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#include <sys/cdefs.h>
36
37__FBSDID("$FreeBSD$");
38
39#ifndef lint
40static const char copyright[] =
41"@(#) Copyright (c) 1991, 1993\n\
42	The Regents of the University of California.  All rights reserved.\n";
43#endif
44
45#ifndef lint
46static const char sccsid[] = "@(#)tail.c	8.1 (Berkeley) 6/6/93";
47#endif
48
49#include <sys/capsicum.h>
50#include <sys/types.h>
51#include <sys/stat.h>
52
53#include <capsicum_helpers.h>
54#include <err.h>
55#include <errno.h>
56#include <getopt.h>
57#include <stdio.h>
58#include <stdlib.h>
59#include <string.h>
60#include <unistd.h>
61
62#include <libcasper.h>
63#include <casper/cap_fileargs.h>
64
65#include "extern.h"
66
67int Fflag, fflag, qflag, rflag, rval, no_files;
68fileargs_t *fa;
69
70static file_info_t *files;
71
72static void obsolete(char **);
73static void usage(void);
74
75static const struct option long_opts[] =
76{
77	{"blocks",	required_argument,	NULL, 'b'},
78	{"bytes",	required_argument,	NULL, 'c'},
79	{"lines",	required_argument,	NULL, 'n'},
80	{NULL,		no_argument,		NULL, 0}
81};
82
83int
84main(int argc, char *argv[])
85{
86	struct stat sb;
87	const char *fn;
88	FILE *fp;
89	off_t off;
90	enum STYLE style;
91	int i, ch, first;
92	file_info_t *file;
93	char *p;
94	cap_rights_t rights;
95
96	/*
97	 * Tail's options are weird.  First, -n10 is the same as -n-10, not
98	 * -n+10.  Second, the number options are 1 based and not offsets,
99	 * so -n+1 is the first line, and -c-1 is the last byte.  Third, the
100	 * number options for the -r option specify the number of things that
101	 * get displayed, not the starting point in the file.  The one major
102	 * incompatibility in this version as compared to historical versions
103	 * is that the 'r' option couldn't be modified by the -lbc options,
104	 * i.e. it was always done in lines.  This version treats -rc as a
105	 * number of characters in reverse order.  Finally, the default for
106	 * -r is the entire file, not 10 lines.
107	 */
108#define	ARG(units, forward, backward) {					\
109	if (style)							\
110		usage();						\
111	off = strtoll(optarg, &p, 10) * (units);                        \
112	if (*p)								\
113		errx(1, "illegal offset -- %s", optarg);		\
114	switch(optarg[0]) {						\
115	case '+':							\
116		if (off)						\
117			off -= (units);					\
118			style = (forward);				\
119		break;							\
120	case '-':							\
121		off = -off;						\
122		/* FALLTHROUGH */					\
123	default:							\
124		style = (backward);					\
125		break;							\
126	}								\
127}
128
129	obsolete(argv);
130	style = NOTSET;
131	off = 0;
132	while ((ch = getopt_long(argc, argv, "+Fb:c:fn:qr", long_opts, NULL)) !=
133	    -1)
134		switch(ch) {
135		case 'F':	/* -F is superset of (and implies) -f */
136			Fflag = fflag = 1;
137			break;
138		case 'b':
139			ARG(512, FBYTES, RBYTES);
140			break;
141		case 'c':
142			ARG(1, FBYTES, RBYTES);
143			break;
144		case 'f':
145			fflag = 1;
146			break;
147		case 'n':
148			ARG(1, FLINES, RLINES);
149			break;
150		case 'q':
151			qflag = 1;
152			break;
153		case 'r':
154			rflag = 1;
155			break;
156		case '?':
157		default:
158			usage();
159		}
160	argc -= optind;
161	argv += optind;
162
163	no_files = argc ? argc : 1;
164
165	cap_rights_init(&rights, CAP_FSTAT, CAP_FSTATFS, CAP_FCNTL,
166	    CAP_MMAP_R);
167	if (fflag)
168		cap_rights_set(&rights, CAP_EVENT);
169	if (caph_rights_limit(STDIN_FILENO, &rights) < 0 ||
170	    caph_limit_stderr() < 0 || caph_limit_stdout() < 0)
171		err(1, "can't limit stdio rights");
172
173	fa = fileargs_init(argc, argv, O_RDONLY, 0, &rights, FA_OPEN);
174	if (fa == NULL)
175		err(1, "unable to init casper");
176
177	caph_cache_catpages();
178	if (caph_enter_casper() < 0)
179		err(1, "unable to enter capability mode");
180
181	/*
182	 * If displaying in reverse, don't permit follow option, and convert
183	 * style values.
184	 */
185	if (rflag) {
186		if (fflag)
187			usage();
188		if (style == FBYTES)
189			style = RBYTES;
190		else if (style == FLINES)
191			style = RLINES;
192	}
193
194	/*
195	 * If style not specified, the default is the whole file for -r, and
196	 * the last 10 lines if not -r.
