1/***********************************************************************
2*                                                                      *
3*               This software is part of the ast package               *
4*          Copyright (c) 1992-2010 AT&T Intellectual Property          *
5*                      and is licensed under the                       *
6*                  Common Public License, Version 1.0                  *
7*                    by AT&T Intellectual Property                     *
8*                                                                      *
9*                A copy of the License is available at                 *
10*            http://www.opensource.org/licenses/cpl1.0.txt             *
11*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
12*                                                                      *
13*              Information and Software Systems Research               *
14*                            AT&T Research                             *
15*                           Florham Park NJ                            *
16*                                                                      *
17*                 Glenn Fowler <gsf@research.att.com>                  *
18*                  David Korn <dgk@research.att.com>                   *
19*                                                                      *
20***********************************************************************/
21#pragma prototyped
22
23/*
24 * print the tail of one or more files
25 *
26 *   David Korn
27 *   Glenn Fowler
28 */
29
30static const char usage[] =
31"+[-?\n@(#)$Id: tail (AT&T Research) 2010-03-23 $\n]"
32USAGE_LICENSE
33"[+NAME?tail - output trailing portion of one or more files ]"
34"[+DESCRIPTION?\btail\b copies one or more input files to standard output "
35	"starting at a designated point for each file.  Copying starts "
36	"at the point indicated by the options and is unlimited in size.]"
37"[+?By default a header of the form \b==> \b\afilename\a\b <==\b "
38	"is output before all but the first file but this can be changed "
39	"with the \b-q\b and \b-v\b options.]"
40"[+?If no \afile\a is given, or if the \afile\a is \b-\b, \btail\b "
41	"copies from standard input. The start of the file is defined "
42	"as the current offset.]"
43"[+?The option argument for \b-c\b can optionally be "
44	"followed by one of the following characters to specify a different "
45	"unit other than a single byte:]{"
46		"[+b?512 bytes.]"
47		"[+k?1 KiB.]"
48		"[+m?1 MiB.]"
49		"[+g?1 GiB.]"
50	"}"
51"[+?For backwards compatibility, \b-\b\anumber\a  is equivalent to "
52	"\b-n\b \anumber\a and \b+\b\anumber\a is equivalent to "
53	"\b-n -\b\anumber\a. \anumber\a may also have these option "
54	"suffixes: \bb c f g k l m r\b.]"
55
56"[n:lines]:[lines:=10?Copy \alines\a lines from each file.  A negative value "
57	"for \alines\a indicates an offset from the end of the file.]"
58"[b:blocks?Copy units of 512 bytes.]"
59"[c:bytes]:?[chars?Copy \achars\a bytes from each file.  A negative value "
60	"for \achars\a indicates an offset from the end of the file.]"
61"[f:forever|follow?Loop forever trying to read more characters as the "
62	"end of each file to copy new data. Ignored if reading from a pipe "
63	"or fifo.]"
64"[h!:headers?Output filename headers.]"
65"[l:lines?Copy units of lines. This is the default.]"
66"[L:log?When a \b--forever\b file times out via \b--timeout\b, verify that "
67	"the curent file has not been renamed and replaced by another file "
68	"of the same name (a common log file practice) before giving up on "
69	"the file.]"
70"[q:quiet?Don't output filename headers. For GNU compatibility.]"
71"[r:reverse?Output lines in reverse order.]"
72"[s:silent?Don't warn about timeout expiration and log file changes.]"
73"[t:timeout?Stop checking after \atimeout\a elapses with no additional "
74	"\b--forever\b output. A separate elapsed time is maintained for "
75	"each file operand. There is no timeout by default. The default "
76	"\atimeout\a unit is seconds. \atimeout\a may be a catenation of 1 "
77	"or more integers, each followed by a 1 character suffix. The suffix "
78	"may be omitted from the last integer, in which case it is "
79	"interpreted as seconds. The supported suffixes are:]:[timeout]{"
80		"[+s?seconds]"
81		"[+m?minutes]"
82		"[+h?hours]"
83		"[+d?days]"
84		"[+w?weeks]"
85		"[+M?months]"
86		"[+y?years]"
87		"[+S?scores]"
88	"}"
89"[v:verbose?Always ouput filename headers.]"
