/* vi: set sw=4 ts=4: */
/*
* run as root, but NOT setuid root
*
* Copyright 1994 Matthew Dillon (dillon@apollo.west.oic.com)
* (version 2.3.2)
* Vladimir Oleynik <dzo@simtreas.ru> (C) 2002
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//config:config CROND
//config: bool "crond (14 kb)"
//config: default y
//config: select FEATURE_SYSLOG
//config: help
//config: Crond is a background daemon that parses individual crontab
//config: files and executes commands on behalf of the users in question.
//config: This is a port of dcron from slackware. It uses files of the
//config: format /var/spool/cron/crontabs/<username> files, for example:
//config: $ cat /var/spool/cron/crontabs/root
//config: # Run daily cron jobs at 4:40 every day:
//config: 40 4 * * * /etc/cron/daily > /dev/null 2>&1
//config:
//config:config FEATURE_CROND_D
//config: bool "Support -d (redirect output to stderr)"
//config: depends on CROND
//config: default y
//config: help
//config: -d N sets loglevel (0:most verbose) and directs all output to stderr.
//config:
//config:config FEATURE_CROND_CALL_SENDMAIL
//config: bool "Report command output via email (using sendmail)"
//config: default y
//config: depends on CROND
//config: help
//config: Command output will be sent to corresponding user via email.
//config:
//config:config FEATURE_CROND_SPECIAL_TIMES
//config: bool "Support special times (@reboot, @daily, etc) in crontabs"
//config: default y
//config: depends on CROND
//config: help
//config: string meaning
//config: ------ -------
//config: @reboot Run once, at startup
//config: @yearly Run once a year: "0 0 1 1 *"
//config: @annually Same as @yearly: "0 0 1 1 *"
//config: @monthly Run once a month: "0 0 1 * *"
//config: @weekly Run once a week: "0 0 * * 0"
//config: @daily Run once a day: "0 0 * * *"
//config: @midnight Same as @daily: "0 0 * * *"
//config: @hourly Run once an hour: "0 * * * *"
//config:
//config:config FEATURE_CROND_DIR
//config: string "crond spool directory"
//config: default "/var/spool/cron"
//config: depends on CROND || CRONTAB
//config: help
//config: Location of crond spool.
//applet:IF_CROND(APPLET(crond, BB_DIR_USR_SBIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_CROND) += crond.o
//usage:#define crond_trivial_usage
//usage: "-fbS -l N " IF_FEATURE_CROND_D("-d N ") "-L LOGFILE -c DIR"
//usage:#define crond_full_usage "\n\n"
//usage: " -f Foreground"
//usage: "\n -b Background (default)"
//usage: "\n -S Log to syslog (default)"
//usage: "\n -l N Set log level. Most verbose 0, default 8"
//usage: IF_FEATURE_CROND_D(
//usage: "\n -d N Set log level, log to stderr"
//usage: )
//usage: "\n -L FILE Log to FILE"
//usage: "\n -c DIR Cron dir. Default:"CONFIG_FEATURE_CROND_DIR"/crontabs"
#include "libbb.h"
#include "common_bufsiz.h"
#include <syslog.h>
#if 0
/* If libc tracks and reuses setenv()-allocated memory, ok to set this to 0 */
/* Neither glibc nor uclibc do that! */
# define SETENV_LEAKS 0
#else
# define SETENV_LEAKS 1
#endif
#define CRON_DIR CONFIG_FEATURE_CROND_DIR
#define CRONTABS CONFIG_FEATURE_CROND_DIR "/crontabs"
#define CRON_REBOOT CONFIG_PID_FILE_PATH "/crond.reboot"
#ifndef SENDMAIL
# define SENDMAIL "sendmail"
#endif
#ifndef SENDMAIL_ARGS
# define SENDMAIL_ARGS "-ti"
#endif
#ifndef CRONUPDATE
# define CRONUPDATE "cron.update"
#endif
#ifndef MAXLINES
# define MAXLINES 256 /* max lines in non-root crontabs */
#endif
typedef struct CronFile {
struct CronFile *cf_next;
struct CronLine *cf_lines;
