blob: 19fd8f6952a1e3b5a802ec186f35ec35f8250275 [file] [log] [blame]
Erik Andersene49d5ec2000-02-08 19:58:47 +00001/* vi: set sw=4 ts=4: */
Matt Kraai55bccf32001-01-05 02:57:53 +00002/*
3 * Mini tail implementation for busybox
4 *
Matt Kraai55bccf32001-01-05 02:57:53 +00005 * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
6 *
Denys Vlasenko0ef64bd2010-08-16 20:14:46 +02007 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
Erik Andersen3fe39dc2000-01-25 18:13:53 +00008 */
Matt Kraai55bccf32001-01-05 02:57:53 +00009
Manuel Novoa III cad53642003-03-19 09:13:01 +000010/* BB_AUDIT SUSv3 compliant (need fancy for -c) */
11/* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */
12/* http://www.opengroup.org/onlinepubs/007904975/utilities/tail.html */
Eric Andersenabc0f4f1999-12-08 23:19:36 +000013
Manuel Novoa III cad53642003-03-19 09:13:01 +000014/* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
15 *
16 * Pretty much rewritten to fix numerous bugs and reduce realloc() calls.
17 * Bugs fixed (although I may have forgotten one or two... it was pretty bad)
18 * 1) mixing printf/write without fflush()ing stdout
19 * 2) no check that any open files are present
20 * 3) optstring had -q taking an arg
21 * 4) no error checking on write in some cases, and a warning even then
22 * 5) q and s interaction bug
23 * 6) no check for lseek error
24 * 7) lseek attempted when count==0 even if arg was +0 (from top)
25 */
26
Denys Vlasenkoaf0255f2013-02-25 01:24:32 +010027//kbuild:lib-$(CONFIG_TAIL) += tail.o
28//kbuild:lib-$(CONFIG_TAIL) += head_tail.o
29
Pere Orga34425382011-03-31 14:43:25 +020030//usage:#define tail_trivial_usage
31//usage: "[OPTIONS] [FILE]..."
32//usage:#define tail_full_usage "\n\n"
33//usage: "Print last 10 lines of each FILE (or stdin) to stdout.\n"
34//usage: "With more than one FILE, precede each with a filename header.\n"
Pere Orga34425382011-03-31 14:43:25 +020035//usage: "\n -f Print data as file grows"
36//usage: IF_FEATURE_FANCY_TAIL(
37//usage: "\n -s SECONDS Wait SECONDS between reads with -f"
38//usage: )
39//usage: "\n -n N[kbm] Print last N lines"
Denys Vlasenko3305c002013-02-25 07:24:44 +010040//usage: "\n -n +N[kbm] Start on Nth line and print the rest"
Pere Orga34425382011-03-31 14:43:25 +020041//usage: IF_FEATURE_FANCY_TAIL(
Denys Vlasenkoaf0255f2013-02-25 01:24:32 +010042//usage: "\n -c [+]N[kbm] Print last N bytes"
Pere Orga34425382011-03-31 14:43:25 +020043//usage: "\n -q Never print headers"
44//usage: "\n -v Always print headers"
45//usage: "\n"
46//usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
Pere Orga34425382011-03-31 14:43:25 +020047//usage: )
48//usage:
49//usage:#define tail_example_usage
50//usage: "$ tail -n 1 /etc/resolv.conf\n"
51//usage: "nameserver 10.0.0.1\n"
52
Denis Vlasenkob6adbf12007-05-26 19:00:18 +000053#include "libbb.h"
Denys Vlasenkoaf0255f2013-02-25 01:24:32 +010054#include "head_tail.h"
Matt Kraai24ac0172000-12-18 21:38:57 +000055
Bernhard Reutner-Fischerd9c2d5f2007-04-04 20:29:15 +000056struct globals {
Denys Vlasenko9e933d92011-05-20 00:30:04 +020057 bool from_top;
58 bool exitcode;
Denys Vlasenko98a4c7c2010-02-04 15:00:15 +010059} FIX_ALIASING;
Bernhard Reutner-Fischerd9c2d5f2007-04-04 20:29:15 +000060#define G (*(struct globals*)&bb_common_bufsiz1)
Denys Vlasenko16714242011-09-21 01:59:15 +020061#define INIT_G() do { } while (0)
Matt Kraai55bccf32001-01-05 02:57:53 +000062
