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c6c2345ca617f604b20750145b7158893091db60
busybox/miscutils/crond.c
Denis Vlasenko f9000c51db crond: code shrink
2007-08-19 18:49:21 +00:00

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/* vi: set sw=4 ts=4: */
/*
* crond -d[#] -c <crondir> -f -b
*
* 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 the GPL v2 or later, see the file LICENSE in this tarball.
*/
#include <sys/syslog.h>
#include "libbb.h"
#ifndef CRONTABS
#define CRONTABS "/var/spool/cron/crontabs"
#endif
#ifndef TMPDIR
#define TMPDIR "/var/spool/cron"
#endif
#ifndef SENDMAIL
#define SENDMAIL "sendmail"
#endif
#ifndef SENDMAIL_ARGS
#define SENDMAIL_ARGS "-ti", "oem"
#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_LineBase;
char *cf_User; /* username */
int cf_Ready; /* bool: one or more jobs ready */
int cf_Running; /* bool: one or more jobs running */
int cf_Deleted; /* marked for deletion, ignore */
} CronFile;
typedef struct CronLine {
struct CronLine *cl_Next;
char *cl_Shell; /* shell command */
pid_t cl_Pid; /* running pid, 0, or armed (-1) */
int cl_MailFlag; /* running pid is for mail */
int cl_MailPos; /* 'empty file' size */
char cl_Mins[60]; /* 0-59 */
char cl_Hrs[24]; /* 0-23 */
char cl_Days[32]; /* 1-31 */
char cl_Mons[12]; /* 0-11 */
char cl_Dow[7]; /* 0-6, beginning sunday */
} CronLine;
#define RUN_RANOUT 1
#define RUN_RUNNING 2
#define RUN_FAILED 3
#define DaemonUid 0
#if ENABLE_DEBUG_CROND_OPTION
static unsigned DebugOpt;
#endif
static unsigned LogLevel = 8;
static const char *LogFile;
static const char *CDir = CRONTABS;
static void startlogger(void);
static void CheckUpdates(void);
static void SynchronizeDir(void);
static int TestJobs(time_t t1, time_t t2);
static void RunJobs(void);
static int CheckJobs(void);
static void RunJob(const char *user, CronLine * line);
#if ENABLE_FEATURE_CROND_CALL_SENDMAIL
static void EndJob(const char *user, CronLine * line);
#else
#define EndJob(user, line) line->cl_Pid = 0
#endif
static void DeleteFile(const char *userName);
static CronFile *FileBase;
static void crondlog(const char *ctl, ...)
{
va_list va;
const char *fmt;
int level = (int) (ctl[0] & 0xf);
int type = level == 20 ?
LOG_ERR : ((ctl[0] & 0100) ? LOG_WARNING : LOG_NOTICE);
va_start(va, ctl);
fmt = ctl + 1;
if (level >= LogLevel) {
#if ENABLE_DEBUG_CROND_OPTION
if (DebugOpt) {
vfprintf(stderr, fmt, va);
} else
#endif
if (LogFile == 0) {
vsyslog(type, fmt, va);
} else {
#if !ENABLE_DEBUG_CROND_OPTION
int logfd = open(LogFile, O_WRONLY | O_CREAT | O_APPEND, 0600);
#else
int logfd = open3_or_warn(LogFile, O_WRONLY | O_CREAT | O_APPEND, 0600);
#endif
if (logfd >= 0) {
vdprintf(logfd, fmt, va);
close(logfd);
}
}
}
va_end(va);
if (ctl[0] & 0200) {
exit(20);
}
}
int crond_main(int ac, char **av);
int crond_main(int ac, char **av)
{
unsigned opt;
char *lopt, *Lopt, *copt;
USE_DEBUG_CROND_OPTION(char *dopt;)
opt_complementary = "f-b:b-f:S-L:L-S" USE_DEBUG_CROND_OPTION(":d-l");
opterr = 0; /* disable getopt 'errors' message. */
opt = getopt32(av, "l:L:fbSc:" USE_DEBUG_CROND_OPTION("d:"),
&lopt, &Lopt, &copt USE_DEBUG_CROND_OPTION(, &dopt));
if (opt & 1) /* -l */
LogLevel = xatou(lopt);
if (opt & 2) /* -L */
if (*Lopt)
LogFile = Lopt;
if (opt & 32) /* -c */
if (*copt)
CDir = copt;
#if ENABLE_DEBUG_CROND_OPTION
if (opt & 64) { /* -d */
DebugOpt = xatou(dopt);
LogLevel = 0;
}
#endif
/* close stdin and stdout, stderr.