char *cf_username;
smallint cf_wants_starting; /* bool: one or more jobs ready */
smallint cf_has_running; /* bool: one or more jobs running */
smallint cf_deleted; /* marked for deletion (but still has running jobs) */
} CronFile;
typedef struct CronLine {
struct CronLine *cl_next;
char *cl_cmd; /* shell command */
pid_t cl_pid; /* >0:running, <0:needs to be started in this minute, 0:dormant */
#define START_ME_REBOOT -2
#define START_ME_NORMAL -1
#if ENABLE_FEATURE_CROND_CALL_SENDMAIL
int cl_empty_mail_size; /* size of mail header only, 0 if no mailfile */
char *cl_mailto; /* whom to mail results, may be NULL */
#endif
char *cl_shell;
/* ordered by size, not in natural order. makes code smaller: */
char cl_Dow[7]; /* 0-6, beginning sunday */
char cl_Mons[12]; /* 0-11 */
char cl_Hrs[24]; /* 0-23 */
char cl_Days[32]; /* 1-31 */
char cl_Mins[60]; /* 0-59 */
} CronLine;
#define DAEMON_UID 0
enum {
OPT_l = (1 << 0),
OPT_L = (1 << 1),
OPT_f = (1 << 2),
OPT_b = (1 << 3),
OPT_S = (1 << 4),
OPT_c = (1 << 5),
OPT_d = (1 << 6) * ENABLE_FEATURE_CROND_D,
};
struct globals {
unsigned log_level; /* = 8; */
time_t crontab_dir_mtime;
const char *log_filename;
const char *crontab_dir_name; /* = CRONTABS; */
CronFile *cron_files;
char *default_shell;
#if SETENV_LEAKS
char *env_var_user;
char *env_var_home;
char *env_var_shell;
char *env_var_logname;
#endif
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define INIT_G() do { \
setup_common_bufsiz(); \
G.log_level = 8; \
G.crontab_dir_name = CRONTABS; \
} while (0)
/* Log levels:
* 0 is the most verbose, default 8.
* For some reason, in fact only 5, 7 and 8 are used.
*/
static void crondlog(unsigned level, const char *msg, va_list va)
{
if (level >= G.log_level) {
/*
* We are called only for info meesages.
* Warnings/errors use plain bb_[p]error_msg's, which
* need not touch syslog_level
* (they are ok with LOG_ERR default).
*/
bb_vinfo_msg(msg, va);
}
}
static void log5(const char *msg, ...)
{
va_list va;
va_start(va, msg);
crondlog(4, msg, va);
va_end(va);
}
static void log7(const char *msg, ...)
{
va_list va;
va_start(va, msg);
crondlog(7, msg, va);
va_end(va);
}
static void log8(const char *msg, ...)
{
va_list va;
va_start(va, msg);
crondlog(8, msg, va);
va_end(va);
}
static const char DowAry[] ALIGN1 =
"sun""mon""tue""wed""thu""fri""sat"
;
static const char MonAry[] ALIGN1 =
"jan""feb""mar""apr""may""jun""jul""aug""sep""oct""nov""dec"
;
static void ParseField(char *user, char *ary, int modvalue, int off,
const char *names, char *ptr)
/* 'names' is a pointer to a set of 3-char abbreviations */
{
char *base = ptr;
int n1 = -1;
int n2 = -1;
// this can't happen due to config_read()
/*if (base == NULL)
return;*/
while (1) {
int skip = 0;
/* Handle numeric digit or symbol or '*' */
if (*ptr == '*') {
n1 = 0; /* everything will be filled */
n2 = modvalue - 1;
skip = 1;
++ptr;
} else if (isdigit(*ptr)) {
char *endp;
if (n1 < 0) {
n1 = strtol(ptr, &endp, 10) + off;
} else {
n2 = strtol(ptr, &endp, 10) + off;
}
ptr = endp; /* gcc likes temp var for &endp */
skip = 1;
} else if (names) {
int i;
for (i = 0; names[i]; i += 3) {
/* was using strncmp before... */
if (strncasecmp(ptr, &names[i], 3) == 0) {
ptr += 3;
if (n1 < 0) {
n1 = i / 3;
} else {
n2 = i / 3;
}
skip = 1;
break;
}
}
}
/* handle optional range '-' */
if (skip == 0) {
goto err;
}
if (*ptr == '-' && n2 < 0) {
++ptr;
continue;
}
/*
* collapse single-value ranges, handle skipmark, and fill
* in the character array appropriately.
