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- /* crontab.c - files used to schedule the execution of programs.
- *
- * Copyright 2014 Ranjan Kumar <ranjankumar.bth@gmail.com>
- *
- * http://pubs.opengroup.org/onlinepubs/9699919799/utilities/crontab.html
- USE_CRONTAB(NEWTOY(crontab, "c:u:elr[!elr]", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_STAYROOT))
- config CRONTAB
- bool "crontab"
- default n
- depends on TOYBOX_FORK
- help
- usage: crontab [-u user] FILE
- [-u user] [-e | -l | -r]
- [-c dir]
- Files used to schedule the execution of programs.
- -c crontab dir
- -e edit user's crontab
- -l list user's crontab
- -r delete user's crontab
- -u user
- FILE Replace crontab by FILE ('-': stdin)
- */
- #define FOR_crontab
- #include "toys.h"
- GLOBALS(
- char *user;
- char *cdir;
- )
- static char *omitspace(char *line)
- {
- while (*line == ' ' || *line == '\t') line++;
- return line;
- }
- /*
- * Names can also be used for the 'month' and 'day of week' fields
- * (First three letters of the particular day or month).
- */
- static int getindex(char *src, int size)
- {
- int i;
- char days[]={"sun""mon""tue""wed""thu""fri""sat"};
- char months[]={"jan""feb""mar""apr""may""jun""jul"
- "aug""sep""oct""nov""dec"};
- char *field = (size == 12) ? months : days;
- // strings are not allowed for min, hour and dom fields.
- if (!(size == 7 || size == 12)) return -1;
- for (i = 0; field[i]; i += 3) {
- if (!strncasecmp(src, &field[i], 3))
- return (i/3);
- }
- return -1;
- }
- static long getval(char *num, long low, long high)
- {
- long val = strtol(num, &num, 10);
- if (*num || (val < low) || (val > high)) return -1;
- return val;
- }
- // Validate minute, hour, day of month, month and day of week fields.
- static int validate_component(int min, int max, char *src)
- {
- int skip = 0;
- char *ptr;
- if (!src) return 1;
- if ((ptr = strchr(src, '/'))) {
- *ptr++ = 0;
- if ((skip = getval(ptr, min, (min ? max: max-1))) < 0) return 1;
- }
- if (*src == '-' || *src == ',') return 1;
- if (*src == '*') {
- if (*(src+1)) return 1;
- }
- else {
- for (;;) {
- char *ctoken = strsep(&src, ","), *dtoken;
- if (!ctoken) break;
- if (!*ctoken) return 1;
- // validate start position.
- dtoken = strsep(&ctoken, "-");
- if (isdigit(*dtoken)) {
- if (getval(dtoken, min, (min ? max : max-1)) < 0) return 1;
- } else if (getindex(dtoken, max) < 0) return 1;
- // validate end position.
