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536 lines
12 KiB
C
536 lines
12 KiB
C
/* update-game-score.c --- Update a score file
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Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
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This file is part of GNU Emacs.
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GNU Emacs is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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GNU Emacs is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Emacs; see the file COPYING. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA. */
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/* This program is allows a game to securely and atomically update a
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score file. It should be installed setuid, owned by an appropriate
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user like `games'.
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Alternatively, it can be compiled without HAVE_SHARED_GAME_DIR
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defined, and in that case it will store scores in the user's home
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directory (it should NOT be setuid).
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Created 2002/03/22, by Colin Walters <walters@debian.org>
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*/
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#include <config.h>
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <errno.h>
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#ifdef HAVE_STRING_H
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#include <string.h>
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#endif
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#ifdef HAVE_STDLIB_H
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#include <stdlib.h>
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#endif
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#include <stdio.h>
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#include <time.h>
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#include <pwd.h>
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#include <ctype.h>
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#ifdef HAVE_FCNTL_H
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#include <fcntl.h>
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#endif
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#ifdef STDC_HEADERS
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#include <stdarg.h>
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#endif
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#include <sys/stat.h>
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/* Needed for SunOS4, for instance. */
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extern char *optarg;
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extern int optind, opterr;
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#define MAX_ATTEMPTS 5
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#define MAX_SCORES 200
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#define MAX_DATA_LEN 1024
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/* Declare the prototype for a general external function. */
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#if defined (PROTOTYPES) || defined (WINDOWSNT)
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#define P_(proto) proto
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#else
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#define P_(proto) ()
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#endif
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#ifndef HAVE_DIFFTIME
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/* OK on POSIX (time_t is arithmetic type) modulo overflow in subtraction. */
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#define difftime(t1, t0) (double)((t1) - (t0))
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#endif
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int
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usage (err)
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int err;
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{
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fprintf (stdout, "Usage: update-game-score [-m MAX ] [ -r ] game/scorefile SCORE DATA\n");
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fprintf (stdout, " update-game-score -h\n");
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fprintf (stdout, " -h\t\tDisplay this help.\n");
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fprintf (stdout, " -m MAX\t\tLimit the maximum number of scores to MAX.\n");
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fprintf (stdout, " -r\t\tSort the scores in increasing order.\n");
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fprintf (stdout, " -d DIR\t\tStore scores in DIR (only if not setuid).\n");
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exit (err);
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}
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int lock_file P_ ((const char *filename, void **state));
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int unlock_file P_ ((const char *filename, void *state));
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struct score_entry
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{
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long score;
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char *username;
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char *data;
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};
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int read_scores P_ ((const char *filename, struct score_entry **scores,
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int *count));
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int push_score P_ ((struct score_entry **scores, int *count,
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int newscore, char *username, char *newdata));
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void sort_scores P_ ((struct score_entry *scores, int count, int reverse));
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int write_scores P_ ((const char *filename, const struct score_entry *scores,
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int count));
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void lose P_ ((const char *msg)) NO_RETURN;
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void
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lose (msg)
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const char *msg;
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{
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fprintf (stderr, "%s\n", msg);
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exit (EXIT_FAILURE);
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}
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void lose_syserr P_ ((const char *msg)) NO_RETURN;
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/* Taken from sysdep.c. */
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#ifndef HAVE_STRERROR
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#ifndef WINDOWSNT
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char *
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strerror (errnum)
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int errnum;
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{
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extern char *sys_errlist[];
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extern int sys_nerr;
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if (errnum >= 0 && errnum < sys_nerr)
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return sys_errlist[errnum];
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return (char *) "Unknown error";
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}
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#endif /* not WINDOWSNT */
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#endif /* ! HAVE_STRERROR */
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void
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lose_syserr (msg)
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const char *msg;
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{
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fprintf (stderr, "%s: %s\n", msg, strerror (errno));
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exit (EXIT_FAILURE);
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}
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char *
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get_user_id P_ ((void))
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{
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char *name;
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struct passwd *buf = getpwuid (getuid ());
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if (!buf)
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{
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int count = 1;
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int uid = (int) getuid ();
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int tuid = uid;
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while (tuid /= 10)
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count++;
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name = malloc (count+1);
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if (!name)
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return NULL;
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sprintf (name, "%d", uid);
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return name;
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}
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return buf->pw_name;
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}
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char *
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get_prefix (running_suid, user_prefix)
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int running_suid;
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char *user_prefix;
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{
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if (!running_suid && user_prefix == NULL)
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lose ("Not using a shared game directory, and no prefix given.");
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if (running_suid)
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{
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#ifdef HAVE_SHARED_GAME_DIR
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return HAVE_SHARED_GAME_DIR;
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#else
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lose ("This program was compiled without HAVE_SHARED_GAME_DIR,\n and should not be suid.");
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#endif
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}
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return user_prefix;
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}
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int
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main (argc, argv)
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int argc;
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char **argv;
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{
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int c, running_suid;
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void *lockstate;
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char *user_id, *scorefile, *prefix, *user_prefix = NULL;