*/
if (n2 < 0) {
n2 = n1;
}
if (*ptr == '/') {
char *endp;
skip = strtol(ptr + 1, &endp, 10);
ptr = endp; /* gcc likes temp var for &endp */
}
/*
* fill array, using a failsafe is the easiest way to prevent
* an endless loop
*/
{
int s0 = 1;
int failsafe = 1024;
--n1;
do {
n1 = (n1 + 1) % modvalue;
if (--s0 == 0) {
ary[n1 % modvalue] = 1;
s0 = skip;
}
if (--failsafe == 0) {
goto err;
}
} while (n1 != n2);
}
if (*ptr != ',') {
break;
}
++ptr;
n1 = -1;
n2 = -1;
}
if (*ptr) {
err:
bb_error_msg("user %s: parse error at %s", user, base);
return;
}
/* can't use log5 (it inserts newlines), open-coding it */
if (G.log_level <= 5 && logmode != LOGMODE_SYSLOG) {
int i;
for (i = 0; i < modvalue; ++i)
fprintf(stderr, "%d", (unsigned char)ary[i]);
bb_putchar_stderr('\n');
}
}
static void FixDayDow(CronLine *line)
{
unsigned i;
int weekUsed = 0;
int daysUsed = 0;
for (i = 0; i < ARRAY_SIZE(line->cl_Dow); ++i) {
if (line->cl_Dow[i] == 0) {
weekUsed = 1;
break;
}
}
for (i = 0; i < ARRAY_SIZE(line->cl_Days); ++i) {
if (line->cl_Days[i] == 0) {
daysUsed = 1;
break;
}
}
if (weekUsed != daysUsed) {
if (weekUsed)
memset(line->cl_Days, 0, sizeof(line->cl_Days));
else /* daysUsed */
memset(line->cl_Dow, 0, sizeof(line->cl_Dow));
}
}
/*
* delete_cronfile() - delete user database
*
* Note: multiple entries for same user may exist if we were unable to
* completely delete a database due to running processes.
*/
//FIXME: we will start a new job even if the old job is running
//if crontab was reloaded: crond thinks that "new" job is different from "old"
//even if they are in fact completely the same. Example
//Crontab was:
// 0-59 * * * * job1
// 0-59 * * * * long_running_job2
//User edits crontab to:
// 0-59 * * * * job1_updated
// 0-59 * * * * long_running_job2
//Bug: crond can now start another long_running_job2 even if old one
//is still running.
//OTOH most other versions of cron do not wait for job termination anyway,
//they end up with multiple copies of jobs if they don't terminate soon enough.
static void delete_cronfile(const char *userName)
{
CronFile **pfile = &G.cron_files;
CronFile *file;
while ((file = *pfile) != NULL) {
if (strcmp(userName, file->cf_username) == 0) {
CronLine **pline = &file->cf_lines;
CronLine *line;
file->cf_has_running = 0;
file->cf_deleted = 1;
while ((line = *pline) != NULL) {
if (line->cl_pid > 0) {
file->cf_has_running = 1;
pline = &line->cl_next;
} else {
*pline = line->cl_next;
free(line->cl_cmd);
free(line);
}
}
if (file->cf_has_running == 0) {
*pfile = file->cf_next;
free(file->cf_username);
free(file);
continue;
}
}
pfile = &file->cf_next;
}
}
static void load_crontab(const char *fileName)
{
struct parser_t *parser;
struct stat sbuf;
int maxLines;
char *tokens[6];
#if ENABLE_FEATURE_CROND_CALL_SENDMAIL
char *mailTo = NULL;
#endif
char *shell = NULL;
delete_cronfile(fileName);
if (!getpwnam(fileName)) {
log7("ignoring file '%s' (no such user)", fileName);
return;
}
parser = config_open(fileName);
if (!parser)
return;
maxLines = (strcmp(fileName, "root") == 0) ? 65535 : MAXLINES;
if (fstat(fileno(parser->fp), &sbuf) == 0 && sbuf.st_uid == DAEMON_UID) {
CronFile *file = xzalloc(sizeof(CronFile));
CronLine **pline;
int n;
file->cf_username = xstrdup(fileName);
pline = &file->cf_lines;
while (1) {
CronLine *line;
if (!--maxLines) {
bb_error_msg("user %s: too many lines", fileName);
break;
}
n = config_read(parser, tokens, 6, 1, "# \t", PARSE_NORMAL | PARSE_KEEP_COPY);
if (!n)
break;
log5("user:%s entry:%s", fileName, parser->data);
/* check if line is setting MAILTO= */
if (is_prefixed_with(tokens[0], "MAILTO=")) {
#if ENABLE_FEATURE_CROND_CALL_SENDMAIL
free(mailTo);
mailTo = (tokens[0][7]) ? xstrdup(&tokens[0][7]) : NULL;
#endif /* otherwise just ignore such lines */
continue;
}
if (is_prefixed_with(tokens[0], "SHELL=")) {
free(shell);
shell = xstrdup(&tokens[0][6]);
continue;
}
//TODO: handle HOME= too? "man crontab" says:
//name = value
//
//where the spaces around the equal-sign (=) are optional, and any subsequent
//non-leading spaces in value will be part of the value assigned to name.
