busybox/miscutils/crontab.c

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/* vi: set sw=4 ts=4: */
/*
* CRONTAB
*
* usually setuid root, -c option only works if getuid() == geteuid()
*
* Copyright 1994 Matthew Dillon (dillon@apollo.west.oic.com)
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* Vladimir Oleynik <dzo@simtreas.ru> (C) 2002
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//config:config CRONTAB
//config: bool "crontab (9.7 kb)"
//config: default y
//config: help
//config: Crontab manipulates the crontab for a particular user. Only
//config: the superuser may specify a different user and/or crontab directory.
//config: Note that busybox binary must be setuid root for this applet to
//config: work properly.
/* Needs to be run by root or be suid root - needs to change /var/spool/cron* files: */
//applet:IF_CRONTAB(APPLET(crontab, BB_DIR_USR_BIN, BB_SUID_REQUIRE))
//kbuild:lib-$(CONFIG_CRONTAB) += crontab.o
//usage:#define crontab_trivial_usage
//usage: "[-c DIR] [-u USER] [-ler]|[FILE]"
//usage:#define crontab_full_usage "\n\n"
//usage: " -c Crontab directory"
//usage: "\n -u User"
//usage: "\n -l List crontab"
//usage: "\n -e Edit crontab"
//usage: "\n -r Delete crontab"
//usage: "\n FILE Replace crontab by FILE ('-': stdin)"
#include "libbb.h"
#define CRONTABS CONFIG_FEATURE_CROND_DIR "/crontabs"
#ifndef CRONUPDATE
#define CRONUPDATE "cron.update"
#endif
static void edit_file(const struct passwd *pas, const char *file)
{
const char *ptr;
pid_t pid;
pid = xvfork();
if (pid) { /* parent */
wait4pid(pid);
return;
}
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/* CHILD - change user and run editor */
/* initgroups, setgid, setuid */
change_identity(pas);
setup_environment(pas->pw_shell,
SETUP_ENV_CHANGEENV | SETUP_ENV_TO_TMP,
pas);
ptr = getenv("VISUAL");
if (!ptr) {
ptr = getenv("EDITOR");
if (!ptr)
ptr = "vi";
}
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BB_EXECLP(ptr, ptr, file, NULL);
bb_perror_msg_and_die("can't execute '%s'", ptr);
}
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int crontab_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int crontab_main(int argc UNUSED_PARAM, char **argv)
{
const struct passwd *pas;
const char *crontab_dir = CRONTABS;
char *tmp_fname;
char *new_fname;
char *user_name; /* -u USER */
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int fd;
int src_fd;
int opt_ler;
/* file [opts] Replace crontab from file
* - [opts] Replace crontab from stdin
* -u user User
* -c dir Crontab directory
* -l List crontab for user
* -e Edit crontab for user
* -r Delete crontab for user
* bbox also supports -d == -r, but most other crontab
* implementations do not. Deprecated.
