369 lines
7.2 KiB
C
369 lines
7.2 KiB
C
/*
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* CRONTAB
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*
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* usually setuid root, -c option only works if getuid() == geteuid()
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*
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* Copyright 1994 Matthew Dillon (dillon@apollo.west.oic.com)
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* May be distributed under the GNU General Public License
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*
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* Vladimir Oleynik <dzo@simtreas.ru> (C) 2002 to be used in busybox
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*
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <string.h>
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#include <errno.h>
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#include <time.h>
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#include <dirent.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <syslog.h>
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#include <signal.h>
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#include <getopt.h>
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#include <sys/ioctl.h>
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#include <sys/wait.h>
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#include <sys/stat.h>
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#include <sys/resource.h>
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#ifndef CRONTABS
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#define CRONTABS "/var/spool/cron/crontabs"
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#endif
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#ifndef TMPDIR
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#define TMPDIR "/var/spool/cron"
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#endif
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#ifndef CRONUPDATE
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#define CRONUPDATE "cron.update"
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#endif
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#ifndef PATH_VI
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#define PATH_VI "/bin/vi" /* location of vi */
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#endif
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#include "busybox.h"
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static const char *CDir = CRONTABS;
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static void EditFile(const char *user, const char *file);
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static int GetReplaceStream(const char *user, const char *file);
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static int ChangeUser(const char *user, short dochdir);
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int
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crontab_main(int ac, char **av)
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{
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enum { NONE, EDIT, LIST, REPLACE, DELETE } option = NONE;
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const struct passwd *pas;
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const char *repFile = NULL;
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int repFd = 0;
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int i;
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char caller[256]; /* user that ran program */
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int UserId;
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UserId = getuid();
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if ((pas = getpwuid(UserId)) == NULL)
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bb_perror_msg_and_die("getpwuid");
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strncpy(caller, pas->pw_name, sizeof(caller));
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i = 1;
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if (ac > 1) {
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if (av[1][0] == '-' && av[1][1] == 0) {
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option = REPLACE;
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++i;
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} else if (av[1][0] != '-') {
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option = REPLACE;
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++i;
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repFile = av[1];
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}
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}
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for (; i < ac; ++i) {
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char *ptr = av[i];
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if (*ptr != '-')
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break;
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ptr += 2;
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switch(ptr[-1]) {
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case 'l':
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if (ptr[-1] == 'l')
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option = LIST;
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/* fall through */
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case 'e':
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if (ptr[-1] == 'e')
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option = EDIT;
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/* fall through */
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case 'd':
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if (ptr[-1] == 'd')
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option = DELETE;
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/* fall through */
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case 'u':
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if (i + 1 < ac && av[i+1][0] != '-') {
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++i;
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if (getuid() == geteuid()) {
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pas = getpwnam(av[i]);
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if (pas) {
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UserId = pas->pw_uid;
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} else {
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bb_error_msg_and_die("user %s unknown", av[i]);
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}
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} else {
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bb_error_msg_and_die("only the superuser may specify a user");
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}
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}
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break;
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case 'c':
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if (getuid() == geteuid()) {
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CDir = (*ptr) ? ptr : av[++i];
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} else {
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bb_error_msg_and_die("-c option: superuser only");
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}
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break;
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default:
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i = ac;
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break;
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}
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}
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if (i != ac || option == NONE)
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bb_show_usage();
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/*
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* Get password entry
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*/
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if ((pas = getpwuid(UserId)) == NULL)
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bb_perror_msg_and_die("getpwuid");
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/*
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* If there is a replacement file, obtain a secure descriptor to it.
