login-utils/utmpdump.c

   1 /*
   2  * utmpdump
   3  *
   4  * Simple program to dump UTMP and WTMP files in raw format, so they can be
   5  * examined.
   6  *
   7  * Based on utmpdump dump from sysvinit suite.
   8  *
   9  * Copyright (C) 1991-2000 Miquel van Smoorenburg <miquels@cistron.nl>
  10  *
  11  * Copyright (C) 1998 Danek Duvall <duvall@alumni.princeton.edu>
  12  * Copyright (C) 2012 Karel Zak <kzak@redhat.com>
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, write to the Free Software
  26  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  27  */
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <utmpx.h>
  32 #include <time.h>
  33 #include <ctype.h>
  34 #include <getopt.h>
  35 #include <unistd.h>
  36 #include <netinet/in.h>
  37 #include <arpa/inet.h>
  38 #include <sys/stat.h>
  39 #ifdef HAVE_INOTIFY_INIT
  40 #include <sys/inotify.h>
  41 #endif
  42
  43 #include "c.h"
  44 #include "nls.h"
  45 #include "timeutils.h"
  46 #include "xalloc.h"
  47 #include "closestream.h"
  48
  49 static time_t strtotime(const char *s_time)
  50 {
  51         struct tm tm;
  52
  53         memset(&tm, '\0', sizeof(struct tm));
  54
  55         if (s_time[0] == ' ' || s_time[0] == '\0')
  56                 return (time_t)0;
  57
  58         if (isdigit(s_time[0])) {
  59                 /* [1998-09-01T01:00:00,000000+00:00]
  60                  * Subseconds are parsed with strtousec().  Timezone is
  61                  * always UTC-0 */
  62                 strptime(s_time, "%Y-%m-%dT%H:%M:%S", &tm);
  63         } else {
  64                 /* [Tue Sep 01 00:00:00 1998 GMT] */
  65                 strptime(s_time, "%a %b %d %T %Y", &tm);
  66                 /* Cheesy way of checking for DST.  This could be needed
  67                  * with legacy dumps that used localtime(3).  */
  68                 if (s_time[26] == 'D')
  69                         tm.tm_isdst = 1;
  70         }
  71         return timegm(&tm);
  72 }
  73
  74 static suseconds_t strtousec(const char *s_time)
  75 {
  76         const char *s = strchr(s_time, ',');
  77         if (s)
  78                 return (suseconds_t) atoi(s + 1);
  79         return 0;
  80 }
  81
  82 #define cleanse(x) xcleanse(x, sizeof(x))
  83 static void xcleanse(char *s, int len)
  84 {
  85         for ( ; *s && len-- > 0; s++)
  86                 if (!isprint(*s) || *s == '[' || *s == ']')
  87                         *s = '?';
  88 }
  89
  90 static void print_utline(struct utmpx *ut, FILE *out)
  91 {
  92         const char *addr_string;
  93         char buffer[INET6_ADDRSTRLEN];
  94         char time_string[40];
  95         struct timeval tv;
  96
  97         if (ut->ut_addr_v6[1] || ut->ut_addr_v6[2] || ut->ut_addr_v6[3])
  98                 addr_string = inet_ntop(AF_INET6, &(ut->ut_addr_v6), buffer, sizeof(buffer));
  99         else
 100                 addr_string = inet_ntop(AF_INET, &(ut->ut_addr_v6), buffer, sizeof(buffer));
 101
 102         tv.tv_sec = ut->ut_tv.tv_sec;
 103         tv.tv_usec = ut->ut_tv.tv_usec;
 104
 105         if (strtimeval_iso(&tv,
 106                            ISO_8601_DATE | ISO_8601_TIME | ISO_8601_COMMAUSEC |
 107                            ISO_8601_TIMEZONE | ISO_8601_GMTIME, time_string,
 108                            sizeof(time_string)) != 0)
 109                 return;
 110         cleanse(ut->ut_id);
 111         cleanse(ut->ut_user);
 112         cleanse(ut->ut_line);
 113         cleanse(ut->ut_host);
 114
 115         /*            type pid    id       user     line     host     addr    time */
 116         fprintf(out, "[%d] [%05d] [%-4.4s] [%-*.*s] [%-*.*s] [%-*.*s] [%-15s] [%s]\n",
 117                ut->ut_type, ut->ut_pid, ut->ut_id,
 118                8, (int)sizeof(ut->ut_user), ut->ut_user,
 119                12, (int)sizeof(ut->ut_line), ut->ut_line,
 120                20, (int)sizeof(ut->ut_host), ut->ut_host,
 121                addr_string, time_string);
 122 }
 123
 124 #ifdef HAVE_INOTIFY_INIT
 125 #define EVENTS          (IN_MODIFY|IN_DELETE_SELF|IN_MOVE_SELF|IN_UNMOUNT)
 126 #define NEVENTS         4
 127
 128 static void roll_file(const char *filename, off_t *size, FILE *out)
 129 {
 130         FILE *in;
 131         struct stat st;
 132         struct utmpx ut;
 133         off_t pos;
 134
 135         if (!(in = fopen(filename, "r")))
 136                 err(EXIT_FAILURE, _("cannot open %s"), filename);
 137
 138         if (fstat(fileno(in), &st) == -1)
 139                 err(EXIT_FAILURE, _("stat of %s failed"), filename);
 140
 141         if (st.st_size == *size)
 142                 goto done;
 143
 144         if (fseek(in, *size, SEEK_SET) != (off_t) -1) {
 145                 while (fread(&ut, sizeof(ut), 1, in) == 1)
 146                         print_utline(&ut, out);
 147         }
 148
 149         pos = ftello(in);
 150         /* If we've successfully read something, use the file position, this
 151          * avoids data duplication.  If we read nothing or hit an error,
 152          * reset to the reported size, this handles truncated files.