*/
enum {
OPT_u = (1 << 0),
OPT_c = (1 << 1),
OPT_l = (1 << 2),
OPT_e = (1 << 3),
OPT_r = (1 << 4),
OPT_ler = OPT_l + OPT_e + OPT_r,
};
getopt32: remove opt_complementary function old new delta vgetopt32 1318 1392 +74 runsvdir_main 703 713 +10 bb_make_directory 423 425 +2 collect_cpu 546 545 -1 opt_chars 3 - -3 opt_complementary 4 - -4 tftpd_main 567 562 -5 ntp_init 476 471 -5 zcip_main 1266 1256 -10 xxd_main 428 418 -10 whois_main 140 130 -10 who_main 463 453 -10 which_main 212 202 -10 wget_main 2535 2525 -10 watchdog_main 291 281 -10 watch_main 222 212 -10 vlock_main 399 389 -10 uuencode_main 332 322 -10 uudecode_main 316 306 -10 unlink_main 45 35 -10 udhcpd_main 1482 1472 -10 udhcpc_main 2762 2752 -10 tune2fs_main 290 280 -10 tunctl_main 366 356 -10 truncate_main 218 208 -10 tr_main 518 508 -10 time_main 1134 1124 -10 tftp_main 286 276 -10 telnetd_main 1873 1863 -10 tcpudpsvd_main 1785 1775 -10 taskset_main 521 511 -10 tar_main 1009 999 -10 tail_main 1644 1634 -10 syslogd_main 1967 1957 -10 switch_root_main 368 358 -10 svlogd_main 1454 1444 -10 sv 1296 1286 -10 stat_main 104 94 -10 start_stop_daemon_main 1028 1018 -10 split_main 542 532 -10 sort_main 796 786 -10 slattach_main 624 614 -10 shuf_main 504 494 -10 setsid_main 96 86 -10 setserial_main 1132 1122 -10 setfont_main 388 378 -10 setconsole_main 78 68 -10 sendmail_main 1209 1199 -10 sed_main 677 667 -10 script_main 1077 1067 -10 run_parts_main 325 315 -10 rtcwake_main 454 444 -10 rm_main 175 165 -10 reformime_main 119 109 -10 readlink_main 123 113 -10 rdate_main 246 236 -10 pwdx_main 189 179 -10 pstree_main 317 307 -10 pscan_main 663 653 -10 popmaildir_main 818 808 -10 pmap_main 80 70 -10 nc_main 1042 1032 -10 mv_main 558 548 -10 mountpoint_main 477 467 -10 mount_main 1264 1254 -10 modprobe_main 768 758 -10 modinfo_main 333 323 -10 mktemp_main 200 190 -10 mkswap_main 324 314 -10 mkfs_vfat_main 1489 1479 -10 microcom_main 715 705 -10 md5_sha1_sum_main 521 511 -10 man_main 867 857 -10 makedevs_main 1052 1042 -10 ls_main 563 553 -10 losetup_main 432 422 -10 loadfont_main 89 79 -10 ln_main 524 514 -10 link_main 75 65 -10 ipcalc_main 544 534 -10 iostat_main 2397 2387 -10 install_main 768 758 -10 id_main 480 470 -10 i2cset_main 1239 1229 -10 i2cget_main 380 370 -10 i2cdump_main 1482 1472 -10 i2cdetect_main 682 672 -10 hwclock_main 406 396 -10 httpd_main 741 731 -10 grep_main 837 827 -10 getty_main 1559 1549 -10 fuser_main 297 287 -10 ftpgetput_main 345 335 -10 ftpd_main 2232 2222 -10 fstrim_main 251 241 -10 fsfreeze_main 77 67 -10 fsck_minix_main 2921 2911 -10 flock_main 314 304 -10 flashcp_main 740 730 -10 flash_eraseall_main 833 823 -10 fdformat_main 532 522 -10 expand_main 680 670 -10 eject_main 335 325 -10 dumpleases_main 630 620 -10 du_main 314 304 -10 dos2unix_main 441 431 -10 diff_main 1350 1340 -10 df_main 1064 1054 -10 date_main 1095 1085 -10 cut_main 961 951 -10 cryptpw_main 228 218 -10 crontab_main 575 565 -10 crond_main 1149 1139 -10 cp_main 370 360 -10 common_traceroute_main 3834 3824 -10 common_ping_main 1767 1757 -10 comm_main 239 229 -10 cmp_main 655 645 -10 chrt_main 379 369 -10 chpst_main 704 694 -10 chpasswd_main 308 298 -10 chown_main 171 161 -10 chmod_main 158 148 -10 cat_main 428 418 -10 bzip2_main 120 110 -10 blkdiscard_main 264 254 -10 base64_main 221 211 -10 arping_main 1665 1655 -10 ar_main 556 546 -10 adjtimex_main 406 396 -10 adduser_main 882 872 -10 addgroup_main 411 401 -10 acpid_main 1198 1188 -10 optstring 11 - -11 opt_string 18 - -18 OPT_STR 25 - -25 ubi_tools_main 1288 1258 -30 ls_options 31 - -31 ------------------------------------------------------------------------------ (add/remove: 0/6 grow/shrink: 3/129 up/down: 86/-1383) Total: -1297 bytes text data bss dec hex filename 915428 485 6876 922789 e14a5 busybox_old 914629 485 6872 921986 e1182 busybox_unstripped Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2017-08-09 01:25:02 +05:30
