, and this
+ * routine has the usual nastiness of trying to find the newlines.  Otherwise,
+ * it is displayed from the line closest to the beginning of the input to
+ * the end.
+ */
+int
+lines(FILE *fp, off_t off)
+{
+	struct {
+		int blen;
+		u_int len;
+		char *l;
+	} *llines;
+	int ch, rc;
+	char *p, *sp;
+	int blen, cnt, recno, wrap;
+
+	if ((llines = malloc(off * sizeof(*llines))) == NULL)
+		err(1, "malloc");
+	bzero(llines, off * sizeof(*llines));
+	sp = NULL;
+	blen = cnt = recno = wrap = 0;
+	rc = 0;
+
+	while ((ch = getc(fp)) != EOF) {
+		if (++cnt > blen) {
+			if ((sp = realloc(sp, blen += 1024)) == NULL)
+				err(1, "realloc");
+			p = sp + cnt - 1;
+		}
+		*p++ = ch;
+		if (ch == '\n') {
+			if ((int)llines[recno].blen < cnt) {
+				llines[recno].blen = cnt + 256;
+				if ((llines[recno].l = realloc(llines[recno].l,
+				    llines[recno].blen)) == NULL)
+					err(1, "realloc");
+			}
+			bcopy(sp, llines[recno].l, llines[recno].len = cnt);
+			cnt = 0;
+			p = sp;
+			if (++recno == off) {
+				wrap = 1;
+				recno = 0;
+			}
+		}
+	}
+	if (ferror(fp)) {
+		ierr();
+		rc = 1;
+		goto done;
+	}
+	if (cnt) {
+		llines[recno].l = sp;
+		sp = NULL;
+		llines[recno].len = cnt;
+		if (++recno == off) {
+			wrap = 1;
+			recno = 0;
+		}
+	}
+
+	if (rflag) {
+		for (cnt = recno - 1; cnt >= 0; --cnt)
+			WR(llines[cnt].l, llines[cnt].len);
+		if (wrap)
+			for (cnt = off - 1; cnt >= recno; --cnt)
+				WR(llines[cnt].l, llines[cnt].len);
+	} else {
+		if (wrap)
+			for (cnt = recno; cnt < off; ++cnt)
+				WR(llines[cnt].l, llines[cnt].len);
+		for (cnt = 0; cnt < recno; ++cnt)
+			WR(llines[cnt].l, llines[cnt].len);
+	}
+done:
+	for (cnt = 0; cnt < off; cnt++)
+		free(llines[cnt].l);
+	free(sp);
+	free(llines);
+	return (rc);
+}
diff --git a/text_cmds/tail/reverse.c b/text_cmds/tail/reverse.c
new file mode 100644
index 0000000..f0a52aa
--- /dev/null
+++ b/text_cmds/tail/reverse.c
@@ -0,0 +1,287 @@
+/*-
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Edward Sze-Tyan Wang.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 THE REGENTS 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.
+ */
+
+#if 0
+#ifndef lint
+static char sccsid[] = "@(#)reverse.c	8.1 (Berkeley) 6/6/93";
+#endif /* not lint */
+#endif
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+
+#include <err.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "extern.h"
+
+static void r_buf(FILE *);
+static void r_reg(FILE *, enum STYLE, off_t, struct stat *);
+
+/*
+ * reverse -- display input in reverse order by line.
+ *
+ * There are six separate cases for this -- regular and non-regular
+ * files by bytes, lines or the whole file.
+ *
+ * BYTES	display N bytes
+ *	REG	mmap the file and display the lines
+ *	NOREG	cyclically read characters into a wrap-around buffer
+ *
+ * LINES	display N lines
+ *	REG	mmap the file and display the lines
+ *	NOREG	cyclically read lines into a wrap-around array of buffers
+ *
+ * FILE		display the entire file
+ *	REG	mmap the file and display the lines
+ *	NOREG	cyclically read input into a linked list of buffers
+ */
+void
+reverse(FILE *fp, enum STYLE style, off_t off, struct stat *sbp)
+{
+	if (style != REVERSE && off == 0)
+		return;
+
+	if (S_ISREG(sbp->st_mode))
+		r_reg(fp, style, off, sbp);
+	else
+		switch(style) {
+		case FBYTES:
+		case RBYTES:
+			bytes(fp, off);
+			break;
+		case FLINES:
+		case RLINES:
+			lines(fp, off);
+			break;
+		case REVERSE:
+			r_buf(fp);
+			break;
+		default:
+			break;
+		}
+}
+
+/*
+ * r_reg -- display a regular file in reverse order by line.