* close unused descriptors - don't need.
* optional detach from controlling terminal
*/
if (!(opt & 4))
bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, av);
xchdir(CDir);
signal(SIGHUP, SIG_IGN); /* ? original crond dies on HUP... */
startlogger(); /* need if syslog mode selected */
/*
* main loop - synchronize to 1 second after the minute, minimum sleep
* of 1 second.
*/
crondlog("\011%s " BB_VER " started, log level %d\n",
applet_name, LogLevel);
SynchronizeDir();
{
time_t t1 = time(NULL);
time_t t2;
long dt;
int rescan = 60;
short sleep_time = 60;
write_pidfile("/var/run/crond.pid");
for (;;) {
sleep((sleep_time + 1) - (short) (time(NULL) % sleep_time));
t2 = time(NULL);
dt = t2 - t1;
/*
* 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 disparity. Disparities over an hour either way
* result in resynchronization. A reverse-indexed disparity
* less then 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 forward-indexed disparity less then
* 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 (--rescan == 0) {
rescan = 60;
SynchronizeDir();
}
CheckUpdates();
#if ENABLE_DEBUG_CROND_OPTION
if (DebugOpt)
crondlog("\005Wakeup dt=%d\n", dt);
#endif
if (dt < -60 * 60 || dt > 60 * 60) {
t1 = t2;
crondlog("\111time disparity of %d minutes detected\n", dt / 60);
} else if (dt > 0) {
TestJobs(t1, t2);
RunJobs();
sleep(5);
if (CheckJobs() > 0) {
sleep_time = 10;
} else {
sleep_time = 60;
}
t1 = t2;
}
}
}
return 0; /* not reached */
}
static int ChangeUser(const char *user)
{
struct passwd *pas;
const char *err_msg;
/*
* Obtain password entry and change privileges
*/
pas = getpwnam(user);
if (pas == 0) {
crondlog("\011failed to get uid for %s", user);
return -1;
}
setenv("USER", pas->pw_name, 1);
setenv("HOME", pas->pw_dir, 1);
setenv("SHELL", DEFAULT_SHELL, 1);
/*
* Change running state to the user in question
*/
err_msg = change_identity_e2str(pas);
if (err_msg) {
crondlog("\011%s for user %s", err_msg, user);
return -1;
}
if (chdir(pas->pw_dir) < 0) {
crondlog("\011chdir failed: %s: %m", pas->pw_dir);
if (chdir(TMPDIR) < 0) {
crondlog("\011chdir failed: %s: %m", TMPDIR);
return -1;
}
}
return pas->pw_uid;
}
static void startlogger(void)
{
if (LogFile == 0) {
openlog(applet_name, LOG_CONS | LOG_PID, LOG_CRON);
}
#if ENABLE_DEBUG_CROND_OPTION
else { /* test logfile */
int logfd;
logfd = open3_or_warn(LogFile, O_WRONLY | O_CREAT | O_APPEND, 0600);
if (logfd >= 0) {
close(logfd);
}
}
#endif
}
static const char DowAry[] ALIGN1 =
"sun""mon""tue""wed""thu""fri""sat"
/* "Sun""Mon""Tue""Wed""Thu""Fri""Sat" */
;
static const char MonAry[] ALIGN1 =
"jan""feb""mar""apr""may""jun""jul""aug""sep""oct""nov""dec"
/* "Jan""Feb""Mar""Apr""May""Jun""Jul""Aug""Sep""Oct""Nov""Dec" */
;
static char *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;
if (base == NULL) {
return NULL;
}
while (*ptr != ' ' && *ptr != '\t' && *ptr != '\n') {
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 (*ptr >= '0' && *ptr <= '9') {
if (n1 < 0) {
n1 = strtol(ptr, &ptr, 10) + off;
} else {
n2 = strtol(ptr, &ptr, 10) + off;
}
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) {