Bernhard Reutner-Fischer73561cc2006-08-28 23:31:54 +000063static void tail_xprint_header(const char *fmt, const char *filename)
64{
Denis Vlasenkoe31f7212006-12-22 16:06:16 +000065 if (fdprintf(STDOUT_FILENO, fmt, filename) < 0)
Bernhard Reutner-Fischer73561cc2006-08-28 23:31:54 +000066 bb_perror_nomsg_and_die();
Bernhard Reutner-Fischer73561cc2006-08-28 23:31:54 +000067}
68
Manuel Novoa III cad53642003-03-19 09:13:01 +000069static ssize_t tail_read(int fd, char *buf, size_t count)
70{
71 ssize_t r;
Denis Vlasenko368a12e2007-10-02 10:17:56 +000072 off_t current;
Paul Fox49054342005-07-20 19:46:32 +000073 struct stat sbuf;
Manuel Novoa III cad53642003-03-19 09:13:01 +000074
Denis Vlasenko368a12e2007-10-02 10:17:56 +000075 /* /proc files report zero st_size, don't lseek them. */
Denys Vlasenko79b021d2009-08-10 03:16:18 +020076 if (fstat(fd, &sbuf) == 0 && sbuf.st_size > 0) {
Denys Vlasenkoa43df642009-08-09 22:06:56 +020077 current = lseek(fd, 0, SEEK_CUR);
Denis Vlasenko368a12e2007-10-02 10:17:56 +000078 if (sbuf.st_size < current)
Denys Vlasenko79b021d2009-08-10 03:16:18 +020079 xlseek(fd, 0, SEEK_SET);
Denys Vlasenkoa43df642009-08-09 22:06:56 +020080 }
Denis Vlasenko368a12e2007-10-02 10:17:56 +000081
Denis Vlasenko226002e2007-10-05 19:17:16 +000082 r = full_read(fd, buf, count);
Denis Vlasenkoe31f7212006-12-22 16:06:16 +000083 if (r < 0) {
Bernhard Reutner-Fischer1b9d7c92006-06-03 22:45:37 +000084 bb_perror_msg(bb_msg_read_error);
Denys Vlasenko9e933d92011-05-20 00:30:04 +020085 G.exitcode = EXIT_FAILURE;
Manuel Novoa III cad53642003-03-19 09:13:01 +000086 }
87
88 return r;
89}
90
Denys Vlasenkoea8b2522010-06-02 12:57:26 +020091#define header_fmt_str "\n==> %s <==\n"
Manuel Novoa III cad53642003-03-19 09:13:01 +000092
Denis Vlasenkoac678ec2007-04-16 22:32:04 +000093static unsigned eat_num(const char *p)
94{
Denis Vlasenko368a12e2007-10-02 10:17:56 +000095 if (*p == '-')
96 p++;
97 else if (*p == '+') {
98 p++;
Denys Vlasenko9e933d92011-05-20 00:30:04 +020099 G.from_top = 1;
Denis Vlasenko368a12e2007-10-02 10:17:56 +0000100 }
Denys Vlasenkoaf0255f2013-02-25 01:24:32 +0100101 return xatou_sfx(p, head_tail_suffixes);
Bernhard Reutner-Fischer84d2d492007-01-24 21:38:10 +0000102}
103
Denis Vlasenko9b49a5e2007-10-11 10:05:36 +0000104int tail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
Eric Andersen98bbd682000-07-31 17:05:58 +0000105int tail_main(int argc, char **argv)
Eric Andersenabc0f4f1999-12-08 23:19:36 +0000106{
Denis Vlasenkoe31f7212006-12-22 16:06:16 +0000107 unsigned count = 10;
Denis Vlasenko459903b2006-11-27 14:44:18 +0000108 unsigned sleep_period = 1;
Denis Vlasenko92c0b822007-05-08 17:27:17 +0000109 const char *str_c, *str_n;
Eric Andersenabc0f4f1999-12-08 23:19:36 +0000110
Manuel Novoa III cad53642003-03-19 09:13:01 +0000111 char *tailbuf;
112 size_t tailbufsize;
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200113 unsigned header_threshhold = 1;
114 unsigned nfiles;
115 int i, opt;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000116
Denis Vlasenkoe31f7212006-12-22 16:06:16 +0000117 int *fds;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000118 const char *fmt;
119
Denys Vlasenko16714242011-09-21 01:59:15 +0200120 INIT_G();
121
Denis Vlasenko08492072006-12-22 13:56:36 +0000122#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
Manuel Novoa III cad53642003-03-19 09:13:01 +0000123 /* Allow legacy syntax of an initial numeric option without -n. */
Denis Vlasenko62a90cd2008-03-17 09:07:36 +0000124 if (argv[1] && (argv[1][0] == '+' || argv[1][0] == '-')
