1 /* vi: set sw=4 ts=4: */
3 * Mini tail implementation for busybox
6 * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
26 #include <sys/types.h>
29 static struct suffix_mult tail_suffixes[] = {
36 #ifndef BB_FEATURE_SIMPLE_TAIL
37 static struct suffix_mult null_suffixes[] = {
42 static const int BYTES = 0;
43 static const int LINES = 1;
49 void tailbuf_append(char *buf, int len)
51 tailbuf = xrealloc(tailbuf, taillen + len);
52 memcpy(tailbuf + taillen, buf, len);
59 s = memchr(tailbuf, '\n', taillen);
60 memmove(tailbuf, s + 1, taillen - ((s + 1) - tailbuf));
61 taillen -= (s + 1) - tailbuf;
65 int tail_main(int argc, char **argv)
67 int from_top = 0, units = LINES, count = 10, sleep_period = 1;
68 int show_headers = 0, hide_headers = 0, follow = 0;
69 int *fds, nfiles = 0, status = EXIT_SUCCESS, nread, nwrite, seen = 0;
70 char *s, *start, *end, buf[BUFSIZ];
73 while ((opt = getopt(argc, argv, "c:fhn:q:s:v")) > 0) {
78 #ifndef BB_FEATURE_SIMPLE_TAIL
84 count = parse_number(optarg, tail_suffixes);
90 #ifndef BB_FEATURE_SIMPLE_TAIL
95 sleep_period = parse_number(optarg, null_suffixes);
106 /* open all the files */
107 fds = (int *)xmalloc(sizeof(int) * (argc - optind + 1));
108 if (argc == optind) {
109 fds[nfiles++] = STDIN_FILENO;
110 argv[optind] = "standard input";
112 for (i = optind; i < argc; i++) {
113 if (strcmp(argv[i], "-") == 0) {
114 fds[nfiles++] = STDIN_FILENO;
115 argv[i] = "standard input";
116 } else if ((fds[nfiles++] = open(argv[i], O_RDONLY)) < 0) {
117 perror_msg("%s", argv[i]);
118 status = EXIT_FAILURE;
123 #ifndef BB_FEATURE_SIMPLE_TAIL
125 if (!from_top && units == BYTES)
126 tailbuf = xmalloc(count);
129 for (i = 0; i < nfiles; i++) {
133 if (show_headers || (!hide_headers && nfiles > 1))
134 printf("%s==> %s <==\n", i == 0 ? "" : "\n", argv[optind + i]);
135 while ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0) {
137 #ifndef BB_FEATURE_SIMPLE_TAIL
138 if (units == BYTES) {
139 if (count - 1 <= seen)
141 else if (count - 1 <= seen + nread)
142 nwrite = nread + seen - (count - 1);
150 if (count - 1 <= seen)
154 for (s = memchr(buf, '\n', nread); s != NULL;
155 s = memchr(s+1, '\n', nread - (s + 1 - buf))) {
156 if (count - 1 <= ++seen) {
157 nwrite = nread - (s + 1 - buf);
163 if (full_write(STDOUT_FILENO, buf + nread - nwrite,
166 status = EXIT_FAILURE;
170 #ifndef BB_FEATURE_SIMPLE_TAIL
171 if (units == BYTES) {
173 memmove(tailbuf, tailbuf + nread, count - nread);
174 memcpy(tailbuf + count - nread, buf, nread);
176 memcpy(tailbuf, buf + nread - count, count);
183 for (start = buf, end = memchr(buf, '\n', nread);
184 end != NULL; start = end+1,
185 end = memchr(start, '\n', nread - (start - buf))) {
186 if (newline && count <= seen)
188 tailbuf_append(start, end - start + 1);
192 if (newline && count <= seen && nread - (start - buf) > 0)
194 tailbuf_append(start, nread - (start - buf));
201 status = EXIT_FAILURE;
204 #ifndef BB_FEATURE_SIMPLE_TAIL
205 if (!from_top && units == BYTES) {
208 if (full_write(STDOUT_FILENO, tailbuf + count - seen, seen) < 0) {
210 status = EXIT_FAILURE;
215 if (!from_top && units == LINES) {
216 if (full_write(STDOUT_FILENO, tailbuf, taillen) < 0) {
218 status = EXIT_FAILURE;
228 for (i = 0; i < nfiles; i++) {
232 if ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0) {
233 if (show_headers || (!hide_headers && nfiles > 1))
234 printf("\n==> %s <==\n", argv[optind + i]);
237 full_write(STDOUT_FILENO, buf, nread);
238 } while ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0);
243 status = EXIT_FAILURE;