| 1 | /* update-game-score.c --- Update a score file |
| 2 | Copyright (C) 2002 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of GNU Emacs. |
| 5 | |
| 6 | GNU Emacs is free software; you can redistribute it and/or modify |
| 7 | it under the terms of the GNU General Public License as published by |
| 8 | the Free Software Foundation; either version 2, or (at your option) |
| 9 | any later version. |
| 10 | |
| 11 | GNU Emacs is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | GNU General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU General Public License |
| 17 | along with GNU Emacs; see the file COPYING. If not, write to |
| 18 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
| 19 | Boston, MA 02111-1307, USA. */ |
| 20 | |
| 21 | /* This program is allows a game to securely and atomically update a |
| 22 | score file. It should be installed setuid, owned by an appropriate |
| 23 | user like `games'. |
| 24 | |
| 25 | Alternatively, it can be compiled without HAVE_SHARED_GAME_DIR |
| 26 | defined, and in that case it will store scores in the user's home |
| 27 | directory (it should NOT be setuid). |
| 28 | |
| 29 | Created 2002/03/22, by Colin Walters <walters@debian.org> |
| 30 | */ |
| 31 | |
| 32 | #define _GNU_SOURCE |
| 33 | |
| 34 | #include <config.h> |
| 35 | |
| 36 | #include <unistd.h> |
| 37 | #include <errno.h> |
| 38 | #include <string.h> |
| 39 | #include <stdlib.h> |
| 40 | #include <stdio.h> |
| 41 | #include <time.h> |
| 42 | #include <pwd.h> |
| 43 | #include <ctype.h> |
| 44 | #include <fcntl.h> |
| 45 | #include <stdarg.h> |
| 46 | #include <sys/stat.h> |
| 47 | |
| 48 | #define MAX_ATTEMPTS 5 |
| 49 | #define MAX_SCORES 200 |
| 50 | #define MAX_DATA_LEN 1024 |
| 51 | |
| 52 | #if !defined (__GNUC__) || __GNUC__ < 2 |
| 53 | #define __attribute__(x) |
| 54 | #endif |
| 55 | |
| 56 | /* Declare the prototype for a general external function. */ |
| 57 | #if defined (PROTOTYPES) || defined (WINDOWSNT) |
| 58 | #define P_(proto) proto |
| 59 | #else |
| 60 | #define P_(proto) () |
| 61 | #endif |
| 62 | |
| 63 | int |
| 64 | usage(err) |
| 65 | int err; |
| 66 | { |
| 67 | fprintf(stdout, "Usage: update-game-score [-m MAX ] [ -r ] game/scorefile SCORE DATA\n"); |
| 68 | fprintf(stdout, " update-game-score -h\n"); |
| 69 | fprintf(stdout, " -h\t\tDisplay this help.\n"); |
| 70 | fprintf(stdout, " -m MAX\t\tLimit the maximum number of scores to MAX.\n"); |
| 71 | fprintf(stdout, " -r\t\tSort the scores in increasing order.\n"); |
| 72 | fprintf(stdout, " -d DIR\t\tStore scores in DIR (only if not setuid).\n"); |
| 73 | exit(err); |
| 74 | } |
| 75 | |
| 76 | int |
| 77 | lock_file P_((const char *filename, void **state)); |
| 78 | int |
| 79 | unlock_file P_((const char *filename, void *state)); |
| 80 | |
| 81 | struct score_entry |
| 82 | { |
| 83 | long score; |
| 84 | char *username; |
| 85 | char *data; |
| 86 | }; |
| 87 | |
| 88 | int |
| 89 | read_scores P_((const char *filename, struct score_entry **scores, |
