| 1 | /* update-game-score.c --- Update a score file |
| 2 | |
| 3 | Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 |
| 4 | Free Software Foundation, Inc. |
| 5 | |
| 6 | Author: Colin Walters <walters@debian.org> |
| 7 | |
| 8 | This file is part of GNU Emacs. |
| 9 | |
| 10 | GNU Emacs is free software: you can redistribute it and/or modify |
| 11 | it under the terms of the GNU General Public License as published by |
| 12 | the Free Software Foundation, either version 3 of the License, or |
| 13 | (at your option) any later version. |
| 14 | |
| 15 | GNU Emacs is distributed in the hope that it will be useful, |
| 16 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | GNU General Public License for more details. |
| 19 | |
| 20 | You should have received a copy of the GNU General Public License |
| 21 | along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */ |
| 22 | |
| 23 | |
| 24 | /* This program is allows a game to securely and atomically update a |
| 25 | score file. It should be installed setuid, owned by an appropriate |
| 26 | user like `games'. |
| 27 | |
| 28 | Alternatively, it can be compiled without HAVE_SHARED_GAME_DIR |
| 29 | defined, and in that case it will store scores in the user's home |
| 30 | directory (it should NOT be setuid). |
| 31 | |
| 32 | Created 2002/03/22. |
| 33 | */ |
| 34 | |
| 35 | #include <config.h> |
| 36 | |
| 37 | #ifdef HAVE_UNISTD_H |
| 38 | #include <unistd.h> |
| 39 | #endif |
| 40 | #include <errno.h> |
| 41 | #ifdef HAVE_STRING_H |
| 42 | #include <string.h> |
| 43 | #endif |
| 44 | #ifdef HAVE_STDLIB_H |
| 45 | #include <stdlib.h> |
| 46 | #endif |
| 47 | #include <stdio.h> |
| 48 | #include <time.h> |
| 49 | #include <pwd.h> |
| 50 | #include <ctype.h> |
| 51 | #ifdef HAVE_FCNTL_H |
| 52 | #include <fcntl.h> |
| 53 | #endif |
| 54 | #ifdef STDC_HEADERS |
| 55 | #include <stdarg.h> |
| 56 | #endif |
| 57 | #include <sys/stat.h> |
| 58 | |
| 59 | /* Needed for SunOS4, for instance. */ |
| 60 | extern char *optarg; |
| 61 | extern int optind, opterr; |
| 62 | |
| 63 | #define MAX_ATTEMPTS 5 |
| 64 | #define MAX_SCORES 200 |
| 65 | #define MAX_DATA_LEN 1024 |
| 66 | |
| 67 | /* Declare the prototype for a general external function. */ |
| 68 | #if defined (PROTOTYPES) || defined (WINDOWSNT) |
| 69 | #define P_(proto) proto |
| 70 | #else |
| 71 | #define P_(proto) () |
| 72 | #endif |
| 73 | |
| 74 | #ifndef HAVE_DIFFTIME |
| 75 | /* OK on POSIX (time_t is arithmetic type) modulo overflow in subtraction. */ |
| 76 | #define difftime(t1, t0) (double)((t1) - (t0)) |
| 77 | #endif |
| 78 | |
| 79 | int |
| 80 | usage (err) |
| 81 | int err; |
| 82 | { |
| 83 | fprintf (stdout, "Usage: update-game-score [-m MAX ] [ -r ] game/scorefile SCORE DATA\n"); |
| 84 | fprintf (stdout, " update-game-score -h\n"); |
| 85 | fprintf (stdout, " -h\t\tDisplay this help.\n"); |
| 86 | fprintf (stdout, " -m MAX\t\tLimit the maximum number of scores to MAX.\n"); |
| 87 | fprintf (stdout, " -r\t\tSort the scores in increasing order.\n"); |
| 88 | fprintf (stdout, " -d DIR\t\tStore scores in DIR (only if not setuid).\n"); |
| 89 | exit (err); |
| 90 | } |
| 91 | |
| 92 | int lock_file P_ ((const char *filename, void **state)); |
| 93 | int unlock_file P_ ((const char *filename, void *state)); |
| 94 | |
