[821] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * CRONTAB
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| 4 | *
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| 5 | * usually setuid root, -c option only works if getuid() == geteuid()
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| 6 | *
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| 7 | * Copyright 1994 Matthew Dillon (dillon@apollo.west.oic.com)
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| 8 | * Vladimir Oleynik <dzo@simtreas.ru> (C) 2002
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| 9 | *
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| 10 | * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
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| 11 | */
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| 12 |
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| 13 | #include "busybox.h"
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| 14 | #include <stdio.h>
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| 15 | #include <stdlib.h>
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| 16 | #include <stdarg.h>
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| 17 | #include <string.h>
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| 18 | #include <errno.h>
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| 19 | #include <time.h>
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| 20 | #include <dirent.h>
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| 21 | #include <fcntl.h>
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| 22 | #include <unistd.h>
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| 23 | #include <syslog.h>
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| 24 | #include <signal.h>
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| 25 | #include <getopt.h>
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| 26 | #include <sys/ioctl.h>
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| 27 | #include <sys/wait.h>
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| 28 | #include <sys/stat.h>
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| 29 | #include <sys/resource.h>
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| 30 |
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| 31 | #ifndef CRONTABS
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| 32 | #define CRONTABS "/var/spool/cron/crontabs"
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| 33 | #endif
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| 34 | #ifndef TMPDIR
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| 35 | #define TMPDIR "/var/spool/cron"
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| 36 | #endif
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| 37 | #ifndef CRONUPDATE
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| 38 | #define CRONUPDATE "cron.update"
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| 39 | #endif
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| 40 | #ifndef PATH_VI
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| 41 | #define PATH_VI "/bin/vi" /* location of vi */
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| 42 | #endif
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| 43 |
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| 44 | static const char *CDir = CRONTABS;
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| 45 |
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| 46 | static void EditFile(const char *user, const char *file);
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| 47 | static int GetReplaceStream(const char *user, const char *file);
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| 48 | static int ChangeUser(const char *user, short dochdir);
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| 49 |
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| 50 | int
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| 51 | crontab_main(int ac, char **av)
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| 52 | {
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| 53 | enum { NONE, EDIT, LIST, REPLACE, DELETE } option = NONE;
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| 54 | const struct passwd *pas;
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| 55 | const char *repFile = NULL;
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| 56 | int repFd = 0;
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| 57 | int i;
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| 58 | char caller[256]; /* user that ran program */
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| 59 | int UserId;
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| 60 |
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| 61 | UserId = getuid();
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| 62 | if ((pas = getpwuid(UserId)) == NULL)
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| 63 | bb_perror_msg_and_die("getpwuid");
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| 64 |
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| 65 | safe_strncpy(caller, pas->pw_name, sizeof(caller));
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| 66 |
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| 67 | i = 1;
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| 68 | if (ac > 1) {
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| 69 | if (av[1][0] == '-' && av[1][1] == 0) {
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| 70 | option = REPLACE;
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| 71 | ++i;
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| 72 | } else if (av[1][0] != '-') {
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| 73 | option = REPLACE;
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| 74 | ++i;
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| 75 | repFile = av[1];
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| 76 | }
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| 77 | }
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| 78 |
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| 79 | for (; i < ac; ++i) {
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| 80 | char *ptr = av[i];
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| 81 |
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| 82 | if (*ptr != '-')
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| 83 | break;
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| 84 | ptr += 2;
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| 85 |
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| 86 | switch(ptr[-1]) {
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| 87 | case 'l':
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| 88 | if (ptr[-1] == 'l')
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| 89 | option = LIST;
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| 90 | /* fall through */
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| 91 | case 'e':
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| 92 | if (ptr[-1] == 'e')
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| 93 | option = EDIT;
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| 94 | /* fall through */
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| 95 | case 'd':
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| 96 | if (ptr[-1] == 'd')
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| 97 | option = DELETE;
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| 98 | /* fall through */
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| 99 | case 'u':
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| 100 | if (i + 1 < ac && av[i+1][0] != '-') {
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| 101 | ++i;
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| 102 | if (getuid() == geteuid()) {
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| 103 | pas = getpwnam(av[i]);
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| 104 | if (pas) {
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| 105 | UserId = pas->pw_uid;
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| 106 | } else {
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| 107 | bb_error_msg_and_die("user %s unknown", av[i]);
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| 108 | }
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| 109 | } else {
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| 110 | bb_error_msg_and_die("only the superuser may specify a user");
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| 111 | }
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| 112 | }
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| 113 | break;
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| 114 | case 'c':
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| 115 | if (getuid() == geteuid()) {
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| 116 | CDir = (*ptr) ? ptr : av[++i];
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| 117 | } else {
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| 118 | bb_error_msg_and_die("-c option: superuser only");
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| 119 | }
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| 120 | break;
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| 121 | default:
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| 122 | i = ac;
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| 123 | break;
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| 124 | }
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| 125 | }
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| 126 | if (i != ac || option == NONE)
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| 127 | bb_show_usage();
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| 128 |
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| 129 | /*
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| 130 | * Get password entry
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| 131 | */
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| 132 |
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| 133 | if ((pas = getpwuid(UserId)) == NULL)
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| 134 | bb_perror_msg_and_die("getpwuid");
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| 135 |
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| 136 | /*
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| 137 | * If there is a replacement file, obtain a secure descriptor to it.