90
91"\n"
92"\n[file ...]\n"
93"\n"
94
95"[+EXIT STATUS?]{"
96	"[+0?All files copied successfully.]"
97	"[+>0?One or more files did not copy.]"
98"}"
99"[+SEE ALSO?\bcat\b(1), \bhead\b(1), \brev\b(1)]"
100;
101
102#include <cmd.h>
103#include <ctype.h>
104#include <ls.h>
105#include <tm.h>
106#include <rev.h>
107
108#define COUNT		(1<<0)
109#define ERROR		(1<<1)
110#define FOLLOW		(1<<2)
111#define HEADERS		(1<<3)
112#define LINES		(1<<4)
113#define LOG		(1<<5)
114#define NEGATIVE	(1<<6)
115#define POSITIVE	(1<<7)
116#define REVERSE		(1<<8)
117#define SILENT		(1<<9)
118#define TIMEOUT		(1<<10)
119#define VERBOSE		(1<<11)
120
121#define NOW		(unsigned long)time(NiL)
122
123#define DEFAULT		10
124
125#ifdef S_ISSOCK
126#define FIFO(m)		(S_ISFIFO(m)||S_ISSOCK(m))
127#else
128#define FIFO(m)		S_ISFIFO(m)
129#endif
130
131struct Tail_s; typedef struct Tail_s Tail_t;
132
133struct Tail_s
134{
135	Tail_t*		next;
136	char*		name;
137	Sfio_t*		sp;
138	Sfoff_t		cur;
139	Sfoff_t		end;
140	unsigned long	expire;
141	long		dev;
142	long		ino;
143	int		fifo;
144};
145
146static const char	header_fmt[] = "\n==> %s <==\n";
147
148/*
149 * if file is seekable, position file to tail location and return offset
150 * otherwise, return -1
151 */
152
153static Sfoff_t
154tailpos(register Sfio_t* fp, register Sfoff_t number, int delim)
155{
156	register size_t		n;
157	register Sfoff_t	offset;
158	register Sfoff_t	first;
159	register Sfoff_t	last;
160	register char*		s;
161	register char*		t;
162	struct stat		st;
163
164	last = sfsize(fp);
165	if ((first = sfseek(fp, (Sfoff_t)0, SEEK_CUR)) < 0)
166		return last || fstat(sffileno(fp), &st) || st.st_size || FIFO(st.st_mode) ? -1 : 0;
167	if (delim < 0)
168	{
169		if ((offset = last - number) < first)
170			return first;
171		return offset;
172	}
173	for (;;)
174	{
175		if ((offset = last - SF_BUFSIZE) < first)
176			offset = first;
177		sfseek(fp, offset, SEEK_SET);
178		n = last - offset;
179		if (!(s = sfreserve(fp, n, SF_LOCKR)))
180			return -1;
181		t = s + n;
182		while (t > s)
183			if (*--t == delim && number-- <= 0)
184			{
185				sfread(fp, s, 0);
186				return offset + (t - s) + 1;
187			}
188		sfread(fp, s, 0);
189		if (offset == first)
190			break;
191		last = offset;
192	}
193	return first;
194}
195
196/*
197 * this code handles tail from a pipe without any size limits
198 */
199
200static void
201pipetail(Sfio_t* infile, Sfio_t* outfile, Sfoff_t number, int delim)
202{
203	register Sfio_t*	out;
204	register Sfoff_t	n;
205	register Sfoff_t	nleft = number;
206	register size_t		a = 2 * SF_BUFSIZE;
207	register int		fno = 0;
208	Sfoff_t			offset[2];
209	Sfio_t*			tmp[2];
210
211	if (delim < 0 && a > number)
212		a = number;
213	out = tmp[0] = sftmp(a);
214	tmp[1] = sftmp(a);
215	offset[0] = offset[1] = 0;
216	while ((n = sfmove(infile, out, number, delim)) > 0)
217	{
218		offset[fno] = sftell(out);
219		if ((nleft -= n) <= 0)
220		{
221			out = tmp[fno= !fno];
222			sfseek(out, (Sfoff_t)0, SEEK_SET);
223			nleft = number;
224		}
225	}
226	if (nleft == number)
227	{
228		offset[fno] = 0;
229		fno= !fno;
230	}
231	sfseek(tmp[0], (Sfoff_t)0, SEEK_SET);
