1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Edward Sze-Tyan Wang.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35
36#include <sys/capsicum.h>
37#include <sys/types.h>
38#include <sys/stat.h>
39
40#include <capsicum_helpers.h>
41#include <err.h>
42#include <errno.h>
43#include <getopt.h>
44#include <stdio.h>
45#include <stdlib.h>
46#include <string.h>
47#include <unistd.h>
48
49#include <libutil.h>
50
51#include <libcasper.h>
52#include <casper/cap_fileargs.h>
53
54#include "extern.h"
55
56int Fflag, fflag, qflag, rflag, rval, no_files, vflag;
57fileargs_t *fa;
58
59static void obsolete(char **);
60static void usage(void) __dead2;
61
62static const struct option long_opts[] =
63{
64	{"blocks",	required_argument,	NULL, 'b'},
65	{"bytes",	required_argument,	NULL, 'c'},
66	{"lines",	required_argument,	NULL, 'n'},
67	{"quiet",	no_argument,		NULL, 'q'},
68	{"silent",	no_argument,		NULL, 'q'},
69	{"verbose",	no_argument,		NULL, 'v'},
70	{NULL,		no_argument,		NULL, 0}
71};
72
73int
74main(int argc, char *argv[])
75{
76	struct stat sb;
77	const char *fn;
78	FILE *fp;
79	off_t off;
80	enum STYLE style;
81	int ch, first;
82	file_info_t file, *filep, *files;
83	cap_rights_t rights;
84
85	/*
86	 * Tail's options are weird.  First, -n10 is the same as -n-10, not
87	 * -n+10.  Second, the number options are 1 based and not offsets,
88	 * so -n+1 is the first line, and -c-1 is the last byte.  Third, the
89	 * number options for the -r option specify the number of things that
90	 * get displayed, not the starting point in the file.  The one major
91	 * incompatibility in this version as compared to historical versions
92	 * is that the 'r' option couldn't be modified by the -lbc options,
93	 * i.e. it was always done in lines.  This version treats -rc as a
94	 * number of characters in reverse order.  Finally, the default for
95	 * -r is the entire file, not 10 lines.
96	 */
97#define	ARG(units, forward, backward) {					\
98	if (style)							\
99		usage();						\
100	if (expand_number(optarg, &off))				\
101		err(1, "illegal offset -- %s", optarg);			\
102	if (off > INT64_MAX / units || off < INT64_MIN / units )	\
103		errx(1, "illegal offset -- %s", optarg);		\
104	switch(optarg[0]) {						\
105	case '+':							\
106		if (off)						\
107			off -= (units);					\
108		style = (forward);					\
109		break;							\
110	case '-':							\
111		off = -off;						\
112		/* FALLTHROUGH */					\
113	default:							\
114		style = (backward);					\
115		break;							\
116	}								\
117}
118
119	obsolete(argv);
120	style = NOTSET;
121	off = 0;
122	while ((ch = getopt_long(argc, argv, "+Fb:c:fn:qrv", long_opts, NULL)) !=
123	    -1)
124		switch(ch) {
125		case 'F':	/* -F is superset of (and implies) -f */
126			Fflag = fflag = 1;
127			break;
128		case 'b':
129			ARG(512, FBYTES, RBYTES);
130			break;
131		case 'c':
132			ARG(1, FBYTES, RBYTES);
133			break;
134		case 'f':
135			fflag = 1;
136			break;
137		case 'n':
138			ARG(1, FLINES, RLINES);
139			break;
140		case 'q':
141			qflag = 1;
142			vflag = 0;
143			break;
144		case 'r':
145			rflag = 1;
146			break;
147		case 'v':
148			vflag = 1;
149			qflag = 0;
150			break;
151		case '?':
152		default:
153			usage();
154		}
155	argc -= optind;
156	argv += optind;
157
158	no_files = argc ? argc : 1;
159
160	cap_rights_init(&rights, CAP_FSTAT, CAP_FSTATFS, CAP_FCNTL,
161	    CAP_MMAP_R);
162	if (fflag)
163		cap_rights_set(&rights, CAP_EVENT);
164	if (caph_rights_limit(STDIN_FILENO, &rights) < 0 ||
165	    caph_limit_stderr() < 0 || caph_limit_stdout() < 0)
166		err(1, "unable to limit stdio rights");
167
168	fa = fileargs_init(argc, argv, O_RDONLY, 0, &rights, FA_OPEN);
169	if (fa == NULL)
170		err(1, "unable to init casper");
171
172	caph_cache_catpages();
173	if (caph_enter_casper() < 0)
174		err(1, "unable to enter capability mode");
175
176	/*
177	 * If displaying in reverse, don't permit follow option, and convert
178	 * style values.
179	 */
180	if (rflag) {
181		if (fflag)
182			usage();
183		if (style == FBYTES)
184			style = RBYTES;
185		else if (style == FLINES)
186			style = RLINES;
187	}
188
189	/*
190	 * If style not specified, the default is the whole file for -r, and
191	 * the last 10 lines if not -r.
