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 the GPL v2 or later, see the file LICENSE in this tarball.
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 < 0) /* failure */
26 bb_perror_msg_and_die("vfork");
27 if (pid) { /* parent */
32 /* CHILD - change user and run editor */
33 /* initgroups, setgid, setuid */
35 setup_environment(DEFAULT_SHELL,
36 SETUP_ENV_CHANGEENV | SETUP_ENV_TO_TMP,
38 ptr = getenv("VISUAL");
40 ptr = getenv("EDITOR");
45 BB_EXECLP(ptr, ptr, file, NULL);
46 bb_perror_msg_and_die("exec %s", ptr);
49 static int open_as_user(const struct passwd *pas, const char *file)
55 if (pid < 0) /* ERROR */
56 bb_perror_msg_and_die("vfork");
57 if (pid) { /* PARENT */
58 if (wait4pid(pid) == 0) {
59 /* exitcode 0: child says it can read */
60 return open(file, O_RDONLY);
66 /* initgroups, setgid, setuid */
68 /* We just try to read one byte. If it works, file is readable
69 * under this user. We signal that by exiting with 0. */
70 _exit(safe_read(xopen(file, O_RDONLY), &c, 1) < 0);
73 int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
74 int crontab_main(int argc UNUSED_PARAM, char **argv)
76 const struct passwd *pas;
77 const char *crontab_dir = CRONTABS;
80 char *user_name; /* -u USER */
85 /* file [opts] Replace crontab from file
86 * - [opts] Replace crontab from stdin
88 * -c dir Crontab directory
89 * -l List crontab for user
90 * -e Edit crontab for user
91 * -r Delete crontab for user
92 * bbox also supports -d == -r, but most other crontab
93 * implementations do not. Deprecated.
101 OPT_ler = OPT_l + OPT_e + OPT_r,
104 opt_complementary = "?1:dr"; /* max one argument; -d implies -r */
105 opt_ler = getopt32(argv, "u:c:lerd", &user_name, &crontab_dir);
108 if (sanitize_env_if_suid()) { /* Clears dangerous stuff, sets PATH */
109 /* Run by non-root */
110 if (opt_ler & (OPT_u|OPT_c))
111 bb_error_msg_and_die(bb_msg_you_must_be_root);
114 if (opt_ler & OPT_u) {
115 pas = xgetpwnam(user_name);
117 pas = xgetpwuid(getuid());
120 #define user_name DONT_USE_ME_BEYOND_THIS_POINT
122 /* From now on, keep only -l, -e, -r bits */
124 if ((opt_ler - 1) & opt_ler) /* more than one bit set? */
127 /* Read replacement file under user's UID/GID/group vector */
128 src_fd = STDIN_FILENO;
129 if (!opt_ler) { /* Replace? */
132 if (NOT_LONE_DASH(argv[0])) {
133 src_fd = open_as_user(pas, argv[0]);
135 bb_error_msg_and_die("user %s cannot read %s",
136 pas->pw_name, argv[0]);
140 /* cd to our crontab directory */
145 /* Handle requested operation */
148 default: /* case OPT_r: Delete */
149 unlink(pas->pw_name);
152 case OPT_l: /* List */
154 char *args[2] = { pas->pw_name, NULL };
157 * the rest go play with cron update file */
160 case OPT_e: /* Edit */
161 tmp_fname = xasprintf("%s.%u", crontab_dir, (unsigned)getpid());
162 /* No O_EXCL: we don't want to be stuck if earlier crontabs
163 * were killed, leaving stale temp file behind */
164 src_fd = xopen3(tmp_fname, O_RDWR|O_CREAT|O_TRUNC, 0600);
165 fchown(src_fd, pas->pw_uid, pas->pw_gid);
166 fd = open(pas->pw_name, O_RDONLY);
168 bb_copyfd_eof(fd, src_fd);
170 xlseek(src_fd, 0, SEEK_SET);
172 close_on_exec_on(src_fd); /* don't want editor to see this fd */
173 edit_file(pas, tmp_fname);
176 case 0: /* Replace (no -l, -e, or -r were given) */
177 new_fname = xasprintf("%s.new", pas->pw_name);
178 fd = open(new_fname, O_WRONLY|O_CREAT|O_TRUNC|O_APPEND, 0600);
180 bb_copyfd_eof(src_fd, fd);
182 xrename(new_fname, pas->pw_name);
184 bb_error_msg("can't create %s/%s",
185 crontab_dir, new_fname);
194 /* Bump notification file. Handle window where crond picks file up
195 * before we can write our entry out.
197 while ((fd = open(CRONUPDATE, O_WRONLY|O_CREAT|O_APPEND, 0600)) >= 0) {
200 fdprintf(fd, "%s\n", pas->pw_name);
201 if (fstat(fd, &st) != 0 || st.st_nlink != 0) {
206 * file was deleted, maybe crond missed our notification */
211 bb_error_msg("can't append to %s/%s",
212 crontab_dir, CRONUPDATE);