source: MondoRescue/trunk/mindi-busybox/coreutils/tail.c

Last change on this file was 821, checked in by Bruno Cornec, 18 years ago

Addition of busybox 1.2.1 as a mindi-busybox new package
This should avoid delivering binary files in mindi not built there (Fedora and Debian are quite serious about that)
File size: 7.0 KB
Line 
1/* vi: set sw=4 ts=4: */
2/*
3 * Mini tail implementation for busybox
4 *
5 * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
6 *
7 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
8 */
9
10/* BB_AUDIT SUSv3 compliant (need fancy for -c) */
11/* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */
12/* http://www.opengroup.org/onlinepubs/007904975/utilities/tail.html */
13
14/* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
15 *
16 * Pretty much rewritten to fix numerous bugs and reduce realloc() calls.
17 * Bugs fixed (although I may have forgotten one or two... it was pretty bad)
18 * 1) mixing printf/write without fflush()ing stdout
19 * 2) no check that any open files are present
20 * 3) optstring had -q taking an arg
21 * 4) no error checking on write in some cases, and a warning even then
22 * 5) q and s interaction bug
23 * 6) no check for lseek error
24 * 7) lseek attempted when count==0 even if arg was +0 (from top)
25 */
26
27#include <stdio.h>
28#include <stdlib.h>
29#include <string.h>
30#include <ctype.h>
31#include <unistd.h>
32#include <fcntl.h>
33#include <sys/stat.h>
34#include "busybox.h"
35
36static const struct suffix_mult tail_suffixes[] = {
37 { "b", 512 },
38 { "k", 1024 },
39 { "m", 1048576 },
40 { NULL, 0 }
41};
42
43static int status;
44
45static void tail_xprint_header(const char *fmt, const char *filename)
46{
47 /* If we get an output error, there is really no sense in continuing. */
48 if (dprintf(STDOUT_FILENO, fmt, filename) < 0) {
49 bb_perror_nomsg_and_die();
50 }
51}
52
53/* len should probably be size_t */
54static void tail_xbb_full_write(const char *buf, size_t len)
55{
56 /* If we get a write error, there is really no sense in continuing. */
57 if (bb_full_write(STDOUT_FILENO, buf, len) < 0) {
58 bb_perror_nomsg_and_die();
59 }
60}
61
62static ssize_t tail_read(int fd, char *buf, size_t count)
63{
64 ssize_t r;
65 off_t current,end;
66 struct stat sbuf;
67
68 end = current = lseek(fd, 0, SEEK_CUR);
69 if (!fstat(fd, &sbuf))
70 end = sbuf.st_size;
71 lseek(fd, end < current ? 0 : current, SEEK_SET);
72 if ((r = safe_read(fd, buf, count)) < 0) {
73 bb_perror_msg(bb_msg_read_error);
74 status = EXIT_FAILURE;
75 }
76
77 return r;
78}
79
80static const char tail_opts[] =
81 "fn:c:"
82#if ENABLE_FEATURE_FANCY_TAIL
83 "qs:v"
84#endif
85 ;
86
87static const char header_fmt[] = "\n==> %s <==\n";
88
89int tail_main(int argc, char **argv)
90{
91 long count = 10;
92 unsigned int sleep_period = 1;
93 int from_top = 0;
94 int follow = 0;
95 int header_threshhold = 1;
96 int count_bytes = 0;
97
98 char *tailbuf;
99 size_t tailbufsize;
100 int taillen = 0;
101 int newline = 0;
102
103 int *fds, nfiles, nread, nwrite, seen, i, opt;
104 char *s, *buf;
105 const char *fmt;
106
107#if !ENABLE_DEBUG_YANK_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
108 /* Allow legacy syntax of an initial numeric option without -n. */
109 if (argc >=2 && ((argv[1][0] == '+') || ((argv[1][0] == '-')
110 /* && (isdigit)(argv[1][1]) */
111 && (((unsigned int)(argv[1][1] - '0')) <= 9))))
112 {
113 optind = 2;
114 optarg = argv[1];
115 goto GET_COUNT;
116 }
117#endif
118
119 while ((opt = getopt(argc, argv, tail_opts)) > 0) {
120 switch (opt) {
121 case 'f':
122 follow = 1;
123 break;
124 case 'c':
125 count_bytes = 1;
126 /* FALLS THROUGH */
127 case 'n':
128#if !ENABLE_DEBUG_YANK_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
129 GET_COUNT:
130#endif
131 count = bb_xgetlarg10_sfx(optarg, tail_suffixes);
132 /* Note: Leading whitespace is an error trapped above. */
133 if (*optarg == '+') {
134 from_top = 1;
135 } else {
136 from_top = 0;
