source: MondoRescue/branches/stable/mindi-busybox/miscutils/crontab.c@ 1247

Last change on this file since 1247 was 821, checked in by Bruno Cornec, 18 years ago

Addition of busybox 1.2.1 as a mindi-busybox new package
This should avoid delivering binary files in mindi not built there (Fedora and Debian are quite serious about that)
File size: 7.0 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 the GPL v2 or later, see the file LICENSE in this tarball.
11 */
12
13#include "busybox.h"
14#include <stdio.h>
15#include <stdlib.h>
16#include <stdarg.h>
17#include <string.h>
18#include <errno.h>
19#include <time.h>
20#include <dirent.h>
21#include <fcntl.h>
22#include <unistd.h>
23#include <syslog.h>
24#include <signal.h>
25#include <getopt.h>
26#include <sys/ioctl.h>
27#include <sys/wait.h>
28#include <sys/stat.h>
29#include <sys/resource.h>
30
31#ifndef CRONTABS
32#define CRONTABS "/var/spool/cron/crontabs"
33#endif
34#ifndef TMPDIR
35#define TMPDIR "/var/spool/cron"
36#endif
37#ifndef CRONUPDATE
38#define CRONUPDATE "cron.update"
39#endif
40#ifndef PATH_VI
41#define PATH_VI "/bin/vi" /* location of vi */
42#endif
43
44static const char *CDir = CRONTABS;
45
46static void EditFile(const char *user, const char *file);
47static int GetReplaceStream(const char *user, const char *file);
48static int ChangeUser(const char *user, short dochdir);
49
50int
51crontab_main(int ac, char **av)
52{
53 enum { NONE, EDIT, LIST, REPLACE, DELETE } option = NONE;
54 const struct passwd *pas;
55 const char *repFile = NULL;
56 int repFd = 0;
57 int i;
58 char caller[256]; /* user that ran program */
59 int UserId;
60
61 UserId = getuid();
62 if ((pas = getpwuid(UserId)) == NULL)
63 bb_perror_msg_and_die("getpwuid");
64
65 safe_strncpy(caller, pas->pw_name, sizeof(caller));
66
67 i = 1;
68 if (ac > 1) {
69 if (av[1][0] == '-' && av[1][1] == 0) {
70 option = REPLACE;
71 ++i;
72 } else if (av[1][0] != '-') {
73 option = REPLACE;
74 ++i;
75 repFile = av[1];
76 }
77 }
78
79 for (; i < ac; ++i) {
80 char *ptr = av[i];
81
82 if (*ptr != '-')
83 break;
84 ptr += 2;
85
86 switch(ptr[-1]) {
87 case 'l':
88 if (ptr[-1] == 'l')
89 option = LIST;
90 /* fall through */
91 case 'e':
92 if (ptr[-1] == 'e')
93 option = EDIT;
94 /* fall through */
95 case 'd':
96 if (ptr[-1] == 'd')
97 option = DELETE;
98 /* fall through */
99 case 'u':
100 if (i + 1 < ac && av[i+1][0] != '-') {
101 ++i;
102 if (getuid() == geteuid()) {
103 pas = getpwnam(av[i]);
104 if (pas) {
105 UserId = pas->pw_uid;
106 } else {
107 bb_error_msg_and_die("user %s unknown", av[i]);
108 }
109 } else {
110 bb_error_msg_and_die("only the superuser may specify a user");
111 }
112 }
113 break;
114 case 'c':
115 if (getuid() == geteuid()) {
116 CDir = (*ptr) ? ptr : av[++i];
117 } else {
118 bb_error_msg_and_die("-c option: superuser only");
119 }
120 break;
121 default:
122 i = ac;
123 break;
124 }
125 }
126 if (i != ac || option == NONE)
127 bb_show_usage();
128
129 /*
130 * Get password entry
131 */
132
133 if ((pas = getpwuid(UserId)) == NULL)
134 bb_perror_msg_and_die("getpwuid");
135
136 /*
137 * If there is a replacement file, obtain a secure descriptor to it.