- if (!ctoken) {
- if (skip) return 1; // case 10/20 or 1,2,4/3
- }
- else if (*ctoken) {// e.g. N-M
- if (isdigit(*ctoken)) {
- if (getval(ctoken, min, (min ? max : max-1)) < 0) return 1;
- } else if (getindex(ctoken, max) < 0) return 1;
- } else return 1; // error condition 'N-'
- }
- }
- return 0;
- }
- static int parse_crontab(char *fname)
- {
- FILE *fp = xfopen(fname, "r");
- long len = 0;
- char *line = NULL;
- size_t allocated_length;
- int lno;
- for (lno = 1; (len = getline(&line, &allocated_length, fp)) > 0; lno++) {
- char *name, *val, *tokens[5] = {0,}, *ptr = line;
- int count = 0;
- if (line[len - 1] == '\n') line[--len] = '\0';
- else {
- snprintf(toybuf, sizeof(toybuf), "'%d': premature EOF\n", lno);
- goto OUT;
- }
- ptr = omitspace(ptr);
- if (!*ptr || *ptr == '#' || *ptr == '@') continue;
- while (count<5) {
- int len = strcspn(ptr, " \t");
- if (ptr[len]) ptr[len++] = '\0';
- tokens[count++] = ptr;
- ptr += len;
- ptr = omitspace(ptr);
- if (!*ptr) break;
- }
- switch (count) {
- case 1: // form SHELL=/bin/sh
- name = tokens[0];
- if ((val = strchr(name, '='))) *val++ = 0;
- if (!val || !*val) {
- snprintf(toybuf, sizeof(toybuf), "'%d': %s\n", lno, line);
- goto OUT;
- }
- break;
- case 2: // form SHELL =/bin/sh or SHELL= /bin/sh
- name = tokens[0];
- if ((val = strchr(name, '='))) {
- *val = 0;
- val = tokens[1];
- } else {
- if (*(tokens[1]) != '=') {
- snprintf(toybuf, sizeof(toybuf), "'%d': %s\n", lno, line);
- goto OUT;
- }
- val = tokens[1] + 1;
- }
- if (!*val) {
- snprintf(toybuf, sizeof(toybuf), "'%d': %s\n", lno, line);
- goto OUT;
- }
- break;
- case 3: // NAME = VAL
- name = tokens[0];
- val = tokens[2];
- if (*(tokens[1]) != '=') {
- snprintf(toybuf, sizeof(toybuf), "'%d': %s\n", lno, line);
- goto OUT;
- }
- break;
- default:
- if (validate_component(0, 60, tokens[0])) {
- snprintf(toybuf, sizeof(toybuf), "'%d': bad minute\n", lno);
- goto OUT;
- }
- if (validate_component(0, 24, tokens[1])) {
- snprintf(toybuf, sizeof(toybuf), "'%d': bad hour\n", lno);
- goto OUT;
- }
- if (validate_component(1, 31, tokens[2])) {
- snprintf(toybuf, sizeof(toybuf), "'%d': bad day-of-month\n", lno);
- goto OUT;
- }
- if (validate_component(1, 12, tokens[3])) {
- snprintf(toybuf, sizeof(toybuf), "'%d': bad month\n", lno);
- goto OUT;
- }
- if (validate_component(0, 7, tokens[4])) {
- snprintf(toybuf, sizeof(toybuf), "'%d': bad day-of-week\n", lno);
- goto OUT;
- }
- if (!*ptr) { // don't have any cmd to execute.
- snprintf(toybuf, sizeof(toybuf), "'%d': bad command\n", lno);
- goto OUT;
- }
- break;
- }
- }
- free(line);
- fclose(fp);
- return 0;
- OUT:
- free(line);
- printf("Error at line no %s", toybuf);
- fclose(fp);
- return 1;
- }
- static void do_list(char *name)
- {
- int fdin;
- snprintf(toybuf, sizeof(toybuf), "%s%s", TT.cdir, name);
- fdin = xopenro(toybuf);
- xsendfile(fdin, 1);
- xclose(fdin);
- }
- static void do_remove(char *name)
- {
- snprintf(toybuf, sizeof(toybuf), "%s%s", TT.cdir, name);
- if (unlink(toybuf))
- error_exit("No crontab for '%s'", name);
- }
- static void update_crontab(char *src, char *dest)
- {
- int fdin, fdout;
- snprintf(toybuf, sizeof(toybuf), "%s%s", TT.cdir, dest);
- fdout = xcreate(toybuf, O_WRONLY|O_CREAT|O_TRUNC, 0600);
- fdin = xopenro(src);
- xsendfile(fdin, fdout);
- xclose(fdin);
- fchown(fdout, getuid(), geteuid());
- xclose(fdout);
- }
- static void do_replace(char *name)
- {
- char *fname = *toys.optargs ? *toys.optargs : "-";
- char tname[] = "/tmp/crontab.XXXXXX";
- if ((*fname == '-') && !*(fname+1)) {
- int tfd = mkstemp(tname);
- if (tfd < 0) perror_exit("mkstemp");
- xsendfile(0, tfd);
- xclose(tfd);
- fname = tname;
- }
- if (parse_crontab(fname))
- error_exit("errors in crontab file '%s', can't install.", fname);
- update_crontab(fname, name);
- unlink(tname);
- }
- static void do_edit(struct passwd *pwd)
- {
- struct stat sb;
- time_t mtime = 0;
- int srcfd, destfd, status;
- pid_t pid, cpid;
- char tname[] = "/tmp/crontab.XXXXXX";
- if ((destfd = mkstemp(tname)) < 0)
- perror_exit("Can't open tmp file");
- fchmod(destfd, 0666);
- snprintf(toybuf, sizeof(toybuf), "%s%s", TT.cdir, pwd->pw_name);
- if (!stat(toybuf, &sb)) { // file exists and have some content.
