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.
13 //usage:#define crontab_trivial_usage
14 //usage: "[-c DIR] [-u USER] [-ler]|[FILE]"
15 //usage:#define crontab_full_usage "\n\n"
16 //usage: " -c Crontab directory"
18 //usage: "\n -l List crontab"
19 //usage: "\n -e Edit crontab"
20 //usage: "\n -r Delete crontab"
21 //usage: "\n FILE Replace crontab by FILE ('-': stdin)"
25 #define CRONTABS CONFIG_FEATURE_CROND_DIR "/crontabs"
27 #define CRONUPDATE "cron.update"
30 static void edit_file(const struct passwd *pas, const char *file)
36 if (pid) { /* parent */
41 /* CHILD - change user and run editor */
42 /* initgroups, setgid, setuid */
44 setup_environment(pas->pw_shell,
45 SETUP_ENV_CHANGEENV | SETUP_ENV_TO_TMP,
47 ptr = getenv("VISUAL");
49 ptr = getenv("EDITOR");
54 BB_EXECLP(ptr, ptr, file, NULL);
55 bb_perror_msg_and_die("can't execute '%s'", ptr);
58 static int open_as_user(const struct passwd *pas, const char *file)
64 if (pid) { /* PARENT */
65 if (wait4pid(pid) == 0) {
66 /* exitcode 0: child says it can read */
67 return open(file, O_RDONLY);
73 /* initgroups, setgid, setuid */
75 /* We just try to read one byte. If it works, file is readable
76 * under this user. We signal that by exiting with 0. */
77 _exit(safe_read(xopen(file, O_RDONLY), &c, 1) < 0);
80 int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
81 int crontab_main(int argc UNUSED_PARAM, char **argv)
83 const struct passwd *pas;
84 const char *crontab_dir = CRONTABS;
87 char *user_name; /* -u USER */
92 /* file [opts] Replace crontab from file
93 * - [opts] Replace crontab from stdin
95 * -c dir Crontab directory
96 * -l List crontab for user
97 * -e Edit crontab for user
98 * -r Delete crontab for user
99 * bbox also supports -d == -r, but most other crontab
100 * implementations do not. Deprecated.
108 OPT_ler = OPT_l + OPT_e + OPT_r,
111 opt_complementary = "?1:dr"; /* max one argument; -d implies -r */
112 opt_ler = getopt32(argv, "u:c:lerd", &user_name, &crontab_dir);
115 if (sanitize_env_if_suid()) { /* Clears dangerous stuff, sets PATH */
116 /* Run by non-root */
117 if (opt_ler & (OPT_u|OPT_c))
118 bb_error_msg_and_die(bb_msg_you_must_be_root);
121 if (opt_ler & OPT_u) {
122 pas = xgetpwnam(user_name);
124 pas = xgetpwuid(getuid());
127 #define user_name DONT_USE_ME_BEYOND_THIS_POINT
129 /* From now on, keep only -l, -e, -r bits */
131 if ((opt_ler - 1) & opt_ler) /* more than one bit set? */
134 /* Read replacement file under user's UID/GID/group vector */
135 src_fd = STDIN_FILENO;
136 if (!opt_ler) { /* Replace? */
139 if (NOT_LONE_DASH(argv[0])) {
140 src_fd = open_as_user(pas, argv[0]);
142 bb_error_msg_and_die("user %s cannot read %s",
143 pas->pw_name, argv[0]);
147 /* cd to our crontab directory */
152 /* Handle requested operation */
155 default: /* case OPT_r: Delete */
156 unlink(pas->pw_name);
159 case OPT_l: /* List */
161 char *args[2] = { pas->pw_name, NULL };
164 * the rest go play with cron update file */
167 case OPT_e: /* Edit */
168 tmp_fname = xasprintf("%s.%u", crontab_dir, (unsigned)getpid());
169 /* No O_EXCL: we don't want to be stuck if earlier crontabs
170 * were killed, leaving stale temp file behind */
171 src_fd = xopen3(tmp_fname, O_RDWR|O_CREAT|O_TRUNC, 0600);
172 fchown(src_fd, pas->pw_uid, pas->pw_gid);
173 fd = open(pas->pw_name, O_RDONLY);
175 bb_copyfd_eof(fd, src_fd);
177 xlseek(src_fd, 0, SEEK_SET);
179 close_on_exec_on(src_fd); /* don't want editor to see this fd */
180 edit_file(pas, tmp_fname);
183 case 0: /* Replace (no -l, -e, or -r were given) */
184 new_fname = xasprintf("%s.new", pas->pw_name);
185 fd = open(new_fname, O_WRONLY|O_CREAT|O_TRUNC|O_APPEND, 0600);
187 bb_copyfd_eof(src_fd, fd);
189 xrename(new_fname, pas->pw_name);
191 bb_error_msg("can't create %s/%s",
192 crontab_dir, new_fname);
201 /* Bump notification file. Handle window where crond picks file up
202 * before we can write our entry out.
204 while ((fd = open(CRONUPDATE, O_WRONLY|O_CREAT|O_APPEND, 0600)) >= 0) {
207 fdprintf(fd, "%s\n", pas->pw_name);
208 if (fstat(fd, &st) != 0 || st.st_nlink != 0) {
213 * file was deleted, maybe crond missed our notification */
218 bb_error_msg("can't append to %s/%s",
219 crontab_dir, CRONUPDATE);