330bc8582d
trying to open files rather than giving up when it encounters an error. ENOENT errors are not reported. As a result, files that are moved away then recreated are not at risk of being 'lost' to tail. Files that are recreated and temporarily have unreadable permissions will be shown when they are fixed. This behaviour is consistent with the GNU version of tail but without the verbiage that goes with the GNU version. This change also fixes error messages accompanying -f and -F. They no longer report problems with (null)! MFC after: 3 weeks
343 lines
8.3 KiB
C
343 lines
8.3 KiB
C
/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Edward Sze-Tyan Wang.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#ifndef lint
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static const char copyright[] =
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"@(#) Copyright (c) 1991, 1993\n\
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The Regents of the University of California. All rights reserved.\n";
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#endif
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#ifndef lint
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static const char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93";
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#endif
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <err.h>
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#include <errno.h>
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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 <unistd.h>
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#include "extern.h"
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int Fflag, fflag, qflag, rflag, rval, no_files;
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file_info_t *files;
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static void obsolete(char **);
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static void usage(void);
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int
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main(int argc, char *argv[])
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{
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struct stat sb;
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const char *fn;
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FILE *fp;
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off_t off;
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enum STYLE style;
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int i, ch, first;
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file_info_t *file;
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char *p;
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/*
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* Tail's options are weird. First, -n10 is the same as -n-10, not
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* -n+10. Second, the number options are 1 based and not offsets,
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* so -n+1 is the first line, and -c-1 is the last byte. Third, the
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* number options for the -r option specify the number of things that
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* get displayed, not the starting point in the file. The one major
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* incompatibility in this version as compared to historical versions
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* is that the 'r' option couldn't be modified by the -lbc options,
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* i.e. it was always done in lines. This version treats -rc as a
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* number of characters in reverse order. Finally, the default for
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* -r is the entire file, not 10 lines.
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*/
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#define ARG(units, forward, backward) { \
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if (style) \
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usage(); \
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off = strtoll(optarg, &p, 10) * (units); \
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if (*p) \
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errx(1, "illegal offset -- %s", optarg); \
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switch(optarg[0]) { \
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case '+': \
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if (off) \
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off -= (units); \
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style = (forward); \
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break; \
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case '-': \
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off = -off; \
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/* FALLTHROUGH */ \
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default: \
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style = (backward); \
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break; \
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} \
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}
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obsolete(argv);
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style = NOTSET;
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off = 0;
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while ((ch = getopt(argc, argv, "Fb:c:fn:qr")) != -1)
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switch(ch) {
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case 'F': /* -F is superset of (and implies) -f */
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Fflag = fflag = 1;
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break;
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case 'b':
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ARG(512, FBYTES, RBYTES);
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break;
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case 'c':
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ARG(1, FBYTES, RBYTES);
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break;
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case 'f':
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fflag = 1;
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break;
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case 'n':
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ARG(1, FLINES, RLINES);
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break;
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case 'q':
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qflag = 1;
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break;
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case 'r':
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rflag = 1;
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break;
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case '?':
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default:
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usage();
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}
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argc -= optind;
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argv += optind;
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no_files = argc ? argc : 1;
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/*
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* If displaying in reverse, don't permit follow option, and convert
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* style values.
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*/
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if (rflag) {
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if (fflag)
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usage();
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if (style == FBYTES)
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style = RBYTES;
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else if (style == FLINES)
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style = RLINES;
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}
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/*
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* If style not specified, the default is the whole file for -r, and
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* the last 10 lines if not -r.