Denis Vlasenko459903b2006-11-27 14:44:18 +0000125 && isdigit(argv[1][1])
126 ) {
Denis Vlasenko3603cd22009-03-27 02:36:02 +0000127 count = eat_num(argv[1]);
Denis Vlasenko62a90cd2008-03-17 09:07:36 +0000128 argv++;
129 argc--;
Robert Griebl13c26fc2002-05-17 22:18:04 +0000130 }
Glenn L McGrath0bd02572005-12-11 03:09:05 +0000131#endif
Robert Griebl13c26fc2002-05-17 22:18:04 +0000132
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200133 /* -s NUM, -F imlies -f */
134 IF_FEATURE_FANCY_TAIL(opt_complementary = "s+:Ff";)
135 opt = getopt32(argv, "fc:n:" IF_FEATURE_FANCY_TAIL("qs:vF"),
Denis Vlasenko5e34ff22009-04-21 11:09:40 +0000136 &str_c, &str_n IF_FEATURE_FANCY_TAIL(,&sleep_period));
Denis Vlasenkoe31f7212006-12-22 16:06:16 +0000137#define FOLLOW (opt & 0x1)
138#define COUNT_BYTES (opt & 0x2)
139 //if (opt & 0x1) // -f
Bernhard Reutner-Fischer84d2d492007-01-24 21:38:10 +0000140 if (opt & 0x2) count = eat_num(str_c); // -c
141 if (opt & 0x4) count = eat_num(str_n); // -n
Bernhard Reutner-Fischer5816ccb2005-12-13 10:48:45 +0000142#if ENABLE_FEATURE_FANCY_TAIL
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200143 /* q: make it impossible for nfiles to be > header_threshhold */
144 if (opt & 0x8) header_threshhold = UINT_MAX; // -q
Denys Vlasenkoa43df642009-08-09 22:06:56 +0200145 //if (opt & 0x10) // -s
Denis Vlasenkoe31f7212006-12-22 16:06:16 +0000146 if (opt & 0x20) header_threshhold = 0; // -v
Denys Vlasenkoa43df642009-08-09 22:06:56 +0200147# define FOLLOW_RETRY (opt & 0x40)
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200148#else
Denys Vlasenkoa43df642009-08-09 22:06:56 +0200149# define FOLLOW_RETRY 0
Matt Kraai55bccf32001-01-05 02:57:53 +0000150#endif
Denis Vlasenko69107412006-12-21 00:43:06 +0000151 argc -= optind;
152 argv += optind;
Matt Kraai55bccf32001-01-05 02:57:53 +0000153
154 /* open all the files */
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200155 fds = xmalloc(sizeof(fds[0]) * (argc + 1));
Denis Vlasenko62a90cd2008-03-17 09:07:36 +0000156 if (!argv[0]) {
Manuel Novoa III cad53642003-03-19 09:13:01 +0000157 struct stat statbuf;
158
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200159 if (fstat(STDIN_FILENO, &statbuf) == 0
160 && S_ISFIFO(statbuf.st_mode)
161 ) {
Denis Vlasenkoe31f7212006-12-22 16:06:16 +0000162 opt &= ~1; /* clear FOLLOW */
Matt Kraai55bccf32001-01-05 02:57:53 +0000163 }
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200164 argv[0] = (char *) bb_msg_standard_input;
Matt Kraai55bccf32001-01-05 02:57:53 +0000165 }
Denis Vlasenko62a90cd2008-03-17 09:07:36 +0000166 nfiles = i = 0;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000167 do {
Denis Vlasenko62a90cd2008-03-17 09:07:36 +0000168 int fd = open_or_warn_stdin(argv[i]);
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200169 if (fd < 0 && !FOLLOW_RETRY) {
Denys Vlasenko9e933d92011-05-20 00:30:04 +0200170 G.exitcode = EXIT_FAILURE;
Bernhard Reutner-Fischerd9c2d5f2007-04-04 20:29:15 +0000171 continue;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000172 }
Denis Vlasenko62a90cd2008-03-17 09:07:36 +0000173 fds[nfiles] = fd;
Bernhard Reutner-Fischerd9c2d5f2007-04-04 20:29:15 +0000174 argv[nfiles++] = argv[i];
Manuel Novoa III cad53642003-03-19 09:13:01 +0000175 } while (++i < argc);
176
Denis Vlasenkoe31f7212006-12-22 16:06:16 +0000177 if (!nfiles)
Manuel Novoa III cad53642003-03-19 09:13:01 +0000178 bb_error_msg_and_die("no files");
