Contents of /tags/mkinitrd-6_1_12/busybox/coreutils/tail.c
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Tue Nov 17 21:24:51 2009 UTC (14 years, 10 months ago) by niro
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Tue Nov 17 21:24:51 2009 UTC (14 years, 10 months ago) by niro
File MIME type: text/plain
File size: 6874 byte(s)
tagged 'mkinitrd-6_1_12'
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 "libbb.h" |
28 | |
29 | static const struct suffix_mult tail_suffixes[] = { |
30 | { "b", 512 }, |
31 | { "k", 1024 }, |
32 | { "m", 1024*1024 }, |
33 | { } |
34 | }; |
35 | |
36 | struct globals { |
37 | bool status; |
38 | }; |
39 | #define G (*(struct globals*)&bb_common_bufsiz1) |
40 | |
41 | static void tail_xprint_header(const char *fmt, const char *filename) |
42 | { |
43 | if (fdprintf(STDOUT_FILENO, fmt, filename) < 0) |
44 | bb_perror_nomsg_and_die(); |
45 | } |
46 | |
47 | static ssize_t tail_read(int fd, char *buf, size_t count) |
48 | { |
49 | ssize_t r; |
50 | off_t current; |
51 | struct stat sbuf; |
52 | |
53 | /* (A good comment is missing here) */ |
54 | current = lseek(fd, 0, SEEK_CUR); |
55 | /* /proc files report zero st_size, don't lseek them. */ |
56 | if (fstat(fd, &sbuf) == 0 && sbuf.st_size) |
57 | if (sbuf.st_size < current) |
58 | lseek(fd, 0, SEEK_SET); |
59 | |
60 | r = full_read(fd, buf, count); |
61 | if (r < 0) { |
62 | bb_perror_msg(bb_msg_read_error); |
63 | G.status = EXIT_FAILURE; |
64 | } |
65 | |
66 | return r; |
67 | } |
68 | |
69 | static const char header_fmt[] ALIGN1 = "\n==> %s <==\n"; |
70 | |
71 | static unsigned eat_num(const char *p) |
72 | { |
73 | if (*p == '-') |
74 | p++; |
75 | else if (*p == '+') { |
76 | p++; |
77 | G.status = 1; /* mark that we saw "+" */ |
78 | } |
79 | return xatou_sfx(p, tail_suffixes); |
80 | } |
81 | |
82 | int tail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
83 | int tail_main(int argc, char **argv) |
84 | { |
85 | unsigned count = 10; |
86 | unsigned sleep_period = 1; |
87 | bool from_top; |
88 | int header_threshhold = 1; |
89 | const char *str_c, *str_n; |
90 | |
91 | char *tailbuf; |
92 | size_t tailbufsize; |
93 | int taillen = 0; |
94 | int newlines_seen = 0; |
95 | int nfiles, nread, nwrite, i, opt; |
96 | unsigned seen; |
97 | |
98 | int *fds; |
99 | char *s, *buf; |
100 | const char *fmt; |
101 | |
102 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL |
103 | /* Allow legacy syntax of an initial numeric option without -n. */ |
104 | if (argv[1] && (argv[1][0] == '+' || argv[1][0] == '-') |
105 | && isdigit(argv[1][1]) |
106 | ) { |
107 | count = eat_num(argv[1]); |
108 | argv++; |
109 | argc--; |
110 | } |
111 | #endif |
112 | |
113 | USE_FEATURE_FANCY_TAIL(opt_complementary = "s+";) /* -s N */ |
114 | opt = getopt32(argv, "fc:n:" USE_FEATURE_FANCY_TAIL("qs:v"), |
115 | &str_c, &str_n USE_FEATURE_FANCY_TAIL(,&sleep_period)); |
116 | #define FOLLOW (opt & 0x1) |
117 | #define COUNT_BYTES (opt & 0x2) |
118 | //if (opt & 0x1) // -f |
119 | if (opt & 0x2) count = eat_num(str_c); // -c |
120 | if (opt & 0x4) count = eat_num(str_n); // -n |
121 | #if ENABLE_FEATURE_FANCY_TAIL |
122 | if (opt & 0x8) header_threshhold = INT_MAX; // -q |
123 | if (opt & 0x20) header_threshhold = 0; // -v |
124 | #endif |
125 | argc -= optind; |
126 | argv += optind; |
127 | from_top = G.status; /* 1 if there was "-c +N" or "-n +N" */ |
128 | G.status = EXIT_SUCCESS; |
129 | |
130 | /* open all the files */ |
131 | fds = xmalloc(sizeof(int) * (argc + 1)); |
132 | if (!argv[0]) { |
133 | struct stat statbuf; |
134 | |
135 | if (!fstat(STDIN_FILENO, &statbuf) && S_ISFIFO(statbuf.st_mode)) { |
136 | opt &= ~1; /* clear FOLLOW */ |
137 | } |
138 | *argv = (char *) bb_msg_standard_input; |
139 | } |
140 | nfiles = i = 0; |
141 | do { |
142 | int fd = open_or_warn_stdin(argv[i]); |
