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