//The value string may be placed in quotes (single or double, but matching)
//to preserve leading or trailing blanks.
//
//Several environment variables are set up automatically by the cron(8) daemon.
//SHELL is set to /bin/sh, and LOGNAME and HOME are set from the /etc/passwd
//line of the crontab's owner. HOME and SHELL may be overridden by settings
//in the crontab; LOGNAME may not.
#if ENABLE_FEATURE_CROND_SPECIAL_TIMES
if (tokens[0][0] == '@') {
/*
* "@daily /a/script/to/run PARAM1 PARAM2..."
*/
typedef struct SpecialEntry {
const char *name;
const char tokens[8];
} SpecialEntry;
static const SpecialEntry SpecAry[] = {
/* hour day month weekday */
{ "yearly", "0\0" "1\0" "1\0" "*" },
{ "annually", "0\0" "1\0" "1\0" "*" },
{ "monthly", "0\0" "1\0" "*\0" "*" },
{ "weekly", "0\0" "*\0" "*\0" "0" },
{ "daily", "0\0" "*\0" "*\0" "*" },
{ "midnight", "0\0" "*\0" "*\0" "*" },
{ "hourly", "*\0" "*\0" "*\0" "*" },
{ "reboot", "" },
};
const SpecialEntry *e = SpecAry;
if (n < 2)
continue;
for (;;) {
if (strcmp(e->name, tokens[0] + 1) == 0) {
/*
* tokens[1] is only the first word of command,
* can'r use it.
* find the entire command in unmodified string:
*/
tokens[5] = skip_whitespace(
skip_non_whitespace(
skip_whitespace(parser->data)));
if (e->tokens[0]) {
char *et = (char*)e->tokens;
/* minute is "0" for all specials */
tokens[0] = (char*)"0";
tokens[1] = et;
tokens[2] = et + 2;
tokens[3] = et + 4;
tokens[4] = et + 6;
}
goto got_it;
}
if (!e->tokens[0])
break;
e++;
}
continue; /* bad line (unrecognized '@foo') */
}
#endif
/* check if a minimum of tokens is specified */
if (n < 6)
continue;
IF_FEATURE_CROND_SPECIAL_TIMES(
got_it:
)
*pline = line = xzalloc(sizeof(*line));
#if ENABLE_FEATURE_CROND_SPECIAL_TIMES
if (tokens[0][0] == '@') { /* "@reboot" line */
file->cf_wants_starting = 1;
line->cl_pid = START_ME_REBOOT; /* wants to start */
/* line->cl_Mins/Hrs/etc stay zero: never match any time */
} else
#endif
{
/* parse date ranges */
ParseField(file->cf_username, line->cl_Mins, 60, 0, NULL, tokens[0]);
ParseField(file->cf_username, line->cl_Hrs, 24, 0, NULL, tokens[1]);
ParseField(file->cf_username, line->cl_Days, 32, 0, NULL, tokens[2]);
ParseField(file->cf_username, line->cl_Mons, 12, -1, MonAry, tokens[3]);
ParseField(file->cf_username, line->cl_Dow, 7, 0, DowAry, tokens[4]);
/*
* fix days and dow - if one is not "*" and the other
* is "*", the other is set to 0, and vise-versa
*/
FixDayDow(line);
}
#if ENABLE_FEATURE_CROND_CALL_SENDMAIL
/* copy mailto (can be NULL) */
line->cl_mailto = xstrdup(mailTo);
#endif
line->cl_shell = xstrdup(shell);
/* copy command */
line->cl_cmd = xstrdup(tokens[5]);
pline = &line->cl_next;