Manuel Novoa III cad53642003-03-19 09:13:01 +0000179
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000180 /* prepare the buffer */
Manuel Novoa III cad53642003-03-19 09:13:01 +0000181 tailbufsize = BUFSIZ;
Denys Vlasenko9e933d92011-05-20 00:30:04 +0200182 if (!G.from_top && COUNT_BYTES) {
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000183 if (tailbufsize < count + BUFSIZ) {
Manuel Novoa III cad53642003-03-19 09:13:01 +0000184 tailbufsize = count + BUFSIZ;
185 }
186 }
Denys Vlasenko9e933d92011-05-20 00:30:04 +0200187 /* tail -c1024m REGULAR_FILE doesn't really need 1G mem block.
188 * (In fact, it doesn't need ANY memory). So delay allocation.
189 */
190 tailbuf = NULL;
Glenn L McGrath4ef5a842003-10-31 00:35:59 +0000191
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000192 /* tail the files */
Denys Vlasenko9e933d92011-05-20 00:30:04 +0200193
194 fmt = header_fmt_str + 1; /* skip leading newline in the header on the first output */
Manuel Novoa III cad53642003-03-19 09:13:01 +0000195 i = 0;
196 do {
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200197 char *buf;
198 int taillen;
199 int newlines_seen;
200 unsigned seen;
201 int nread;
Denys Vlasenko79b021d2009-08-10 03:16:18 +0200202 int fd = fds[i];
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200203
Denys Vlasenko79b021d2009-08-10 03:16:18 +0200204 if (ENABLE_FEATURE_FANCY_TAIL && fd < 0)
Denys Vlasenko0851d122011-09-17 00:12:24 +0200205 continue; /* may happen with -F */
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200206
Manuel Novoa III cad53642003-03-19 09:13:01 +0000207 if (nfiles > header_threshhold) {
208 tail_xprint_header(fmt, argv[i]);
Denys Vlasenkoea8b2522010-06-02 12:57:26 +0200209 fmt = header_fmt_str;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000210 }
211
Denys Vlasenko9e933d92011-05-20 00:30:04 +0200212 if (!G.from_top) {
Denys Vlasenko79b021d2009-08-10 03:16:18 +0200213 off_t current = lseek(fd, 0, SEEK_END);
Denis Vlasenko69ca5a72008-03-23 03:28:40 +0000214 if (current > 0) {
Denys Vlasenko79b021d2009-08-10 03:16:18 +0200215 unsigned off;
216 if (COUNT_BYTES) {
217 /* Optimizing count-bytes case if the file is seekable.
218 * Beware of backing up too far.
219 * Also we exclude files with size 0 (because of /proc/xxx) */
220 if (count == 0)
221 continue; /* showing zero bytes is easy :) */
222 current -= count;
223 if (current < 0)
224 current = 0;
225 xlseek(fd, current, SEEK_SET);
226 bb_copyfd_size(fd, STDOUT_FILENO, count);
227 continue;
228 }
229#if 1 /* This is technically incorrect for *LONG* strings, but very useful */
230 /* Optimizing count-lines case if the file is seekable.
231 * We assume the lines are <64k.
232 * (Users complain that tail takes too long
233 * on multi-gigabyte files) */
234 off = (count | 0xf); /* for small counts, be more paranoid */
235 if (off > (INT_MAX / (64*1024)))
236 off = (INT_MAX / (64*1024));
237 current -= off * (64*1024);
Denis Vlasenko69ca5a72008-03-23 03:28:40 +0000238 if (current < 0)
239 current = 0;
Denys Vlasenko79b021d2009-08-10 03:16:18 +0200240 xlseek(fd, current, SEEK_SET);
241#endif
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000242 }
243 }
244
Denys Vlasenko9e933d92011-05-20 00:30:04 +0200245 if (!tailbuf)
246 tailbuf = xmalloc(tailbufsize);
247
Manuel Novoa III cad53642003-03-19 09:13:01 +0000248 buf = tailbuf;
249 taillen = 0;
Denys Vlasenkoa43df642009-08-09 22:06:56 +0200250 /* "We saw 1st line/byte".
