/usr.bin/tail/tail.c
C | 338 lines | 232 code | 30 blank | 76 comment | 60 complexity | 06bdb81f199592d9d610e3bfee855e93 MD5 | raw file
Possible License(s): MPL-2.0-no-copyleft-exception, BSD-3-Clause, LGPL-2.0, LGPL-2.1, BSD-2-Clause, 0BSD, JSON, AGPL-1.0, GPL-2.0
- /*-
- * 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.
- * 4. 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>
- __FBSDID("$FreeBSD$");
- #ifndef lint
- static const char copyright[] =
- "@(#) Copyright (c) 1991, 1993\n\
- The Regents of the University of California. All rights reserved.\n";
- #endif
- #ifndef lint
- static const char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93";
- #endif
- #include <sys/types.h>
- #include <sys/stat.h>
- #include <err.h>
- #include <errno.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <unistd.h>
- #include "extern.h"
- int Fflag, fflag, qflag, rflag, rval, no_files;
- static file_info_t *files;
- static void obsolete(char **);
- static void usage(void);
- int
- main(int argc, char *argv[])
- {
- struct stat sb;
- const char *fn;
- FILE *fp;
- off_t off;
- enum STYLE style;
- int i, ch, first;
- file_info_t *file;
- char *p;
- /*
- * 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) \
- errx(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;
- off = 0;
- while ((ch = getopt(argc, argv, "Fb:c:fn:qr")) != -1)
- switch(ch) {
- case 'F': /* -F is superset of (and implies) -f */
- Fflag = fflag = 1;
- 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 'q':
- qflag = 1;
- break;
- case 'r':
- rflag = 1;
- break;
- case '?':
- default:
- usage();
- }
- argc -= optind;
- argv += optind;
- no_files = argc ? argc : 1;
- /*
- * 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 && fflag) {
- files = (struct file_info *) malloc(no_files *
- sizeof(struct file_info));
- if (!files)
- err(1, "Couldn't malloc space for file descriptors.");
- for (file = files; (fn = *argv++); file++) {
- file->file_name = strdup(fn);
- if (! file->file_name)
- errx(1, "Couldn't malloc space for file name.");
- if ((file->fp = fopen(file->file_name, "r")) == NULL ||
- fstat(fileno(file->fp), &file->st)) {
- if (file->fp != NULL) {
- fclose(file->fp);
- file->fp = NULL;
- }
- if (!Fflag || errno != ENOENT)
- ierr(file->file_name);
- }
- }
- follow(files, style, off);
- for (i = 0, file = files; i < no_files; i++, file++) {
- free(file->file_name);
- }
- free(files);
- } else if (*argv) {
- for (first = 1; (fn = *argv++);) {
- if ((fp = fopen(fn, "r")) == NULL ||
- fstat(fileno(fp), &sb)) {
- ierr(fn);
- continue;
- }
- if (argc > 1 && !qflag) {
- (void)printf("%s==> %s <==\n",
- first ? "" : "\n", fn);
- first = 0;
- (void)fflush(stdout);
- }
- if (rflag)
- reverse(fp, fn, style, off, &sb);
- else
- forward(fp, fn, style, off, &sb);
- }
- } else {
- fn = "stdin";
- if (fstat(fileno(stdin), &sb)) {
- ierr(fn);
- 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, fn, style, off, &sb);
- else
- forward(stdin, fn, 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][Ffr] 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)) {
- /* 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)
- err(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 == '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:
- errx(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 'f':
- case 'r':
- continue;
- /* Illegal option, return and let getopt handle it. */
- default:
- return;
- }
- }
- }
- static void
- usage(void)
- {
- (void)fprintf(stderr,
- "usage: tail [-F | -f | -r] [-q] [-b # | -c # | -n #]"
- " [file ...]\n");
- exit(1);
- }