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)
25 if (pid) { /* parent */
30 /* CHILD - change user and run editor */
31 /* initgroups, setgid, setuid */
33 setup_environment(DEFAULT_SHELL,
34 SETUP_ENV_CHANGEENV | SETUP_ENV_TO_TMP,
36 ptr = getenv("VISUAL");
38 ptr = getenv("EDITOR");
43 BB_EXECLP(ptr, ptr, file, NULL);
44 bb_perror_msg_and_die("exec %s", ptr);
47 static int open_as_user(const struct passwd *pas, const char *file)
53 if (pid) { /* PARENT */
54 if (wait4pid(pid) == 0) {
55 /* exitcode 0: child says it can read */
56 return open(file, O_RDONLY);
62 /* initgroups, setgid, setuid */
64 /* We just try to read one byte. If it works, file is readable
65 * under this user. We signal that by exiting with 0. */
66 _exit(safe_read(xopen(file, O_RDONLY), &c, 1) < 0);
69 int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
70 int crontab_main(int argc UNUSED_PARAM, char **argv)
72 const struct passwd *pas;
73 const char *crontab_dir = CRONTABS;
76 char *user_name; /* -u USER */
81 /* file [opts] Replace crontab from file
82 * - [opts] Replace crontab from stdin
84 * -c dir Crontab directory
85 * -l List crontab for user
86 * -e Edit crontab for user
87 * -r Delete crontab for user
88 * bbox also supports -d == -r, but most other crontab
89 * implementations do not. Deprecated.
97 OPT_ler = OPT_l + OPT_e + OPT_r,
100 opt_complementary = "?1:dr"; /* max one argument; -d implies -r */
101 opt_ler = getopt32(argv, "u:c:lerd", &user_name, &crontab_dir);
104 if (sanitize_env_if_suid()) { /* Clears dangerous stuff, sets PATH */
105 /* Run by non-root */
106 if (opt_ler & (OPT_u|OPT_c))
107 bb_error_msg_and_die(bb_msg_you_must_be_root);
110 if (opt_ler & OPT_u) {
111 pas = xgetpwnam(user_name);
113 pas = xgetpwuid(getuid());
116 #define user_name DONT_USE_ME_BEYOND_THIS_POINT
118 /* From now on, keep only -l, -e, -r bits */
120 if ((opt_ler - 1) & opt_ler) /* more than one bit set? */
123 /* Read replacement file under user's UID/GID/group vector */
124 src_fd = STDIN_FILENO;
125 if (!opt_ler) { /* Replace? */
128 if (NOT_LONE_DASH(argv[0])) {
129 src_fd = open_as_user(pas, argv[0]);
131 bb_error_msg_and_die("user %s cannot read %s",
132 pas->pw_name, argv[0]);
136 /* cd to our crontab directory */
141 /* Handle requested operation */
144 default: /* case OPT_r: Delete */
145 unlink(pas->pw_name);
148 case OPT_l: /* List */
150 char *args[2] = { pas->pw_name, NULL };
153 * the rest go play with cron update file */
156 case OPT_e: /* Edit */
157 tmp_fname = xasprintf("%s.%u", crontab_dir, (unsigned)getpid());
158 /* No O_EXCL: we don't want to be stuck if earlier crontabs
159 * were killed, leaving stale temp file behind */
160 src_fd = xopen3(tmp_fname, O_RDWR|O_CREAT|O_TRUNC, 0600);
161 fchown(src_fd, pas->pw_uid, pas->pw_gid);
162 fd = open(pas->pw_name, O_RDONLY);
164 bb_copyfd_eof(fd, src_fd);
166 xlseek(src_fd, 0, SEEK_SET);
168 close_on_exec_on(src_fd); /* don't want editor to see this fd */
169 edit_file(pas, tmp_fname);
172 case 0: /* Replace (no -l, -e, or -r were given) */
173 new_fname = xasprintf("%s.new", pas->pw_name);
174 fd = open(new_fname, O_WRONLY|O_CREAT|O_TRUNC|O_APPEND, 0600);
176 bb_copyfd_eof(src_fd, fd);
178 xrename(new_fname, pas->pw_name);
180 bb_error_msg("can't create %s/%s",
181 crontab_dir, new_fname);
190 /* Bump notification file. Handle window where crond picks file up
191 * before we can write our entry out.
193 while ((fd = open(CRONUPDATE, O_WRONLY|O_CREAT|O_APPEND, 0600)) >= 0) {
196 fdprintf(fd, "%s\n", pas->pw_name);
197 if (fstat(fd, &st) != 0 || st.st_nlink != 0) {
202 * file was deleted, maybe crond missed our notification */
207 bb_error_msg("can't append to %s/%s",
208 crontab_dir, CRONUPDATE);