+ */
+static void
+r_reg(FILE *fp, enum STYLE style, off_t off, struct stat *sbp)
+{
+	struct mapinfo map;
+	off_t curoff, size, lineend;
+	int i;
+
+	if (!(size = sbp->st_size))
+		return;
+
+	map.start = NULL;
+	map.mapoff = map.maxoff = size;
+	map.fd = fileno(fp);
+
+	/*
+	 * Last char is special, ignore whether newline or not. Note that
+	 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
+	 */
+	curoff = size - 2;
+	lineend = size;
+	while (curoff >= 0) {
+		if (curoff < map.mapoff ||
+		    curoff >= map.mapoff + (off_t)map.maplen) {
+			if (maparound(&map, curoff) != 0) {
+				ierr();
+				return;
+			}
+		}
+		for (i = curoff - map.mapoff; i >= 0; i--) {
+			if (style == RBYTES && --off == 0)
+				break;
+			if (map.start[i] == '\n')
+				break;
+		}
+		/* `i' is either the map offset of a '\n', or -1. */
+		curoff = map.mapoff + i;
+		if (i < 0)
+			continue;
+
+		/* Print the line and update offsets. */
+		if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) {
+			ierr();
+			return;
+		}
+		lineend = curoff + 1;
+		curoff--;
+
+		if (style == RLINES)
+			off--;
+
+		if (off == 0 && style != REVERSE) {
+			/* Avoid printing anything below. */
+			curoff = 0;
+			break;
+		}
+	}
+	if (curoff < 0 && mapprint(&map, 0, lineend) != 0) {
+		ierr();
+		return;
+	}
+	if (map.start != NULL && munmap(map.start, map.maplen))
+		ierr();
+}
+
+typedef struct bf {
+	struct bf *next;
+	struct bf *prev;
+	int len;
+	char *l;
+} BF;
+
+/*
+ * r_buf -- display a non-regular file in reverse order by line.
+ *
+ * This is the function that saves the entire input, storing the data in a
+ * doubly linked list of buffers and then displays them in reverse order.
+ * It has the usual nastiness of trying to find the newlines, as there's no
+ * guarantee that a newline occurs anywhere in the file, let alone in any
+ * particular buffer.  If we run out of memory, input is discarded (and the
+ * user warned).
+ */
+static void
+r_buf(FILE *fp)
+{
+	BF *mark, *tl, *tr;
+	int ch, len, llen;
+	char *p;
+	off_t enomem;
+
+#define	BSZ	(128 * 1024)
+	for (mark = NULL, enomem = 0;;) {
+		/*
+		 * Allocate a new block and link it into place in a doubly
+		 * linked list.  If out of memory, toss the LRU block and
+		 * keep going.
+		 */
+		if (enomem || (tl = malloc(sizeof(BF))) == NULL ||
+		    (tl->l = malloc(BSZ)) == NULL) {
+			if (!mark)
+				err(1, "malloc");
+			tl = enomem ? tl->next : mark;
+			enomem += tl->len;
+		} else if (mark) {
+			tl->next = mark;
+			tl->prev = mark->prev;
+			mark->prev->next = tl;
+			mark->prev = tl;
+		} else {
+			mark = tl;
+			mark->next = mark->prev = mark;
+		}
+
+		/* Fill the block with input data. */
+		for (p = tl->l, len = 0;
+		    len < BSZ && (ch = getc(fp)) != EOF; ++len)
+			*p++ = ch;
+
+		if (ferror(fp)) {
+			ierr();
+			return;
+		}
+
+		/*
+		 * If no input data for this block and we tossed some data,
+		 * recover it.
+		 */
+		if (!len && enomem) {
+			enomem -= tl->len;
+			tl = tl->prev;
+			break;
+		}
+
+		tl->len = len;
+		if (ch == EOF)
+			break;
+	}
+
+	if (enomem) {
+		warnx("warning: %jd bytes discarded", (intmax_t)enomem);
+		rval = 1;
+	}
+
+	/*
+	 * Step through the blocks in the reverse order read.  The last char
+	 * is special, ignore whether newline or not.