Denys Vlasenko79b021d2009-08-10 03:16:18 +0200251 * Used only by +N code ("start from Nth", 1-based): */
Manuel Novoa III cad53642003-03-19 09:13:01 +0000252 seen = 1;
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000253 newlines_seen = 0;
Denys Vlasenko0851d122011-09-17 00:12:24 +0200254 while ((nread = tail_read(fd, buf, tailbufsize - taillen)) > 0) {
Denys Vlasenko9e933d92011-05-20 00:30:04 +0200255 if (G.from_top) {
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200256 int nwrite = nread;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000257 if (seen < count) {
Denys Vlasenkoa43df642009-08-09 22:06:56 +0200258 /* We need to skip a few more bytes/lines */
Denis Vlasenkoe31f7212006-12-22 16:06:16 +0000259 if (COUNT_BYTES) {
Manuel Novoa III cad53642003-03-19 09:13:01 +0000260 nwrite -= (count - seen);
Denys Vlasenko0851d122011-09-17 00:12:24 +0200261 seen += nread;
Glenn L McGrath4ef5a842003-10-31 00:35:59 +0000262 } else {
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200263 char *s = buf;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000264 do {
265 --nwrite;
Denis Vlasenkoe31f7212006-12-22 16:06:16 +0000266 if (*s++ == '\n' && ++seen == count) {
Matt Kraai55bccf32001-01-05 02:57:53 +0000267 break;
268 }
Manuel Novoa III cad53642003-03-19 09:13:01 +0000269 } while (nwrite);
270 }
271 }
Denys Vlasenko6eaeb772010-03-12 22:16:25 +0100272 if (nwrite > 0)
273 xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite);
Manuel Novoa III cad53642003-03-19 09:13:01 +0000274 } else if (count) {
Denis Vlasenkoe31f7212006-12-22 16:06:16 +0000275 if (COUNT_BYTES) {
Manuel Novoa III cad53642003-03-19 09:13:01 +0000276 taillen += nread;
Denis Vlasenko77ad97f2008-05-13 02:27:31 +0000277 if (taillen > (int)count) {
Manuel Novoa III cad53642003-03-19 09:13:01 +0000278 memmove(tailbuf, tailbuf + taillen - count, count);
279 taillen = count;
280 }
Glenn L McGrath4ef5a842003-10-31 00:35:59 +0000281 } else {
Manuel Novoa III cad53642003-03-19 09:13:01 +0000282 int k = nread;
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000283 int newlines_in_buf = 0;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000284
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000285 do { /* count '\n' in last read */
286 k--;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000287 if (buf[k] == '\n') {
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000288 newlines_in_buf++;
Matt Kraai55bccf32001-01-05 02:57:53 +0000289 }
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000290 } while (k);
Manuel Novoa III cad53642003-03-19 09:13:01 +0000291
Denis Vlasenko77ad97f2008-05-13 02:27:31 +0000292 if (newlines_seen + newlines_in_buf < (int)count) {
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000293 newlines_seen += newlines_in_buf;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000294 taillen += nread;
Matt Kraai55bccf32001-01-05 02:57:53 +0000295 } else {
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000296 int extra = (buf[nread-1] != '\n');
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200297 char *s;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000298
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000299 k = newlines_seen + newlines_in_buf + extra - count;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000300 s = tailbuf;
301 while (k) {
302 if (*s == '\n') {
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000303 k--;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000304 }
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000305 s++;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000306 }
