1/*-
2 * Copyright (c) 1991, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Edward Sze-Tyan Wang.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#include <sys/cdefs.h>
34
35__FBSDID("$FreeBSD: stable/11/usr.bin/tail/tail.c 332482 2018-04-13 17:57:00Z kevans $");
36
37#ifndef lint
38static const char copyright[] =
39"@(#) Copyright (c) 1991, 1993\n\
40	The Regents of the University of California.  All rights reserved.\n";
41#endif
42
43#ifndef lint
44static const char sccsid[] = "@(#)tail.c	8.1 (Berkeley) 6/6/93";
45#endif
46
47#include <sys/types.h>
48#include <sys/stat.h>
49
50#include <err.h>
51#include <errno.h>
52#include <getopt.h>
53#include <stdio.h>
54#include <stdlib.h>
55#include <string.h>
56#include <unistd.h>
57
58#include "extern.h"
59
60int Fflag, fflag, qflag, rflag, rval, no_files;
61
62static file_info_t *files;
63
64static void obsolete(char **);
65static void usage(void);
66
67static const struct option long_opts[] =
68{
69	{"blocks",	required_argument,	NULL, 'b'},
70	{"bytes",	required_argument,	NULL, 'c'},
71	{"lines",	required_argument,	NULL, 'n'},
72	{NULL,		no_argument,		NULL, 0}
73};
74
75int
76main(int argc, char *argv[])
77{
78	struct stat sb;
79	const char *fn;
80	FILE *fp;
81	off_t off;
82	enum STYLE style;
83	int i, ch, first;
84	file_info_t *file;
85	char *p;
86
87	/*
88	 * Tail's options are weird.  First, -n10 is the same as -n-10, not
89	 * -n+10.  Second, the number options are 1 based and not offsets,
90	 * so -n+1 is the first line, and -c-1 is the last byte.  Third, the
91	 * number options for the -r option specify the number of things that
92	 * get displayed, not the starting point in the file.  The one major
93	 * incompatibility in this version as compared to historical versions
94	 * is that the 'r' option couldn't be modified by the -lbc options,
95	 * i.e. it was always done in lines.  This version treats -rc as a
96	 * number of characters in reverse order.  Finally, the default for
97	 * -r is the entire file, not 10 lines.
98	 */
99#define	ARG(units, forward, backward) {					\
100	if (style)							\
101		usage();						\
102	off = strtoll(optarg, &p, 10) * (units);                        \
103	if (*p)								\
104		errx(1, "illegal offset -- %s", optarg);		\
105	switch(optarg[0]) {						\
106	case '+':							\
107		if (off)						\
108			off -= (units);					\
109			style = (forward);				\
110		break;							\
111	case '-':							\
112		off = -off;						\
113		/* FALLTHROUGH */					\
114	default:							\
115		style = (backward);					\
116		break;							\
117	}								\
118}
119
120	obsolete(argv);
121	style = NOTSET;
122	off = 0;
123	while ((ch = getopt_long(argc, argv, "+Fb:c:fn:qr", long_opts, NULL)) !=
124	    -1)
125		switch(ch) {
126		case 'F':	/* -F is superset of (and implies) -f */
127			Fflag = fflag = 1;
128			break;
129		case 'b':
130			ARG(512, FBYTES, RBYTES);
131			break;
132		case 'c':
133			ARG(1, FBYTES, RBYTES);
134			break;
135		case 'f':
136			fflag = 1;
137			break;
138		case 'n':
139			ARG(1, FLINES, RLINES);
140			break;
141		case 'q':
142			qflag = 1;
143			break;
144		case 'r':
145			rflag = 1;
146			break;
147		case '?':
148		default:
149			usage();
150		}
151	argc -= optind;
152	argv += optind;
153
154	no_files = argc ? argc : 1;
155
156	/*
157	 * If displaying in reverse, don't permit follow option, and convert
158	 * style values.
159	 */
160	if (rflag) {
161		if (fflag)
162			usage();
163		if (style == FBYTES)
164			style = RBYTES;
165		else if (style == FLINES)
166			style = RLINES;
167	}
168
169	/*
170	 * If style not specified, the default is the whole file for -r, and
171	 * the last 10 lines if not -r.