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| 138 | */
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| 139 |
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| 140 | if (repFile) {
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| 141 | repFd = GetReplaceStream(caller, repFile);
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| 142 | if (repFd < 0)
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| 143 | bb_error_msg_and_die("unable to read replacement file");
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| 144 | }
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| 145 |
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| 146 | /*
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| 147 | * Change directory to our crontab directory
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| 148 | */
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| 149 |
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| 150 | bb_xchdir(CDir);
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| 151 |
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| 152 | /*
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| 153 | * Handle options as appropriate
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| 154 | */
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| 155 |
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| 156 | switch(option) {
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| 157 | case LIST:
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| 158 | {
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| 159 | FILE *fi;
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| 160 | char buf[1024];
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| 161 |
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| 162 | if ((fi = fopen(pas->pw_name, "r"))) {
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| 163 | while (fgets(buf, sizeof(buf), fi) != NULL)
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| 164 | fputs(buf, stdout);
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| 165 | fclose(fi);
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| 166 | } else {
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| 167 | bb_error_msg("no crontab for %s", pas->pw_name);
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| 168 | }
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| 169 | }
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| 170 | break;
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| 171 | case EDIT:
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| 172 | {
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| 173 | FILE *fi;
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| 174 | int fd;
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| 175 | int n;
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| 176 | char tmp[128];
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| 177 | char buf[1024];
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| 178 |
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| 179 | snprintf(tmp, sizeof(tmp), TMPDIR "/crontab.%d", getpid());
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| 180 | fd = bb_xopen3(tmp, O_RDWR|O_CREAT|O_TRUNC|O_EXCL, 0600);
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| 181 | chown(tmp, getuid(), getgid());
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| 182 | if ((fi = fopen(pas->pw_name, "r"))) {
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| 183 | while ((n = fread(buf, 1, sizeof(buf), fi)) > 0)
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| 184 | write(fd, buf, n);
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| 185 | }
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| 186 | EditFile(caller, tmp);
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| 187 | remove(tmp);
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| 188 | lseek(fd, 0L, 0);
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| 189 | repFd = fd;
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| 190 | }
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| 191 | option = REPLACE;
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| 192 | /* fall through */
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| 193 | case REPLACE:
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| 194 | {
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| 195 | char buf[1024];
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| 196 | char path[1024];
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| 197 | int fd;
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| 198 | int n;
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| 199 |
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| 200 | snprintf(path, sizeof(path), "%s.new", pas->pw_name);
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| 201 | if ((fd = open(path, O_CREAT|O_TRUNC|O_APPEND|O_WRONLY, 0600)) >= 0) {
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| 202 | while ((n = read(repFd, buf, sizeof(buf))) > 0) {
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| 203 | write(fd, buf, n);
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| 204 | }
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| 205 | close(fd);
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| 206 | rename(path, pas->pw_name);
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| 207 | } else {
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| 208 | bb_error_msg("unable to create %s/%s", CDir, path);
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| 209 | }
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| 210 | close(repFd);
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| 211 | }
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| 212 | break;
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| 213 | case DELETE:
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| 214 | remove(pas->pw_name);
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| 215 | break;
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| 216 | case NONE:
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| 217 | default:
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| 218 | break;
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| 219 | }
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| 220 |
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| 221 | /*
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| 222 | * Bump notification file. Handle window where crond picks file up
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| 223 | * before we can write our entry out.
