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/*
34 * Copyright (c) 2013, Joyent, Inc. All rights reserved.
35 */
36
37#include <sys/param.h>
38#include <sys/mount.h>
39#include <sys/types.h>
40#include <sys/stat.h>
41#include <sys/statfs.h>
42#include <sys/statvfs.h>
43#include <sys/time.h>
44#include <sys/mman.h>
45#include <sys/poll.h>
46#include <port.h>
47#include <err.h>
48#include <errno.h>
49#include <fcntl.h>
50#include <limits.h>
51#include <stdio.h>
52#include <stdlib.h>
53#include <string.h>
54#include <strings.h>
55#include <unistd.h>
56
57#include "extern.h"
58
59static void rlines(FILE *, const char *fn, off_t, struct stat *);
60static int show(file_info_t *);
61static void set_events(file_info_t *files);
62
63/* defines for inner loop actions */
64#define	USE_SLEEP	0
65#define	USE_PORT	1
66#define	ADD_EVENTS	2
67
68int port;
69int action = USE_PORT;
70
71static const file_info_t *last;
72
73/*
74 * forward -- display the file, from an offset, forward.
75 *
76 * There are eight separate cases for this -- regular and non-regular
77 * files, by bytes or lines and from the beginning or end of the file.
78 *
79 * FBYTES	byte offset from the beginning of the file
80 *	REG	seek
81 *	NOREG	read, counting bytes
82 *
83 * FLINES	line offset from the beginning of the file
84 *	REG	read, counting lines
85 *	NOREG	read, counting lines
86 *
87 * RBYTES	byte offset from the end of the file
88 *	REG	seek
89 *	NOREG	cyclically read characters into a wrap-around buffer
90 *
91 * RLINES
92 *	REG	mmap the file and step back until reach the correct offset.
93 *	NOREG	cyclically read lines into a wrap-around array of buffers
94 */
95void
96forward(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
97{
98	int ch;
99
100	switch (style) {
101	case FBYTES:
102		if (off == 0)
103			break;
104		if (S_ISREG(sbp->st_mode)) {
105			if (sbp->st_size < off)
106				off = sbp->st_size;
107			if (fseeko(fp, off, SEEK_SET) == -1) {
108				ierr(fn);
109				return;
110			}
111		} else while (off--)
112			if ((ch = getc(fp)) == EOF) {
113				if (ferror(fp)) {
114					ierr(fn);
115					return;
116				}
117				break;
118			}
119		break;
120	case FLINES:
121		if (off == 0)
122			break;
123		for (;;) {
124			if ((ch = getc(fp)) == EOF) {
125				if (ferror(fp)) {
126					ierr(fn);
127					return;
128				}
129				break;
130			}
131			if (ch == '\n' && !--off)
132				break;
133		}
134		break;
135	case RBYTES:
136		if (S_ISREG(sbp->st_mode)) {
137			if (sbp->st_size >= off &&
138			    fseeko(fp, -off, SEEK_END) == -1) {
139				ierr(fn);
140				return;
141			}
142		} else if (off == 0) {
143			while (getc(fp) != EOF)
144				;
145			if (ferror(fp)) {
146				ierr(fn);
147				return;
148			}
149		} else
150			if (bytes(fp, fn, off))
151				return;
152		break;
153	case RLINES:
154		if (S_ISREG(sbp->st_mode))
155			if (!off) {
156				if (fseeko(fp, (off_t)0, SEEK_END) == -1) {
157					ierr(fn);
158					return;
159				}
160			} else
161				rlines(fp, fn, off, sbp);
162		else if (off == 0) {
163			while (getc(fp) != EOF)
164				;
165			if (ferror(fp)) {
166				ierr(fn);
167				return;
168			}
169		} else
170			if (lines(fp, fn, off))
171				return;
172		break;
173	default:
174		break;
175	}
176
177	while ((ch = getc(fp)) != EOF)
178		if (putchar(ch) == EOF)
179			oerr();
180	if (ferror(fp)) {
181		ierr(fn);
182		return;
183	}
184	(void) fflush(stdout);
185}
186
187/*
188 * rlines -- display the last offset lines of the file.