| 90 | int *count)); |
| 91 | int |
| 92 | push_score P_((struct score_entry **scores, int *count, |
| 93 | int newscore, char *username, char *newdata)); |
| 94 | void |
| 95 | sort_scores P_((struct score_entry *scores, int count, int reverse)); |
| 96 | int |
| 97 | write_scores P_((const char *filename, const struct score_entry *scores, |
| 98 | int count)); |
| 99 | |
| 100 | void lose P_((const char *msg)) |
| 101 | __attribute__ ((noreturn)); |
| 102 | |
| 103 | void lose(msg) |
| 104 | const char *msg; |
| 105 | { |
| 106 | fprintf(stderr, "%s\n", msg); |
| 107 | exit(1); |
| 108 | } |
| 109 | |
| 110 | void lose_syserr P_((const char *msg)) |
| 111 | __attribute__ ((noreturn)); |
| 112 | |
| 113 | void lose_syserr(msg) |
| 114 | const char *msg; |
| 115 | { |
| 116 | fprintf(stderr, "%s: %s\n", msg, strerror(errno)); |
| 117 | exit(1); |
| 118 | } |
| 119 | |
| 120 | char * |
| 121 | get_user_id(void) |
| 122 | { |
| 123 | char *name; |
| 124 | struct passwd *buf = getpwuid(getuid()); |
| 125 | if (!buf) |
| 126 | { |
| 127 | int count = 1; |
| 128 | int uid = (int) getuid(); |
| 129 | int tuid = uid; |
| 130 | while (tuid /= 10) |
| 131 | count++; |
| 132 | name = malloc(count+1); |
| 133 | if (!name) |
| 134 | return NULL; |
| 135 | sprintf(name, "%d", uid); |
| 136 | return name; |
| 137 | } |
| 138 | return buf->pw_name; |
| 139 | } |
| 140 | |
| 141 | char * |
| 142 | get_prefix(running_suid, user_prefix) |
| 143 | int running_suid; |
| 144 | char *user_prefix; |
| 145 | { |
| 146 | if (!running_suid && user_prefix == NULL) |
| 147 | lose("Not using a shared game directory, and no prefix given."); |
| 148 | if (running_suid) |
| 149 | { |
| 150 | #ifdef HAVE_SHARED_GAME_DIR |
| 151 | return HAVE_SHARED_GAME_DIR; |
| 152 | #else |
| 153 | lose("This program was compiled without HAVE_SHARED_GAME_DIR,\n and should not be suid."); |
| 154 | #endif |
| 155 | } |
| 156 | return user_prefix; |
| 157 | } |
| 158 | |
| 159 | int |
| 160 | main(argc, argv) |
| 161 | int argc; |
| 162 | char **argv; |
| 163 | { |
| 164 | int c, running_suid; |
| 165 | void *lockstate; |
| 166 | char *user_id, *scorefile, *prefix, *user_prefix = NULL; |
| 167 | struct stat buf; |
| 168 | struct score_entry *scores; |
| 169 | int newscore, scorecount, reverse = 0, max = MAX_SCORES; |
| 170 | char *newdata; |
| 171 | |
| 172 | srand(time(0)); |
| 173 | |
| 174 | while ((c = getopt(argc, argv, "hrm:d:")) != -1) |
| 175 | switch (c) |
| 176 | { |
| 177 | case 'h': |
| 178 | usage(0); |
| 179 | break; |
| 180 | case 'd': |
| 181 | user_prefix = optarg; |
| 182 | break; |
| 183 | case 'r': |
| 184 | reverse = 1; |
| 185 | break; |
| 186 | case 'm': |
| 187 | max = atoi(optarg); |
| 188 | if (max > MAX_SCORES) |
| 189 | max = MAX_SCORES; |
| 190 | break; |
| 191 | default: |
| 192 | usage(1); |
| 193 | } |
| 194 | |
| 195 | if (optind+3 != argc) |
| 196 | usage(1); |
| 197 | |
| 198 | running_suid = (getuid() != geteuid()); |
| 199 | |
| 200 | prefix = get_prefix(running_suid, user_prefix); |