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| 224 | */
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| 225 |
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| 226 | if (option == REPLACE || option == DELETE) {
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| 227 | FILE *fo;
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| 228 | struct stat st;
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| 229 |
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| 230 | while ((fo = fopen(CRONUPDATE, "a"))) {
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| 231 | fprintf(fo, "%s\n", pas->pw_name);
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| 232 | fflush(fo);
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| 233 | if (fstat(fileno(fo), &st) != 0 || st.st_nlink != 0) {
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| 234 | fclose(fo);
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| 235 | break;
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| 236 | }
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| 237 | fclose(fo);
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| 238 | /* loop */
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| 239 | }
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| 240 | if (fo == NULL) {
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| 241 | bb_error_msg("unable to append to %s/%s", CDir, CRONUPDATE);
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| 242 | }
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| 243 | }
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| 244 | return 0;
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| 245 | }
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| 246 |
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| 247 | static int
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| 248 | GetReplaceStream(const char *user, const char *file)
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| 249 | {
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| 250 | int filedes[2];
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| 251 | int pid;
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| 252 | int fd;
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| 253 | int n;
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| 254 | char buf[1024];
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| 255 |
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| 256 | if (pipe(filedes) < 0) {
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| 257 | perror("pipe");
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| 258 | return(-1);
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| 259 | }
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| 260 | if ((pid = fork()) < 0) {
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| 261 | perror("fork");
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| 262 | return(-1);
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| 263 | }
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| 264 | if (pid > 0) {
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| 265 | /*
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| 266 | * PARENT
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| 267 | */
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| 268 |
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| 269 | close(filedes[1]);
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| 270 | if (read(filedes[0], buf, 1) != 1) {
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| 271 | close(filedes[0]);
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| 272 | filedes[0] = -1;
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| 273 | }
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| 274 | return(filedes[0]);
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| 275 | }
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| 276 |
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| 277 | /*
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| 278 | * CHILD
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| 279 | */
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| 280 |
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| 281 | close(filedes[0]);
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| 282 |
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| 283 | if (ChangeUser(user, 0) < 0)
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| 284 | exit(0);
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| 285 |
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| 286 | bb_default_error_retval = 0;
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| 287 | fd = bb_xopen3(file, O_RDONLY, 0);
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| 288 | buf[0] = 0;
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| 289 | write(filedes[1], buf, 1);
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| 290 | while ((n = read(fd, buf, sizeof(buf))) > 0) {
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| 291 | write(filedes[1], buf, n);
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| 292 | }
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| 293 | exit(0);
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| 294 | }
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| 295 |
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| 296 | static void
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| 297 | EditFile(const char *user, const char *file)
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| 298 | {
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| 299 | int pid;
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| 300 |
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| 301 | if ((pid = fork()) == 0) {
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| 302 | /*
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| 303 | * CHILD - change user and run editor
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| 304 | */
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| 305 | char *ptr;
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| 306 | char visual[1024];
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| 307 |
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| 308 | if (ChangeUser(user, 1) < 0)
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| 309 | exit(0);
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| 310 | if ((ptr = getenv("VISUAL")) == NULL || strlen(ptr) > 256)
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| 311 | ptr = PATH_VI;
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| 312 |
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| 313 | snprintf(visual, sizeof(visual), "%s %s", ptr, file);
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| 314 | execl(DEFAULT_SHELL, DEFAULT_SHELL, "-c", visual, NULL);
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| 315 | perror("exec");
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| 316 | exit(0);
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| 317 | }
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| 318 | if (pid < 0) {
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| 319 | /*
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| 320 | * PARENT - failure
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| 321 | */
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| 322 | bb_perror_msg_and_die("fork");
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| 323 | }
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| 324 | wait4(pid, NULL, 0, NULL);
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| 325 | }
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| 326 |
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| 327 | static int
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| 328 | ChangeUser(const char *user, short dochdir)
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| 329 | {
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| 330 | struct passwd *pas;
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| 331 |
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| 332 | /*
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| 333 | * Obtain password entry and change privileges
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| 334 | */
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| 335 |
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| 336 | if ((pas = getpwnam(user)) == NULL) {
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| 337 | bb_perror_msg_and_die("failed to get uid for %s", user);
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| 338 | return(-1);
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| 339 | }
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| 340 | setenv("USER", pas->pw_name, 1);
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| 341 | setenv("HOME", pas->pw_dir, 1);
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| 342 | setenv("SHELL", DEFAULT_SHELL, 1);
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| 343 |
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| 344 | /*
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| 345 | * Change running state to the user in question
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| 346 | */
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| 347 | change_identity(pas);
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| 348 |
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| 349 | if (dochdir) {
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| 350 | if (chdir(pas->pw_dir) < 0) {
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| 351 | bb_perror_msg("chdir failed: %s %s", user, pas->pw_dir);
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| 352 | bb_xchdir(TMPDIR);
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| 353 | }
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| 354 | }
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| 355 | return(pas->pw_uid);
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| 356 | }
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