A cleanup patch from Jeff Garzik to static-ify a number of
[oweals/busybox.git] / tail.c
1 /* vi: set sw=4 ts=4: */
2 /*
3  * Mini tail implementation for busybox
4  *
5  *
6  * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
7  *
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.
12  *
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.
17  *
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
21  *
22  */
23
24
25 #include <fcntl.h>
26 #include <getopt.h>
27 #include <string.h>
28 #include <stdlib.h>
29 #include <unistd.h>
30 #include <sys/types.h>
31 #include "busybox.h"
32
33 static const struct suffix_mult tail_suffixes[] = {
34         { "b", 512 },
35         { "k", 1024 },
36         { "m", 1048576 },
37         { NULL, 0 }
38 };
39
40 static const int BYTES = 0;
41 static const int LINES = 1;
42
43 static char *tailbuf;
44 static int taillen;
45 static int newline;
46
47 static void tailbuf_append(char *buf, int len)
48 {
49         tailbuf = xrealloc(tailbuf, taillen + len);
50         memcpy(tailbuf + taillen, buf, len);
51         taillen += len;
52 }
53
54 static void tailbuf_trunc()
55 {
56         char *s;
57         s = memchr(tailbuf, '\n', taillen);
58         memmove(tailbuf, s + 1, taillen - ((s + 1) - tailbuf));
59         taillen -= (s + 1) - tailbuf;
60         newline = 0;
61 }
62
63 int tail_main(int argc, char **argv)
64 {
65         int from_top = 0, units = LINES, count = 10, sleep_period = 1;
66         int show_headers = 0, hide_headers = 0, follow = 0;
67         int *fds, nfiles = 0, status = EXIT_SUCCESS, nread, nwrite, seen = 0;
68         char *s, *start, *end, buf[BUFSIZ];
69         int i, opt;
70
71         while ((opt = getopt(argc, argv, "c:fhn:q:s:v")) > 0) {
72                 switch (opt) {
73                         case 'f':
74                                 follow = 1;
75                                 break;
76 #ifndef BB_FEATURE_SIMPLE_TAIL
77                         case 'c':
78                                 units = BYTES;
79                                 /* FALLS THROUGH */
80 #endif
81                         case 'n':
82                                 count = parse_number(optarg, tail_suffixes);
83                                 if (count < 0)
84                                         count = -count;
85                                 if (optarg[0] == '+')
86                                         from_top = 1;
87                                 break;
88 #ifndef BB_FEATURE_SIMPLE_TAIL
89                         case 'q':
90                                 hide_headers = 1;
91                                 break;
92                         case 's':
93                                 sleep_period = parse_number(optarg, 0);
94                                 break;
95                         case 'v':
96                                 show_headers = 1;
97                                 break;
98 #endif
99                         default:
100                                 show_usage();
101                 }
102         }
103
104         /* open all the files */
105         fds = (int *)xmalloc(sizeof(int) * (argc - optind + 1));
106         if (argc == optind) {
107                 fds[nfiles++] = STDIN_FILENO;
108                 argv[optind] = "standard input";
109         } else {
110                 for (i = optind; i < argc; i++) {
111                         if (strcmp(argv[i], "-") == 0) {
112                                 fds[nfiles++] = STDIN_FILENO;
113                                 argv[i] = "standard input";
114                         } else if ((fds[nfiles++] = open(argv[i], O_RDONLY)) < 0) {
115                                 perror_msg("%s", argv[i]);
116                                 status = EXIT_FAILURE;
117                         }
118                 }
119         }
120         
121 #ifndef BB_FEATURE_SIMPLE_TAIL
122         /* tail the files */
123         if (!from_top && units == BYTES)
124                 tailbuf = xmalloc(count);
125 #endif
126
127         for (i = 0; i < nfiles; i++) {
128                 if (fds[i] == -1)
129                         continue;
130                 seen = 0;
131                 if (show_headers || (!hide_headers && nfiles > 1))
132                         printf("%s==> %s <==\n", i == 0 ? "" : "\n", argv[optind + i]);
133                 while ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0) {
134                         if (from_top) {
135 #ifndef BB_FEATURE_SIMPLE_TAIL
136                                 if (units == BYTES) {
137                                         if (count - 1 <= seen)
138                                                 nwrite = nread;
139                                         else if (count - 1 <= seen + nread)
140                                                 nwrite = nread + seen - (count - 1);
141                                         else
142                                                 nwrite = 0;
143                                         seen += nread;
144                                 } else {
145 #else
146                                 {
