xref: /third_party/toybox/toys/pending/crontab.c (revision 0f66f451) 
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
7USE_CRONTAB(NEWTOY(crontab, "c:u:elr[!elr]", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_STAYROOT))
8
9config 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
30GLOBALS(
31  char *user;
32  char *cdir;
33)
34
35static 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 */
45static 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
63static 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.
72static 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
114static int parse_crontab(char *fname)
115{
116  FILE *fp = xfopen(fname, "r");
117  long len = 0;
118  char *line = NULL;
119  size_t allocated_length;
120  int lno;
121
122  for (lno = 1; (len = getline(&line, &allocated_length, fp)) > 0; lno++) {
123    char *name, *val, *tokens[5] = {0,}, *ptr = line;
124    int count = 0;
125
126    if (line[len - 1] == '\n') line[--len] = '\0';
127    else {
128      snprintf(toybuf, sizeof(toybuf), "'%d': premature EOF\n", lno);
129      goto OUT;
130    }
131
132    ptr = omitspace(ptr);
133    if (!*ptr || *ptr == '#' || *ptr == '@') continue;
134    while (count<5) {
135      int len = strcspn(ptr, " \t");
136
137      if (ptr[len]) ptr[len++] = '\0';
138      tokens[count++] = ptr;
139      ptr += len;
140      ptr = omitspace(ptr);
141      if (!*ptr) break;
142    }
143    switch (count) {
144      case 1: // form SHELL=/bin/sh
145        name = tokens[0];
146        if ((val = strchr(name, '='))) *val++ = 0;
147        if (!val || !*val) {
148          snprintf(toybuf, sizeof(toybuf), "'%d': %s\n", lno, line);
149          goto OUT;
150        }
151        break;
152      case 2: // form SHELL =/bin/sh or SHELL= /bin/sh
153        name = tokens[0];
154        if ((val = strchr(name, '='))) {
155          *val = 0;
156          val = tokens[1];
157        } else {
158          if (*(tokens[1]) != '=') {
159            snprintf(toybuf, sizeof(toybuf), "'%d': %s\n", lno, line);
160            goto OUT;
161          }
162          val = tokens[1] + 1;
163        }
164        if (!*val) {
165          snprintf(toybuf, sizeof(toybuf), "'%d': %s\n", lno, line);
166          goto OUT;
167        }
168        break;
169      case 3: // NAME = VAL
170        name = tokens[0];
171        val = tokens[2];
172        if (*(tokens[1]) != '=') {
173          snprintf(toybuf, sizeof(toybuf), "'%d': %s\n", lno, line);
174          goto OUT;
175        }
176        break;
177      default:
178        if (validate_component(0, 60, tokens[0])) {
179          snprintf(toybuf, sizeof(toybuf), "'%d': bad minute\n", lno);
180          goto OUT;
181        }
182        if (validate_component(0, 24, tokens[1])) {
183          snprintf(toybuf, sizeof(toybuf), "'%d': bad hour\n", lno);
184          goto OUT;
185        }
186        if (validate_component(1, 31, tokens[2])) {
187          snprintf(toybuf, sizeof(toybuf), "'%d': bad day-of-month\n", lno);
188          goto OUT;
189        }
190        if (validate_component(1, 12, tokens[3])) {
191          snprintf(toybuf, sizeof(toybuf), "'%d': bad month\n", lno);
192          goto OUT;
193        }
194        if (validate_component(0, 7, tokens[4])) {
195          snprintf(toybuf, sizeof(toybuf), "'%d': bad day-of-week\n", lno);
196          goto OUT;
197        }
198        if (!*ptr) { // don't have any cmd to execute.