192	 */
193	if (style == NOTSET) {
194		if (rflag) {
195			off = 0;
196			style = REVERSE;
197		} else {
198			off = 10;
199			style = RLINES;
200		}
201	}
202
203	if (*argv && fflag) {
204		files = malloc(no_files * sizeof(struct file_info));
205		if (files == NULL)
206			err(1, "failed to allocate memory for file descriptors");
207
208		for (filep = files; (fn = *argv++); filep++) {
209			filep->file_name = fn;
210			filep->fp = fileargs_fopen(fa, filep->file_name, "r");
211			if (filep->fp == NULL ||
212			    fstat(fileno(filep->fp), &filep->st)) {
213				if (filep->fp != NULL) {
214					fclose(filep->fp);
215					filep->fp = NULL;
216				}
217				if (!Fflag || errno != ENOENT)
218					ierr(filep->file_name);
219			}
220		}
221		follow(files, style, off);
222		free(files);
223	} else if (*argv) {
224		for (first = 1; (fn = *argv++);) {
225			if ((fp = fileargs_fopen(fa, fn, "r")) == NULL ||
226			    fstat(fileno(fp), &sb)) {
227				ierr(fn);
228				continue;
229			}
230			if (vflag || (qflag == 0 && argc > 1)) {
231				printfn(fn, !first);
232				first = 0;
233			}
234
235			if (rflag)
236				reverse(fp, fn, style, off, &sb);
237			else
238				forward(fp, fn, style, off, &sb);
239		}
240	} else {
241		fn = "stdin";
242
243		if (fstat(fileno(stdin), &sb)) {
244			ierr(fn);
245			exit(1);
246		}
247
248		/*
249		 * Determine if input is a pipe.  4.4BSD will set the SOCKET
250		 * bit in the st_mode field for pipes.  Fix this then.
251		 */
252		if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 &&
253		    errno == ESPIPE) {
254			errno = 0;
255			fflag = 0;		/* POSIX.2 requires this. */
256		}
257
258		if (rflag) {
259			reverse(stdin, fn, style, off, &sb);
260		} else if (fflag) {
261			file.file_name = fn;
262			file.fp = stdin;
263			file.st = sb;
264			follow(&file, style, off);
265		} else {
266			forward(stdin, fn, style, off, &sb);
267		}
268	}
269	fileargs_free(fa);
270	exit(rval);
271}
272
273/*
274 * Convert the obsolete argument form into something that getopt can handle.
275 * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't
276 * the option argument for a -b, -c or -n option gets converted.
277 */
278static void
279obsolete(char *argv[])
280{
281	char *ap, *p, *t;
282	size_t len;
283	char *start;
284
285	while ((ap = *++argv)) {
286		/* Return if "--" or not an option of any form. */
287		if (ap[0] != '-') {
288			if (ap[0] != '+')
289				return;
290		} else if (ap[1] == '-')
291			return;
292
293		switch(*++ap) {
294		/* Old-style option. */
295		case '0': case '1': case '2': case '3': case '4':
296		case '5': case '6': case '7': case '8': case '9':
297
298			/* Malloc space for dash, new option and argument. */
299			len = strlen(*argv);
300			if ((start = p = malloc(len + 3)) == NULL)
301				err(1, "failed to allocate memory");
302			*p++ = '-';
303
304			/*
305			 * Go to the end of the option argument.  Save off any
306			 * trailing options (-3lf) and translate any trailing
307			 * output style characters.
308			 */
309			t = *argv + len - 1;
310			if (*t == 'F' || *t == 'f' || *t == 'r') {
311				*p++ = *t;
312				*t-- = '\0';
313			}
314			switch(*t) {
315			case 'b':
316				*p++ = 'b';
317				*t = '\0';
318				break;
319			case 'c':
320				*p++ = 'c';
321				*t = '\0';
322				break;
323			case 'l':
324				*t = '\0';
325				/* FALLTHROUGH */
326			case '0': case '1': case '2': case '3': case '4':
327			case '5': case '6': case '7': case '8': case '9':
328				*p++ = 'n';
329				break;
330			default:
331				errx(1, "illegal option -- %s", *argv);
332			}
333			*p++ = *argv[0];
334			(void)strcpy(p, ap);
335			*argv = start;
336			continue;
337
338		/*
339		 * Options w/ arguments, skip the argument and continue
340		 * with the next option.
341		 */
342		case 'b':
343		case 'c':
344		case 'n':
345			if (!ap[1])
346				++argv;
347			/* FALLTHROUGH */
348		/* Options w/o arguments, continue with the next option. */
349		case 'F':
350		case 'f':
351		case 'r':
352			continue;
353
354		/* Illegal option, return and let getopt handle it. */
355		default:
356			return;
357		}
358	}
359}
360
361static void
362usage(void)
363{
364	(void)fprintf(stderr,
365	    "usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]"
366	    " [file ...]\n");
367	exit(1);
368}
369