330 lines
7.4 KiB
C
330 lines
7.4 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Mini tail implementation for busybox
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*
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* Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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/* BB_AUDIT SUSv3 compliant (need fancy for -c) */
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/* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */
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/* http://www.opengroup.org/onlinepubs/007904975/utilities/tail.html */
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/* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
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*
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* Pretty much rewritten to fix numerous bugs and reduce realloc() calls.
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* Bugs fixed (although I may have forgotten one or two... it was pretty bad)
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* 1) mixing printf/write without fflush()ing stdout
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* 2) no check that any open files are present
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* 3) optstring had -q taking an arg
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* 4) no error checking on write in some cases, and a warning even then
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* 5) q and s interaction bug
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* 6) no check for lseek error
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* 7) lseek attempted when count==0 even if arg was +0 (from top)
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <ctype.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/stat.h>
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#include "busybox.h"
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static const struct suffix_mult tail_suffixes[] = {
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{ "b", 512 },
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{ "k", 1024 },
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{ "m", 1048576 },
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{ NULL, 0 }
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};
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static int status
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#if EXIT_SUCCESS != 0
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= EXIT_SUCCESS /* If it is 0 (paranoid check), let bss initialize it. */
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#endif
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;
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static void tail_xprint_header(const char *fmt, const char *filename)
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{
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/* If we get an output error, there is really no sense in continuing. */
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if (dprintf(STDOUT_FILENO, fmt, filename) < 0) {
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bb_perror_nomsg_and_die();
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}
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}
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/* len should probably be size_t */
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static void tail_xbb_full_write(const char *buf, size_t len)
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{
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/* If we get a write error, there is really no sense in continuing. */
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if (bb_full_write(STDOUT_FILENO, buf, len) < 0) {
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bb_perror_nomsg_and_die();
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}
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}
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static ssize_t tail_read(int fd, char *buf, size_t count)
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{
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ssize_t r;
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if ((r = safe_read(fd, buf, count)) < 0) {
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bb_perror_msg("read");
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status = EXIT_FAILURE;
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}
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return r;
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}
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static const char tail_opts[] =
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"fn:c:"
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#ifdef CONFIG_FEATURE_FANCY_TAIL
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"qs:v"
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#endif
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;
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static const char header_fmt[] = "\n==> %s <==\n";
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int tail_main(int argc, char **argv)
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{
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long count = 10;
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unsigned int sleep_period = 1;
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int from_top = 0;
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int follow = 0;
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int header_threshhold = 1;
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int count_bytes = 0;
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char *tailbuf;
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size_t tailbufsize;
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int taillen = 0;
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int newline = 0;
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int *fds, nfiles, nread, nwrite, seen, i, opt;
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char *s, *buf;
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const char *fmt;
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/* Allow legacy syntax of an initial numeric option without -n. */
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if (argc >=2 && ((argv[1][0] == '+') || ((argv[1][0] == '-')
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/* && (isdigit)(argv[1][1]) */
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&& (((unsigned int)(argv[1][1] - '0')) <= 9))))
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{
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optind = 2;
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optarg = argv[1];
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goto GET_COUNT;
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}
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while ((opt = getopt(argc, argv, tail_opts)) > 0) {
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switch (opt) {
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case 'f':
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follow = 1;
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break;
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case 'c':
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count_bytes = 1;
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/* FALLS THROUGH */
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case 'n':
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GET_COUNT:
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count = bb_xgetlarg10_sfx(optarg, tail_suffixes);
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/* Note: Leading whitespace is an error trapped above. */
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if (*optarg == '+') {
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from_top = 1;
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} else {
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from_top = 0;
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}
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if (count < 0) {
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count = -count;
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}
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break;
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#ifdef CONFIG_FEATURE_FANCY_TAIL
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case 'q':
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header_threshhold = INT_MAX;
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break;
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case 's':
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sleep_period =bb_xgetularg10_bnd(optarg, 0, UINT_MAX);
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break;
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case 'v':
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header_threshhold = 0;
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break;
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#endif
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default:
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bb_show_usage();
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}
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}
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/* open all the files */
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fds = (int *)xmalloc(sizeof(int) * (argc - optind + 1));
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argv += optind;
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nfiles = i = 0;
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if ((argc -= optind) == 0) {
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struct stat statbuf;
