1 /* vi: set sw=4 ts=4: */
5 * usually setuid root, -c option only works if getuid() == geteuid()
7 * Copyright 1994 Matthew Dillon (dillon@apollo.west.oic.com)
8 * Vladimir Oleynik <dzo@simtreas.ru> (C) 2002
10 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
15 #define CRONTABS CONFIG_FEATURE_CROND_DIR "/crontabs"
17 #define CRONUPDATE "cron.update"
20 static void edit_file(const struct passwd *pas, const char *file)
26 if (pid) { /* parent */
31 /* CHILD - change user and run editor */
32 /* initgroups, setgid, setuid */
34 setup_environment(pas->pw_shell,
35 SETUP_ENV_CHANGEENV | SETUP_ENV_TO_TMP,
37 ptr = getenv("VISUAL");
39 ptr = getenv("EDITOR");
44 BB_EXECLP(ptr, ptr, file, NULL);
45 bb_perror_msg_and_die("can't execute '%s'", ptr);
48 static int open_as_user(const struct passwd *pas, const char *file)
54 if (pid) { /* PARENT */
55 if (wait4pid(pid) == 0) {
56 /* exitcode 0: child says it can read */
57 return open(file, O_RDONLY);
63 /* initgroups, setgid, setuid */
65 /* We just try to read one byte. If it works, file is readable
66 * under this user. We signal that by exiting with 0. */
67 _exit(safe_read(xopen(file, O_RDONLY), &c, 1) < 0);
70 int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
71 int crontab_main(int argc UNUSED_PARAM, char **argv)
73 const struct passwd *pas;
74 const char *crontab_dir = CRONTABS;
77 char *user_name; /* -u USER */
82 /* file [opts] Replace crontab from file
83 * - [opts] Replace crontab from stdin
85 * -c dir Crontab directory
86 * -l List crontab for user
87 * -e Edit crontab for user
88 * -r Delete crontab for user
89 * bbox also supports -d == -r, but most other crontab
90 * implementations do not. Deprecated.
98 OPT_ler = OPT_l + OPT_e + OPT_r,
101 opt_complementary = "?1:dr"; /* max one argument; -d implies -r */
102 opt_ler = getopt32(argv, "u:c:lerd", &user_name, &crontab_dir);
105 if (sanitize_env_if_suid()) { /* Clears dangerous stuff, sets PATH */
106 /* Run by non-root */
107 if (opt_ler & (OPT_u|OPT_c))
108 bb_error_msg_and_die(bb_msg_you_must_be_root);
111 if (opt_ler & OPT_u) {
112 pas = xgetpwnam(user_name);
114 pas = xgetpwuid(getuid());
117 #define user_name DONT_USE_ME_BEYOND_THIS_POINT
119 /* From now on, keep only -l, -e, -r bits */
121 if ((opt_ler - 1) & opt_ler) /* more than one bit set? */
124 /* Read replacement file under user's UID/GID/group vector */
125 src_fd = STDIN_FILENO;
126 if (!opt_ler) { /* Replace? */
129 if (NOT_LONE_DASH(argv[0])) {
130 src_fd = open_as_user(pas, argv[0]);
132 bb_error_msg_and_die("user %s cannot read %s",
133 pas->pw_name, argv[0]);
137 /* cd to our crontab directory */
142 /* Handle requested operation */
145 default: /* case OPT_r: Delete */
146 unlink(pas->pw_name);
149 case OPT_l: /* List */
151 char *args[2] = { pas->pw_name, NULL };
154 * the rest go play with cron update file */
157 case OPT_e: /* Edit */
158 tmp_fname = xasprintf("%s.%u", crontab_dir, (unsigned)getpid());
159 /* No O_EXCL: we don't want to be stuck if earlier crontabs
160 * were killed, leaving stale temp file behind */
161 src_fd = xopen3(tmp_fname, O_RDWR|O_CREAT|O_TRUNC, 0600);
162 fchown(src_fd, pas->pw_uid, pas->pw_gid);
163 fd = open(pas->pw_name, O_RDONLY);
165 bb_copyfd_eof(fd, src_fd);
167 xlseek(src_fd, 0, SEEK_SET);
169 close_on_exec_on(src_fd); /* don't want editor to see this fd */
170 edit_file(pas, tmp_fname);
173 case 0: /* Replace (no -l, -e, or -r were given) */
174 new_fname = xasprintf("%s.new", pas->pw_name);
175 fd = open(new_fname, O_WRONLY|O_CREAT|O_TRUNC|O_APPEND, 0600);
177 bb_copyfd_eof(src_fd, fd);
179 xrename(new_fname, pas->pw_name);
181 bb_error_msg("can't create %s/%s",
182 crontab_dir, new_fname);
191 /* Bump notification file. Handle window where crond picks file up
192 * before we can write our entry out.
194 while ((fd = open(CRONUPDATE, O_WRONLY|O_CREAT|O_APPEND, 0600)) >= 0) {
197 fdprintf(fd, "%s\n", pas->pw_name);
198 if (fstat(fd, &st) != 0 || st.st_nlink != 0) {
203 * file was deleted, maybe crond missed our notification */
208 bb_error_msg("can't append to %s/%s",
209 crontab_dir, CRONUPDATE);