1 /* crontab.c - files used to schedule the execution of programs.
2 *
3 * Copyright 2014 Ranjan Kumar <ranjankumar.bth@gmail.com>
4 *
5 * http://pubs.opengroup.org/onlinepubs/9699919799/utilities/crontab.html
6
7 USE_CRONTAB(NEWTOY(crontab, "c:u:elr[!elr]", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_STAYROOT))
8
9 config CRONTAB
10 bool "crontab"
11 default n
12 depends on TOYBOX_FORK
13 help
14 usage: crontab [-u user] FILE
15 [-u user] [-e | -l | -r]
16 [-c dir]
17
18 Files used to schedule the execution of programs.
19
20 -c crontab dir
21 -e edit user's crontab
22 -l list user's crontab
23 -r delete user's crontab
24 -u user
25 FILE Replace crontab by FILE ('-': stdin)
26 */
27 #define FOR_crontab
28 #include "toys.h"
29
GLOBALS(char * user;char * cdir;)30 GLOBALS(
31 char *user;
32 char *cdir;
33 )
34
35 static char *omitspace(char *line)
36 {
37 while (*line == ' ' || *line == '\t') line++;
38 return line;
39 }
40
41 /*
42 * Names can also be used for the 'month' and 'day of week' fields
43 * (First three letters of the particular day or month).
44 */
getindex(char * src,int size)45 static int getindex(char *src, int size)
46 {
47 int i;
48 char days[]={"sun""mon""tue""wed""thu""fri""sat"};
49 char months[]={"jan""feb""mar""apr""may""jun""jul"
50 "aug""sep""oct""nov""dec"};
51 char *field = (size == 12) ? months : days;
52
53 // strings are not allowed for min, hour and dom fields.
54 if (!(size == 7 || size == 12)) return -1;
55
56 for (i = 0; field[i]; i += 3) {
57 if (!strncasecmp(src, &field[i], 3))
58 return (i/3);
59 }
60 return -1;
61 }
62
getval(char * num,long low,long high)63 static long getval(char *num, long low, long high)
64 {
65 long val = strtol(num, &num, 10);
66
67 if (*num || (val < low) || (val > high)) return -1;
68 return val;
69 }
70
71 // Validate minute, hour, day of month, month and day of week fields.
validate_component(int min,int max,char * src)72 static int validate_component(int min, int max, char *src)
73 {
74 int skip = 0;
75 char *ptr;
76
77 if (!src) return 1;
78 if ((ptr = strchr(src, '/'))) {
79 *ptr++ = 0;
80 if ((skip = getval(ptr, min, (min ? max: max-1))) < 0) return 1;
81 }
82
83 if (*src == '-' || *src == ',') return 1;
84 if (*src == '*') {
85 if (*(src+1)) return 1;
86 }
87 else {
88 for (;;) {
89 char *ctoken = strsep(&src, ","), *dtoken;
90
91 if (!ctoken) break;
92 if (!*ctoken) return 1;
93
94 // validate start position.
95 dtoken = strsep(&ctoken, "-");
96 if (isdigit(*dtoken)) {
97 if (getval(dtoken, min, (min ? max : max-1)) < 0) return 1;
98 } else if (getindex(dtoken, max) < 0) return 1;
99
100 // validate end position.