//bb_error_msg("M[%s]F[%s][%s][%s][%s][%s][%s]", mailTo, tokens[0], tokens[1], tokens[2], tokens[3], tokens[4], tokens[5]);
}
*pline = NULL;
file->cf_next = G.cron_files;
G.cron_files = file;
}
config_close(parser);
#if ENABLE_FEATURE_CROND_CALL_SENDMAIL
free(mailTo);
#endif
free(shell);
}
static void process_cron_update_file(void)
{
FILE *fi;
char buf[256];
fi = fopen_for_read(CRONUPDATE);
if (fi != NULL) {
unlink(CRONUPDATE);
while (fgets(buf, sizeof(buf), fi) != NULL) {
/* use first word only */
skip_non_whitespace(buf)[0] = '\0';
load_crontab(buf);
}
fclose(fi);
}
}
static void rescan_crontab_dir(void)
{
CronFile *file;
/* Delete all files until we only have ones with running jobs (or none) */
again:
for (file = G.cron_files; file; file = file->cf_next) {
if (!file->cf_deleted) {
delete_cronfile(file->cf_username);
goto again;
}
}
/* Remove cron update file */
unlink(CRONUPDATE);
/* Re-chdir, in case directory was renamed & deleted */
xchdir(G.crontab_dir_name);
/* Scan directory and add associated users */
{
DIR *dir = opendir(".");
struct dirent *den;
/* xopendir exists, but "can't open '.'" is not informative */
if (!dir)
bb_error_msg_and_die("can't open '%s'", G.crontab_dir_name);
while ((den = readdir(dir)) != NULL) {
if (strchr(den->d_name, '.') != NULL) {
continue;
}
load_crontab(den->d_name);
}
closedir(dir);
}
}
#if SETENV_LEAKS
/* We set environment *before* vfork (because we want to use vfork),
* so we cannot use setenv() - repeated calls to setenv() may leak memory!
* Using putenv(), and freeing memory after unsetenv() won't leak */
static void safe_setenv(char **pvar_val, const char *var, const char *val)
{
char *var_val = *pvar_val;
if (var_val) {
bb_unsetenv_and_free(var_val);
}
*pvar_val = xasprintf("%s=%s", var, val);
putenv(*pvar_val);
}
#endif
static void set_env_vars(struct passwd *pas, const char *shell)
{
/* POSIX requires crond to set up at least HOME, LOGNAME, PATH, SHELL.
* We assume crond inherited suitable PATH.
*/
#if SETENV_LEAKS
safe_setenv(&G.env_var_logname, "LOGNAME", pas->pw_name);
safe_setenv(&G.env_var_user, "USER", pas->pw_name);
safe_setenv(&G.env_var_home, "HOME", pas->pw_dir);
safe_setenv(&G.env_var_shell, "SHELL", shell);
#else
xsetenv("LOGNAME", pas->pw_name);
xsetenv("USER", pas->pw_name);
xsetenv("HOME", pas->pw_dir);
xsetenv("SHELL", shell);
#endif
}
static void change_user(struct passwd *pas)
{
/* careful: we're after vfork! */
change_identity(pas); /* - initgroups, setgid, setuid */
if (chdir(pas->pw_dir) < 0) {
bb_error_msg("can't change directory to '%s'", pas->pw_dir);
xchdir(CRON_DIR);
}
}
// TODO: sendmail should be _run-time_ option, not compile-time!