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struct stat buf;
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struct score_entry *scores;
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int newscore, scorecount, reverse = 0, max = MAX_SCORES;
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char *newdata;
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srand (time (0));
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while ((c = getopt (argc, argv, "hrm:d:")) != -1)
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switch (c)
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{
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case 'h':
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usage (EXIT_SUCCESS);
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break;
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case 'd':
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user_prefix = optarg;
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break;
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case 'r':
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reverse = 1;
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break;
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case 'm':
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max = atoi (optarg);
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if (max > MAX_SCORES)
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max = MAX_SCORES;
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break;
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default:
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usage (EXIT_FAILURE);
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}
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if (optind+3 != argc)
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usage (EXIT_FAILURE);
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running_suid = (getuid () != geteuid ());
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prefix = get_prefix (running_suid, user_prefix);
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scorefile = malloc (strlen (prefix) + strlen (argv[optind]) + 2);
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if (!scorefile)
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lose_syserr ("Couldn't allocate score file");
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strcpy (scorefile, prefix);
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strcat (scorefile, "/");
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strcat (scorefile, argv[optind]);
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newscore = atoi (argv[optind+1]);
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newdata = argv[optind+2];
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if (strlen (newdata) > MAX_DATA_LEN)
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newdata[MAX_DATA_LEN] = '\0';
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user_id = get_user_id ();
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if (user_id == NULL)
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lose_syserr ("Couldn't determine user id");
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if (stat (scorefile, &buf) < 0)
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lose_syserr ("Failed to access scores file");
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if (lock_file (scorefile, &lockstate) < 0)
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lose_syserr ("Failed to lock scores file");
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if (read_scores (scorefile, &scores, &scorecount) < 0)
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{
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unlock_file (scorefile, lockstate);
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lose_syserr ("Failed to read scores file");
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}
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push_score (&scores, &scorecount, newscore, user_id, newdata);
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/* Limit the number of scores. If we're using reverse sorting, then
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we should increment the beginning of the array, to skip over the
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*smallest* scores. Otherwise, we just decrement the number of
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scores, since the smallest will be at the end. */
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if (scorecount > MAX_SCORES)
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scorecount -= (scorecount - MAX_SCORES);
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if (reverse)
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scores += (scorecount - MAX_SCORES);
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sort_scores (scores, scorecount, reverse);
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if (write_scores (scorefile, scores, scorecount) < 0)
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{
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unlock_file (scorefile, lockstate);
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lose_syserr ("Failed to write scores file");
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}
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unlock_file (scorefile, lockstate);
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exit (EXIT_SUCCESS);
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}
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int
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read_score (f, score)
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FILE *f;
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struct score_entry *score;
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{
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int c;
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if (feof (f))
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return 1;
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while ((c = getc (f)) != EOF
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&& isdigit (c))
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{
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score->score *= 10;
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score->score += (c-48);
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}
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while ((c = getc (f)) != EOF
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&& isspace (c))
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;
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if (c == EOF)
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return -1;
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ungetc (c, f);
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#ifdef HAVE_GETDELIM
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{
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size_t count = 0;
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if (getdelim (&score->username, &count, ' ', f) < 1
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|| score->username == NULL)
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return -1;
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/* Trim the space */
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score->username[strlen (score->username)-1] = '\0';
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}
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#else
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{
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int unameread = 0;
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int unamelen = 30;
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char *username = malloc (unamelen);
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if (!username)
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return -1;
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while ((c = getc (f)) != EOF
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&& !isspace (c))
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{
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if (unameread >= unamelen-1)
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if (!(username = realloc (username, unamelen *= 2)))
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return -1;
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username[unameread] = c;
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unameread++;
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}
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if (c == EOF)
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return -1;
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username[unameread] = '\0';
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score->username = username;
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}
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#endif
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#ifdef HAVE_GETLINE
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score->data = NULL;
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errno = 0;
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{
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size_t len;
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if (getline (&score->data, &len, f) < 0)
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return -1;
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score->data[strlen (score->data)-1] = '\0';
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}
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#else
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{
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int cur = 0;
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int len = 16;
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char *buf = malloc (len);
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if (!buf)
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return -1;
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while ((c = getc (f)) != EOF
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&& c != '\n')
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{
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if (cur >= len-1)
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{
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if (!(buf = realloc (buf, len *= 2)))
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return -1;
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}
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buf[cur] = c;
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cur++;
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}
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score->data = buf;
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score->data[cur] = '\0';
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}
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#endif
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return 0;
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}
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int
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read_scores (filename, scores, count)
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const char *filename;
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struct score_entry **scores;
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int *count;
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{
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int readval, scorecount, cursize;
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struct score_entry *ret;