101 if (!ctoken) {
102 if (skip) return 1; // case 10/20 or 1,2,4/3
103 }
104 else if (*ctoken) {// e.g. N-M
105 if (isdigit(*ctoken)) {
106 if (getval(ctoken, min, (min ? max : max-1)) < 0) return 1;
107 } else if (getindex(ctoken, max) < 0) return 1;
108 } else return 1; // error condition 'N-'
109 }
110 }
111 return 0;
112 }
113
parse_crontab(char * fname)114 static int parse_crontab(char *fname)
115 {
116 char *line;
117 int lno, fd = xopenro(fname);
118 long plen = 0;
119
120 for (lno = 1; (line = get_rawline(fd, &plen, '\n')); lno++,free(line)) {
121 char *name, *val, *tokens[5] = {0,}, *ptr = line;
122 int count = 0;
123
124 if (line[plen - 1] == '\n') line[--plen] = '\0';
125 else {
126 snprintf(toybuf, sizeof(toybuf), "'%d': premature EOF\n", lno);
127 goto OUT;
128 }
129
130 ptr = omitspace(ptr);
131 if (!*ptr || *ptr == '#' || *ptr == '@') continue;
132 while (count<5) {
133 int len = strcspn(ptr, " \t");
134
135 if (ptr[len]) ptr[len++] = '\0';
136 tokens[count++] = ptr;
137 ptr += len;
138 ptr = omitspace(ptr);
139 if (!*ptr) break;
140 }
141 switch (count) {
142 case 1: // form SHELL=/bin/sh
143 name = tokens[0];
144 if ((val = strchr(name, '='))) *val++ = 0;
145 if (!val || !*val) {
146 snprintf(toybuf, sizeof(toybuf), "'%d': %s\n", lno, line);
147 goto OUT;
148 }
149 break;
150 case 2: // form SHELL =/bin/sh or SHELL= /bin/sh
151 name = tokens[0];
152 if ((val = strchr(name, '='))) {
153 *val = 0;
154 val = tokens[1];
155 } else {
156 if (*(tokens[1]) != '=') {
157 snprintf(toybuf, sizeof(toybuf), "'%d': %s\n", lno, line);
158 goto OUT;
159 }
160 val = tokens[1] + 1;
161 }
162 if (!*val) {
163 snprintf(toybuf, sizeof(toybuf), "'%d': %s\n", lno, line);
164 goto OUT;
165 }
166 break;
167 case 3: // NAME = VAL
168 name = tokens[0];
169 val = tokens[2];
170 if (*(tokens[1]) != '=') {
171 snprintf(toybuf, sizeof(toybuf), "'%d': %s\n", lno, line);
172 goto OUT;
173 }
174 break;
175 default:
176 if (validate_component(0, 60, tokens[0])) {
177 snprintf(toybuf, sizeof(toybuf), "'%d': bad minute\n", lno);
178 goto OUT;
179 }
180 if (validate_component(0, 24, tokens[1])) {
181 snprintf(toybuf, sizeof(toybuf), "'%d': bad hour\n", lno);
182 goto OUT;
183 }
184 if (validate_component(1, 31, tokens[2])) {
185 snprintf(toybuf, sizeof(toybuf), "'%d': bad day-of-month\n", lno);
186 goto OUT;
187 }
188 if (validate_component(1, 12, tokens[3])) {
189 snprintf(toybuf, sizeof(toybuf), "'%d': bad month\n", lno);
190 goto OUT;
191 }
192 if (validate_component(0, 7, tokens[4])) {
193 snprintf(toybuf, sizeof(toybuf), "'%d': bad day-of-week\n", lno);
194 goto OUT;
195 }
196 if (!*ptr) { // don't have any cmd to execute.
197 snprintf(toybuf, sizeof(toybuf), "'%d': bad command\n", lno);
198 goto OUT;
199 }
200 break;
201 }
202 }
203 xclose(fd);
204 return 0;
205 OUT:
206 free(line);
207 printf("Error at line no %s", toybuf);
208 xclose(fd);
209 return 1;
210 }
211
do_list(char * name)212 static void do_list(char *name)
213 {
214 int fdin;
215
216 snprintf(toybuf, sizeof(toybuf), "%s%s", TT.cdir, name);
217 fdin = xopenro(toybuf);
218 xsendfile(fdin, 1);
219 xclose(fdin);
220 }
221
do_remove(char * name)222 static void do_remove(char *name)
223 {
224 snprintf(toybuf, sizeof(toybuf), "%s%s", TT.cdir, name);
225 if (unlink(toybuf))
226 error_exit("No crontab for '%s'", name);
227 }
228
update_crontab(char * src,char * dest)229 static void update_crontab(char *src, char *dest)
230 {
231 int fdin, fdout;
232
233 snprintf(toybuf, sizeof(toybuf), "%s%s", TT.cdir, dest);
234 fdout = xcreate(toybuf, O_WRONLY|O_CREAT|O_TRUNC, 0600);
235 fdin = xopenro(src);
236 xsendfile(fdin, fdout);
237 xclose(fdin);
238
239 fchown(fdout, getuid(), geteuid());
240 xclose(fdout);
241 }
242
do_replace(char * name)243 static void do_replace(char *name)
244 {
245 char *fname = *toys.optargs ? *toys.optargs : "-";
246 char tname[] = "/tmp/crontab.XXXXXX";
247
248 if ((*fname == '-') && !*(fname+1)) {
249 int tfd = mkstemp(tname);
250
251 if (tfd < 0) perror_exit("mkstemp");
252 xsendfile(0, tfd);
253 xclose(tfd);
254 fname = tname;
255 }
256
257 if (parse_crontab(fname))
258 error_exit("errors in crontab file '%s', can't install.", fname);
259 update_crontab(fname, name);
260 unlink(tname);
261 }
262
do_edit(struct passwd * pwd)263 static void do_edit(struct passwd *pwd)
264 {
265 struct stat sb;
266 time_t mtime = 0;
267 int srcfd, destfd, status;
268 pid_t pid, cpid;
269 char tname[] = "/tmp/crontab.XXXXXX";
270
271 if ((destfd = mkstemp(tname)) < 0)
272 perror_exit("Can't open tmp file");
273
274 fchmod(destfd, 0666);
275 snprintf(toybuf, sizeof(toybuf), "%s%s", TT.cdir, pwd->pw_name);
276
277 if (!stat(toybuf, &sb)) { // file exists and have some content.