232
233	/*
234	 * see whether both files are needed
235	 */
236
237	if (offset[fno])
238	{
239		sfseek(tmp[1], (Sfoff_t)0, SEEK_SET);
240		if ((n = number - nleft) > 0)
241			sfmove(tmp[!fno], NiL, n, delim);
242		if ((n = offset[!fno] - sftell(tmp[!fno])) > 0)
243			sfmove(tmp[!fno], outfile, n, -1);
244	}
245	else
246		fno = !fno;
247	sfmove(tmp[fno], outfile, offset[fno], -1);
248	sfclose(tmp[0]);
249	sfclose(tmp[1]);
250}
251
252/*
253 * (re)initialize a tail stream
254 */
255
256static int
257init(Tail_t* tp, Sfoff_t number, int delim, int flags, const char** format)
258{
259	Sfoff_t		offset;
260	Sfio_t*		op;
261	struct stat	st;
262
263	tp->fifo = 0;
264	if (tp->sp)
265	{
266		offset = 0;
267		if (tp->sp == sfstdin)
268			tp->sp = 0;
269	}
270	else if (!number)
271		offset = 0;
272	else
273		offset = 1;
274	if (!tp->name || streq(tp->name, "-"))
275	{
276		tp->name = "/dev/stdin";
277		tp->sp = sfstdin;
278	}
279	else if (!(tp->sp = sfopen(tp->sp, tp->name, "r")))
280	{
281		error(ERROR_system(0), "%s: cannot open", tp->name);
282		return -1;
283	}
284	sfset(tp->sp, SF_SHARE, 0);
285	if (offset)
286	{
287		if (number < 0 || !number && (flags & POSITIVE))
288		{
289			sfset(tp->sp, SF_SHARE, !(flags & FOLLOW));
290			if (number < -1)
291			{
292				sfmove(tp->sp, NiL, -number - 1, delim);
293				offset = sfseek(tp->sp, (Sfoff_t)0, SEEK_CUR);
294			}
295			else
296				offset = 0;
297		}
298		else if ((offset = tailpos(tp->sp, number, delim)) >= 0)
299			sfseek(tp->sp, offset, SEEK_SET);
300		else if (fstat(sffileno(tp->sp), &st))
301		{
302			error(ERROR_system(0), "%s: cannot stat", tp->name);
303			goto bad;
304		}
305		else if (!FIFO(st.st_mode))
306		{
307			error(ERROR_SYSTEM|2, "%s: cannot position file to tail", tp->name);
308			goto bad;
309		}
310		else
311		{
312			tp->fifo = 1;
313			if (flags & (HEADERS|VERBOSE))
314			{
315				sfprintf(sfstdout, *format, tp->name);
316				*format = header_fmt;
317			}
318			op = (flags & REVERSE) ? sftmp(4*SF_BUFSIZE) : sfstdout;
319			pipetail(tp->sp ? tp->sp : sfstdin, op, number, delim);
320			if (flags & REVERSE)
321			{
322				sfseek(op, (Sfoff_t)0, SEEK_SET);
323				rev_line(op, sfstdout, (Sfoff_t)0);
324				sfclose(op);
325			}
326		}
327	}
328	tp->cur = tp->end = offset;
329	if (flags & LOG)
330	{
331		if (fstat(sffileno(tp->sp), &st))
332		{
333			error(ERROR_system(0), "%s: cannot stat", tp->name);
334			goto bad;
335		}
336		tp->dev = st.st_dev;
337		tp->ino = st.st_ino;
338	}
339	return 0;
340 bad:
341	if (tp->sp != sfstdin)
342		sfclose(tp->sp);
343	tp->sp = 0;
344	return -1;
345}
346
347/*
348 * convert number with validity diagnostics
349 */
350
351static intmax_t
352num(register const char* s, char** e, int* f, int o)
353{
354	intmax_t	number;
355	char*		t;
356	int		c;
357
358	*f &= ~(ERROR|NEGATIVE|POSITIVE);
359	if ((c = *s) == '-')
360	{
361		*f |= NEGATIVE;
362		s++;
363	}
364	else if (c == '+')
365	{
366		*f |= POSITIVE;
367		s++;
368	}
369	while (*s == '0' && isdigit(*(s + 1)))
370		s++;
371	errno = 0;
372	number = strtonll(s, &t, NiL, 0);
373	if (t == s)
374		number = DEFAULT;
375	if (o && *t)
376	{
377		number = 0;