| 95 | struct score_entry |
| 96 | { |
| 97 | long score; |
| 98 | char *username; |
| 99 | char *data; |
| 100 | }; |
| 101 | |
| 102 | int read_scores P_ ((const char *filename, struct score_entry **scores, |
| 103 | int *count)); |
| 104 | int push_score P_ ((struct score_entry **scores, int *count, |
| 105 | int newscore, char *username, char *newdata)); |
| 106 | void sort_scores P_ ((struct score_entry *scores, int count, int reverse)); |
| 107 | int write_scores P_ ((const char *filename, const struct score_entry *scores, |
| 108 | int count)); |
| 109 | |
| 110 | void lose P_ ((const char *msg)) NO_RETURN; |
| 111 | |
| 112 | void |
| 113 | lose (msg) |
| 114 | const char *msg; |
| 115 | { |
| 116 | fprintf (stderr, "%s\n", msg); |
| 117 | exit (EXIT_FAILURE); |
| 118 | } |
| 119 | |
| 120 | void lose_syserr P_ ((const char *msg)) NO_RETURN; |
| 121 | |
| 122 | /* Taken from sysdep.c. */ |
| 123 | #ifndef HAVE_STRERROR |
| 124 | #ifndef WINDOWSNT |
| 125 | char * |
| 126 | strerror (errnum) |
| 127 | int errnum; |
| 128 | { |
| 129 | extern char *sys_errlist[]; |
| 130 | extern int sys_nerr; |
| 131 | |
| 132 | if (errnum >= 0 && errnum < sys_nerr) |
| 133 | return sys_errlist[errnum]; |
| 134 | return (char *) "Unknown error"; |
| 135 | } |
| 136 | #endif /* not WINDOWSNT */ |
| 137 | #endif /* ! HAVE_STRERROR */ |
| 138 | |
| 139 | void |
| 140 | lose_syserr (msg) |
| 141 | const char *msg; |
| 142 | { |
| 143 | fprintf (stderr, "%s: %s\n", msg, strerror (errno)); |
| 144 | exit (EXIT_FAILURE); |
| 145 | } |
| 146 | |
| 147 | char * |
| 148 | get_user_id P_ ((void)) |
| 149 | { |
| 150 | char *name; |
| 151 | struct passwd *buf = getpwuid (getuid ()); |
| 152 | if (!buf) |
| 153 | { |
| 154 | int count = 1; |
| 155 | int uid = (int) getuid (); |
| 156 | int tuid = uid; |
| 157 | while (tuid /= 10) |
| 158 | count++; |
| 159 | name = malloc (count+1); |
| 160 | if (!name) |
| 161 | return NULL; |
| 162 | sprintf (name, "%d", uid); |
| 163 | return name; |
| 164 | } |
| 165 | return buf->pw_name; |
| 166 | } |
| 167 | |
| 168 | char * |
| 169 | get_prefix (running_suid, user_prefix) |
| 170 | int running_suid; |
| 171 | char *user_prefix; |
| 172 | { |
| 173 | if (!running_suid && user_prefix == NULL) |
| 174 | lose ("Not using a shared game directory, and no prefix given."); |
| 175 | if (running_suid) |
| 176 | { |
| 177 | #ifdef HAVE_SHARED_GAME_DIR |
| 178 | return HAVE_SHARED_GAME_DIR; |
| 179 | #else |
| 180 | lose ("This program was compiled without HAVE_SHARED_GAME_DIR,\n and should not be suid."); |
| 181 | #endif |
| 182 | } |
| 183 | return user_prefix; |
| 184 | } |
| 185 | |
| 186 | int |
| 187 | main (argc, argv) |
| 188 | int argc; |
| 189 | char **argv; |
| 190 | { |
| 191 | int c, running_suid; |
| 192 | void *lockstate; |
| 193 | char *user_id, *scorefile, *prefix, *user_prefix = NULL; |
| 194 | struct stat buf; |
| 195 | struct score_entry *scores; |
| 196 | int newscore, scorecount, reverse = 0, max = MAX_SCORES; |
| 197 | char *newdata; |
| 198 | |
| 199 | srand (time (0)); |
| 200 | |
| 201 | while ((c = getopt (argc, argv, "hrm:d:")) != -1) |
| 202 | switch (c) |
| 203 | { |
| 204 | case 'h': |
| 205 | usage (EXIT_SUCCESS); |
| 206 | break; |
| 207 | case 'd': |
| 208 | user_prefix = optarg; |
| 209 | break; |
