[3320] | 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 source tree.
|
---|
| 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 | { "", 0 }
|
---|
| 34 | };
|
---|
| 35 |
|
---|
| 36 | struct globals {
|
---|
| 37 | bool status;
|
---|
| 38 | } FIX_ALIASING;
|
---|
| 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 | /* /proc files report zero st_size, don't lseek them. */
|
---|
| 54 | if (fstat(fd, &sbuf) == 0 && sbuf.st_size > 0) {
|
---|
| 55 | current = lseek(fd, 0, SEEK_CUR);
|
---|
| 56 | if (sbuf.st_size < current)
|
---|
| 57 | xlseek(fd, 0, SEEK_SET);
|
---|
| 58 | }
|
---|
| 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 | #define header_fmt_str "\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 | const char *str_c, *str_n;
|
---|
| 89 |
|
---|
| 90 | char *tailbuf;
|
---|
| 91 | size_t tailbufsize;
|
---|
| 92 | unsigned header_threshhold = 1;
|
---|
| 93 | unsigned nfiles;
|
---|
| 94 | int i, opt;
|
---|
| 95 |
|
---|
| 96 | int *fds;
|
---|
| 97 | const char *fmt;
|
---|
| 98 |
|
---|
| 99 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
|
---|
| 100 | /* Allow legacy syntax of an initial numeric option without -n. */
|
---|
| 101 | if (argv[1] && (argv[1][0] == '+' || argv[1][0] == '-')
|
---|
| 102 | && isdigit(argv[1][1])
|
---|
| 103 | ) {
|
---|
| 104 | count = eat_num(argv[1]);
|
---|
| 105 | argv++;
|
---|
| 106 | argc--;
|
---|
| 107 | }
|
---|
| 108 | #endif
|
---|
| 109 |
|
---|
| 110 | /* -s NUM, -F imlies -f */
|
---|
| 111 | IF_FEATURE_FANCY_TAIL(opt_complementary = "s+:Ff";)
|
---|
| 112 | opt = getopt32(argv, "fc:n:" IF_FEATURE_FANCY_TAIL("qs:vF"),
|
---|
| 113 | &str_c, &str_n IF_FEATURE_FANCY_TAIL(,&sleep_period));
|
---|
| 114 | #define FOLLOW (opt & 0x1)
|
---|
| 115 | #define COUNT_BYTES (opt & 0x2)
|
---|
| 116 | //if (opt & 0x1) // -f
|
---|
| 117 | if (opt & 0x2) count = eat_num(str_c); // -c
|
---|
| 118 | if (opt & 0x4) count = eat_num(str_n); // -n
|
---|
| 119 | #if ENABLE_FEATURE_FANCY_TAIL
|
---|
| 120 | /* q: make it impossible for nfiles to be > header_threshhold */
|
---|
| 121 | if (opt & 0x8) header_threshhold = UINT_MAX; // -q
|
---|
| 122 | //if (opt & 0x10) // -s
|
---|
| 123 | if (opt & 0x20) header_threshhold = 0; // -v
|
---|
| 124 | # define FOLLOW_RETRY (opt & 0x40)
|
---|
| 125 | #else
|
---|
| 126 | # define FOLLOW_RETRY 0
|
---|
| 127 | #endif
|
---|
| 128 | argc -= optind;
|
---|
| 129 | argv += optind;
|
---|
| 130 | from_top = G.status; /* 1 if there was "-c +N" or "-n +N" */
|
---|
| 131 | G.status = EXIT_SUCCESS;
|
---|
| 132 |
|
---|
| 133 | /* open all the files */
|
---|
| 134 | fds = xmalloc(sizeof(fds[0]) * (argc + 1));
|
---|
| 135 | if (!argv[0]) {
|
---|
| 136 | struct stat statbuf;
|
---|
| 137 |
|
---|
| 138 | if (fstat(STDIN_FILENO, &statbuf) == 0
|
---|
| 139 | && S_ISFIFO(statbuf.st_mode)
|
---|
| 140 | ) {
|
---|
| 141 | opt &= ~1; /* clear FOLLOW */
|
---|
| 142 | }
|
---|
| 143 | argv[0] = (char *) bb_msg_standard_input;
|
---|
| 144 | }
|
---|
| 145 | nfiles = i = 0;
|
---|
| 146 | do {
|
---|
| 147 | int fd = open_or_warn_stdin(argv[i]);
|
---|
| 148 | if (fd < 0 && !FOLLOW_RETRY) {
|
---|
| 149 | G.status = EXIT_FAILURE;
|
---|
| 150 | continue;
|
---|
| 151 | }
|
---|
| 152 | fds[nfiles] = fd;
|
---|
| 153 | argv[nfiles++] = argv[i];
|
---|
| 154 | } while (++i < argc);
|
---|
| 155 |
|
---|
| 156 | if (!nfiles)
|
---|
| 157 | bb_error_msg_and_die("no files");
|
