/* update-game-score.c --- Update a score file Copyright (C) 2002 Free Software Foundation, Inc. This file is part of GNU Emacs. GNU Emacs is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Emacs is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Emacs; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /* This program is allows a game to securely and atomically update a score file. It should be installed setgid, owned by an appropriate group like `games'. Created 2002/03/22, by Colin Walters */ #define _GNU_SOURCE #include #include #include #include #include #include #include #include #include // #include "config.h" #define MAX_ATTEMPTS 5 #define SCORE_FILE_PREFIX "/var/games/emacs/" int usage(int err) { fprintf(stdout, "Usage: update-game-score [-m MAX ] [ -r ] game/scorefile SCORE DATA\n"); fprintf(stdout, " update-game-score -h\n"); fprintf(stdout, " -h\t\tDisplay this help.\n"); fprintf(stdout, " -m MAX\t\tLimit the maximum number of scores to MAX.\n"); fprintf(stdout, " -r\t\tSort the scores in increasing order.\n"); exit(err); } int lock_file(const char *filename, void **state); int unlock_file(const char *filename, void *state); struct score_entry { long score; char *data; }; int read_scores(const char *filename, struct score_entry **scores, int *count); int push_score(struct score_entry **scores, int *count, int newscore, char *newdata); void sort_scores(struct score_entry *scores, int count, int reverse); int write_scores(const char *filename, const struct score_entry *scores, int count); int main(int argc, char **argv) { int c; void *lockstate; char *scorefile; struct stat buf; struct score_entry *scores; int newscore, scorecount, reverse = 0, max = -1; char *newdata; srand(time(0)); while ((c = getopt(argc, argv, "hrm:")) != -1) switch (c) { case 'h': usage(0); break; case 'r': reverse = 1; break; case 'm': max = atoi(optarg); break; default: usage(1); } if (optind+3 != argc) usage(1); scorefile = malloc(strlen(SCORE_FILE_PREFIX) + strlen(argv[optind]) + 20); if (!scorefile) { fprintf(stderr, "Couldn't create score file name: %s\n", strerror(errno)); goto fail; } strcpy(scorefile, SCORE_FILE_PREFIX); strcat(scorefile, argv[optind]); newscore = atoi(argv[optind+1]); newdata = argv[optind+2]; if (stat(scorefile, &buf) < 0) { fprintf(stderr, "Failed to access scores file \"%s\": %s\n", scorefile, strerror(errno)); goto fail; } if (lock_file(scorefile, &lockstate) < 0) { fprintf(stderr, "Failed to lock scores file \"%s\": %s\n", scorefile, strerror(errno)); goto fail; } if (read_scores(scorefile, &scores, &scorecount) < 0) { fprintf(stderr, "Failed to read scores file \"%s\": %s\n", scorefile, strerror(errno)); goto fail_unlock; } push_score(&scores, &scorecount, newscore, newdata); sort_scores(scores, scorecount, reverse); if (write_scores(scorefile, scores, scorecount) < 0) { fprintf(stderr, "Failed to write scores file \"%s\": %s\n", scorefile, strerror(errno)); goto fail_unlock; } unlock_file(scorefile, lockstate); exit(0); fail_unlock: unlock_file(scorefile, lockstate); fail: exit(1); } int read_score(FILE *f, struct score_entry *score) { int c; if (feof(f)) return 1; while ((c = getc(f)) != EOF && isdigit(c)) { score->score *= 10; score->score += (c-48); } #ifdef HAVE_GETLINE score->data = NULL; errno = ESUCCES; { int len; if (getline(&score->data, &len, f) < 0) return -1; } #else /* We should probably just copy the getline code into here from glibc, instead of this halfassed solution. */ score->data = malloc(122); score->data[0] = '\0'; if (!fgets(score->data, 120, f)) return -1; #endif /* Trim the