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FILE *f = fopen (filename, "r");
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if (!f)
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return -1;
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scorecount = 0;
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cursize = 16;
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ret = (struct score_entry *) malloc (sizeof (struct score_entry) * cursize);
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if (!ret)
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return -1;
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while ((readval = read_score (f, &ret[scorecount])) == 0)
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{
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/* We encoutered an error */
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if (readval < 0)
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return -1;
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scorecount++;
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if (scorecount >= cursize)
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{
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cursize *= 2;
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ret = (struct score_entry *)
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realloc (ret, (sizeof (struct score_entry) * cursize));
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if (!ret)
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return -1;
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}
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}
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*count = scorecount;
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*scores = ret;
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return 0;
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}
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int
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score_compare (a, b)
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const void *a;
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const void *b;
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{
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const struct score_entry *sa = (const struct score_entry *) a;
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const struct score_entry *sb = (const struct score_entry *) b;
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return (sb->score > sa->score) - (sb->score < sa->score);
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}
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int
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score_compare_reverse (a, b)
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const void *a;
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const void *b;
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{
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const struct score_entry *sa = (const struct score_entry *) a;
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const struct score_entry *sb = (const struct score_entry *) b;
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return (sa->score > sb->score) - (sa->score < sb->score);
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}
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int
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push_score (scores, count, newscore, username, newdata)
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struct score_entry **scores;
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int *count; int newscore;
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char *username;
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char *newdata;
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{
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struct score_entry *newscores
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= (struct score_entry *) realloc (*scores,
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sizeof (struct score_entry) * ((*count) + 1));
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if (!newscores)
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return -1;
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newscores[*count].score = newscore;
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newscores[*count].username = username;
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newscores[*count].data = newdata;
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(*count) += 1;
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*scores = newscores;
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return 0;
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}
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void
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sort_scores (scores, count, reverse)
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struct score_entry *scores;
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int count;
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int reverse;
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{
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qsort (scores, count, sizeof (struct score_entry),
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reverse ? score_compare_reverse : score_compare);
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}
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int
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write_scores (filename, scores, count)
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const char *filename;
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const struct score_entry * scores;
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int count;
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{
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FILE *f;
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int i;
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char *tempfile = malloc (strlen (filename) + strlen (".tempXXXXXX") + 1);
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if (!tempfile)
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return -1;
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strcpy (tempfile, filename);
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strcat (tempfile, ".tempXXXXXX");
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#ifdef HAVE_MKSTEMP
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if (mkstemp (tempfile) < 0
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#else
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if (mktemp (tempfile) != tempfile
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#endif
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|| !(f = fopen (tempfile, "w")))
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return -1;
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for (i = 0; i < count; i++)
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if (fprintf (f, "%ld %s %s\n", scores[i].score, scores[i].username,
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scores[i].data) < 0)
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return -1;
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fclose (f);
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if (rename (tempfile, filename) < 0)
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return -1;
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if (chmod (filename, 0644) < 0)
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return -1;
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return 0;
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}
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int
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lock_file (filename, state)
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const char *filename;
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void **state;
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{
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int fd;
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struct stat buf;
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int attempts = 0;
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char *lockext = ".lockfile";
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char *lockpath = malloc (strlen (filename) + strlen (lockext) + 60);
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if (!lockpath)
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return -1;
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strcpy (lockpath, filename);
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strcat (lockpath, lockext);
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*state = lockpath;
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trylock:
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attempts++;
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/* If the lock is over an hour old, delete it. */
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if (stat (lockpath, &buf) == 0
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&& (difftime (buf.st_ctime, time (NULL) > 60*60)))
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unlink (lockpath);
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fd = open (lockpath, O_CREAT | O_EXCL, 0600);
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if (fd < 0)
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{
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if (errno == EEXIST)
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{
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/* Break the lock; we won't corrupt the file, but we might
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lose some scores. */
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if (attempts > MAX_ATTEMPTS)
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{
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unlink (lockpath);
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attempts = 0;
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}
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sleep ((rand () % 2)+1);
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goto trylock;
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}
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else
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return -1;
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}
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close (fd);
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return 0;
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}
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int
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unlock_file (filename, state)
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const char *filename;
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void *state;
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{
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char *lockpath = (char *) state;
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int ret = unlink (lockpath);
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int saved_errno = errno;
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free (lockpath);
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errno = saved_errno;
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return ret;
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}
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/* arch-tag: 2bf5c52e-4beb-463a-954e-c58b9c64736b
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(do not change this comment) */
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/* update-game-score.c ends here */
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