378		*f |= ERROR;
379		error(2, "-%c: %s: invalid numeric argument -- unknown suffix", o, s);
380	}
381	else if (errno)
382	{
383		*f |= ERROR;
384		if (o)
385			error(2, "-%c: %s: invalid numeric argument -- out of range", o, s);
386		else
387			error(2, "%s: invalid numeric argument -- out of range", s);
388	}
389	else
390	{
391		*f |= COUNT;
392		if (t > s && isalpha(*(t - 1)))
393			*f &= ~LINES;
394		if (c == '-')
395			number = -number;
396	}
397	if (e)
398		*e = t;
399	return number;
400}
401
402int
403b_tail(int argc, char** argv, void* context)
404{
405	register Sfio_t*	ip;
406	register int		n;
407	register int		i;
408	int			delim;
409	int			flags = HEADERS|LINES;
410	int			blocks = 0;
411	char*			s;
412	char*			t;
413	char*			r;
414	char*			file;
415	Sfoff_t			offset;
416	Sfoff_t			number = DEFAULT;
417	unsigned long		timeout = 0;
418	struct stat		st;
419	const char*		format = header_fmt+1;
420	ssize_t			z;
421	ssize_t			w;
422	Sfio_t*			op;
423	register Tail_t*	fp;
424	register Tail_t*	pp;
425	register Tail_t*	hp;
426	Tail_t*			files;
427
428	cmdinit(argc, argv, context, ERROR_CATALOG, 0);
429	for (;;)
430	{
431		switch (n = optget(argv, usage))
432		{
433		case 0:
434			if (!(flags & FOLLOW) && argv[opt_info.index] && (argv[opt_info.index][0] == '-' || argv[opt_info.index][0] == '+') && !argv[opt_info.index][1])
435			{
436				number = argv[opt_info.index][0] == '-' ? 10 : -10;
437				flags |= LINES;
438				opt_info.index++;
439				continue;
440			}
441			break;
442		case 'b':
443			blocks = 512;
444			flags &= ~LINES;
445			if (opt_info.option[0] == '+')
446				number = -number;
447			continue;
448		case 'c':
449			flags &= ~LINES;
450			if (opt_info.arg == argv[opt_info.index - 1])
451			{
452				strtol(opt_info.arg, &s, 10);
453				if (*s)
454				{
455					opt_info.index--;
456					t = "";
457					goto suffix;
458				}
459			}
460			else if (opt_info.arg && isalpha(*opt_info.arg))
461			{
462				t = opt_info.arg;
463				goto suffix;
464			}
465			/*FALLTHROUGH*/
466		case 'n':
467			flags |= COUNT;
468			if (s = opt_info.arg)
469				number = num(s, &s, &flags, n);
470			else
471			{
472				number = DEFAULT;
473				flags &= ~(ERROR|NEGATIVE|POSITIVE);
474				s = "";
475			}
476			if (n != 'n' && s && isalpha(*s))
477			{
478				t = s;
479				goto suffix;
480			}
481			if (flags & ERROR)
482				continue;
483			if (flags & (NEGATIVE|POSITIVE))
484				number = -number;
485			if (opt_info.option[0]=='+')
486				number = -number;
487			continue;
488		case 'f':
489			flags |= FOLLOW;
490			continue;
491		case 'h':
492			if (opt_info.num)
493				flags |= HEADERS;
494			else
495				flags &= ~HEADERS;
496			continue;
497		case 'l':
498			flags |= LINES;
499			if (opt_info.option[0] == '+')
500				number = -number;
501			continue;
502		case 'L':
503			flags |= LOG;
504			continue;
505		case 'q':
506			flags &= ~HEADERS;
507			continue;
508		case 'r':
509			flags |= REVERSE;
510			continue;
511		case 's':
512			flags |= SILENT;
513			continue;
514		case 't':
515			flags |= TIMEOUT;
516			timeout = strelapsed(opt_info.arg, &s, 1);
517			if (*s)