+	 */
+	for (mark = tl;;) {
+		for (p = tl->l + (len = tl->len) - 1, llen = 0; len--;
+		    --p, ++llen)
+			if (*p == '\n') {
+				if (llen) {
+					WR(p + 1, llen);
+					llen = 0;
+				}
+				if (tl == mark)
+					continue;
+				for (tr = tl->next; tr->len; tr = tr->next) {
+					WR(tr->l, tr->len);
+					tr->len = 0;
+					if (tr == mark)
+						break;
+				}
+			}
+		tl->len = llen;
+		if ((tl = tl->prev) == mark)
+			break;
+	}
+	tl = tl->next;
+	if (tl->len) {
+		WR(tl->l, tl->len);
+		tl->len = 0;
+	}
+	while ((tl = tl->next)->len) {
+		WR(tl->l, tl->len);
+		tl->len = 0;
+	}
+}
diff --git a/text_cmds/tail/tail.1 b/text_cmds/tail/tail.1
new file mode 100644
index 0000000..251511a
--- /dev/null
+++ b/text_cmds/tail/tail.1
@@ -0,0 +1,188 @@
+.\" Copyright (c) 1980, 1990, 1991, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" the Institute of Electrical and Electronics Engineers, Inc.
+.\"
+.\" 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.
+.\" 3. All advertising materials mentioning features or use of this software
+.\"    must display the following acknowledgement:
+.\"	This product includes software developed by the University of
+.\"	California, Berkeley and its contributors.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 THE REGENTS 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.
+.\"
+.\"	@(#)tail.1	8.1 (Berkeley) 6/6/93
+.\" $FreeBSD$
+.\"
+.Dd June 29, 2006
+.Dt TAIL 1
+.Os
+.Sh NAME
+.Nm tail
+.Nd display the last part of a file
+.Sh SYNOPSIS
+.Nm
+.Op Fl F | f | r
+.Op Fl q
+.Oo
+.Fl b Ar number | Fl c Ar number | Fl n Ar number
+.Oc
+.Op Ar
+.Sh DESCRIPTION
+The
+.Nm
+utility displays the contents of
+.Ar file
+or, by default, its standard input, to the standard output.
+.Pp
+The display begins at a byte, line or 512-byte block location in the
+input.
+Numbers having a leading plus
+.Pq Ql +
+sign are relative to the beginning
+of the input, for example,
+.Dq Li "-c +2"
+starts the display at the second
+byte of the input.
+Numbers having a leading minus
+.Pq Ql -
+sign or no explicit sign are
+relative to the end of the input, for example,
+.Dq Li "-n 2"
+displays the last two lines of the input.
+The default starting location is
+.Dq Li "-n 10" ,
+or the last 10 lines of the input.
+.Pp
+The options are as follows:
+.Bl -tag -width indent
+.It Fl b Ar number
+The location is
+.Ar number
+512-byte blocks.
+.It Fl c Ar number
+The location is
+.Ar number
+bytes.
+.It Fl f
+The
+.Fl f
+option causes
+.Nm
+to not stop when end of file is reached, but rather to wait for additional
+data to be appended to the input.
+The
+.Fl f
+option is ignored if the standard input is a pipe, but not if it is a FIFO.
+.It Fl F
+The
+.Fl F
+option implies the
+.Fl f
+option, but
+.Nm
+will also check to see if the file being followed has been renamed or rotated.
+The file is closed and reopened when
+.Nm
+detects that the filename being read from has a new inode number.
+The
+.Fl F
+option is ignored if reading from standard input rather than a file.
+.It Fl n Ar number
+The location is
+.Ar number
+lines.
+.It Fl q
+Suppresses printing of headers when multiple files are being examined.
+.It Fl r
+The
+.Fl r
+option causes the input to be displayed in reverse order, by line.
+Additionally, this option changes the meaning of the
+.Fl b , c
+and
+.Fl n
+options.
+When the
+.Fl r
+option is specified, these options specify the number of bytes, lines
+or 512-byte blocks to display, instead of the bytes, lines or blocks
+from the beginning or end of the input from which to begin the display.
+The default for the
+.Fl r
+option is to display all of the input.
+.El
+.Pp
+If more than a single file is specified, each file is preceded by a
+header consisting of the string
+.Dq Li "==> " Ns Ar XXX Ns Li " <=="
+where
+.Ar XXX
+is the name of the file unless
+.Fl q
+flag is specified.
+.Sh EXIT STATUS
+.Ex -std
+.Sh SEE ALSO
+.Xr cat 1 ,
+.Xr head 1 ,
+.Xr sed 1
+.Sh STANDARDS
+The
+.Nm
+utility is expected to be a superset of the
+.St -p1003.2-92
+specification.
+In particular, the
+.Fl F ,
+.Fl b
+and
+.Fl r
+options are extensions to that standard.
+.Pp
+The historic command line syntax of
+.Nm
+is supported by this implementation.