| 201 | |
| 202 | scorefile = malloc(strlen(prefix) + strlen(argv[optind]) + 2); |
| 203 | if (!scorefile) |
| 204 | lose_syserr("Couldn't allocate score file"); |
| 205 | |
| 206 | strcpy(scorefile, prefix); |
| 207 | strcat(scorefile, "/"); |
| 208 | strcat(scorefile, argv[optind]); |
| 209 | newscore = atoi(argv[optind+1]); |
| 210 | newdata = argv[optind+2]; |
| 211 | if (strlen(newdata) > MAX_DATA_LEN) |
| 212 | newdata[MAX_DATA_LEN] = '\0'; |
| 213 | |
| 214 | if ((user_id = get_user_id()) == NULL) |
| 215 | lose_syserr("Couldn't determine user id"); |
| 216 | |
| 217 | if (stat(scorefile, &buf) < 0) |
| 218 | lose_syserr("Failed to access scores file"); |
| 219 | |
| 220 | if (lock_file(scorefile, &lockstate) < 0) |
| 221 | lose_syserr("Failed to lock scores file"); |
| 222 | |
| 223 | if (read_scores(scorefile, &scores, &scorecount) < 0) |
| 224 | { |
| 225 | unlock_file(scorefile, lockstate); |
| 226 | lose_syserr("Failed to read scores file"); |
| 227 | } |
| 228 | push_score(&scores, &scorecount, newscore, user_id, newdata); |
| 229 | /* Limit the number of scores. If we're using reverse sorting, then |
| 230 | we should increment the beginning of the array, to skip over the |
| 231 | *smallest* scores. Otherwise, we just decrement the number of |
| 232 | scores, since the smallest will be at the end. */ |
| 233 | if (scorecount > MAX_SCORES) |
| 234 | scorecount -= (scorecount - MAX_SCORES); |
| 235 | if (reverse) |
| 236 | scores += (scorecount - MAX_SCORES); |
| 237 | sort_scores(scores, scorecount, reverse); |
| 238 | if (write_scores(scorefile, scores, scorecount) < 0) |
| 239 | { |
| 240 | unlock_file(scorefile, lockstate); |
| 241 | lose_syserr("Failed to write scores file"); |
| 242 | } |
| 243 | unlock_file(scorefile, lockstate); |
| 244 | exit(0); |
| 245 | } |
| 246 | |
| 247 | int |
| 248 | read_score(f, score) |
| 249 | FILE *f; |
| 250 | struct score_entry *score; |
| 251 | { |
| 252 | int c; |
| 253 | if (feof(f)) |
| 254 | return 1; |
| 255 | while ((c = getc(f)) != EOF |
| 256 | && isdigit(c)) |
| 257 | { |
| 258 | score->score *= 10; |
| 259 | score->score += (c-48); |
| 260 | } |
| 261 | while ((c = getc(f)) != EOF |
| 262 | && isspace(c)) |
| 263 | ; |
| 264 | if (c == EOF) |
| 265 | return -1; |
| 266 | ungetc(c, f); |
| 267 | #ifdef HAVE_GETDELIM |
| 268 | { |
| 269 | size_t count = 0; |
| 270 | if (getdelim(&score->username, &count, ' ', f) < 1 |
| 271 | || score->username == NULL) |
| 272 | return -1; |
| 273 | /* Trim the space */ |
| 274 | score->username[strlen(score->username)-1] = '\0'; |
| 275 | } |
| 276 | #else |
| 277 | { |
| 278 | int unameread = 0; |
| 279 | int unamelen = 30; |
| 280 | char *username = malloc(unamelen); |
| 281 | if (!username) |
| 282 | return -1; |
| 283 | |
| 284 | while ((c = getc(f)) != EOF |
| 285 | && !isspace(c)) |
| 286 | { |
| 287 | if (unameread >= unamelen-1) |
| 288 | if (!(username = realloc(username, unamelen *= 2))) |
| 289 | return -1; |
| 290 | username[unameread] = c; |