138 */
139
140 if (repFile) {
141 repFd = GetReplaceStream(caller, repFile);
142 if (repFd < 0)
143 bb_error_msg_and_die("unable to read replacement file");
144 }
145
146 /*
147 * Change directory to our crontab directory
148 */
149
150 bb_xchdir(CDir);
151
152 /*
153 * Handle options as appropriate
154 */
155
156 switch(option) {
157 case LIST:
158 {
159 FILE *fi;
160 char buf[1024];
161
162 if ((fi = fopen(pas->pw_name, "r"))) {
163 while (fgets(buf, sizeof(buf), fi) != NULL)
164 fputs(buf, stdout);
165 fclose(fi);
166 } else {
167 bb_error_msg("no crontab for %s", pas->pw_name);
168 }
169 }
170 break;
171 case EDIT:
172 {
173 FILE *fi;
174 int fd;
175 int n;
176 char tmp[128];
177 char buf[1024];
178
179 snprintf(tmp, sizeof(tmp), TMPDIR "/crontab.%d", getpid());
180 fd = bb_xopen3(tmp, O_RDWR|O_CREAT|O_TRUNC|O_EXCL, 0600);
181 chown(tmp, getuid(), getgid());
182 if ((fi = fopen(pas->pw_name, "r"))) {
183 while ((n = fread(buf, 1, sizeof(buf), fi)) > 0)
184 write(fd, buf, n);
185 }
186 EditFile(caller, tmp);
187 remove(tmp);
188 lseek(fd, 0L, 0);
189 repFd = fd;
190 }
191 option = REPLACE;
192 /* fall through */
193 case REPLACE:
194 {
195 char buf[1024];
196 char path[1024];
197 int fd;
198 int n;
199
200 snprintf(path, sizeof(path), "%s.new", pas->pw_name);
201 if ((fd = open(path, O_CREAT|O_TRUNC|O_APPEND|O_WRONLY, 0600)) >= 0) {
202 while ((n = read(repFd, buf, sizeof(buf))) > 0) {
203 write(fd, buf, n);
204 }
205 close(fd);
206 rename(path, pas->pw_name);
207 } else {
208 bb_error_msg("unable to create %s/%s", CDir, path);
209 }
210 close(repFd);
211 }
212 break;
213 case DELETE:
214 remove(pas->pw_name);
215 break;
216 case NONE:
217 default:
218 break;
219 }
220
221 /*
222 * Bump notification file. Handle window where crond picks file up
223 * before we can write our entry out.
224 */
225
226 if (option == REPLACE || option == DELETE) {
227 FILE *fo;
228 struct stat st;
229
230 while ((fo = fopen(CRONUPDATE, "a"))) {
231 fprintf(fo, "%s\n", pas->pw_name);
232 fflush(fo);
233 if (fstat(fileno(fo), &st) != 0 || st.st_nlink != 0) {
234 fclose(fo);
235 break;
236 }
237 fclose(fo);
238 /* loop */
239 }
240 if (fo == NULL) {
241 bb_error_msg("unable to append to %s/%s", CDir, CRONUPDATE);
242 }
243 }
244 return 0;
245}
246
247static int
248GetReplaceStream(const char *user, const char *file)
249{
250 int filedes[2];
251 int pid;
252 int fd;
253 int n;
254 char buf[1024];
255
256 if (pipe(filedes) < 0) {
257 perror("pipe");
258 return(-1);
259 }
260 if ((pid = fork()) < 0) {
261 perror("fork");
262 return(-1);
263 }
264 if (pid > 0) {
265 /*
266 * PARENT
267 */
268
269 close(filedes[1]);
270 if (read(filedes[0], buf, 1) != 1) {
271 close(filedes[0]);
272 filedes[0] = -1;
273 }
274 return(filedes[0]);
275 }
276
277 /*
278 * CHILD
279 */
280
281 close(filedes[0]);
282
283 if (ChangeUser(user, 0) < 0)
284 exit(0);
285
286 bb_default_error_retval = 0;
287 fd = bb_xopen3(file, O_RDONLY, 0);
288 buf[0] = 0;
289 write(filedes[1], buf, 1);
290 while ((n = read(fd, buf, sizeof(buf))) > 0) {
291 write(filedes[1], buf, n);
292 }
293 exit(0);
294}
295
296static void
297EditFile(const char *user, const char *file)
298{
299 int pid;
300
301 if ((pid = fork()) == 0) {
302 /*
303 * CHILD - change user and run editor
304 */
305 char *ptr;
306 char visual[1024];
307
308 if (ChangeUser(user, 1) < 0)
309 exit(0);
310 if ((ptr = getenv("VISUAL")) == NULL || strlen(ptr) > 256)
311 ptr = PATH_VI;
312
313 snprintf(visual, sizeof(visual), "%s %s", ptr, file);
314 execl(DEFAULT_SHELL, DEFAULT_SHELL, "-c", visual, NULL);
315 perror("exec");
316 exit(0);
317 }
318 if (pid < 0) {
319 /*
320 * PARENT - failure
321 */
322 bb_perror_msg_and_die("fork");
323 }
324 wait4(pid, NULL, 0, NULL);
325}
326
327static int
328ChangeUser(const char *user, short dochdir)
329{
330 struct passwd *pas;
331
332 /*
333 * Obtain password entry and change privileges
334 */
335
336 if ((pas = getpwnam(user)) == NULL) {
337 bb_perror_msg_and_die("failed to get uid for %s", user);
338 return(-1);
339 }
340 setenv("USER", pas->pw_name, 1);
341 setenv("HOME", pas->pw_dir, 1);
342 setenv("SHELL", DEFAULT_SHELL, 1);
343
344 /*
345 * Change running state to the user in question
346 */
347 change_identity(pas);
348
349 if (dochdir) {
350 if (chdir(pas->pw_dir) < 0) {
351 bb_perror_msg("chdir failed: %s %s", user, pas->pw_dir);
352 bb_xchdir(TMPDIR);
353 }
354 }
355 return(pas->pw_uid);
356}
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