197	 */
198	if (style == NOTSET) {
199		if (rflag) {
200			off = 0;
201			style = REVERSE;
202		} else {
203			off = 10;
204			style = RLINES;
205		}
206	}
207
208	if (*argv && fflag) {
209		files = (struct file_info *) malloc(no_files *
210		    sizeof(struct file_info));
211		if (!files)
212			err(1, "Couldn't malloc space for file descriptors.");
213
214		for (file = files; (fn = *argv++); file++) {
215			file->file_name = strdup(fn);
216			if (! file->file_name)
217				errx(1, "Couldn't malloc space for file name.");
218			file->fp = fileargs_fopen(fa, file->file_name, "r");
219			if (file->fp == NULL ||
220			    fstat(fileno(file->fp), &file->st)) {
221				if (file->fp != NULL) {
222					fclose(file->fp);
223					file->fp = NULL;
224				}
225				if (!Fflag || errno != ENOENT)
226					ierr(file->file_name);
227			}
228		}
229		follow(files, style, off);
230		for (i = 0, file = files; i < no_files; i++, file++) {
231		    free(file->file_name);
232		}
233		free(files);
234	} else if (*argv) {
235		for (first = 1; (fn = *argv++);) {
236			if ((fp = fileargs_fopen(fa, fn, "r")) == NULL ||
237			    fstat(fileno(fp), &sb)) {
238				ierr(fn);
239				continue;
240			}
241			if (argc > 1 && !qflag) {
242				printfn(fn, !first);
243				first = 0;
244			}
245
246			if (rflag)
247				reverse(fp, fn, style, off, &sb);
248			else
249				forward(fp, fn, style, off, &sb);
250		}
251	} else {
252		fn = "stdin";
253
254		if (fstat(fileno(stdin), &sb)) {
255			ierr(fn);
256			exit(1);
257		}
258
259		/*
260		 * Determine if input is a pipe.  4.4BSD will set the SOCKET
261		 * bit in the st_mode field for pipes.  Fix this then.
262		 */
263		if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 &&
264		    errno == ESPIPE) {
265			errno = 0;
266			fflag = 0;		/* POSIX.2 requires this. */
267		}
268
269		if (rflag)
270			reverse(stdin, fn, style, off, &sb);
271		else
272			forward(stdin, fn, style, off, &sb);
273	}
274	fileargs_free(fa);
275	exit(rval);
276}
277
278/*
279 * Convert the obsolete argument form into something that getopt can handle.
280 * This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't
281 * the option argument for a -b, -c or -n option gets converted.
282 */
283static void
284obsolete(char *argv[])
285{
286	char *ap, *p, *t;
287	size_t len;
288	char *start;
289
290	while ((ap = *++argv)) {
291		/* Return if "--" or not an option of any form. */
292		if (ap[0] != '-') {
293			if (ap[0] != '+')
294				return;
295		} else if (ap[1] == '-')
296			return;
297
298		switch(*++ap) {
299		/* Old-style option. */
300		case '0': case '1': case '2': case '3': case '4':
301		case '5': case '6': case '7': case '8': case '9':
302
303			/* Malloc space for dash, new option and argument. */
304			len = strlen(*argv);
305			if ((start = p = malloc(len + 3)) == NULL)
306				err(1, "malloc");
307			*p++ = '-';
308
309			/*
310			 * Go to the end of the option argument.  Save off any
311			 * trailing options (-3lf) and translate any trailing
312			 * output style characters.
313			 */
314			t = *argv + len - 1;
315			if (*t == 'F' || *t == 'f' || *t == 'r') {
316				*p++ = *t;
317				*t-- = '\0';
318			}
319			switch(*t) {
320			case 'b':
321				*p++ = 'b';
322				*t = '\0';
323				break;
324			case 'c':
325				*p++ = 'c';
326				*t = '\0';
327				break;
328			case 'l':
329				*t = '\0';
330				/* FALLTHROUGH */
331			case '0': case '1': case '2': case '3': case '4':
332			case '5': case '6': case '7': case '8': case '9':
333				*p++ = 'n';
334				break;
335			default:
336				errx(1, "illegal option -- %s", *argv);
337			}
338			*p++ = *argv[0];
339			(void)strcpy(p, ap);
340			*argv = start;
341			continue;
342
343		/*
344		 * Options w/ arguments, skip the argument and continue
345		 * with the next option.
346		 */
347		case 'b':
348		case 'c':
349		case 'n':
350			if (!ap[1])
351				++argv;
352			/* FALLTHROUGH */
353		/* Options w/o arguments, continue with the next option. */
354		case 'F':
355		case 'f':
356		case 'r':
357			continue;
358
359		/* Illegal option, return and let getopt handle it. */
360		default:
361			return;
362		}
363	}
364}
365
366static void
367usage(void)
368{
369	(void)fprintf(stderr,
370	    "usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]"
371	    " [file ...]\n");
372	exit(1);
373}
374