opt_ler = getopt32(argv, "^" "u:c:lerd" "\0" "?1:dr"/*max one arg; -d implies -r*/,
&user_name, &crontab_dir
);
argv += optind;
if (sanitize_env_if_suid()) { /* Clears dangerous stuff, sets PATH */
/* Run by non-root */
if (opt_ler & (OPT_u|OPT_c))
bb_error_msg_and_die(bb_msg_you_must_be_root);
}
if (opt_ler & OPT_u) {
pas = xgetpwnam(user_name);
} else {
pas = xgetpwuid(getuid());
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}
#define user_name DONT_USE_ME_BEYOND_THIS_POINT
/* From now on, keep only -l, -e, -r bits */
opt_ler &= OPT_ler;
if ((opt_ler - 1) & opt_ler) /* more than one bit set? */
bb_show_usage();
/* Read replacement file under user's UID/GID/group vector */
src_fd = STDIN_FILENO;
if (!opt_ler) { /* Replace? */
if (!argv[0])
bb_show_usage();
if (NOT_LONE_DASH(argv[0])) {
src_fd = xopen_as_uid_gid(argv[0], O_RDONLY, pas->pw_uid, pas->pw_gid);
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}
}
/* cd to our crontab directory */
xchdir(crontab_dir);
tmp_fname = NULL;
/* Handle requested operation */
switch (opt_ler) {
default: /* case OPT_r: Delete */
unlink(pas->pw_name);
break;
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case OPT_l: /* List */
{
char *args[2] = { pas->pw_name, NULL };
return bb_cat(args);
/* list exits,
* the rest go play with cron update file */
}
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case OPT_e: /* Edit */
tmp_fname = xasprintf("%s.%u", crontab_dir, (unsigned)getpid());
/* No O_EXCL: we don't want to be stuck if earlier crontabs
* were killed, leaving stale temp file behind */
src_fd = xopen3(tmp_fname, O_RDWR|O_CREAT|O_TRUNC, 0600);
fchown(src_fd, pas->pw_uid, pas->pw_gid);
fd = open(pas->pw_name, O_RDONLY);
if (fd >= 0) {
bb_copyfd_eof(fd, src_fd);
close(fd);
xlseek(src_fd, 0, SEEK_SET);
}
close_on_exec_on(src_fd); /* don't want editor to see this fd */
edit_file(pas, tmp_fname);
/* fall through */
case 0: /* Replace (no -l, -e, or -r were given) */
new_fname = xasprintf("%s.new", pas->pw_name);
fd = open(new_fname, O_WRONLY|O_CREAT|O_TRUNC|O_APPEND, 0600);
if (fd >= 0) {
bb_copyfd_eof(src_fd, fd);
close(fd);
xrename(new_fname, pas->pw_name);
} else {
bb_error_msg("can't create %s/%s",
crontab_dir, new_fname);
}
if (tmp_fname)
unlink(tmp_fname);
/*free(tmp_fname);*/
/*free(new_fname);*/
} /* switch */
/* Bump notification file. Handle window where crond picks file up
* before we can write our entry out.
*/
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while ((fd = open(CRONUPDATE, O_WRONLY|O_CREAT|O_APPEND, 0600)) >= 0) {
struct stat st;
fdprintf(fd, "%s\n", pas->pw_name);
if (fstat(fd, &st) != 0 || st.st_nlink != 0) {
/*close(fd);*/
break;
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}
/* st.st_nlink == 0:
* file was deleted, maybe crond missed our notification */
close(fd);
/* loop */
}
if (fd < 0) {
bb_error_msg("can't append to %s/%s",
crontab_dir, CRONUPDATE);
}
return 0;
}