/*-
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Edward Sze-Tyan Wang.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1991, 1993\
The Regents of the University of California. All rights reserved.");
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93";
#endif
__RCSID("$NetBSD: tail.c,v 1.20 2018/03/06 03:33:26 eadler Exp $");
#endif /* not lint */
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "extern.h"
int fflag, rflag, rval;
const char *fname;
static void obsolete(char **);
static void usage(void) __dead;
int
main(int argc, char *argv[])
{
struct stat sb;
FILE *fp;
off_t off;
enum STYLE style;
int ch, first;
char *p;
int qflag = 0;
int vflag = 0;
setprogname(argv[0]);
off = 0;
/*
* Tail's options are weird. First, -n10 is the same as -n-10, not
* -n+10. Second, the number options are 1 based and not offsets,
* so -n+1 is the first line, and -c-1 is the last byte. Third, the
* number options for the -r option specify the number of things that
* get displayed, not the starting point in the file. The one major
* incompatibility in this version as compared to historical versions
* is that the 'r' option couldn't be modified by the -lbc options,
* i.e., it was always done in lines. This version treats -rc as a
* number of characters in reverse order. Finally, the default for
* -r is the entire file, not 10 lines.
*/
#define ARG(units, forward, backward) { \
if (style) \
usage(); \
off = strtoll(optarg, &p, 10) * (units); \
if (*p) \
xerrx(1, "illegal offset -- %s", optarg); \
switch(optarg[0]) { \
case '+': \
if (off) \
off -= (units); \
style = (forward); \
break; \
case '-': \
off = -off; \
/* FALLTHROUGH */ \
default: \
style = (backward); \
break; \
} \
}
obsolete(argv);
style = NOTSET;
if (strcmp(getprogname(), "tac") == 0) {
qflag = 1;
vflag = 0;
rflag = 1;
argc -= 1;
argv += 1;
} else { /* tail */
while ((ch = getopt(argc, argv, "Fb:c:fn:rqv")) != -1)
switch(ch) {
case 'F':
fflag = 2;
break;
case 'b':
ARG(512, FBYTES, RBYTES);
break;
case 'c':
ARG(1, FBYTES, RBYTES);
break;
case 'f':
fflag = 1;
break;
case 'n':
ARG(1, FLINES, RLINES);
break;
case 'r':
rflag = 1;
break;
case 'q':
qflag = 1;
vflag = 0;
break;
case 'v':
qflag = 0;
vflag = 1;
break;
case '?':
default:
usage();
}
argc -= optind;
argv += optind;
}
if (fflag && argc > 1)
xerrx(1,
"-f and -F options only appropriate for a single file");
/*
* If displaying in reverse, don't permit follow option, and convert
* style values.
*/
if (rflag) {
if (fflag)
usage();
if (style == FBYTES)
style = RBYTES;
else if (style == FLINES)
style = RLINES;
}
/*
* If style not specified, the default is the whole file for -r, and
* the last 10 lines if not -r.
*/
if (style == NOTSET) {
if (rflag) {
off = 0;
style = REVERSE;
} else {
off = 10;
style = RLINES;
}
}
if (*argv)
for (first = 1; (fname = *argv++) != NULL;) {
if ((fp = fopen(fname, "r")) == NULL ||
fstat(fileno(fp), &sb)) {
ierr();
continue;
}
if (vflag || (qflag == 0 && argc > 1)) {
(void)printf("%s==> %s <==\n",
first ? "" : "\n", fname);
first = 0;
(void)fflush(stdout);
}
if (rflag)
reverse(fp, style, off, &sb);
else
forward(fp, style, off, &sb);
(void)fclose(fp);
}
else {
fname = "stdin";
if (fstat(fileno(stdin), &sb)) {
ierr();
exit(1);
}
/*
* Determine if input is a pipe. 4.4BSD will set the SOCKET
* bit in the st_mode field for pipes. Fix this then.
*/
if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 &&
errno == ESPIPE) {
errno = 0;
fflag = 0; /* POSIX.2 requires this. */
}
if (rflag)
reverse(stdin, style, off, &sb);
else
forward(stdin, style, off, &sb);
}
exit(rval);
}
/*
* Convert the obsolete argument form into something that getopt can handle.
* This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't
* the option argument for a -b, -c or -n option gets converted.
*/
static void
obsolete(char *argv[])
{
char *ap, *p, *t;
size_t len;
char *start;
while ((ap = *++argv) != NULL) {
/* Return if "--" or not an option of any form. */
if (ap[0] != '-') {
if (ap[0] != '+')
return;
} else if (ap[1] == '-')
return;
switch (*++ap) {
/* Old-style option. */
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
/* Malloc space for dash, new option and argument. */
len = strlen(*argv);
if ((start = p = malloc(len + 3)) == NULL)
xerr(1, "malloc");
*p++ = '-';
/*
* Go to the end of the option argument. Save off any
* trailing options (-3lf) and translate any trailing
* output style characters.
*/
t = *argv + len - 1;
if (*t == 'f' || *t == 'r') {
*p++ = *t;
*t-- = '\0';
}
switch(*t) {
case 'b':
*p++ = 'b';
*t = '\0';
break;
case 'c':
*p++ = 'c';
*t = '\0';
break;
case 'l':
*t = '\0';
/* FALLTHROUGH */
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
*p++ = 'n';
break;
default:
xerrx(1, "illegal option -- %s", *argv);
}
*p++ = *argv[0];
(void)strcpy(p, ap);
*argv = start;
continue;
/*
* Options w/ arguments, skip the argument and continue
* with the next option.
*/
case 'b':
case 'c':
case 'n':
if (!ap[1])
++argv;
/* FALLTHROUGH */
/* Options w/o arguments, continue with the next option. */
case 'f':
case 'r':
continue;
/* Illegal option, return and let getopt handle it. */
default:
return;
}
}
}
static void
usage(void)
{
(void)fprintf(stderr,
"Usage: %s [-qv] [-f | -F | -r] [-b # | -c # | -n #] [file ...]\n",
getprogname());
exit(1);
}