- if (sb.st_size) {
- srcfd = xopenro(toybuf);
- xsendfile(srcfd, destfd);
- xclose(srcfd);
- }
- } else printf("No crontab for '%s'- using an empty one\n", pwd->pw_name);
- xclose(destfd);
- if (!stat(tname, &sb)) mtime = sb.st_mtime;
- RETRY:
- if (!(pid = xfork())) {
- char *prog = pwd->pw_shell;
- xsetuser(pwd);
- if (pwd->pw_uid) {
- if (setenv("USER", pwd->pw_name, 1)) _exit(1);
- if (setenv("LOGNAME", pwd->pw_name, 1)) _exit(1);
- }
- if (setenv("HOME", pwd->pw_dir, 1)) _exit(1);
- if (setenv("SHELL",((!prog || !*prog) ? "/bin/sh" : prog), 1)) _exit(1);
- if (!(prog = getenv("VISUAL"))) {
- if (!(prog = getenv("EDITOR")))
- prog = "vi";
- }
- execlp(prog, prog, tname, (char *) NULL);
- perror_exit("can't execute '%s'", prog);
- }
- // Parent Process.
- do {
- cpid = waitpid(pid, &status, 0);
- } while ((cpid == -1) && (errno == EINTR));
- if (!stat(tname, &sb) && (mtime == sb.st_mtime)) {
- printf("%s: no changes made to crontab\n", toys.which->name);
- unlink(tname);
- return;
- }
- printf("%s: installing new crontab\n", toys.which->name);
- if (parse_crontab(tname)) {
- fprintf(stderr, "errors in crontab file, can't install.\n"
- "Do you want to retry the same edit? ");
- if (!yesno(0)) {
- error_msg("edits left in '%s'", tname);
- return;
- }
- goto RETRY;
- }
- // parsing of crontab success; update the crontab.
- update_crontab(tname, pwd->pw_name);
- unlink(tname);
- }
- void crontab_main(void)
- {
- struct passwd *pwd = NULL;
- long FLAG_elr = toys.optflags & (FLAG_e|FLAG_l|FLAG_r);
- if (TT.cdir && (TT.cdir[strlen(TT.cdir)-1] != '/'))
- TT.cdir = xmprintf("%s/", TT.cdir);
- if (!TT.cdir) TT.cdir = xstrdup("/var/spool/cron/crontabs/");
- if (toys.optflags & FLAG_u) {
- if (getuid()) error_exit("must be privileged to use -u");
- pwd = xgetpwnam(TT.user);
- } else pwd = xgetpwuid(getuid());
- if (!toys.optc) {
- if (!FLAG_elr) {
- if (toys.optflags & FLAG_u)
- help_exit("file name must be specified for replace");
- do_replace(pwd->pw_name);
- }
- else if (toys.optflags & FLAG_e) do_edit(pwd);
- else if (toys.optflags & FLAG_l) do_list(pwd->pw_name);
- else if (toys.optflags & FLAG_r) do_remove(pwd->pw_name);
- } else {
- if (FLAG_elr) help_exit("no arguments permitted after this option");
- do_replace(pwd->pw_name);
- }
- if (!(toys.optflags & FLAG_c)) free(TT.cdir);
- }
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