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*/
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if (style == NOTSET) {
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if (rflag) {
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off = 0;
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style = REVERSE;
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} else {
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off = 10;
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style = RLINES;
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}
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}
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if (*argv && fflag) {
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files = (struct file_info *) malloc(no_files *
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sizeof(struct file_info));
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if (!files)
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err(1, "Couldn't malloc space for file descriptors.");
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for (file = files; (fn = *argv++); file++) {
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file->file_name = strdup(fn);
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if (! file->file_name)
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errx(1, "Couldn't malloc space for file name.");
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if ((file->fp = fopen(file->file_name, "r")) == NULL ||
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fstat(fileno(file->fp), &file->st)) {
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if (file->fp != NULL) {
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fclose(file->fp);
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file->fp = NULL;
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}
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if (!Fflag || errno != ENOENT)
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ierr(file->file_name);
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}
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}
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follow(files, style, off);
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for (i = 0, file = files; i < no_files; i++, file++) {
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free(file->file_name);
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}
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free(files);
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} else if (*argv) {
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for (first = 1; (fn = *argv++);) {
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if ((fp = fopen(fn, "r")) == NULL ||
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fstat(fileno(fp), &sb)) {
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ierr(fn);
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continue;
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}
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if (argc > 1 && !qflag) {
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(void)printf("%s==> %s <==\n",
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first ? "" : "\n", fn);
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first = 0;
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(void)fflush(stdout);
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}
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if (rflag)
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reverse(fp, fn, style, off, &sb);
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else
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forward(fp, fn, style, off, &sb);
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}
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} else {
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fn = "stdin";
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if (fstat(fileno(stdin), &sb)) {
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ierr(fn);
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exit(1);
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}
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/*
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* Determine if input is a pipe. 4.4BSD will set the SOCKET
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* bit in the st_mode field for pipes. Fix this then.
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*/
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if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 &&
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errno == ESPIPE) {
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errno = 0;
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fflag = 0; /* POSIX.2 requires this. */
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}
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if (rflag)
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reverse(stdin, fn, style, off, &sb);
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else
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forward(stdin, fn, style, off, &sb);
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}
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exit(rval);
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}
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/*
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* Convert the obsolete argument form into something that getopt can handle.
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* This means that anything of the form [+-][0-9][0-9]*[lbc][Ffr] that isn't
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* the option argument for a -b, -c or -n option gets converted.
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*/
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static void
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obsolete(char *argv[])
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{
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char *ap, *p, *t;
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size_t len;
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char *start;
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while ((ap = *++argv)) {
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/* Return if "--" or not an option of any form. */
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if (ap[0] != '-') {
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if (ap[0] != '+')
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return;
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} else if (ap[1] == '-')
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return;
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switch(*++ap) {
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/* Old-style option. */
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case '0': case '1': case '2': case '3': case '4':
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case '5': case '6': case '7': case '8': case '9':
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/* Malloc space for dash, new option and argument. */
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len = strlen(*argv);
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if ((start = p = malloc(len + 3)) == NULL)
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err(1, "malloc");
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*p++ = '-';
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/*
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* Go to the end of the option argument. Save off any
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* trailing options (-3lf) and translate any trailing
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* output style characters.
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*/
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t = *argv + len - 1;
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if (*t == 'F' || *t == 'f' || *t == 'r') {
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*p++ = *t;
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*t-- = '\0';
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}
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switch(*t) {
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case 'b':
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*p++ = 'b';
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*t = '\0';
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break;
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case 'c':
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*p++ = 'c';
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*t = '\0';
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break;
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case 'l':
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*t = '\0';
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/* FALLTHROUGH */
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case '0': case '1': case '2': case '3': case '4':
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case '5': case '6': case '7': case '8': case '9':
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*p++ = 'n';
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break;
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default:
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errx(1, "illegal option -- %s", *argv);
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}
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*p++ = *argv[0];
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(void)strcpy(p, ap);
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*argv = start;
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continue;
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/*
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* Options w/ arguments, skip the argument and continue
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* with the next option.
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*/
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case 'b':
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case 'c':
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case 'n':
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if (!ap[1])
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++argv;
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/* FALLTHROUGH */
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/* Options w/o arguments, continue with the next option. */
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case 'F':
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case 'f':
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case 'r':
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continue;
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/* Illegal option, return and let getopt handle it. */
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default:
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return;
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}
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}
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}
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static void
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usage(void)
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{
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(void)fprintf(stderr,
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"usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]"
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" [file ...]\n");
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exit(1);
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}
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