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if (!fstat(STDIN_FILENO, &statbuf) && S_ISFIFO(statbuf.st_mode)) {
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follow = 0;
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}
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/* --argv; */
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*argv = (char *) bb_msg_standard_input;
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goto DO_STDIN;
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}
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do {
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if ((argv[i][0] == '-') && !argv[i][1]) {
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DO_STDIN:
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fds[nfiles] = STDIN_FILENO;
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} else if ((fds[nfiles] = open(argv[i], O_RDONLY)) < 0) {
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bb_perror_msg("%s", argv[i]);
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status = EXIT_FAILURE;
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continue;
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}
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argv[nfiles] = argv[i];
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++nfiles;
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} while (++i < argc);
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if (!nfiles) {
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bb_error_msg_and_die("no files");
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}
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tailbufsize = BUFSIZ;
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/* tail the files */
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if (from_top < count_bytes) { /* Each is 0 or 1, so true iff 0 < 1. */
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/* Hence, !from_top && count_bytes */
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if (tailbufsize < count) {
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tailbufsize = count + BUFSIZ;
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}
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}
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buf = tailbuf = xmalloc(tailbufsize);
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fmt = header_fmt + 1; /* Skip header leading newline on first output. */
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i = 0;
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do {
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/* Be careful. It would be possible to optimize the count-bytes
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* case if the file is seekable. If you do though, remember that
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* starting file position may not be the beginning of the file.
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* Beware of backing up too far. See example in wc.c.
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*/
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if ((!(count|from_top)) && (lseek(fds[i], 0, SEEK_END) >= 0)) {
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continue;
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}
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if (nfiles > header_threshhold) {
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tail_xprint_header(fmt, argv[i]);
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fmt = header_fmt;
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}
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buf = tailbuf;
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taillen = 0;
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seen = 1;
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while ((nread = tail_read(fds[i], buf, tailbufsize-taillen)) > 0) {
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if (from_top) {
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nwrite = nread;
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if (seen < count) {
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if (count_bytes) {
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nwrite -= (count - seen);
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seen = count;
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} else {
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s = buf;
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do {
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--nwrite;
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if ((*s++ == '\n') && (++seen == count)) {
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break;
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}
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} while (nwrite);
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}
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}
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tail_xbb_full_write(buf + nread - nwrite, nwrite);
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} else if (count) {
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if (count_bytes) {
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taillen += nread;
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if (taillen > count) {
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memmove(tailbuf, tailbuf + taillen - count, count);
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taillen = count;
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}
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} else {
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int k = nread;
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int nbuf = 0;
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while (k) {
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--k;
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if (buf[k] == '\n') {
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++nbuf;
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}
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}
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if (newline + nbuf < count) {
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newline += nbuf;
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taillen += nread;
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} else {
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int extra = 0;
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if (buf[nread-1] != '\n') {
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extra = 1;
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}
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k = newline + nbuf + extra - count;
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s = tailbuf;
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while (k) {
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if (*s == '\n') {
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--k;
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}
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++s;
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}
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taillen += nread - (s - tailbuf);
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memmove(tailbuf, s, taillen);
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newline = count - extra;
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}
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if (tailbufsize < taillen + BUFSIZ) {
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tailbufsize = taillen + BUFSIZ;
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tailbuf = xrealloc(tailbuf, tailbufsize);
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}
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}
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buf = tailbuf + taillen;
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}
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}
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if (!from_top) {
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tail_xbb_full_write(tailbuf, taillen);
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}
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taillen = 0;
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} while (++i < nfiles);
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buf = xrealloc(tailbuf, BUFSIZ);
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fmt = NULL;
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while (follow) {
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sleep(sleep_period);
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i = 0;
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do {
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if (nfiles > header_threshhold) {
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fmt = header_fmt;
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}
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while ((nread = tail_read(fds[i], buf, sizeof(buf))) > 0) {
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if (fmt) {
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tail_xprint_header(fmt, argv[i]);
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fmt = NULL;
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}
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tail_xbb_full_write(buf, nread);
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}
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} while (++i < nfiles);
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}
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return status;
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}
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