189 */
190static void
191rlines(FILE *fp, const char *fn, off_t off, struct stat *sbp)
192{
193	struct mapinfo map;
194	off_t curoff, size;
195	int i;
196
197	if ((size = sbp->st_size) == 0)
198		return;
199	map.start = NULL;
200	map.fd = fileno(fp);
201	map.mapoff = map.maxoff = size;
202
203	/*
204	 * Last char is special, ignore whether newline or not. Note that
205	 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
206	 */
207	curoff = size - 2;
208	while (curoff >= 0) {
209		if (curoff < map.mapoff && maparound(&map, curoff) != 0) {
210			ierr(fn);
211			return;
212		}
213		for (i = curoff - map.mapoff; i >= 0; i--)
214			if (map.start[i] == '\n' && --off == 0)
215				break;
216		/* `i' is either the map offset of a '\n', or -1. */
217		curoff = map.mapoff + i;
218		if (i >= 0)
219			break;
220	}
221	curoff++;
222	if (mapprint(&map, curoff, size - curoff) != 0) {
223		ierr(fn);
224		exit(1);
225	}
226
227	/* Set the file pointer to reflect the length displayed. */
228	if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) {
229		ierr(fn);
230		return;
231	}
232	if (map.start != NULL && munmap(map.start, map.maplen)) {
233		ierr(fn);
234		return;
235	}
236}
237
238static int
239show(file_info_t *file)
240{
241	int ch;
242
243	while ((ch = getc(file->fp)) != EOF) {
244		if (last != file && no_files > 1) {
245			if (!qflag)
246				(void) printf("\n==> %s <==\n",
247				    file->file_name);
248			last = file;
249		}
250		if (putchar(ch) == EOF)
251			oerr();
252	}
253	(void) fflush(stdout);
254	if (ferror(file->fp)) {
255		(void) fclose(file->fp);
256		file->fp = NULL;
257		ierr(file->file_name);
258		return (0);
259	}
260	clearerr(file->fp);
261	return (1);
262}
263
264static void
265associate(file_info_t *file, boolean_t assoc, port_event_t *ev)
266{
267	char buf[64], *name;
268	int i;
269
270	if (action != USE_PORT || file->fp == NULL)
271		return;
272
273	if (!S_ISREG(file->st.st_mode)) {
274		/*
275		 * For FIFOs, we use PORT_SOURCE_FD as our port event source.
276		 */
277		if (assoc) {
278			(void) port_associate(port, PORT_SOURCE_FD,
279			    fileno(file->fp), POLLIN, file);
280		} else {
281			(void) port_dissociate(port, PORT_SOURCE_FD,
282			    fileno(file->fp));
283		}
284
285		return;
286	}
287
288	bzero(&file->fobj, sizeof (file->fobj));
289
290	if (!Fflag) {
291		/*
292		 * PORT_SOURCE_FILE only allows us to specify a file name, not
293		 * a file descriptor.  If we are following a specific file (as
294		 * opposed to a file name) and we were to specify the name of
295		 * the file to port_associate() and that file were moved
296		 * aside, we would not be able to reassociate an event because
297		 * we would not know a name that would resolve to the new file
298		 * (indeed, there might not be such a name -- the file may
299		 * have been unlinked).  But there _is_ a name that we know
300		 * maps to the file and doesn't change: the name of the
301		 * representation of the open file descriptor in /proc.  We
302		 * therefore associate with this name (and the underlying
303		 * file), not the name of the file as specified at the command
304		 * line.  This also has the (desirable) side-effect of
305		 * insulating against FILE_RENAME_FROM and FILE_RENAME_TO
306		 * events that we need to ignore to assure that we don't lose
307		 * FILE_TRUNC events.
308		 */
309		(void) snprintf(buf,
310		    sizeof (buf), "/proc/self/fd/%d", fileno(file->fp));
311		name = buf;
312	} else {
313		name = file->file_name;
314	}
315
316	/*
317	 * Note that portfs uses the address of the specified file_obj_t to
318	 * tag an association; if one creates a different association with a
319	 * (different) file_obj_t that happens to be at the same address,
320	 * the first association will be implicitly removed.  To assure that
321	 * each association has a disjoint file_obj_t, we allocate the memory
322	 * for each in the file_info, not on the stack.
323	 */
324	file->fobj[0].fo_name = name;
325	file->fobj[1].fo_name = name;
326
327	if (assoc) {
328		/*
329		 * To assure that we cannot possibly drop a FILE_TRUNC event,
330		 * we have two different PORT_SOURCE_FILE associations with the
331		 * port:  one to get only FILE_MODIFIED events and another to
332		 * get only FILE_TRUNC events.  This assures that we always
333		 * have an active association for FILE_TRUNC events when the
334		 * seek offset is non-zero.  Note that the association order
335		 * _must_ be FILE_TRUNC followed by FILE_MODIFIED:  if a single
336		 * event induces both a FILE_TRUNC and a FILE_MODIFIED (as
337		 * a VE_CREATE vnode event does), we must process the
338		 * FILE_TRUNC before FILE_MODIFIED -- and the order in which
339		 * these are processed will be the association order.  So
340		 * if we see a FILE_TRUNC, we dissociate/reassociate the
341		 * FILE_MODIFIED association.