| 210 | case 'r': |
| 211 | reverse = 1; |
| 212 | break; |
| 213 | case 'm': |
| 214 | max = atoi (optarg); |
| 215 | if (max > MAX_SCORES) |
| 216 | max = MAX_SCORES; |
| 217 | break; |
| 218 | default: |
| 219 | usage (EXIT_FAILURE); |
| 220 | } |
| 221 | |
| 222 | if (optind+3 != argc) |
| 223 | usage (EXIT_FAILURE); |
| 224 | |
| 225 | running_suid = (getuid () != geteuid ()); |
| 226 | |
| 227 | prefix = get_prefix (running_suid, user_prefix); |
| 228 | |
| 229 | scorefile = malloc (strlen (prefix) + strlen (argv[optind]) + 2); |
| 230 | if (!scorefile) |
| 231 | lose_syserr ("Couldn't allocate score file"); |
| 232 | |
| 233 | strcpy (scorefile, prefix); |
| 234 | strcat (scorefile, "/"); |
| 235 | strcat (scorefile, argv[optind]); |
| 236 | newscore = atoi (argv[optind+1]); |
| 237 | newdata = argv[optind+2]; |
| 238 | if (strlen (newdata) > MAX_DATA_LEN) |
| 239 | newdata[MAX_DATA_LEN] = '\0'; |
| 240 | |
| 241 | user_id = get_user_id (); |
| 242 | if (user_id == NULL) |
| 243 | lose_syserr ("Couldn't determine user id"); |
| 244 | |
| 245 | if (stat (scorefile, &buf) < 0) |
| 246 | lose_syserr ("Failed to access scores file"); |
| 247 | |
| 248 | if (lock_file (scorefile, &lockstate) < 0) |
| 249 | lose_syserr ("Failed to lock scores file"); |
| 250 | |
| 251 | if (read_scores (scorefile, &scores, &scorecount) < 0) |
| 252 | { |
| 253 | unlock_file (scorefile, lockstate); |
| 254 | lose_syserr ("Failed to read scores file"); |
| 255 | } |
| 256 | push_score (&scores, &scorecount, newscore, user_id, newdata); |
| 257 | /* Limit the number of scores. If we're using reverse sorting, then |
| 258 | we should increment the beginning of the array, to skip over the |
| 259 | *smallest* scores. Otherwise, we just decrement the number of |
| 260 | scores, since the smallest will be at the end. */ |
| 261 | if (scorecount > MAX_SCORES) |
| 262 | scorecount -= (scorecount - MAX_SCORES); |
| 263 | if (reverse) |
| 264 | scores += (scorecount - MAX_SCORES); |
| 265 | sort_scores (scores, scorecount, reverse); |
| 266 | if (write_scores (scorefile, scores, scorecount) < 0) |
| 267 | { |
| 268 | unlock_file (scorefile, lockstate); |
| 269 | lose_syserr ("Failed to write scores file"); |
| 270 | } |
| 271 | unlock_file (scorefile, lockstate); |
| 272 | exit (EXIT_SUCCESS); |
| 273 | } |
| 274 | |
| 275 | int |
| 276 | read_score (f, score) |
| 277 | FILE *f; |
| 278 | struct score_entry *score; |
| 279 | { |
| 280 | int c; |
| 281 | if (feof (f)) |
| 282 | return 1; |
| 283 | while ((c = getc (f)) != EOF |
| 284 | && isdigit (c)) |
| 285 | { |
| 286 | score->score *= 10; |
| 287 | score->score += (c-48); |
| 288 | } |
| 289 | while ((c = getc (f)) != EOF |
| 290 | && isspace (c)) |
| 291 | ; |
| 292 | if (c == EOF) |
| 293 | return -1; |
| 294 | ungetc (c, f); |
| 295 | #ifdef HAVE_GETDELIM |
| 296 | { |
| 297 | size_t count = 0; |
| 298 | if (getdelim (&score->username, &count, ' ', f) < 1 |
| 299 | || score->username == NULL) |
| 300 | return -1; |
| 301 | /* Trim the space */ |
| 302 | score->username[strlen (score->username)-1] = '\0'; |
| 303 | } |
| 304 | #else |
| 305 | { |
| 306 | int unameread = 0; |
| 307 | int unamelen = 30; |
| 308 | char *username = malloc (unamelen); |
| 309 | if (!username) |
| 310 | return -1; |
| 311 | |