+The only difference between this implementation and historic versions
+of
+.Nm ,
+once the command line syntax translation has been done, is that the
+.Fl b ,
+.Fl c
+and
+.Fl n
+options modify the
+.Fl r
+option, i.e.,
+.Dq Li "-r -c 4"
+displays the last 4 characters of the last line
+of the input, while the historic tail (using the historic syntax
+.Dq Li -4cr )
+would ignore the
+.Fl c
+option and display the last 4 lines of the input.
+.Sh HISTORY
+A
+.Nm
+command appeared in PWB UNIX.
diff --git a/text_cmds/tail/tail.c b/text_cmds/tail/tail.c
new file mode 100644
index 0000000..57129ef
--- /dev/null
+++ b/text_cmds/tail/tail.c
@@ -0,0 +1,349 @@
+/*-
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Edward Sze-Tyan Wang.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 THE REGENTS 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.
+ */
+
+#include <sys/cdefs.h>
+
+__FBSDID("$FreeBSD$");
+
+#ifndef lint
+static const char copyright[] =
+"@(#) Copyright (c) 1991, 1993\n\
+	The Regents of the University of California.  All rights reserved.\n";
+#endif
+
+#ifndef lint
+static const char sccsid[] = "@(#)tail.c	8.1 (Berkeley) 6/6/93";
+#endif
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <err.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "extern.h"
+
+int Fflag, fflag, qflag, rflag, rval, no_files;
+const char *fname;
+
+file_info_t *files;
+
+static void obsolete(char **);
+static void usage(void);
+
+int
+main(int argc, char *argv[])
+{
+	struct stat sb;
+	FILE *fp;
+	off_t off;
+	enum STYLE style;
+	int i, ch, first;
+	file_info_t *file;
+	char *p;
+
+	/*
+	 * Tail's options are weird.  First, -n10 is the same as -n-10, not
+	 * -n+10.  Second, the number options are 1 based and not offsets,
+	 * so -n+1 is the first line, and -c-1 is the last byte.  Third, the
+	 * number options for the -r option specify the number of things that
+	 * get displayed, not the starting point in the file.  The one major
+	 * incompatibility in this version as compared to historical versions
+	 * is that the 'r' option couldn't be modified by the -lbc options,
+	 * i.e. it was always done in lines.  This version treats -rc as a
+	 * number of characters in reverse order.  Finally, the default for
+	 * -r is the entire file, not 10 lines.
+	 */
+#define	ARG(units, forward, backward) {					\
+	if (style)							\
+		usage();						\
+	off = strtoll(optarg, &p, 10) * (units);                        \
+	if (*p)								\
+		errx(1, "illegal offset -- %s", optarg);		\
+	switch(optarg[0]) {						\
+	case '+':							\
+		if (off)						\
+			off -= (units);					\
+			style = (forward);				\
+		break;							\
+	case '-':							\
+		off = -off;						\
+		/* FALLTHROUGH */					\
+	default:							\
+		style = (backward);					\
+		break;							\
+	}								\
+}
+
+	obsolete(argv);
+	style = NOTSET;
+	while ((ch = getopt(argc, argv, "Fb:c:fn:qr")) != -1)
+		switch(ch) {
+		case 'F':	/* -F is superset of (and implies) -f */
+			Fflag = fflag = 1;
+			break;
+		case 'b':
+			ARG(512, FBYTES, RBYTES);
+			break;
+		case 'c':
+			ARG(1, FBYTES, RBYTES);
+			break;
+		case 'f':
+			fflag = 1;
+			break;
+		case 'n':
+			ARG(1, FLINES, RLINES);
+			break;
+		case 'q':
+			qflag = 1;
+			break;
+		case 'r':
+			rflag = 1;
+			break;
+		case '?':
+		default:
+			usage();
+		}
+	argc -= optind;
+	argv += optind;
+
+	no_files = argc ? argc : 1;
+
+	/*
+	 * If displaying in reverse, don't permit follow option, and convert
+	 * style values.
+	 */
+	if (rflag) {
+		if (fflag)
+			usage();
+		if (style == FBYTES)
+			style = RBYTES;
+		else if (style == FLINES)
+			style = RLINES;
+	}
+
+	/*
+	 * If style not specified, the default is the whole file for -r, and
+	 * the last 10 lines if not -r.
+	 */
+	if (style == NOTSET) {
+		if (rflag) {
+			off = 0;
+			style = REVERSE;
+		} else {
+			off = 10;
+			style = RLINES;
+		}
+	}
+
+	if (fflag && !argc) {
+		/*
+		 * Determine if input is a pipe.  4.4BSD will set the SOCKET
+		 * bit in the st_mode field for pipes.  Fix this then.