147 #endif
148                                         if (count - 1 <= seen)
149                                                 nwrite = nread;
150                                         else {
151                                                 nwrite = 0;
152                                                 for (s = memchr(buf, '\n', nread); s != NULL;
153                                                                 s = memchr(s+1, '\n', nread - (s + 1 - buf))) {
154                                                         if (count - 1 <= ++seen) {
155                                                                 nwrite = nread - (s + 1 - buf);
156                                                                 break;
157                                                         }
158                                                 }
159                                         }
160                                 }
161                                 if (full_write(STDOUT_FILENO, buf + nread - nwrite,
162                                                         nwrite) < 0) {
163                                         perror_msg("write");
164                                         status = EXIT_FAILURE;
165                                         break;
166                                 }
167                         } else {
168 #ifndef BB_FEATURE_SIMPLE_TAIL
169                                 if (units == BYTES) {
170                                         if (nread < count) {
171                                                 memmove(tailbuf, tailbuf + nread, count - nread);
172                                                 memcpy(tailbuf + count - nread, buf, nread);
173                                         } else {
174                                                 memcpy(tailbuf, buf + nread - count, count);
175                                         }
176                                         seen += nread;
177                                 } else {
178 #else
179                                 {
180 #endif
181                                         for (start = buf, end = memchr(buf, '\n', nread);
182                                                         end != NULL; start = end+1,
183                                                         end = memchr(start, '\n', nread - (start - buf))) {
184                                                 if (newline && count <= seen)
185                                                         tailbuf_trunc();
186                                                 tailbuf_append(start, end - start + 1);
187                                                 seen++;
188                                                 newline = 1;
189                                         }
190                                         if (newline && count <= seen && nread - (start - buf) > 0)
191                                                 tailbuf_trunc();
192                                         tailbuf_append(start, nread - (start - buf));
193                                 }
194                         }
195                 }
196
197                 if (nread < 0) {
198                         perror_msg("read");
199                         status = EXIT_FAILURE;
200                 }
201
202 #ifndef BB_FEATURE_SIMPLE_TAIL
203                 if (!from_top && units == BYTES) {
204                         if (count < seen)
205                                 seen = count;
206                         if (full_write(STDOUT_FILENO, tailbuf + count - seen, seen) < 0) {
207                                 perror_msg("write");
208                                 status = EXIT_FAILURE;
209                         }
210                 }
211 #endif
212
213                 if (!from_top && units == LINES) {
214                         if (full_write(STDOUT_FILENO, tailbuf, taillen) < 0) {
215                                 perror_msg("write");
216                                 status = EXIT_FAILURE;
217                         }
218                 }
219
220                 taillen = 0;
221         }
222
223         while (follow) {
224                 sleep(sleep_period);
225
226                 for (i = 0; i < nfiles; i++) {
227                         if (fds[i] == -1)
228                                 continue;
229
230                         if ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0) {
231                                 if (show_headers || (!hide_headers && nfiles > 1))
232                                         printf("\n==> %s <==\n", argv[optind + i]);
233
234                                 do {
235                                         full_write(STDOUT_FILENO, buf, nread);
236                                 } while ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0);
237                         }
238
239                         if (nread < 0) {
240                                 perror_msg("read");
241                                 status = EXIT_FAILURE;
242                         }
243                 }
244         }
245
246         return status;
247 }