---|
| 158 |
|
---|
| 159 | /* prepare the buffer */
|
---|
| 160 | tailbufsize = BUFSIZ;
|
---|
| 161 | if (!from_top && COUNT_BYTES) {
|
---|
| 162 | if (tailbufsize < count + BUFSIZ) {
|
---|
| 163 | tailbufsize = count + BUFSIZ;
|
---|
| 164 | }
|
---|
| 165 | }
|
---|
| 166 | tailbuf = xmalloc(tailbufsize);
|
---|
| 167 |
|
---|
| 168 | /* tail the files */
|
---|
| 169 | fmt = header_fmt_str + 1; /* skip header leading newline on first output */
|
---|
| 170 | i = 0;
|
---|
| 171 | do {
|
---|
| 172 | char *buf;
|
---|
| 173 | int taillen;
|
---|
| 174 | int newlines_seen;
|
---|
| 175 | unsigned seen;
|
---|
| 176 | int nread;
|
---|
| 177 | int fd = fds[i];
|
---|
| 178 |
|
---|
| 179 | if (ENABLE_FEATURE_FANCY_TAIL && fd < 0)
|
---|
| 180 | continue; /* may happen with -E */
|
---|
| 181 |
|
---|
| 182 | if (nfiles > header_threshhold) {
|
---|
| 183 | tail_xprint_header(fmt, argv[i]);
|
---|
| 184 | fmt = header_fmt_str;
|
---|
| 185 | }
|
---|
| 186 |
|
---|
| 187 | if (!from_top) {
|
---|
| 188 | off_t current = lseek(fd, 0, SEEK_END);
|
---|
| 189 | if (current > 0) {
|
---|
| 190 | unsigned off;
|
---|
| 191 | if (COUNT_BYTES) {
|
---|
| 192 | /* Optimizing count-bytes case if the file is seekable.
|
---|
| 193 | * Beware of backing up too far.
|
---|
| 194 | * Also we exclude files with size 0 (because of /proc/xxx) */
|
---|
| 195 | if (count == 0)
|
---|
| 196 | continue; /* showing zero bytes is easy :) */
|
---|
| 197 | current -= count;
|
---|
| 198 | if (current < 0)
|
---|
| 199 | current = 0;
|
---|
| 200 | xlseek(fd, current, SEEK_SET);
|
---|
| 201 | bb_copyfd_size(fd, STDOUT_FILENO, count);
|
---|
| 202 | continue;
|
---|
| 203 | }
|
---|
| 204 | #if 1 /* This is technically incorrect for *LONG* strings, but very useful */
|
---|
| 205 | /* Optimizing count-lines case if the file is seekable.
|
---|
| 206 | * We assume the lines are <64k.
|
---|
| 207 | * (Users complain that tail takes too long
|
---|
| 208 | * on multi-gigabyte files) */
|
---|
| 209 | off = (count | 0xf); /* for small counts, be more paranoid */
|
---|
| 210 | if (off > (INT_MAX / (64*1024)))
|
---|
| 211 | off = (INT_MAX / (64*1024));
|
---|
| 212 | current -= off * (64*1024);
|
---|
| 213 | if (current < 0)
|
---|
| 214 | current = 0;
|
---|
| 215 | xlseek(fd, current, SEEK_SET);
|
---|
| 216 | #endif
|
---|
| 217 | }
|
---|
| 218 | }
|
---|
| 219 |
|
---|
| 220 | buf = tailbuf;
|
---|
| 221 | taillen = 0;
|
---|
| 222 | /* "We saw 1st line/byte".
|
---|
| 223 | * Used only by +N code ("start from Nth", 1-based): */
|
---|
| 224 | seen = 1;
|
---|
| 225 | newlines_seen = 0;
|
---|
| 226 | while ((nread = tail_read(fd, buf, tailbufsize-taillen)) > 0) {
|
---|
| 227 | if (from_top) {
|
---|
| 228 | int nwrite = nread;
|
---|
| 229 | if (seen < count) {
|
---|
| 230 | /* We need to skip a few more bytes/lines */
|
---|
| 231 | if (COUNT_BYTES) {
|
---|
| 232 | nwrite -= (count - seen);
|
---|
| 233 | seen = count;
|
---|
| 234 | } else {
|
---|
| 235 | char *s = buf;
|
---|
| 236 | do {
|
---|
| 237 | --nwrite;
|
---|
| 238 | if (*s++ == '\n' && ++seen == count) {
|
---|
| 239 | break;
|
---|
| 240 | }
|
---|
| 241 | } while (nwrite);
|
---|
| 242 | }
|
---|
| 243 | }
|
---|
| 244 | if (nwrite > 0)
|
---|
| 245 | xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite);
|
---|
| 246 | } else if (count) {
|
---|
| 247 | if (COUNT_BYTES) {
|
---|
| 248 | taillen += nread;
|
---|