#if ENABLE_FEATURE_CROND_CALL_SENDMAIL
static pid_t
fork_job(const char *user, int mailFd, CronLine *line, bool run_sendmail)
{
struct passwd *pas;
const char *shell, *prog;
smallint sv_logmode;
pid_t pid;
/* prepare things before vfork */
pas = getpwnam(user);
if (!pas) {
bb_error_msg("can't get uid for %s", user);
goto err;
}
shell = line->cl_shell ? line->cl_shell : G.default_shell;
prog = run_sendmail ? SENDMAIL : shell;
set_env_vars(pas, shell);
sv_logmode = logmode;
pid = vfork();
if (pid == 0) {
/* CHILD */
/* initgroups, setgid, setuid, and chdir to home or CRON_DIR */
change_user(pas);
log5("child running %s", prog);
if (mailFd >= 0) {
xmove_fd(mailFd, run_sendmail ? 0 : 1);
dup2(1, 2);
}
/* crond 3.0pl1-100 puts tasks in separate process groups */
bb_setpgrp();
if (!run_sendmail)
execlp(prog, prog, "-c", line->cl_cmd, (char *) NULL);
else
execlp(prog, prog, SENDMAIL_ARGS, (char *) NULL);
/*
* I want this error message on stderr too,
* even if other messages go only to syslog:
*/
logmode |= LOGMODE_STDIO;
bb_error_msg_and_die("can't execute '%s' for user %s", prog, user);
}
logmode = sv_logmode;
if (pid < 0) {
bb_perror_msg("vfork");
err:
pid = 0;
} /* else: PARENT, FORK SUCCESS */
/*
* Close the mail file descriptor.. we can't just leave it open in
* a structure, closing it later, because we might run out of descriptors
*/
if (mailFd >= 0) {
close(mailFd);
}
return pid;
}
static pid_t start_one_job(const char *user, CronLine *line)
{
char mailFile[128];
int mailFd = -1;
line->cl_pid = 0;
line->cl_empty_mail_size = 0;
if (line->cl_mailto) {
/* Open mail file (owner is root so nobody can screw with it) */
snprintf(mailFile, sizeof(mailFile), "%s/cron.%s.%d", CRON_DIR, user, getpid());
mailFd = open(mailFile, O_CREAT | O_TRUNC | O_WRONLY | O_EXCL | O_APPEND, 0600);
if (mailFd >= 0) {
fdprintf(mailFd, "To: %s\nSubject: cron: %s\n\n", line->cl_mailto,
line->cl_cmd);
line->cl_empty_mail_size = lseek(mailFd, 0, SEEK_CUR);
} else {
bb_error_msg("can't create mail file %s for user %s, "
"discarding output", mailFile, user);
}
}
line->cl_pid = fork_job(user, mailFd, line, /*sendmail?*/ 0);
if (mailFd >= 0) {
if (line->cl_pid <= 0) {
unlink(mailFile);
} else {
/* rename mail-file based on pid of process */
char *mailFile2 = xasprintf("%s/cron.%s.%d", CRON_DIR, user, (int)line->cl_pid);
rename(mailFile, mailFile2); // TODO: xrename?
free(mailFile2);
}
}
return line->cl_pid;
}
/*
* process_finished_job - called when job terminates and when mail terminates
*/
static void process_finished_job(const char *user, CronLine *line)
{
pid_t pid;
int mailFd;
char mailFile[128];
struct stat sbuf;
pid = line->cl_pid;
line->cl_pid = 0;
if (pid <= 0) {
/* No job */
return;
}
if (line->cl_empty_mail_size <= 0) {
/* End of job and no mail file, or end of sendmail job */
return;
}
/*
* End of primary job - check for mail file.
* If size has changed and the file is still valid, we send it.