 153          */
 154         *size = (pos != -1 && pos != *size) ? pos : st.st_size;
 155
 156 done:
 157         fclose(in);
 158 }
 159
 160 static int follow_by_inotify(FILE *in, const char *filename, FILE *out)
 161 {
 162         char buf[NEVENTS * sizeof(struct inotify_event)];
 163         int fd, wd, event;
 164         ssize_t length;
 165         off_t size;
 166
 167         fd = inotify_init();
 168         if (fd == -1)
 169                 return -1;      /* probably reached any limit ... */
 170
 171         size = ftello(in);
 172         fclose(in);
 173
 174         wd = inotify_add_watch(fd, filename, EVENTS);
 175         if (wd == -1)
 176                 err(EXIT_FAILURE, _("%s: cannot add inotify watch."), filename);
 177
 178         while (wd >= 0) {
 179                 errno = 0;
 180                 length = read(fd, buf, sizeof(buf));
 181
 182                 if (length < 0 && (errno == EINTR || errno == EAGAIN))
 183                         continue;
 184                 if (length < 0)
 185                         err(EXIT_FAILURE, _("%s: cannot read inotify events"),
 186                                     filename);
 187
 188                 for (event = 0; event < length;) {
 189                         struct inotify_event *ev =
 190                                     (struct inotify_event *) &buf[event];
 191
 192                         if (ev->mask & IN_MODIFY)
 193                                 roll_file(filename, &size, out);
 194                         else {
 195                                 close(wd);
 196                                 wd = -1;
 197                                 break;
 198                         }
 199                         event += sizeof(struct inotify_event) + ev->len;
 200                 }
 201         }
 202
 203         close(fd);
 204         return 0;
 205 }
 206 #endif /* HAVE_INOTIFY_INIT */
 207
 208 static FILE *dump(FILE *in, const char *filename, int follow, FILE *out)
 209 {
 210         struct utmpx ut;
 211
 212         if (follow)
 213                 ignore_result( fseek(in, -10 * sizeof(ut), SEEK_END) );
 214
 215         while (fread(&ut, sizeof(ut), 1, in) == 1)
 216                 print_utline(&ut, out);
 217
 218         if (!follow)
 219                 return in;
 220
 221 #ifdef HAVE_INOTIFY_INIT
 222         if (follow_by_inotify(in, filename, out) == 0)
 223                 return NULL;                            /* file already closed */
 224         else
 225 #endif
 226                 /* fallback for systems without inotify or with non-free
 227                  * inotify instances */
 228                 for (;;) {
 229                         while (fread(&ut, sizeof(ut), 1, in) == 1)
 230                                 print_utline(&ut, out);
 231                         sleep(1);
 232                 }
 233
 234         return in;
 235 }
 236
 237
 238 /* This function won't work properly if there's a ']' or a ' ' in the real
 239  * token.  Thankfully, this should never happen.  */
 240 static int gettok(char *line, char *dest, int size, int eatspace)
 241 {
 242         int bpos, epos, eaten;
 243
 244         bpos = strchr(line, '[') - line;
 245         if (bpos < 0)
 246                 errx(EXIT_FAILURE, _("Extraneous newline in file. Exiting."));
 247
 248         line += 1 + bpos;
 249         epos = strchr(line, ']') - line;
 250         if (epos < 0)
 251                 errx(EXIT_FAILURE, _("Extraneous newline in file. Exiting."));
 252
 253         line[epos] = '\0';
 254         eaten = bpos + epos + 1;
 255
 256         if (eatspace) {
 257                 char *t;
 258                 if ((t = strchr(line, ' ')))
 259                         *t = 0;
 260         }
 261         strncpy(dest, line, size);
 262
 263         return eaten + 1;
 264 }
 265
 266 static void undump(FILE *in, FILE *out)
 267 {
 268         struct utmpx ut;
 269         char s_addr[INET6_ADDRSTRLEN + 1], s_time[29], *linestart, *line;
 270         int count = 0;
 271
 272         linestart = xmalloc(1024 * sizeof(*linestart));
 273         s_time[28] = 0;
 274
 275         while (fgets(linestart, 1023, in)) {
 276                 line = linestart;
 277                 memset(&ut, '\0', sizeof(ut));
 278                 sscanf(line, "[%hd] [%d] [%4c] ", &ut.ut_type, &ut.ut_pid, ut.ut_id);
 279
 280                 line += 19;
 281                 line += gettok(line, ut.ut_user, sizeof(ut.ut_user), 1);
 282                 line += gettok(line, ut.ut_line, sizeof(ut.ut_line), 1);
 283                 line += gettok(line, ut.ut_host, sizeof(ut.ut_host), 1);
 284                 line += gettok(line, s_addr, sizeof(s_addr) - 1, 1);
 285                 gettok(line, s_time, sizeof(s_time) - 1, 0);
 286                 if (strchr(s_addr, '.'))