342		 */
343		if (ev == NULL || (ev->portev_events & FILE_TRUNC) ||
344		    !(ev->portev_events & (FILE_MODIFIED | FILE_TRUNC))) {
345			(void) port_associate(port, PORT_SOURCE_FILE,
346			    (uintptr_t)&file->fobj[0], FILE_TRUNC, file);
347			(void) port_dissociate(port, PORT_SOURCE_FILE,
348			    (uintptr_t)&file->fobj[1]);
349			ev = NULL;
350		}
351
352		if (ev == NULL || (ev->portev_events & FILE_MODIFIED) ||
353		    !(ev->portev_events & (FILE_MODIFIED | FILE_TRUNC))) {
354			(void) port_associate(port, PORT_SOURCE_FILE,
355			    (uintptr_t)&file->fobj[1], FILE_MODIFIED, file);
356		}
357	} else {
358		for (i = 0; i <= 1; i++) {
359			(void) port_dissociate(port, PORT_SOURCE_FILE,
360			    (uintptr_t)&file->fobj[i]);
361		}
362	}
363}
364
365static void
366set_events(file_info_t *files)
367{
368	int i;
369	file_info_t *file;
370
371	for (i = 0, file = files; i < no_files; i++, file++) {
372		if (! file->fp)
373			continue;
374
375		(void) fstat(fileno(file->fp), &file->st);
376
377		associate(file, B_TRUE, NULL);
378	}
379}
380
381/*
382 * follow -- display the file, from an offset, forward.
383 *
384 */
385void
386follow(file_info_t *files, enum STYLE style, off_t off)
387{
388	int active, ev_change, i, n = -1;
389	struct stat sb2;
390	file_info_t *file;
391	struct timespec ts;
392	port_event_t ev;
393
394	/* Position each of the files */
395
396	file = files;
397	active = 0;
398	n = 0;
399	for (i = 0; i < no_files; i++, file++) {
400		if (file->fp) {
401			active = 1;
402			n++;
403			if (no_files > 1 && !qflag)
404				(void) printf("\n==> %s <==\n",
405				    file->file_name);
406			forward(file->fp, file->file_name, style, off,
407			    &file->st);
408			if (Fflag && fileno(file->fp) != STDIN_FILENO)
409				n++;
410		}
411	}
412	if (!Fflag && !active)
413		return;
414
415	last = --file;
416
417	if (action == USE_PORT &&
418	    (stat("/proc/self/fd", &sb2) == -1 || !S_ISDIR(sb2.st_mode) ||
419	    (port = port_create()) == -1))
420		action = USE_SLEEP;
421
422	set_events(files);
423
424	for (;;) {
425		ev_change = 0;
426		if (Fflag) {
427			for (i = 0, file = files; i < no_files; i++, file++) {
428				if (!file->fp) {
429					file->fp = fopen(file->file_name, "r");
430					if (file->fp != NULL &&
431					    fstat(fileno(file->fp), &file->st)
432					    == -1) {
433						(void) fclose(file->fp);
434						file->fp = NULL;
435					}
436					if (file->fp != NULL)
437						ev_change++;
438					continue;
439				}
440				if (fileno(file->fp) == STDIN_FILENO)
441					continue;
442				if (stat(file->file_name, &sb2) == -1) {
443					if (errno != ENOENT)
444						ierr(file->file_name);
445					(void) show(file);
446					(void) fclose(file->fp);
447					file->fp = NULL;
448					ev_change++;
449					continue;
450				}
451
452				if (sb2.st_ino != file->st.st_ino ||
453				    sb2.st_dev != file->st.st_dev ||
454				    sb2.st_nlink == 0) {
455					(void) show(file);
456					associate(file, B_FALSE, NULL);
457					file->fp = freopen(file->file_name, "r",
458					    file->fp);
459					if (file->fp != NULL) {
460						(void) memcpy(&file->st, &sb2,
461						    sizeof (struct stat));
462					} else if (errno != ENOENT)
463						ierr(file->file_name);
464					ev_change++;
465				}
466			}
467		}
468
469		for (i = 0, file = files; i < no_files; i++, file++)
470			if (file->fp && !show(file))
471				ev_change++;
472
473		if (ev_change)
474			set_events(files);
475
476		switch (action) {
477		case USE_PORT:
478			ts.tv_sec = 1;
479			ts.tv_nsec = 0;
480
481			/*
482			 * In the -F case we set a timeout to ensure that
483			 * we re-stat the file at least once every second.
484			 */
485			n = port_get(port, &ev, Fflag ? &ts : NULL);
486
487			if (n == 0) {
488				file = (file_info_t *)ev.portev_user;
489				associate(file, B_TRUE, &ev);
490
491				if (ev.portev_events & FILE_TRUNC)
492					(void) fseek(file->fp, 0, SEEK_SET);
493			}
494
495			break;
496
497		case USE_SLEEP:
498			(void) usleep(250000);
499			break;
500		}
501	}
502}
503