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*/
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if (repFile) {
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repFd = GetReplaceStream(caller, repFile);
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if (repFd < 0)
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bb_error_msg_and_die("unable to read replacement file");
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}
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/*
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* Change directory to our crontab directory
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*/
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if (chdir(CDir) < 0)
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bb_perror_msg_and_die("cannot change dir to %s", CDir);
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/*
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* Handle options as appropriate
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*/
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switch(option) {
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case LIST:
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{
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FILE *fi;
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char buf[1024];
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if ((fi = fopen(pas->pw_name, "r"))) {
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while (fgets(buf, sizeof(buf), fi) != NULL)
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fputs(buf, stdout);
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fclose(fi);
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} else {
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bb_error_msg("no crontab for %s", pas->pw_name);
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}
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}
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break;
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case EDIT:
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{
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FILE *fi;
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int fd;
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int n;
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char tmp[128];
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char buf[1024];
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snprintf(tmp, sizeof(tmp), TMPDIR "/crontab.%d", getpid());
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if ((fd = open(tmp, O_RDWR|O_CREAT|O_TRUNC|O_EXCL, 0600)) >= 0) {
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chown(tmp, getuid(), getgid());
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if ((fi = fopen(pas->pw_name, "r"))) {
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while ((n = fread(buf, 1, sizeof(buf), fi)) > 0)
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write(fd, buf, n);
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}
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EditFile(caller, tmp);
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remove(tmp);
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lseek(fd, 0L, 0);
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repFd = fd;
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} else {
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bb_error_msg_and_die("unable to create %s", tmp);
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}
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}
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option = REPLACE;
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/* fall through */
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case REPLACE:
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{
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char buf[1024];
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char path[1024];
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int fd;
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int n;
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snprintf(path, sizeof(path), "%s.new", pas->pw_name);
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if ((fd = open(path, O_CREAT|O_TRUNC|O_APPEND|O_WRONLY, 0600)) >= 0) {
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while ((n = read(repFd, buf, sizeof(buf))) > 0) {
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write(fd, buf, n);
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}
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close(fd);
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rename(path, pas->pw_name);
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} else {
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bb_error_msg("unable to create %s/%s", CDir, path);
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}
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close(repFd);
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}
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break;
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case DELETE:
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remove(pas->pw_name);
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break;
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case NONE:
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default:
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break;
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}
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/*
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* Bump notification file. Handle window where crond picks file up
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* before we can write our entry out.
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*/
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if (option == REPLACE || option == DELETE) {
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FILE *fo;
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struct stat st;
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while ((fo = fopen(CRONUPDATE, "a"))) {
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fprintf(fo, "%s\n", pas->pw_name);
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fflush(fo);
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if (fstat(fileno(fo), &st) != 0 || st.st_nlink != 0) {
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fclose(fo);
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break;
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}
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fclose(fo);
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/* loop */
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}
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if (fo == NULL) {
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bb_error_msg("unable to append to %s/%s", CDir, CRONUPDATE);
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}
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}
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return 0;
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}
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static int
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GetReplaceStream(const char *user, const char *file)
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{
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int filedes[2];
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int pid;
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int fd;
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int n;
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char buf[1024];
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if (pipe(filedes) < 0) {
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perror("pipe");
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return(-1);
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}
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if ((pid = fork()) < 0) {
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perror("fork");
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return(-1);
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}
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if (pid > 0) {
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/*
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* PARENT
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*/
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close(filedes[1]);
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if (read(filedes[0], buf, 1) != 1) {
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close(filedes[0]);
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filedes[0] = -1;
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}
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return(filedes[0]);
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}
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/*
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* CHILD
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*/
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close(filedes[0]);
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if (ChangeUser(user, 0) < 0)
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exit(0);
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fd = open(file, O_RDONLY);
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if (fd < 0) {
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bb_error_msg("unable to open %s", file);
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exit(0);
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}
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buf[0] = 0;
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write(filedes[1], buf, 1);
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while ((n = read(fd, buf, sizeof(buf))) > 0) {
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write(filedes[1], buf, n);
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}
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exit(0);
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}
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static void
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EditFile(const char *user, const char *file)
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{
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int pid;
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if ((pid = fork()) == 0) {
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/*
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* CHILD - change user and run editor
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*/
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char *ptr;
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char visual[1024];
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if (ChangeUser(user, 1) < 0)
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exit(0);
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if ((ptr = getenv("VISUAL")) == NULL || strlen(ptr) > 256)
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ptr = PATH_VI;
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snprintf(visual, sizeof(visual), "%s %s", ptr, file);
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execl(DEFAULT_SHELL, DEFAULT_SHELL, "-c", visual, NULL);
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perror("exec");
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exit(0);
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}
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if (pid < 0) {
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/*
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* PARENT - failure
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*/
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bb_perror_msg_and_die("fork");
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}
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wait4(pid, NULL, 0, NULL);
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}
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static int
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ChangeUser(const char *user, short dochdir)
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{
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struct passwd *pas;
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/*
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* Obtain password entry and change privilages
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*/
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if ((pas = getpwnam(user)) == 0) {
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bb_perror_msg_and_die("failed to get uid for %s", user);
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return(-1);
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}
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setenv("USER", pas->pw_name, 1);
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setenv("HOME", pas->pw_dir, 1);
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setenv("SHELL", DEFAULT_SHELL, 1);
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/*
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* Change running state to the user in question
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*/
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change_identity(pas);
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if (dochdir) {
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if (chdir(pas->pw_dir) < 0) {
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bb_perror_msg_and_die("chdir failed: %s %s", user, pas->pw_dir);
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if (chdir(TMPDIR) < 0) {
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bb_perror_msg_and_die("chdir failed: %s %s", user, TMPDIR);
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return(-1);
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}
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}
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}
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return(pas->pw_uid);
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}
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