| 291 | unameread++; |
| 292 | } |
| 293 | if (c == EOF) |
| 294 | return -1; |
| 295 | username[unameread] = '\0'; |
| 296 | score->username = username; |
| 297 | } |
| 298 | #endif |
| 299 | #ifdef HAVE_GETLINE |
| 300 | score->data = NULL; |
| 301 | errno = 0; |
| 302 | { |
| 303 | size_t len; |
| 304 | if (getline(&score->data, &len, f) < 0) |
| 305 | return -1; |
| 306 | score->data[strlen(score->data)-1] = '\0'; |
| 307 | } |
| 308 | #else |
| 309 | { |
| 310 | int cur = 0; |
| 311 | int len = 16; |
| 312 | char *buf = malloc(len); |
| 313 | if (!buf) |
| 314 | return -1; |
| 315 | while ((c = getc(f)) != EOF |
| 316 | && c != '\n') |
| 317 | { |
| 318 | if (cur >= len-1) |
| 319 | { |
| 320 | if (!(buf = realloc(buf, len *= 2))) |
| 321 | return -1; |
| 322 | } |
| 323 | buf[cur] = c; |
| 324 | cur++; |
| 325 | } |
| 326 | score->data = buf; |
| 327 | score->data[cur] = '\0'; |
| 328 | } |
| 329 | #endif |
| 330 | return 0; |
| 331 | } |
| 332 | |
| 333 | int |
| 334 | read_scores(filename, scores, count) |
| 335 | const char *filename; |
| 336 | struct score_entry **scores; |
| 337 | int *count; |
| 338 | { |
| 339 | int readval, scorecount, cursize; |
| 340 | struct score_entry *ret; |
| 341 | FILE *f = fopen(filename, "r"); |
| 342 | if (!f) |
| 343 | return -1; |
| 344 | scorecount = 0; |
| 345 | cursize = 16; |
| 346 | ret = malloc(sizeof(struct score_entry) * cursize); |
| 347 | if (!ret) |
| 348 | return -1; |
| 349 | while ((readval = read_score(f, &ret[scorecount])) == 0) |
| 350 | { |
| 351 | /* We encoutered an error */ |
| 352 | if (readval < 0) |
| 353 | return -1; |
| 354 | scorecount++; |
| 355 | if (scorecount >= cursize) |
| 356 | { |
| 357 | ret = realloc(ret, cursize *= 2); |
| 358 | if (!ret) |
| 359 | return -1; |
| 360 | } |
| 361 | } |
| 362 | *count = scorecount; |
| 363 | *scores = ret; |
| 364 | return 0; |
| 365 | } |
| 366 | |
| 367 | int |
| 368 | score_compare(a, b) |
| 369 | const void *a; |
| 370 | const void *b; |
| 371 | { |
| 372 | const struct score_entry *sa = (const struct score_entry *) a; |
| 373 | const struct score_entry *sb = (const struct score_entry *) b; |
| 374 | return (sb->score > sa->score) - (sb->score < sa->score); |
| 375 | } |
| 376 | |
| 377 | int |
| 378 | score_compare_reverse(a, b) |
| 379 | const void *a; |
| 380 | const void *b; |
| 381 | { |
| 382 | const struct score_entry *sa = (const struct score_entry *) a; |
| 383 | const struct score_entry *sb = (const struct score_entry *) b; |
| 384 | return (sa->score > sb->score) - (sa->score < sb->score); |
| 385 | } |
| 386 | |
| 387 | int |
| 388 | push_score(scores, count, newscore, username, newdata) |
| 389 | struct score_entry **scores; |
| 390 | int *count; int newscore; |
| 391 | char *username; |
| 392 | char *newdata; |
| 393 | { |
| 394 | struct score_entry *newscores = realloc(*scores, |
| 395 | sizeof(struct score_entry) * ((*count) + 1)); |
| 396 | if (!newscores) |
| 397 | return -1; |
| 398 | newscores[*count].score = newscore; |