Manuel Novoa III cad53642003-03-19 09:13:01 +0000307 taillen += nread - (s - tailbuf);
308 memmove(tailbuf, s, taillen);
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000309 newlines_seen = count - extra;
Matt Kraai55bccf32001-01-05 02:57:53 +0000310 }
Denis Vlasenko77ad97f2008-05-13 02:27:31 +0000311 if (tailbufsize < (size_t)taillen + BUFSIZ) {
Manuel Novoa III cad53642003-03-19 09:13:01 +0000312 tailbufsize = taillen + BUFSIZ;
313 tailbuf = xrealloc(tailbuf, tailbufsize);
Matt Kraai55bccf32001-01-05 02:57:53 +0000314 }
Eric Andersend5fa3e32000-08-02 16:42:58 +0000315 }
Manuel Novoa III cad53642003-03-19 09:13:01 +0000316 buf = tailbuf + taillen;
Eric Andersend5fa3e32000-08-02 16:42:58 +0000317 }
Denis Vlasenkoe8419c92008-02-19 00:38:10 +0000318 } /* while (tail_read() > 0) */
Denys Vlasenko9e933d92011-05-20 00:30:04 +0200319 if (!G.from_top) {
Denis Vlasenkoe31f7212006-12-22 16:06:16 +0000320 xwrite(STDOUT_FILENO, tailbuf, taillen);
Matt Kraai55bccf32001-01-05 02:57:53 +0000321 }
Manuel Novoa III cad53642003-03-19 09:13:01 +0000322 } while (++i < nfiles);
323
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200324 tailbuf = xrealloc(tailbuf, BUFSIZ);
Manuel Novoa III cad53642003-03-19 09:13:01 +0000325
326 fmt = NULL;
Matt Kraai55bccf32001-01-05 02:57:53 +0000327
Denis Vlasenkoe31f7212006-12-22 16:06:16 +0000328 if (FOLLOW) while (1) {
Matt Kraai55bccf32001-01-05 02:57:53 +0000329 sleep(sleep_period);
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200330
Manuel Novoa III cad53642003-03-19 09:13:01 +0000331 i = 0;
332 do {
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200333 int nread;
334 const char *filename = argv[i];
335 int fd = fds[i];
336
337 if (FOLLOW_RETRY) {
338 struct stat sbuf, fsbuf;
339
340 if (fd < 0
341 || fstat(fd, &fsbuf) < 0
342 || stat(filename, &sbuf) < 0
343 || fsbuf.st_dev != sbuf.st_dev
344 || fsbuf.st_ino != sbuf.st_ino
345 ) {
346 int new_fd;
347
348 if (fd >= 0)
349 close(fd);
350 new_fd = open(filename, O_RDONLY);
351 if (new_fd >= 0) {
352 bb_error_msg("%s has %s; following end of new file",
353 filename, (fd < 0) ? "appeared" : "been replaced"
354 );
355 } else if (fd >= 0) {
356 bb_perror_msg("%s has become inaccessible", filename);
357 }
358 fds[i] = fd = new_fd;
359 }
360 }
361 if (ENABLE_FEATURE_FANCY_TAIL && fd < 0)
362 continue;
Manuel Novoa III cad53642003-03-19 09:13:01 +0000363 if (nfiles > header_threshhold) {
Denys Vlasenkoea8b2522010-06-02 12:57:26 +0200364 fmt = header_fmt_str;
Matt Kraai55bccf32001-01-05 02:57:53 +0000365 }
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200366 while ((nread = tail_read(fd, tailbuf, BUFSIZ)) > 0) {
Manuel Novoa III cad53642003-03-19 09:13:01 +0000367 if (fmt) {
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200368 tail_xprint_header(fmt, filename);
Manuel Novoa III cad53642003-03-19 09:13:01 +0000369 fmt = NULL;
370 }
Eric Lammerts3b5a6642009-07-22 00:31:27 +0200371 xwrite(STDOUT_FILENO, tailbuf, nread);
Matt Kraai55bccf32001-01-05 02:57:53 +0000372 }
Manuel Novoa III cad53642003-03-19 09:13:01 +0000373 } while (++i < nfiles);
Denys Vlasenko9e933d92011-05-20 00:30:04 +0200374 } /* while (1) */
375
Bernhard Reutner-Fischerd9c2d5f2007-04-04 20:29:15 +0000376 if (ENABLE_FEATURE_CLEAN_UP) {
377 free(fds);
Alexander Shishkin2348e092010-10-21 00:25:45 +0200378 free(tailbuf);
Bernhard Reutner-Fischerd9c2d5f2007-04-04 20:29:15 +0000379 }
Denys Vlasenko9e933d92011-05-20 00:30:04 +0200380 return G.exitcode;
Matt Kraai55bccf32001-01-05 02:57:53 +0000381}