172	 */
173	if (style == NOTSET) {
174		if (rflag) {
175			off = 0;
176			style = REVERSE;
177		} else {
178			off = 10;
179			style = RLINES;
180		}
181	}
182
183	if (*argv && fflag) {
184		files = (struct file_info *) malloc(no_files *
185		    sizeof(struct file_info));
186		if (!files)
187			err(1, "Couldn't malloc space for file descriptors.");
188
189		for (file = files; (fn = *argv++); file++) {
190			file->file_name = strdup(fn);
191			if (! file->file_name)
192				errx(1, "Couldn't malloc space for file name.");
193			if ((file->fp = fopen(file->file_name, "r")) == NULL ||
194			    fstat(fileno(file->fp), &file->st)) {
195				if (file->fp != NULL) {
196					fclose(file->fp);
197					file->fp = NULL;
198				}
199				if (!Fflag || errno != ENOENT)
200					ierr(file->file_name);
201			}
202		}
203		follow(files, style, off);
204		for (i = 0, file = files; i < no_files; i++, file++) {
205		    free(file->file_name);
206		}
207		free(files);
208	} else if (*argv) {
209		for (first = 1; (fn = *argv++);) {
210			if ((fp = fopen(fn, "r")) == NULL ||
211			    fstat(fileno(fp), &sb)) {
212				ierr(fn);
213				continue;
214			}
215			if (argc > 1 && !qflag) {
216				printfn(fn, !first);
217				first = 0;
218			}
219
220			if (rflag)
221				reverse(fp, fn, style, off, &sb);
222			else
223				forward(fp, fn, style, off, &sb);
224		}
225	} else {
226		fn = "stdin";
227
228		if (fstat(fileno(stdin), &sb)) {
229			ierr(fn);
230			exit(1);
231		}
232
233		/*
234		 * Determine if input is a pipe.  4.4BSD will set the SOCKET
235		 * bit in the st_mode field for pipes.  Fix this then.
236		 */
237		if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 &&
238		    errno == ESPIPE) {
239			errno = 0;
240			fflag = 0;		/* POSIX.2 requires this. */
241		}
242
243		if (rflag)
244			reverse(stdin, fn, style, off, &sb);
245		else
246			forward(stdin, fn, style, off, &sb);
247	}
248	exit(rval);
249}
250
251/*
252 * Convert the obsolete argument form into something that getopt can handle.
253 * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't
254 * the option argument for a -b, -c or -n option gets converted.
255 */
256static void
257obsolete(char *argv[])
258{
259	char *ap, *p, *t;
260	size_t len;
261	char *start;
262
263	while ((ap = *++argv)) {
264		/* Return if "--" or not an option of any form. */
265		if (ap[0] != '-') {
266			if (ap[0] != '+')
267				return;
268		} else if (ap[1] == '-')
269			return;
270
271		switch(*++ap) {
272		/* Old-style option. */
273		case '0': case '1': case '2': case '3': case '4':
274		case '5': case '6': case '7': case '8': case '9':
275
276			/* Malloc space for dash, new option and argument. */
277			len = strlen(*argv);
278			if ((start = p = malloc(len + 3)) == NULL)
279				err(1, "malloc");
280			*p++ = '-';
281
282			/*
283			 * Go to the end of the option argument.  Save off any
284			 * trailing options (-3lf) and translate any trailing
285			 * output style characters.
286			 */
287			t = *argv + len - 1;
288			if (*t == 'F' || *t == 'f' || *t == 'r') {
289				*p++ = *t;
290				*t-- = '\0';
291			}
292			switch(*t) {
293			case 'b':
294				*p++ = 'b';
295				*t = '\0';
296				break;
297			case 'c':
298				*p++ = 'c';
299				*t = '\0';
300				break;
301			case 'l':
302				*t = '\0';
303				/* FALLTHROUGH */
304			case '0': case '1': case '2': case '3': case '4':
305			case '5': case '6': case '7': case '8': case '9':
306				*p++ = 'n';
307				break;
308			default:
309				errx(1, "illegal option -- %s", *argv);
310			}
311			*p++ = *argv[0];
312			(void)strcpy(p, ap);
313			*argv = start;
314			continue;
315
316		/*
317		 * Options w/ arguments, skip the argument and continue
318		 * with the next option.
319		 */
320		case 'b':
321		case 'c':
322		case 'n':
323			if (!ap[1])
324				++argv;
325			/* FALLTHROUGH */
326		/* Options w/o arguments, continue with the next option. */
327		case 'F':
328		case 'f':
329		case 'r':
330			continue;
331
332		/* Illegal option, return and let getopt handle it. */
333		default:
334			return;
335		}
336	}
337}
338
339static void
340usage(void)
341{
342	(void)fprintf(stderr,
343	    "usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]"
344	    " [file ...]\n");
345	exit(1);
346}
347