518				error(ERROR_exit(1), "%s: invalid elapsed time [%s]", opt_info.arg, s);
519			continue;
520		case 'v':
521			flags |= VERBOSE;
522			continue;
523		case ':':
524			/* handle old style arguments */
525			if (!(r = argv[opt_info.index]) || !opt_info.offset)
526			{
527				error(2, "%s", opt_info.arg);
528				break;
529			}
530			s = r + opt_info.offset - 1;
531			if (i = *(s - 1) == '-' || *(s - 1) == '+')
532				s--;
533			if ((number = num(s, &t, &flags, 0)) && i)
534				number = -number;
535			goto compatibility;
536		suffix:
537			r = 0;
538			if (opt_info.option[0] == '+')
539				number = -number;
540		compatibility:
541			for (;;)
542			{
543				switch (*t++)
544				{
545				case 0:
546					if (r)
547						opt_info.offset = t - r - 1;
548					break;
549				case 'c':
550					flags &= ~LINES;
551					continue;
552				case 'f':
553					flags |= FOLLOW;
554					continue;
555				case 'l':
556					flags |= LINES;
557					continue;
558				case 'r':
559					flags |= REVERSE;
560					continue;
561				default:
562					error(2, "%s: invalid suffix", t - 1);
563					if (r)
564						opt_info.offset = strlen(r);
565					break;
566				}
567				break;
568			}
569			continue;
570		case '?':
571			error(ERROR_usage(2), "%s", opt_info.arg);
572			break;
573		}
574		break;
575	}
576	argv += opt_info.index;
577	if (!*argv)
578	{
579		flags &= ~HEADERS;
580		if (fstat(0, &st))
581			error(ERROR_system(0), "/dev/stdin: cannot stat");
582		else if (FIFO(st.st_mode))
583			flags &= ~FOLLOW;
584	}
585	else if (!*(argv + 1))
586		flags &= ~HEADERS;
587	delim = (flags & LINES) ? '\n' : -1;
588	if (blocks)
589		number *= blocks;
590	if (flags & REVERSE)
591	{
592		if (delim < 0)
593			error(2, "--reverse requires line mode");
594		if (!(flags & COUNT))
595			number = -1;
596		flags &= ~FOLLOW;
597	}
598	if ((flags & (FOLLOW|TIMEOUT)) == TIMEOUT)
599	{
600		flags &= ~TIMEOUT;
601		timeout = 0;
602		error(ERROR_warn(0), "--timeout ignored for --noforever");
603	}
604	if ((flags & (LOG|TIMEOUT)) == LOG)
605	{
606		flags &= ~LOG;
607		error(ERROR_warn(0), "--log ignored for --notimeout");
608	}
609	if (error_info.errors)
610		error(ERROR_usage(2), "%s", optusage(NiL));
611	if (flags & FOLLOW)
612	{
613		if (!(fp = (Tail_t*)stakalloc(argc * sizeof(Tail_t))))
614			error(ERROR_system(1), "out of space");
615		files = 0;
616		s = *argv;
617		do
618		{
619			fp->name = s;
620			fp->sp = 0;
621			if (!init(fp, number, delim, flags, &format))
622			{
623				fp->expire = timeout ? (NOW + timeout + 1) : 0;
624				if (files)
625					pp->next = fp;
626				else
627					files = fp;
628				pp = fp;
629				fp++;
630			}
631		} while (s && (s = *++argv));
632		if (!files)
633			return error_info.errors != 0;
634		pp->next = 0;
635		hp = 0;
636		n = 1;
637		while (fp = files)
638		{
639			if (n)
640				n = 0;
641			else
642				sleep(1);
643			pp = 0;
644			while (fp)
645			{
646				if (fstat(sffileno(fp->sp), &st))
647					error(ERROR_system(0), "%s: cannot stat", fp->name);
648				else if (fp->fifo || fp->end < st.st_size)
649				{
650					n = 1;
651					if (timeout)
652						fp->expire = NOW + timeout;
653					z = fp->fifo ? SF_UNBOUND : st.st_size - fp->cur;