278 if (sb.st_size) {
279 srcfd = xopenro(toybuf);
280 xsendfile(srcfd, destfd);
281 xclose(srcfd);
282 }
283 } else printf("No crontab for '%s'- using an empty one\n", pwd->pw_name);
284 xclose(destfd);
285
286 if (!stat(tname, &sb)) mtime = sb.st_mtime;
287
288 RETRY:
289 if (!(pid = xfork())) {
290 char *prog = pwd->pw_shell;
291
292 xsetuser(pwd);
293 if (pwd->pw_uid) {
294 if (setenv("USER", pwd->pw_name, 1)) _exit(1);
295 if (setenv("LOGNAME", pwd->pw_name, 1)) _exit(1);
296 }
297 if (setenv("HOME", pwd->pw_dir, 1)) _exit(1);
298 if (setenv("SHELL",((!prog || !*prog) ? "/bin/sh" : prog), 1)) _exit(1);
299
300 if (!(prog = getenv("VISUAL"))) {
301 if (!(prog = getenv("EDITOR")))
302 prog = "vi";
303 }
304 execlp(prog, prog, tname, (char *) NULL);
305 perror_exit("can't execute '%s'", prog);
306 }
307
308 // Parent Process.
309 do {
310 cpid = waitpid(pid, &status, 0);
311 } while ((cpid == -1) && (errno == EINTR));
312
313 if (!stat(tname, &sb) && (mtime == sb.st_mtime)) {
314 printf("%s: no changes made to crontab\n", toys.which->name);
315 unlink(tname);
316 return;
317 }
318 printf("%s: installing new crontab\n", toys.which->name);
319 if (parse_crontab(tname)) {
320 fprintf(stderr, "errors in crontab file, can't install.\n"
321 "Do you want to retry the same edit? ");
322 if (!yesno(0)) {
323 error_msg("edits left in '%s'", tname);
324 return;
325 }
326 goto RETRY;
327 }
328 // parsing of crontab success; update the crontab.
329 update_crontab(tname, pwd->pw_name);
330 unlink(tname);
331 }
332
crontab_main(void)333 void crontab_main(void)
334 {
335 struct passwd *pwd = NULL;
336 long FLAG_elr = toys.optflags & (FLAG_e|FLAG_l|FLAG_r);
337
338 if (TT.cdir && (TT.cdir[strlen(TT.cdir)-1] != '/'))
339 TT.cdir = xmprintf("%s/", TT.cdir);
340 if (!TT.cdir) TT.cdir = xstrdup("/var/spool/cron/crontabs/");
341
342 if (toys.optflags & FLAG_u) {
343 if (getuid()) error_exit("must be privileged to use -u");
344 pwd = xgetpwnam(TT.user);
345 } else pwd = xgetpwuid(getuid());
346
347 if (!toys.optc) {
348 if (!FLAG_elr) {
349 if (toys.optflags & FLAG_u)
350 help_exit("file name must be specified for replace");
351 do_replace(pwd->pw_name);
352 }
353 else if (toys.optflags & FLAG_e) do_edit(pwd);
354 else if (toys.optflags & FLAG_l) do_list(pwd->pw_name);
355 else if (toys.optflags & FLAG_r) do_remove(pwd->pw_name);
356 } else {
357 if (FLAG_elr) help_exit("no arguments permitted after this option");
358 do_replace(pwd->pw_name);
359 }
360 if (!(toys.optflags & FLAG_c)) free(TT.cdir);
361 }
362