source: MondoRescue/branches/3.2/mindi-busybox/miscutils/crontab.c

Last change on this file was 3232, checked in by Bruno Cornec, 10 years ago
  • Update mindi-busybox to 1.21.1
File size: 5.4 KB
Line 
1/* vi: set sw=4 ts=4: */
2/*
3 * CRONTAB
4 *
5 * usually setuid root, -c option only works if getuid() == geteuid()
6 *
7 * Copyright 1994 Matthew Dillon (dillon@apollo.west.oic.com)
8 * Vladimir Oleynik <dzo@simtreas.ru> (C) 2002
9 *
10 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
11 */
12
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"
17//usage: "\n -u User"
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)"
22
23#include "libbb.h"
24
25#define CRONTABS CONFIG_FEATURE_CROND_DIR "/crontabs"
26#ifndef CRONUPDATE
27#define CRONUPDATE "cron.update"
28#endif
29
30static void edit_file(const struct passwd *pas, const char *file)
31{
32 const char *ptr;
33 pid_t pid;
34
35 pid = xvfork();
36 if (pid) { /* parent */
37 wait4pid(pid);
38 return;
39 }
40
41 /* CHILD - change user and run editor */
42 /* initgroups, setgid, setuid */
43 change_identity(pas);
44 setup_environment(pas->pw_shell,
45 SETUP_ENV_CHANGEENV | SETUP_ENV_TO_TMP,
46 pas);
47 ptr = getenv("VISUAL");
48 if (!ptr) {
49 ptr = getenv("EDITOR");
50 if (!ptr)
51 ptr = "vi";
52 }
53
54 BB_EXECLP(ptr, ptr, file, NULL);
55 bb_perror_msg_and_die("can't execute '%s'", ptr);
56}
57
58static int open_as_user(const struct passwd *pas, const char *file)
59{
60 pid_t pid;
61 char c;
62
63 pid = xvfork();
64 if (pid) { /* PARENT */
65 if (wait4pid(pid) == 0) {
66 /* exitcode 0: child says it can read */
67 return open(file, O_RDONLY);
68 }
69 return -1;
70 }
71
72 /* CHILD */
73 /* initgroups, setgid, setuid */
74 change_identity(pas);
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);
78}
79
80int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
81int crontab_main(int argc UNUSED_PARAM, char **argv)
82{
83 const struct passwd *pas;
84 const char *crontab_dir = CRONTABS;
85 char *tmp_fname;
86 char *new_fname;
87 char *user_name; /* -u USER */
88 int fd;
89 int src_fd;
90 int opt_ler;
91
92 /* file [opts] Replace crontab from file
93 * - [opts] Replace crontab from stdin
94 * -u user User
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.
101 */
102 enum {
103 OPT_u = (1 << 0),
104 OPT_c = (1 << 1),
105 OPT_l = (1 << 2),
106 OPT_e = (1 << 3),
107 OPT_r = (1 << 4),
108 OPT_ler = OPT_l + OPT_e + OPT_r,
109 };
110
111 opt_complementary = "?1:dr"; /* max one argument; -d implies -r */
112 opt_ler = getopt32(argv, "u:c:lerd", &user_name, &crontab_dir);
113 argv += optind;
114
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);
119 }
120
121 if (opt_ler & OPT_u) {
122 pas = xgetpwnam(user_name);
123 } else {
124 pas = xgetpwuid(getuid());
125 }
126
127#define user_name DONT_USE_ME_BEYOND_THIS_POINT
128
129 /* From now on, keep only -l, -e, -r bits */
130 opt_ler &= OPT_ler;
131 if ((opt_ler - 1) & opt_ler) /* more than one bit set? */
132 bb_show_usage();
133
134 /* Read replacement file under user's UID/GID/group vector */
135 src_fd = STDIN_FILENO;
136 if (!opt_ler) { /* Replace? */
137 if (!argv[0])
138 bb_show_usage();
139 if (NOT_LONE_DASH(argv[0])) {
140 src_fd = open_as_user(pas, argv[0]);
141 if (src_fd < 0)
142 bb_error_msg_and_die("user %s cannot read %s",
143 pas->pw_name, argv[0]);
144 }
145 }
146
147 /* cd to our crontab directory */
148 xchdir(crontab_dir);
149
150 tmp_fname = NULL;
151
152 /* Handle requested operation */
153 switch (opt_ler) {
154
155 default: /* case OPT_r: Delete */
156 unlink(pas->pw_name);
157 break;
158
159 case OPT_l: /* List */
160 {
161 char *args[2] = { pas->pw_name, NULL };
162 return bb_cat(args);
163 /* list exits,
164 * the rest go play with cron update file */
165 }
166
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);
174 if (fd >= 0) {
175 bb_copyfd_eof(fd, src_fd);
176 close(fd);
177 xlseek(src_fd, 0, SEEK_SET);
178 }
179 close_on_exec_on(src_fd); /* don't want editor to see this fd */
180 edit_file(pas, tmp_fname);
181 /* fall through */
182
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);
186 if (fd >= 0) {
187 bb_copyfd_eof(src_fd, fd);
188 close(fd);
189 xrename(new_fname, pas->pw_name);
190 } else {
191 bb_error_msg("can't create %s/%s",
192 crontab_dir, new_fname);
193 }
194 if (tmp_fname)
195 unlink(tmp_fname);
196 /*free(tmp_fname);*/
197 /*free(new_fname);*/
198
199 } /* switch */
200
201 /* Bump notification file. Handle window where crond picks file up
202 * before we can write our entry out.
203 */
204 while ((fd = open(CRONUPDATE, O_WRONLY|O_CREAT|O_APPEND, 0600)) >= 0) {
205 struct stat st;
206
207 fdprintf(fd, "%s\n", pas->pw_name);
208 if (fstat(fd, &st) != 0 || st.st_nlink != 0) {
209 /*close(fd);*/
210 break;
211 }
212 /* st.st_nlink == 0:
213 * file was deleted, maybe crond missed our notification */
214 close(fd);
215 /* loop */
216 }
217 if (fd < 0) {
218 bb_error_msg("can't append to %s/%s",
219 crontab_dir, CRONUPDATE);
220 }
221 return 0;
222}
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