*/
snprintf(mailFile, sizeof(mailFile), "%s/cron.%s.%d", CRON_DIR, user, (int)pid);
mailFd = open(mailFile, O_RDONLY);
unlink(mailFile);
if (mailFd < 0) {
return;
}
if (fstat(mailFd, &sbuf) < 0
|| sbuf.st_uid != DAEMON_UID
|| sbuf.st_nlink != 0
|| sbuf.st_size == line->cl_empty_mail_size
|| !S_ISREG(sbuf.st_mode)
) {
close(mailFd);
return;
}
line->cl_empty_mail_size = 0;
/* if (line->cl_mailto) - always true if cl_empty_mail_size was nonzero */
line->cl_pid = fork_job(user, mailFd, line, /*sendmail?*/ 1);
}
#else /* !ENABLE_FEATURE_CROND_CALL_SENDMAIL */
static pid_t start_one_job(const char *user, CronLine *line)
{
const char *shell;
struct passwd *pas;
pid_t pid;
pas = getpwnam(user);
if (!pas) {
bb_error_msg("can't get uid for %s", user);
goto err;
}
/* Prepare things before vfork */
shell = line->cl_shell ? line->cl_shell : G.default_shell;
set_env_vars(pas, shell);
/* Fork as the user in question and run program */
pid = vfork();
if (pid == 0) {
/* CHILD */
/* initgroups, setgid, setuid, and chdir to home or CRON_DIR */
change_user(pas);
log5("child running %s", shell);
/* crond 3.0pl1-100 puts tasks in separate process groups */
bb_setpgrp();
execl(shell, shell, "-c", line->cl_cmd, (char *) NULL);
bb_error_msg_and_die("can't execute '%s' for user %s", shell, user);
}
if (pid < 0) {
bb_perror_msg("vfork");
err:
pid = 0;
}
line->cl_pid = pid;
return pid;
}
#define process_finished_job(user, line) ((line)->cl_pid = 0)
#endif /* !ENABLE_FEATURE_CROND_CALL_SENDMAIL */
/*
* Determine which jobs need to be run. Under normal conditions, the
* period is about a minute (one scan). Worst case it will be one
* hour (60 scans).
*/
static void flag_starting_jobs(time_t t1, time_t t2)
{
time_t t;
/* Find jobs > t1 and <= t2 */
for (t = t1 - t1 % 60; t <= t2; t += 60) {
struct tm *ptm;
CronFile *file;
CronLine *line;
if (t <= t1)
continue;
ptm = localtime(&t);
for (file = G.cron_files; file; file = file->cf_next) {
log5("file %s:", file->cf_username);
if (file->cf_deleted)
continue;
for (line = file->cf_lines; line; line = line->cl_next) {
log5(" line %s", line->cl_cmd);
if (line->cl_Mins[ptm->tm_min]
&& line->cl_Hrs[ptm->tm_hour]
&& (line->cl_Days[ptm->tm_mday] || line->cl_Dow[ptm->tm_wday])
&& line->cl_Mons[ptm->tm_mon]
) {
log5(" job: %d %s",
(int)line->cl_pid, line->cl_cmd);
if (line->cl_pid > 0) {
log8("user %s: process already running: %s",
file->cf_username, line->cl_cmd);
} else if (line->cl_pid == 0) {
line->cl_pid = START_ME_NORMAL;
file->cf_wants_starting = 1;
}
}
}
}
}
}
#if ENABLE_FEATURE_CROND_SPECIAL_TIMES
static int touch_reboot_file(void)
{
int fd = open(CRON_REBOOT, O_WRONLY | O_CREAT | O_EXCL | O_TRUNC, 0000);
if (fd >= 0) {
close(fd);
return 1;
}
/* File (presumably) exists - this is not the first run after reboot */
return 0;
}
#endif
static void start_jobs(int wants_start)
{
CronFile *file;
CronLine *line;
for (file = G.cron_files; file; file = file->cf_next) {
if (!file->cf_wants_starting)
continue;
file->cf_wants_starting = 0;
for (line = file->cf_lines; line; line = line->cl_next) {
pid_t pid;
if (line->cl_pid != wants_start)
continue;
pid = start_one_job(file->cf_username, line);
log8("USER %s pid %3d cmd %s",
file->cf_username, (int)pid, line->cl_cmd);
if (pid < 0) {
file->cf_wants_starting = 1;
}
if (pid > 0) {
file->cf_has_running = 1;
}
}
}
}
/*
* Check for job completion, return number of jobs still running after
* all done.
*/
static int check_completions(void)
{
CronFile *file;
CronLine *line;
int num_still_running = 0;
for (file = G.cron_files; file; file = file->cf_next) {
if (!file->cf_has_running)
continue;
file->cf_has_running = 0;
for (line = file->cf_lines; line; line = line->cl_next) {
int r;
if (line->cl_pid <= 0)
continue;
r = waitpid(line->cl_pid, NULL, WNOHANG);
if (r < 0 || r == line->cl_pid) {
process_finished_job(file->cf_username, line);
if (line->cl_pid == 0) {
/* sendmail was not started for it */
continue;
}
/* else: sendmail was started, job is still running, fall thru */
}
/* else: r == 0: "process is still running" */
file->cf_has_running = 1;
}
//FIXME: if !file->cf_has_running && file->deleted: delete it!