newline */ score->data[strlen(score->data)-1] = '\0'; return 0; } int read_scores(const char *filename, struct score_entry **scores, int *count) { int readval, scorecount, cursize; struct score_entry *ret; FILE *f = fopen(filename, "r"); if (!f) return -1; scorecount = 0; cursize = 16; ret = malloc(sizeof(struct score_entry) * cursize); if (!ret) return -1; while ((readval = read_score(f, &ret[scorecount])) == 0) { /* We encoutered an error */ if (readval < 0) return -1; scorecount++; if (scorecount >= cursize) { ret = realloc(ret, cursize *= 2); if (!ret) return -1; } } *count = scorecount; *scores = ret; return 0; } int score_compare(const void *a, const void *b) { const struct score_entry *sa = (const struct score_entry *) a; const struct score_entry *sb = (const struct score_entry *) b; return (sb->score > sa->score) - (sb->score < sa->score); } int score_compare_reverse(const void *a, const void *b) { const struct score_entry *sa = (const struct score_entry *) a; const struct score_entry *sb = (const struct score_entry *) b; return (sa->score > sb->score) - (sa->score < sb->score); } int push_score(struct score_entry **scores, int *count, int newscore, char *newdata) { struct score_entry *newscores = realloc(*scores, sizeof(struct score_entry) * ((*count) + 1)); if (!newscores) return -1; newscores[*count].score = newscore; newscores[*count].data = newdata; (*count) += 1; *scores = newscores; return 0; } void sort_scores(struct score_entry *scores, int count, int reverse) { qsort(scores, count, sizeof(struct score_entry), reverse ? score_compare_reverse : score_compare); } int write_scores(const char *filename, const struct score_entry *scores, int count) { FILE *f; int i; char *tempfile = malloc(strlen(filename) + strlen(".tempXXXXXX") + 1); if (!tempfile) return -1; strcpy(tempfile, filename); strcat(tempfile, ".tempXXXXXX"); if (mkstemp(tempfile) < 0 || !(f = fopen(tempfile, "w"))) return -1; for (i = 0; i < count; i++) if (fprintf(f, "%ld %s\n", scores[i].score, scores[i].data) < 0) return -1; fclose(f); rename(tempfile, filename); return 0; } #if 0 int lock_file(const char *filename, void **state) { struct flock lock; int *istate; int fd, attempts = 0, ret = 0; lock.l_type = F_WRLCK; lock.l_whence = SEEK_SET; lock.l_start = 0; lock.l_len = 0; istate = malloc(sizeof(int)); if (!istate) return -1; if ((fd = open(filename, O_RDWR, 0600)) < 0) return -1; *istate = fd; trylock: attempts++; if ((ret = fcntl(fd, F_GETLK, &lock)) == -1) { if (ret == EACCES || ret == EAGAIN) if (attempts > MAX_ATTEMPTS) exit(1); else { sleep((rand() % 3)+1); goto trylock; } else ret = 0 ; } else ret = 0; *state = istate; return ret; } int unlock_file(const char *filename, void *state) { int fd, ret; fd = *((int *) state); free(state); ret = close(fd); return ret; } #else int lock_file(const char *filename, void **state) { int fd; int attempts = 0; char *lockext = ".lockfile"; char *lockpath = malloc(strlen(filename) + strlen(lockext) + 60); if (!lockpath) return -1; strcpy(lockpath, filename); strcat(lockpath, lockext); *state = lockpath; trylock: attempts++; if ((fd = open(lockpath, O_CREAT | O_EXCL, 0600)) < 0) { if (errno == EEXIST) { /* Break the lock; we won't corrupt the file, but we might lose some scores. */ if (attempts > MAX_ATTEMPTS) unlink(lockpath); else sleep((rand() % 2)+1); goto trylock; } else return -1; } close(fd); return 0; } int unlock_file(const char *filename, void *state) { char *lockpath = (char *) state; int ret = unlink(lockpath); int saved_errno = errno; free(lockpath); errno = saved_errno; return ret; } #endif