137 }
138 if (count < 0) {
139 count = -count;
140 }
141 break;
142#if ENABLE_FEATURE_FANCY_TAIL
143 case 'q':
144 header_threshhold = INT_MAX;
145 break;
146 case 's':
147 sleep_period =bb_xgetularg10_bnd(optarg, 0, UINT_MAX);
148 break;
149 case 'v':
150 header_threshhold = 0;
151 break;
152#endif
153 default:
154 bb_show_usage();
155 }
156 }
157
158 /* open all the files */
159 fds = (int *)xmalloc(sizeof(int) * (argc - optind + 1));
160
161 argv += optind;
162 nfiles = i = 0;
163
164 if ((argc -= optind) == 0) {
165 struct stat statbuf;
166
167 if (!fstat(STDIN_FILENO, &statbuf) && S_ISFIFO(statbuf.st_mode)) {
168 follow = 0;
169 }
170 /* --argv; */
171 *argv = (char *) bb_msg_standard_input;
172 goto DO_STDIN;
173 }
174
175 do {
176 if ((argv[i][0] == '-') && !argv[i][1]) {
177 DO_STDIN:
178 fds[nfiles] = STDIN_FILENO;
179 } else if ((fds[nfiles] = open(argv[i], O_RDONLY)) < 0) {
180 bb_perror_msg("%s", argv[i]);
181 status = EXIT_FAILURE;
182 continue;
183 }
184 argv[nfiles] = argv[i];
185 ++nfiles;
186 } while (++i < argc);
187
188 if (!nfiles) {
189 bb_error_msg_and_die("no files");
190 }
191
192 tailbufsize = BUFSIZ;
193
194 /* tail the files */
195 if (from_top < count_bytes) { /* Each is 0 or 1, so true iff 0 < 1. */
196 /* Hence, !from_top && count_bytes */
197 if (tailbufsize < count) {
198 tailbufsize = count + BUFSIZ;
199 }
200 }
201
202 buf = tailbuf = xmalloc(tailbufsize);
203
204 fmt = header_fmt + 1; /* Skip header leading newline on first output. */
205 i = 0;
206 do {
207 /* Be careful. It would be possible to optimize the count-bytes
208 * case if the file is seekable. If you do though, remember that
209 * starting file position may not be the beginning of the file.
210 * Beware of backing up too far. See example in wc.c.
211 */
212 if ((!(count|from_top)) && (lseek(fds[i], 0, SEEK_END) >= 0)) {
213 continue;
214 }
215
216 if (nfiles > header_threshhold) {
217 tail_xprint_header(fmt, argv[i]);
218 fmt = header_fmt;
219 }
220
221 buf = tailbuf;
222 taillen = 0;
223 seen = 1;
224 newline = 0;
225
226 while ((nread = tail_read(fds[i], buf, tailbufsize-taillen)) > 0) {
227 if (from_top) {
228 nwrite = nread;
229 if (seen < count) {
230 if (count_bytes) {
231 nwrite -= (count - seen);
232 seen = count;
233 } else {
234 s = buf;
235 do {
236 --nwrite;
237 if ((*s++ == '\n') && (++seen == count)) {
238 break;
239 }
240 } while (nwrite);
241 }
242 }
243 tail_xbb_full_write(buf + nread - nwrite, nwrite);
244 } else if (count) {
245 if (count_bytes) {
246 taillen += nread;
247 if (taillen > count) {
248 memmove(tailbuf, tailbuf + taillen - count, count);
249 taillen = count;
250 }
251 } else {
252 int k = nread;
253 int nbuf = 0;
254
255 while (k) {
256 --k;
257 if (buf[k] == '\n') {
258 ++nbuf;
259 }
260 }
261
262 if (newline + nbuf < count) {
263 newline += nbuf;
264 taillen += nread;
265
266 } else {
267 int extra = 0;
268 if (buf[nread-1] != '\n') {
269 extra = 1;
270 }
271
272 k = newline + nbuf + extra - count;
273 s = tailbuf;
274 while (k) {
275 if (*s == '\n') {
276 --k;
277 }
278 ++s;
279 }
280
281 taillen += nread - (s - tailbuf);
282 memmove(tailbuf, s, taillen);
283 newline = count - extra;
284 }
285 if (tailbufsize < taillen + BUFSIZ) {
286 tailbufsize = taillen + BUFSIZ;
287 tailbuf = xrealloc(tailbuf, tailbufsize);
288 }
289 }
290 buf = tailbuf + taillen;
291 }
292 }
293
294 if (!from_top) {
295 tail_xbb_full_write(tailbuf, taillen);
296 }
297
298 taillen = 0;
299 } while (++i < nfiles);
300
301 buf = xrealloc(tailbuf, BUFSIZ);
302
303 fmt = NULL;
304
305 while (follow) {
306 sleep(sleep_period);
307 i = 0;
308 do {
309 if (nfiles > header_threshhold) {
310 fmt = header_fmt;
311 }
312 while ((nread = tail_read(fds[i], buf, sizeof(buf))) > 0) {
313 if (fmt) {
314 tail_xprint_header(fmt, argv[i]);
315 fmt = NULL;
316 }
317 tail_xbb_full_write(buf, nread);
318 }
319 } while (++i < nfiles);
320 }
321
322 return status;
323}
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