| 249 | if (taillen > (int)count) {
|
---|
| 250 | memmove(tailbuf, tailbuf + taillen - count, count);
|
---|
| 251 | taillen = count;
|
---|
| 252 | }
|
---|
| 253 | } else {
|
---|
| 254 | int k = nread;
|
---|
| 255 | int newlines_in_buf = 0;
|
---|
| 256 |
|
---|
| 257 | do { /* count '\n' in last read */
|
---|
| 258 | k--;
|
---|
| 259 | if (buf[k] == '\n') {
|
---|
| 260 | newlines_in_buf++;
|
---|
| 261 | }
|
---|
| 262 | } while (k);
|
---|
| 263 |
|
---|
| 264 | if (newlines_seen + newlines_in_buf < (int)count) {
|
---|
| 265 | newlines_seen += newlines_in_buf;
|
---|
| 266 | taillen += nread;
|
---|
| 267 | } else {
|
---|
| 268 | int extra = (buf[nread-1] != '\n');
|
---|
| 269 | char *s;
|
---|
| 270 |
|
---|
| 271 | k = newlines_seen + newlines_in_buf + extra - count;
|
---|
| 272 | s = tailbuf;
|
---|
| 273 | while (k) {
|
---|
| 274 | if (*s == '\n') {
|
---|
| 275 | k--;
|
---|
| 276 | }
|
---|
| 277 | s++;
|
---|
| 278 | }
|
---|
| 279 | taillen += nread - (s - tailbuf);
|
---|
| 280 | memmove(tailbuf, s, taillen);
|
---|
| 281 | newlines_seen = count - extra;
|
---|
| 282 | }
|
---|
| 283 | if (tailbufsize < (size_t)taillen + BUFSIZ) {
|
---|
| 284 | tailbufsize = taillen + BUFSIZ;
|
---|
| 285 | tailbuf = xrealloc(tailbuf, tailbufsize);
|
---|
| 286 | }
|
---|
| 287 | }
|
---|
| 288 | buf = tailbuf + taillen;
|
---|
| 289 | }
|
---|
| 290 | } /* while (tail_read() > 0) */
|
---|
| 291 | if (!from_top) {
|
---|
| 292 | xwrite(STDOUT_FILENO, tailbuf, taillen);
|
---|
| 293 | }
|
---|
| 294 | } while (++i < nfiles);
|
---|
| 295 |
|
---|
| 296 | tailbuf = xrealloc(tailbuf, BUFSIZ);
|
---|
| 297 |
|
---|
| 298 | fmt = NULL;
|
---|
| 299 |
|
---|
| 300 | if (FOLLOW) while (1) {
|
---|
| 301 | sleep(sleep_period);
|
---|
| 302 |
|
---|
| 303 | i = 0;
|
---|
| 304 | do {
|
---|
| 305 | int nread;
|
---|
| 306 | const char *filename = argv[i];
|
---|
| 307 | int fd = fds[i];
|
---|
| 308 |
|
---|
| 309 | if (FOLLOW_RETRY) {
|
---|
| 310 | struct stat sbuf, fsbuf;
|
---|
| 311 |
|
---|
| 312 | if (fd < 0
|
---|
| 313 | || fstat(fd, &fsbuf) < 0
|
---|
| 314 | || stat(filename, &sbuf) < 0
|
---|
| 315 | || fsbuf.st_dev != sbuf.st_dev
|
---|
| 316 | || fsbuf.st_ino != sbuf.st_ino
|
---|
| 317 | ) {
|
---|
| 318 | int new_fd;
|
---|
| 319 |
|
---|
| 320 | if (fd >= 0)
|
---|
| 321 | close(fd);
|
---|
| 322 | new_fd = open(filename, O_RDONLY);
|
---|
| 323 | if (new_fd >= 0) {
|
---|
| 324 | bb_error_msg("%s has %s; following end of new file",
|
---|
| 325 | filename, (fd < 0) ? "appeared" : "been replaced"
|
---|
| 326 | );
|
---|
| 327 | } else if (fd >= 0) {
|
---|
| 328 | bb_perror_msg("%s has become inaccessible", filename);
|
---|
| 329 | }
|
---|
| 330 | fds[i] = fd = new_fd;
|
---|
| 331 | }
|
---|
| 332 | }
|
---|
| 333 | if (ENABLE_FEATURE_FANCY_TAIL && fd < 0)
|
---|
| 334 | continue;
|
---|
| 335 | if (nfiles > header_threshhold) {
|
---|
| 336 | fmt = header_fmt_str;
|
---|
| 337 | }
|
---|
| 338 | while ((nread = tail_read(fd, tailbuf, BUFSIZ)) > 0) {
|
---|
| 339 | if (fmt) {
|
---|
| 340 | tail_xprint_header(fmt, filename);
|
---|
| 341 | fmt = NULL;
|
---|
| 342 | }
|
---|
| 343 | xwrite(STDOUT_FILENO, tailbuf, nread);
|
---|
| 344 | }
|
---|
| 345 | } while (++i < nfiles);
|
---|
| 346 | }
|
---|
| 347 | if (ENABLE_FEATURE_CLEAN_UP) {
|
---|
| 348 | free(fds);
|
---|
| 349 | free(tailbuf);
|
---|
| 350 | }
|
---|
| 351 | return G.status;
|
---|
| 352 | }
|
---|