| 312 | while ((c = getc (f)) != EOF |
| 313 | && !isspace (c)) |
| 314 | { |
| 315 | if (unameread >= unamelen-1) |
| 316 | if (!(username = realloc (username, unamelen *= 2))) |
| 317 | return -1; |
| 318 | username[unameread] = c; |
| 319 | unameread++; |
| 320 | } |
| 321 | if (c == EOF) |
| 322 | return -1; |
| 323 | username[unameread] = '\0'; |
| 324 | score->username = username; |
| 325 | } |
| 326 | #endif |
| 327 | #ifdef HAVE_GETLINE |
| 328 | score->data = NULL; |
| 329 | errno = 0; |
| 330 | { |
| 331 | size_t len; |
| 332 | if (getline (&score->data, &len, f) < 0) |
| 333 | return -1; |
| 334 | score->data[strlen (score->data)-1] = '\0'; |
| 335 | } |
| 336 | #else |
| 337 | { |
| 338 | int cur = 0; |
| 339 | int len = 16; |
| 340 | char *buf = malloc (len); |
| 341 | if (!buf) |
| 342 | return -1; |
| 343 | while ((c = getc (f)) != EOF |
| 344 | && c != '\n') |
| 345 | { |
| 346 | if (cur >= len-1) |
| 347 | { |
| 348 | if (!(buf = realloc (buf, len *= 2))) |
| 349 | return -1; |
| 350 | } |
| 351 | buf[cur] = c; |
| 352 | cur++; |
| 353 | } |
| 354 | score->data = buf; |
| 355 | score->data[cur] = '\0'; |
| 356 | } |
| 357 | #endif |
| 358 | return 0; |
| 359 | } |
| 360 | |
| 361 | int |
| 362 | read_scores (filename, scores, count) |
| 363 | const char *filename; |
| 364 | struct score_entry **scores; |
| 365 | int *count; |
| 366 | { |
| 367 | int readval, scorecount, cursize; |
| 368 | struct score_entry *ret; |
| 369 | FILE *f = fopen (filename, "r"); |
| 370 | if (!f) |
| 371 | return -1; |
| 372 | scorecount = 0; |
| 373 | cursize = 16; |
| 374 | ret = (struct score_entry *) malloc (sizeof (struct score_entry) * cursize); |
| 375 | if (!ret) |
| 376 | return -1; |
| 377 | while ((readval = read_score (f, &ret[scorecount])) == 0) |
| 378 | { |
| 379 | /* We encoutered an error */ |
| 380 | if (readval < 0) |
| 381 | return -1; |
| 382 | scorecount++; |
| 383 | if (scorecount >= cursize) |
| 384 | { |
| 385 | cursize *= 2; |
| 386 | ret = (struct score_entry *) |
| 387 | realloc (ret, (sizeof (struct score_entry) * cursize)); |
| 388 | if (!ret) |
| 389 | return -1; |
| 390 | } |
| 391 | } |
| 392 | *count = scorecount; |
| 393 | *scores = ret; |
| 394 | return 0; |
| 395 | } |
| 396 | |
| 397 | int |
| 398 | score_compare (a, b) |
| 399 | const void *a; |
| 400 | const void *b; |
| 401 | { |
| 402 | const struct score_entry *sa = (const struct score_entry *) a; |
| 403 | const struct score_entry *sb = (const struct score_entry *) b; |
| 404 | return (sb->score > sa->score) - (sb->score < sa->score); |
| 405 | } |
| 406 | |
| 407 | int |
| 408 | score_compare_reverse (a, b) |
| 409 | const void *a; |
| 410 | const void *b; |
| 411 | { |
| 412 | const struct score_entry *sa = (const struct score_entry *) a; |
| 413 | const struct score_entry *sb = (const struct score_entry *) b; |
| 414 | return (sa->score > sb->score) - (sa->score < sb->score); |
| 415 | } |
| 416 | |
| 417 | int |
| 418 | push_score (scores, count, newscore, username, newdata) |
| 419 | struct score_entry **scores; |
| 420 | int *count; int newscore; |
| 421 | char *username; |
| 422 | char *newdata; |
| 423 | { |
| 424 | struct score_entry *newscores |
| 425 | = (struct score_entry *) realloc (*scores, |
| 426 | sizeof (struct score_entry) * ((*count) + 1)); |