| 399 | newscores[*count].username = username; |
| 400 | newscores[*count].data = newdata; |
| 401 | (*count) += 1; |
| 402 | *scores = newscores; |
| 403 | return 0; |
| 404 | } |
| 405 | |
| 406 | void |
| 407 | sort_scores(scores, count, reverse) |
| 408 | struct score_entry *scores; |
| 409 | int count; |
| 410 | int reverse; |
| 411 | { |
| 412 | qsort(scores, count, sizeof(struct score_entry), |
| 413 | reverse ? score_compare_reverse : score_compare); |
| 414 | } |
| 415 | |
| 416 | int |
| 417 | write_scores(filename, scores, count) |
| 418 | const char *filename; |
| 419 | const struct score_entry * scores; |
| 420 | int count; |
| 421 | { |
| 422 | FILE *f; |
| 423 | int i; |
| 424 | char *tempfile = malloc(strlen(filename) + strlen(".tempXXXXXX") + 1); |
| 425 | if (!tempfile) |
| 426 | return -1; |
| 427 | strcpy(tempfile, filename); |
| 428 | strcat(tempfile, ".tempXXXXXX"); |
| 429 | #ifdef HAVE_MKSTEMP |
| 430 | if (mkstemp(tempfile) < 0 |
| 431 | #else |
| 432 | if (mktemp(tempfile) != tempfile |
| 433 | #endif |
| 434 | || !(f = fopen(tempfile, "w"))) |
| 435 | return -1; |
| 436 | for (i = 0; i < count; i++) |
| 437 | if (fprintf(f, "%ld %s %s\n", scores[i].score, scores[i].username, |
| 438 | scores[i].data) < 0) |
| 439 | return -1; |
| 440 | fclose(f); |
| 441 | if (rename(tempfile, filename) < 0) |
| 442 | return -1; |
| 443 | if (chmod(filename, 0644) < 0) |
| 444 | return -1; |
| 445 | return 0; |
| 446 | } |
| 447 | |
| 448 | int |
| 449 | lock_file(filename, state) |
| 450 | const char *filename; |
| 451 | void **state; |
| 452 | { |
| 453 | int fd; |
| 454 | struct stat buf; |
| 455 | int attempts = 0; |
| 456 | char *lockext = ".lockfile"; |
| 457 | char *lockpath = malloc(strlen(filename) + strlen(lockext) + 60); |
| 458 | if (!lockpath) |
| 459 | return -1; |
| 460 | strcpy(lockpath, filename); |
| 461 | strcat(lockpath, lockext); |
| 462 | *state = lockpath; |
| 463 | trylock: |
| 464 | attempts++; |
| 465 | /* If the lock is over an hour old, delete it. */ |
| 466 | if (stat(lockpath, &buf) == 0 |
| 467 | && (difftime(buf.st_ctime, time(NULL) > 60*60))) |
| 468 | unlink(lockpath); |
| 469 | if ((fd = open(lockpath, O_CREAT | O_EXCL, 0600)) < 0) |
| 470 | { |
| 471 | if (errno == EEXIST) |
| 472 | { |
| 473 | /* Break the lock; we won't corrupt the file, but we might |
| 474 | lose some scores. */ |
| 475 | if (attempts > MAX_ATTEMPTS) |
| 476 | { |
| 477 | unlink(lockpath); |
| 478 | attempts = 0; |
| 479 | } |
| 480 | sleep((rand() % 2)+1); |
| 481 | goto trylock; |
| 482 | } |
| 483 | else |
| 484 | return -1; |
| 485 | } |
| 486 | close(fd); |
| 487 | return 0; |
| 488 | } |
| 489 | |
| 490 | int |
| 491 | unlock_file(filename, state) |
| 492 | const char *filename; |
| 493 | void *state; |
| 494 | { |
| 495 | char *lockpath = (char *) state; |
| 496 | int ret = unlink(lockpath); |
| 497 | int saved_errno = errno; |
| 498 | free(lockpath); |
| 499 | errno = saved_errno; |
| 500 | return ret; |
| 501 | } |