+		 */
+		if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 &&
+		    errno == ESPIPE) {
+			errno = 0;
+			fflag = 0;		/* POSIX.2 requires this. */
+		}
+	}
+
+	if (fflag) {
+		files = (struct file_info *) malloc(no_files * sizeof(struct file_info));
+		if (! files)
+			err(1, "Couldn't malloc space for file descriptors.");
+
+		for (file = files; (fname = argc ? *argv++ : "stdin"); file++) {
+			file->file_name = malloc(strlen(fname)+1);
+			if (! file->file_name)
+				errx(1, "Couldn't malloc space for file name.");
+			strncpy(file->file_name, fname, strlen(fname)+1);
+			file->fp = argc ? fopen(file->file_name, "r") : stdin;
+			if (file->fp == NULL ||
+			    fstat(fileno(file->fp), &file->st)) {
+				file->fp = NULL;
+				ierr();
+				continue;
+			}
+			if (!argc)
+				break;
+		}
+		follow(files, style, off);
+		for (i = 0, file = files; i < no_files; i++, file++) {
+		    free(file->file_name);
+		}
+		free(files);
+	} else if (*argv) {
+		for (first = 1; (fname = *argv++);) {
+			if ((fp = fopen(fname, "r")) == NULL ||
+			    fstat(fileno(fp), &sb)) {
+				ierr();
+				continue;
+			}
+			if (argc > 1 && !qflag) {
+				(void)printf("%s==> %s <==\n",
+				    first ? "" : "\n", fname);
+				first = 0;
+				(void)fflush(stdout);
+			}
+
+#ifdef __APPLE__
+			/* 3849683: don't read a directory */
+			if (S_IFDIR == (sb.st_mode & S_IFMT))
+				continue;
+#endif
+
+			if (rflag)
+				reverse(fp, style, off, &sb);
+			else
+				forward(fp, style, off, &sb);
+		}
+	} else {
+		fname = "stdin";
+
+		if (fstat(fileno(stdin), &sb)) {
+			ierr();
+			exit(1);
+		}
+
+		if (rflag)
+			reverse(stdin, style, off, &sb);
+		else
+			forward(stdin, style, off, &sb);
+	}
+	exit(rval);
+}
+
+/*
+ * Convert the obsolete argument form into something that getopt can handle.
+ * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't
+ * the option argument for a -b, -c or -n option gets converted.
+ */
+static void
+obsolete(char *argv[])
+{
+	char *ap, *p, *t;
+	size_t len;
+	char *start;
+
+	while ((ap = *++argv)) {
+		/* Return if "--" or not an option of any form. */
+		if (ap[0] != '-') {
+			if (ap[0] != '+')
+				return;
+		} else if (ap[1] == '-')
+			return;
+
+		switch(*++ap) {
+		/* Old-style option. */
+		case '0': case '1': case '2': case '3': case '4':
+		case '5': case '6': case '7': case '8': case '9':
+
+			/* Malloc space for dash, new option and argument. */
+			len = strlen(*argv);
+			if ((start = p = malloc(len + 3)) == NULL)
+				err(1, "malloc");
+			*p++ = '-';
+
+			/*
+			 * Go to the end of the option argument.  Save off any
+			 * trailing options (-3lf) and translate any trailing
+			 * output style characters.
+			 */
+			t = *argv + len - 1;
+			if (*t == 'F' || *t == 'f' || *t == 'r') {
+				*p++ = *t;
+				*t-- = '\0';
+			}
+			switch(*t) {
+			case 'b':
+				*p++ = 'b';
+				*t = '\0';
+				break;
+			case 'c':
+				*p++ = 'c';
+				*t = '\0';
+				break;
+			case 'l':
+				*t = '\0';
+				/* FALLTHROUGH */
+			case '0': case '1': case '2': case '3': case '4':
+			case '5': case '6': case '7': case '8': case '9':
+				*p++ = 'n';
+				break;
+			default:
+				errx(1, "illegal option -- %s", *argv);
+			}
+			*p++ = *argv[0];
+			(void)strcpy(p, ap);
+			*argv = start;
+			continue;
+
+		/*
+		 * Options w/ arguments, skip the argument and continue
+		 * with the next option.
+		 */
+		case 'b':
+		case 'c':
+		case 'n':
+			if (!ap[1])
+				++argv;
+			/* FALLTHROUGH */
+		/* Options w/o arguments, continue with the next option. */
+		case 'F':
+		case 'f':
+		case 'r':
+			continue;
+
+		/* Illegal option, return and let getopt handle it. */
+		default:
+			return;
+		}
+	}
+}
+
+static void
+usage(void)
+{
+	(void)fprintf(stderr,
+	    "usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]"
+	    " [file ...]\n");
+	exit(1);
+}