 287                         inet_pton(AF_INET, s_addr, &(ut.ut_addr_v6));
 288                 else
 289                         inet_pton(AF_INET6, s_addr, &(ut.ut_addr_v6));
 290
 291                 ut.ut_tv.tv_sec = strtotime(s_time);
 292                 ut.ut_tv.tv_usec = strtousec(s_time);
 293
 294                 ignore_result( fwrite(&ut, sizeof(ut), 1, out) );
 295
 296                 ++count;
 297         }
 298
 299         free(linestart);
 300 }
 301
 302 static void __attribute__((__noreturn__)) usage(FILE *out)
 303 {
 304         fputs(USAGE_HEADER, out);
 305
 306         fprintf(out,
 307                 _(" %s [options] [filename]\n"), program_invocation_short_name);
 308
 309         fputs(USAGE_SEPARATOR, out);
 310         fputs(_("Dump UTMP and WTMP files in raw format.\n"), out);
 311
 312         fputs(USAGE_OPTIONS, out);
 313         fputs(_(" -f, --follow         output appended data as the file grows\n"), out);
 314         fputs(_(" -r, --reverse        write back dumped data into utmp file\n"), out);
 315         fputs(_(" -o, --output <file>  write to file instead of standard output\n"), out);
 316         fputs(USAGE_HELP, out);
 317         fputs(USAGE_VERSION, out);
 318
 319         fprintf(out, USAGE_MAN_TAIL("utmpdump(1)"));
 320         exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
 321 }
 322
 323 int main(int argc, char **argv)
 324 {
 325         int c;
 326         FILE *in = NULL, *out = NULL;
 327         int reverse = 0, follow = 0;
 328         const char *filename = NULL;
 329
 330         static const struct option longopts[] = {
 331                 { "follow",  0, 0, 'f' },
 332                 { "reverse", 0, 0, 'r' },
 333                 { "output",  required_argument, 0, 'o' },
 334                 { "help",    0, 0, 'h' },
 335                 { "version", 0, 0, 'V' },
 336                 { NULL, 0, 0, 0 }
 337         };
 338
 339         setlocale(LC_ALL, "");
 340         bindtextdomain(PACKAGE, LOCALEDIR);
 341         textdomain(PACKAGE);
 342         atexit(close_stdout);
 343
 344         while ((c = getopt_long(argc, argv, "fro:hV", longopts, NULL)) != -1) {
 345                 switch (c) {
 346                 case 'r':
 347                         reverse = 1;
 348                         break;
 349
 350                 case 'f':
 351                         follow = 1;
 352                         break;
 353
 354                 case 'o':
 355                         out = fopen(optarg, "w");
 356                         if (!out)
 357                                 err(EXIT_FAILURE, _("cannot open %s"),
 358                                     optarg);
 359                         break;
 360
 361                 case 'h':
 362                         usage(stdout);
 363                         break;
 364                 case 'V':
 365                         printf(UTIL_LINUX_VERSION);
 366                         return EXIT_SUCCESS;
 367                 default:
 368                         errtryhelp(EXIT_FAILURE);
 369                 }
 370         }
 371
 372         if (!out)
 373                 out = stdout;
 374
 375         if (optind < argc) {
 376                 filename = argv[optind];
 377                 in = fopen(filename, "r");
 378                 if (!in)
 379                         err(EXIT_FAILURE, _("cannot open %s"), filename);
 380         } else {
 381                 if (follow)
 382                         errx(EXIT_FAILURE, _("following standard input is unsupported"));
 383                 filename = "/dev/stdin";
 384                 in = stdin;
 385         }
 386
 387         if (reverse) {
 388                 fprintf(stderr, _("Utmp undump of %s\n"), filename);
 389                 undump(in, out);
 390         } else {
 391                 fprintf(stderr, _("Utmp dump of %s\n"), filename);
 392                 in = dump(in, filename, follow, out);
 393         }
 394
 395         if (out != stdout && close_stream(out))
 396                 err(EXIT_FAILURE, _("write failed"));
 397
 398         if (in && in != stdin)
 399                 fclose(in);
 400
 401         return EXIT_SUCCESS;
 402 }