//otherwise deleted entries will stay forever, right?
num_still_running += file->cf_has_running;
}
return num_still_running;
}
static void reopen_logfile_to_stderr(void)
{
if (G.log_filename) {
int logfd = open_or_warn(G.log_filename, O_WRONLY | O_CREAT | O_APPEND);
if (logfd >= 0)
xmove_fd(logfd, STDERR_FILENO);
}
}
int crond_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int crond_main(int argc UNUSED_PARAM, char **argv)
{
time_t t2;
unsigned rescan;
unsigned sleep_time;
unsigned opts;
INIT_G();
opts = getopt32(argv, "^"
"l:L:fbSc:" IF_FEATURE_CROND_D("d:")
"\0"
/* "-b after -f is ignored", and so on for every pair a-b */
"f-b:b-f:S-L:L-S" IF_FEATURE_CROND_D(":d-l")
/* -l and -d have numeric param */
":l+" IF_FEATURE_CROND_D(":d+")
,
&G.log_level, &G.log_filename, &G.crontab_dir_name
IF_FEATURE_CROND_D(,&G.log_level)
);
/* both -d N and -l N set the same variable: G.log_level */
if (!(opts & OPT_f)) {
/* close stdin, stdout, stderr.
* close unused descriptors - don't need them. */
bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv);
}
if (!(opts & OPT_d) && G.log_filename == NULL) {
/* logging to syslog */
openlog(applet_name, LOG_CONS | LOG_PID, LOG_CRON);
logmode = LOGMODE_SYSLOG;
}
//signal(SIGHUP, SIG_IGN); /* ? original crond dies on HUP... */
reopen_logfile_to_stderr();
xchdir(G.crontab_dir_name);
/* $SHELL, or current UID's shell, or DEFAULT_SHELL */
/* Useful on Android where DEFAULT_SHELL /bin/sh may not exist */
G.default_shell = xstrdup(get_shell_name());
log8("crond (busybox "BB_VER") started, log level %d", G.log_level);
rescan_crontab_dir();
write_pidfile_std_path_and_ext("crond");
#if ENABLE_FEATURE_CROND_SPECIAL_TIMES
if (touch_reboot_file())
start_jobs(START_ME_REBOOT); /* start @reboot entries, if any */
#endif
/* Main loop */
t2 = time(NULL);
rescan = 60;
sleep_time = 60;
for (;;) {
struct stat sbuf;
time_t t1;
long dt;
/* Synchronize to 1 minute, minimum 1 second */
t1 = t2;
sleep(sleep_time - (time(NULL) % sleep_time));
t2 = time(NULL);
dt = (long)t2 - (long)t1;
reopen_logfile_to_stderr();
/*
* The file 'cron.update' is checked to determine new cron
* jobs. The directory is rescanned once an hour to deal
* with any screwups.
*
* Check for time jump. Disparities over an hour either way
* result in resynchronization. A negative disparity
* less than an hour causes us to effectively sleep until we
* match the original time (i.e. no re-execution of jobs that
* have just been run). A positive disparity less than
* an hour causes intermediate jobs to be run, but only once
* in the worst case.
*
* When running jobs, the inequality used is greater but not
* equal to t1, and less then or equal to t2.
*/
if (stat(G.crontab_dir_name, &sbuf) != 0)
sbuf.st_mtime = 0; /* force update (once) if dir was deleted */
if (G.crontab_dir_mtime != sbuf.st_mtime) {
G.crontab_dir_mtime = sbuf.st_mtime;
rescan = 1;
}
if (--rescan == 0) {
rescan = 60;
rescan_crontab_dir();
}
process_cron_update_file();
log5("wakeup dt=%ld", dt);
if (dt < -60 * 60 || dt > 60 * 60) {
bb_info_msg("time disparity of %ld minutes detected", dt / 60);
/* and we do not run any jobs in this case */
} else if (dt > 0) {
/* Usual case: time advances forward, as expected */
flag_starting_jobs(t1, t2);
start_jobs(START_ME_NORMAL);
sleep_time = 60;
if (check_completions() > 0) {
/* some jobs are still running */
sleep_time = 10;
}
}
/* else: time jumped back, do not run any jobs */
} /* for (;;) */
return 0; /* not reached */
}