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emacs/lib-src/update-game-score.c
2007-07-25 05:08:27 +00:00

536 lines
12 KiB
C

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