654					i = 0;
655					if ((s = sfreserve(fp->sp, z, SF_LOCKR)) || (z = sfvalue(fp->sp)) && (s = sfreserve(fp->sp, z, SF_LOCKR)) && (i = 1))
656					{
657						z = sfvalue(fp->sp);
658						for (r = s + z; r > s && *(r - 1) != '\n'; r--);
659						if ((w = r - s) || i && (w = z))
660						{
661							if ((flags & (HEADERS|VERBOSE)) && hp != fp)
662							{
663								hp = fp;
664								sfprintf(sfstdout, format, fp->name);
665								format = header_fmt;
666							}
667							fp->cur += w;
668							sfwrite(sfstdout, s, w);
669						}
670						else
671							w = 0;
672						sfread(fp->sp, s, w);
673						fp->end += w;
674					}
675					goto next;
676				}
677				else if (!timeout || fp->expire > NOW)
678					goto next;
679				else
680				{
681					if (flags & LOG)
682					{
683						i = 3;
684						while (--i && stat(fp->name, &st))
685							sleep(1);
686						if (i && (fp->dev != st.st_dev || fp->ino != st.st_ino) && !init(fp, 0, 0, flags, &format))
687						{
688							if (!(flags & SILENT))
689								error(ERROR_warn(0), "%s: log file change", fp->name);
690							fp->expire = NOW + timeout;
691							goto next;
692						}
693					}
694					if (!(flags & SILENT))
695						error(ERROR_warn(0), "%s: %s timeout", fp->name, fmtelapsed(timeout, 1));
696				}
697				if (fp->sp && fp->sp != sfstdin)
698					sfclose(fp->sp);
699				if (pp)
700					pp = pp->next = fp->next;
701				else
702					files = files->next;
703				fp = fp->next;
704				continue;
705			next:
706				pp = fp;
707				fp = fp->next;
708			}
709			if (sfsync(sfstdout))
710				error(ERROR_system(1), "write error");
711		}
712	}
713	else
714	{
715		if (file = *argv)
716			argv++;
717		do
718		{
719			if (!file || streq(file, "-"))
720			{
721				file = "/dev/stdin";
722				ip = sfstdin;
723			}
724			else if (!(ip = sfopen(NiL, file, "r")))
725			{
726				error(ERROR_system(0), "%s: cannot open", file);
727				continue;
728			}
729			if (flags & (HEADERS|VERBOSE))
730			{
731				sfprintf(sfstdout, format, file);
732				format = header_fmt;
733			}
734			if (number < 0 || !number && (flags & POSITIVE))
735			{
736				sfset(ip, SF_SHARE, 1);
737				if (number < -1)
738					sfmove(ip, NiL, -number - 1, delim);
739				if (flags & REVERSE)
740					rev_line(ip, sfstdout, sfseek(ip, (Sfoff_t)0, SEEK_CUR));
741				else
742					sfmove(ip, sfstdout, SF_UNBOUND, -1);
743			}
744			else
745			{
746				sfset(ip, SF_SHARE, 0);
747				if ((offset = tailpos(ip, number, delim)) >= 0)
748				{
749					if (flags & REVERSE)
750						rev_line(ip, sfstdout, offset);
751					else
752					{
753						sfseek(ip, offset, SEEK_SET);
754						sfmove(ip, sfstdout, SF_UNBOUND, -1);
755					}
756				}
757				else
758				{
759					op = (flags & REVERSE) ? sftmp(4*SF_BUFSIZE) : sfstdout;
760					pipetail(ip, op, number, delim);
761					if (flags & REVERSE)
762					{
763						sfseek(op, (Sfoff_t)0, SEEK_SET);
764						rev_line(op, sfstdout, (Sfoff_t)0);
765						sfclose(op);
766					}
767					flags = 0;
768				}
769			}
770			if (ip != sfstdin)
771				sfclose(ip);
772		} while (file = *argv++);
773	}
774	return error_info.errors != 0;
775}
776