| 427 | if (!newscores) |
| 428 | return -1; |
| 429 | newscores[*count].score = newscore; |
| 430 | newscores[*count].username = username; |
| 431 | newscores[*count].data = newdata; |
| 432 | (*count) += 1; |
| 433 | *scores = newscores; |
| 434 | return 0; |
| 435 | } |
| 436 | |
| 437 | void |
| 438 | sort_scores (scores, count, reverse) |
| 439 | struct score_entry *scores; |
| 440 | int count; |
| 441 | int reverse; |
| 442 | { |
| 443 | qsort (scores, count, sizeof (struct score_entry), |
| 444 | reverse ? score_compare_reverse : score_compare); |
| 445 | } |
| 446 | |
| 447 | int |
| 448 | write_scores (filename, scores, count) |
| 449 | const char *filename; |
| 450 | const struct score_entry * scores; |
| 451 | int count; |
| 452 | { |
| 453 | FILE *f; |
| 454 | int i; |
| 455 | char *tempfile = malloc (strlen (filename) + strlen (".tempXXXXXX") + 1); |
| 456 | if (!tempfile) |
| 457 | return -1; |
| 458 | strcpy (tempfile, filename); |
| 459 | strcat (tempfile, ".tempXXXXXX"); |
| 460 | #ifdef HAVE_MKSTEMP |
| 461 | if (mkstemp (tempfile) < 0 |
| 462 | #else |
| 463 | if (mktemp (tempfile) != tempfile |
| 464 | #endif |
| 465 | || !(f = fopen (tempfile, "w"))) |
| 466 | return -1; |
| 467 | for (i = 0; i < count; i++) |
| 468 | if (fprintf (f, "%ld %s %s\n", scores[i].score, scores[i].username, |
| 469 | scores[i].data) < 0) |
| 470 | return -1; |
| 471 | fclose (f); |
| 472 | if (rename (tempfile, filename) < 0) |
| 473 | return -1; |
| 474 | if (chmod (filename, 0644) < 0) |
| 475 | return -1; |
| 476 | return 0; |
| 477 | } |
| 478 | |
| 479 | int |
| 480 | lock_file (filename, state) |
| 481 | const char *filename; |
| 482 | void **state; |
| 483 | { |
| 484 | int fd; |
| 485 | struct stat buf; |
| 486 | int attempts = 0; |
| 487 | char *lockext = ".lockfile"; |
| 488 | char *lockpath = malloc (strlen (filename) + strlen (lockext) + 60); |
| 489 | if (!lockpath) |
| 490 | return -1; |
| 491 | strcpy (lockpath, filename); |
| 492 | strcat (lockpath, lockext); |
| 493 | *state = lockpath; |
| 494 | trylock: |
| 495 | attempts++; |
| 496 | /* If the lock is over an hour old, delete it. */ |
| 497 | if (stat (lockpath, &buf) == 0 |
| 498 | && (difftime (buf.st_ctime, time (NULL) > 60*60))) |
| 499 | unlink (lockpath); |
| 500 | fd = open (lockpath, O_CREAT | O_EXCL, 0600); |
| 501 | if (fd < 0) |
| 502 | { |
| 503 | if (errno == EEXIST) |
| 504 | { |
| 505 | /* Break the lock; we won't corrupt the file, but we might |
| 506 | lose some scores. */ |
| 507 | if (attempts > MAX_ATTEMPTS) |
| 508 | { |
| 509 | unlink (lockpath); |
| 510 | attempts = 0; |
| 511 | } |
| 512 | sleep ((rand () % 2)+1); |
| 513 | goto trylock; |
| 514 | } |
| 515 | else |
| 516 | return -1; |
| 517 | } |
| 518 | close (fd); |
| 519 | return 0; |
| 520 | } |
| 521 | |
| 522 | int |
| 523 | unlock_file (filename, state) |
| 524 | const char *filename; |
| 525 | void *state; |
| 526 | { |
| 527 | char *lockpath = (char *) state; |
| 528 | int ret = unlink (lockpath); |
| 529 | int saved_errno = errno; |
| 530 | free (lockpath); |
| 531 | errno = saved_errno; |
| 532 | return ret; |
| 533 | } |
| 534 | |
| 535 | /* arch-tag: 2bf5c52e-4beb-463a-954e-c58b9c64736b |
| 536 | (do not change this comment) */ |
| 537 | |
| 538 | /* update-game-score.c ends here */ |