199          snprintf(toybuf, sizeof(toybuf), "'%d': bad command\n", lno);
200          goto OUT;
201        }
202        break;
203    }
204  }
205  free(line);
206  fclose(fp);
207  return 0;
208OUT:
209  free(line);
210  printf("Error at line no %s", toybuf);
211  fclose(fp);
212  return 1;
213}
214
215static void do_list(char *name)
216{
217  int fdin;
218
219  snprintf(toybuf, sizeof(toybuf), "%s%s", TT.cdir, name);
220  fdin = xopenro(toybuf);
221  xsendfile(fdin, 1);
222  xclose(fdin);
223}
224
225static void do_remove(char *name)
226{
227  snprintf(toybuf, sizeof(toybuf), "%s%s", TT.cdir, name);
228  if (unlink(toybuf))
229    error_exit("No crontab for '%s'", name);
230}
231
232static void update_crontab(char *src, char *dest)
233{
234  int fdin, fdout;
235
236  snprintf(toybuf, sizeof(toybuf), "%s%s", TT.cdir, dest);
237  fdout = xcreate(toybuf, O_WRONLY|O_CREAT|O_TRUNC, 0600);
238  fdin = xopenro(src);
239  xsendfile(fdin, fdout);
240  xclose(fdin);
241
242  fchown(fdout, getuid(), geteuid());
243  xclose(fdout);
244}
245
246static void do_replace(char *name)
247{
248  char *fname = *toys.optargs ? *toys.optargs : "-";
249  char tname[] = "/tmp/crontab.XXXXXX";
250
251  if ((*fname == '-') && !*(fname+1)) {
252    int tfd = mkstemp(tname);
253
254    if (tfd < 0) perror_exit("mkstemp");
255    xsendfile(0, tfd);
256    xclose(tfd);
257    fname = tname;
258  }
259
260  if (parse_crontab(fname))
261    error_exit("errors in crontab file '%s', can't install.", fname);
262  update_crontab(fname, name);
263  unlink(tname);
264}
265
266static void do_edit(struct passwd *pwd)
267{
268  struct stat sb;
269  time_t mtime = 0;
270  int srcfd, destfd, status;
271  pid_t pid, cpid;
272  char tname[] = "/tmp/crontab.XXXXXX";
273
274  if ((destfd = mkstemp(tname)) < 0)
275    perror_exit("Can't open tmp file");
276
277  fchmod(destfd, 0666);
278  snprintf(toybuf, sizeof(toybuf), "%s%s", TT.cdir, pwd->pw_name);
279
280  if (!stat(toybuf, &sb)) { // file exists and have some content.
281    if (sb.st_size) {
282      srcfd = xopenro(toybuf);
283      xsendfile(srcfd, destfd);
284      xclose(srcfd);
285    }
286  } else printf("No crontab for '%s'- using an empty one\n", pwd->pw_name);
287  xclose(destfd);
288
289  if (!stat(tname, &sb)) mtime = sb.st_mtime;
290
291RETRY:
292  if (!(pid = xfork())) {
293    char *prog = pwd->pw_shell;
294
295    xsetuser(pwd);
296    if (pwd->pw_uid) {
297      if (setenv("USER", pwd->pw_name, 1)) _exit(1);
298      if (setenv("LOGNAME", pwd->pw_name, 1)) _exit(1);
299    }
300    if (setenv("HOME", pwd->pw_dir, 1)) _exit(1);
301    if (setenv("SHELL",((!prog || !*prog) ? "/bin/sh" : prog), 1)) _exit(1);
302
303    if (!(prog = getenv("VISUAL"))) {
304      if (!(prog = getenv("EDITOR")))
305        prog = "vi";
306    }
307    execlp(prog, prog, tname, (char *) NULL);
308    perror_exit("can't execute '%s'", prog);
309  }
310
311  // Parent Process.
312  do {
313    cpid = waitpid(pid, &status, 0);
314  } while ((cpid == -1) && (errno == EINTR));
315
316  if (!stat(tname, &sb) && (mtime == sb.st_mtime)) {
317    printf("%s: no changes made to crontab\n", toys.which->name);
318    unlink(tname);
319    return;
320  }
321  printf("%s: installing new crontab\n", toys.which->name);
322  if (parse_crontab(tname)) {
323    fprintf(stderr, "errors in crontab file, can't install.\n"
324        "Do you want to retry the same edit? ");
325    if (!yesno(0)) {
326      error_msg("edits left in '%s'", tname);
327      return;
328    }
329    goto RETRY;
330  }
331  // parsing of crontab success; update the crontab.
332  update_crontab(tname, pwd->pw_name);
333  unlink(tname);
334}
335
336void crontab_main(void)
337{
338  struct passwd *pwd = NULL;
339  long FLAG_elr = toys.optflags & (FLAG_e|FLAG_l|FLAG_r);
340
341  if (TT.cdir && (TT.cdir[strlen(TT.cdir)-1] != '/'))
342    TT.cdir = xmprintf("%s/", TT.cdir);
343  if (!TT.cdir) TT.cdir = xstrdup("/var/spool/cron/crontabs/");
344
345  if (toys.optflags & FLAG_u) {
346    if (getuid()) error_exit("must be privileged to use -u");
347    pwd = xgetpwnam(TT.user);
348  } else pwd = xgetpwuid(getuid());
349
350  if (!toys.optc) {
351    if (!FLAG_elr) {
352      if (toys.optflags & FLAG_u)
353        help_exit("file name must be specified for replace");
354      do_replace(pwd->pw_name);
355    }
356    else if (toys.optflags & FLAG_e) do_edit(pwd);
357    else if (toys.optflags & FLAG_l) do_list(pwd->pw_name);
358    else if (toys.optflags & FLAG_r) do_remove(pwd->pw_name);
359  } else {
360    if (FLAG_elr) help_exit("no arguments permitted after this option");
361    do_replace(pwd->pw_name);
362  }
363  if (!(toys.optflags & FLAG_c)) free(TT.cdir);
364}
365