143 | if (fd < 0) { |
144 | G.status = EXIT_FAILURE; |
145 | continue; |
146 | } |
147 | fds[nfiles] = fd; |
148 | argv[nfiles++] = argv[i]; |
149 | } while (++i < argc); |
150 | |
151 | if (!nfiles) |
152 | bb_error_msg_and_die("no files"); |
153 | |
154 | /* prepare the buffer */ |
155 | tailbufsize = BUFSIZ; |
156 | if (!from_top && COUNT_BYTES) { |
157 | if (tailbufsize < count + BUFSIZ) { |
158 | tailbufsize = count + BUFSIZ; |
159 | } |
160 | } |
161 | tailbuf = xmalloc(tailbufsize); |
162 | |
163 | /* tail the files */ |
164 | fmt = header_fmt + 1; /* Skip header leading newline on first output. */ |
165 | i = 0; |
166 | do { |
167 | if (nfiles > header_threshhold) { |
168 | tail_xprint_header(fmt, argv[i]); |
169 | fmt = header_fmt; |
170 | } |
171 | |
172 | /* Optimizing count-bytes case if the file is seekable. |
173 | * Beware of backing up too far. |
174 | * Also we exclude files with size 0 (because of /proc/xxx) */ |
175 | if (COUNT_BYTES && !from_top) { |
176 | off_t current = lseek(fds[i], 0, SEEK_END); |
177 | if (current > 0) { |
178 | if (count == 0) |
179 | continue; /* showing zero lines is easy :) */ |
180 | current -= count; |
181 | if (current < 0) |
182 | current = 0; |
183 | xlseek(fds[i], current, SEEK_SET); |
184 | bb_copyfd_size(fds[i], STDOUT_FILENO, count); |
185 | continue; |
186 | } |
187 | } |
188 | |
189 | buf = tailbuf; |
190 | taillen = 0; |
191 | seen = 1; |
192 | newlines_seen = 0; |
193 | while ((nread = tail_read(fds[i], buf, tailbufsize-taillen)) > 0) { |
194 | if (from_top) { |
195 | nwrite = nread; |
196 | if (seen < count) { |
197 | if (COUNT_BYTES) { |
198 | nwrite -= (count - seen); |
199 | seen = count; |
200 | } else { |
201 | s = buf; |
202 | do { |
203 | --nwrite; |
204 | if (*s++ == '\n' && ++seen == count) { |
205 | break; |
206 | } |
207 | } while (nwrite); |
208 | } |
209 | } |
210 | xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite); |
211 | } else if (count) { |
212 | if (COUNT_BYTES) { |
213 | taillen += nread; |
214 | if (taillen > (int)count) { |
215 | memmove(tailbuf, tailbuf + taillen - count, count); |
216 | taillen = count; |
217 | } |
218 | } else { |
219 | int k = nread; |
220 | int newlines_in_buf = 0; |
221 | |
222 | do { /* count '\n' in last read */ |
223 | k--; |
224 | if (buf[k] == '\n') { |
225 | newlines_in_buf++; |
226 | } |
227 | } while (k); |
228 | |
229 | if (newlines_seen + newlines_in_buf < (int)count) { |
230 | newlines_seen += newlines_in_buf; |
231 | taillen += nread; |
232 | } else { |
233 | int extra = (buf[nread-1] != '\n'); |
234 | |
235 | k = newlines_seen + newlines_in_buf + extra - count; |
236 | s = tailbuf; |
237 | while (k) { |
238 | if (*s == '\n') { |
239 | k--; |
240 | } |
241 | s++; |
242 | } |
243 | taillen += nread - (s - tailbuf); |
244 | memmove(tailbuf, s, taillen); |
245 | newlines_seen = count - extra; |
246 | } |
247 | if (tailbufsize < (size_t)taillen + BUFSIZ) { |
248 | tailbufsize = taillen + BUFSIZ; |
249 | tailbuf = xrealloc(tailbuf, tailbufsize); |
250 | } |
251 | } |
252 | buf = tailbuf + taillen; |
253 | } |
254 | } /* while (tail_read() > 0) */ |
255 | if (!from_top) { |
256 | xwrite(STDOUT_FILENO, tailbuf, taillen); |
257 | } |
258 | } while (++i < nfiles); |
259 | |
260 | buf = xrealloc(tailbuf, BUFSIZ); |
261 | |
262 | fmt = NULL; |
263 | |
264 | if (FOLLOW) while (1) { |
265 | sleep(sleep_period); |
266 | i = 0; |
267 | do { |
268 | if (nfiles > header_threshhold) { |
269 | fmt = header_fmt; |
270 | } |
271 | while ((nread = tail_read(fds[i], buf, BUFSIZ)) > 0) { |
272 | if (fmt) { |
273 | tail_xprint_header(fmt, argv[i]); |
274 | fmt = NULL; |
275 | } |
276 | xwrite(STDOUT_FILENO, buf, nread); |
277 | } |
278 | } while (++i < nfiles); |
279 | } |
280 | if (ENABLE_FEATURE_CLEAN_UP) { |
281 | free(fds); |
282 | } |
283 | return G.status; |
284 | } |