crondlog("\111failed user %s parsing %s\n", user, base);
return NULL;
}
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 == '/') {
skip = strtol(ptr + 1, &ptr, 10);
}
/*
* 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;
}
}
while (n1 != n2 && --failsafe);
if (failsafe == 0) {
crondlog("\111failed user %s parsing %s\n", user, base);
return NULL;
}
}
if (*ptr != ',') {
break;
}
++ptr;
n1 = -1;
n2 = -1;
}
if (*ptr != ' ' && *ptr != '\t' && *ptr != '\n') {
crondlog("\111failed user %s parsing %s\n", user, base);
return NULL;
}
while (*ptr == ' ' || *ptr == '\t' || *ptr == '\n') {
++ptr;
}
#if ENABLE_DEBUG_CROND_OPTION
if (DebugOpt) {
int i;
for (i = 0; i < modvalue; ++i) {
crondlog("\005%d", ary[i]);
}
crondlog("\005\n");
}
#endif
return ptr;
}
static void FixDayDow(CronLine * line)
{
int i;
int weekUsed = 0;
int daysUsed = 0;
for (i = 0; i < (int)(ARRAY_SIZE(line->cl_Dow)); ++i) {
if (line->cl_Dow[i] == 0) {
weekUsed = 1;
break;
}
}
for (i = 0; i < (int)(ARRAY_SIZE(line->cl_Days)); ++i) {
if (line->cl_Days[i] == 0) {
daysUsed = 1;
break;
}
}
if (weekUsed && !daysUsed) {
memset(line->cl_Days, 0, sizeof(line->cl_Days));
}
if (daysUsed && !weekUsed) {
memset(line->cl_Dow, 0, sizeof(line->cl_Dow));
}
}
static void SynchronizeFile(const char *fileName)
{
int maxEntries = MAXLINES;
int maxLines;
char buf[1024];
if (strcmp(fileName, "root") == 0) {
maxEntries = 65535;
}
maxLines = maxEntries * 10;
if (fileName) {
FILE *fi;
DeleteFile(fileName);
fi = fopen(fileName, "r");
if (fi != NULL) {
struct stat sbuf;
if (fstat(fileno(fi), &sbuf) == 0 && sbuf.st_uid == DaemonUid) {
CronFile *file = xzalloc(sizeof(CronFile));
CronLine **pline;
file->cf_User = strdup(fileName);
pline = &file->cf_LineBase;
while (fgets(buf, sizeof(buf), fi) != NULL && --maxLines) {
CronLine line;
char *ptr;
trim(buf);
if (buf[0] == 0 || buf[0] == '#') {
continue;
}
if (--maxEntries == 0) {
break;
}
memset(&line, 0, sizeof(line));
#if ENABLE_DEBUG_CROND_OPTION
if (DebugOpt) {
crondlog("\111User %s Entry %s\n", fileName, buf);
}
#endif
/* parse date ranges */
ptr = ParseField(file->cf_User, line.cl_Mins, 60, 0, NULL, buf);
ptr = ParseField(file->cf_User, line.cl_Hrs, 24, 0, NULL, ptr);
ptr = ParseField(file->cf_User, line.cl_Days, 32, 0, NULL, ptr);
ptr = ParseField(file->cf_User, line.cl_Mons, 12, -1, MonAry, ptr);
ptr = ParseField(file->cf_User, line.cl_Dow, 7, 0, DowAry, ptr);
/* check failure */
if (ptr == NULL) {
continue;
}
/*
* fix days and dow - if one is not * and the other
* is *, the other is set to 0, and vise-versa
*/
FixDayDow(&line);
*pline = xzalloc(sizeof(CronLine));
**pline = line;
/* copy command */
(*pline)->cl_Shell = strdup(ptr);
#if ENABLE_DEBUG_CROND_OPTION
if (DebugOpt) {
crondlog("\111 Command %s\n", ptr);
}
#endif
pline = &((*pline)->cl_Next);
}
*pline = NULL;
file->cf_Next = FileBase;
FileBase = file;
if (maxLines == 0 || maxEntries == 0) {
crondlog("\111Maximum number of lines reached for user %s\n", fileName);
}
}
fclose(fi);
}
}
}
static void CheckUpdates(void)
{
FILE *fi;
char buf[256];
fi = fopen(CRONUPDATE, "r");
if (fi != NULL) {
remove(CRONUPDATE);
while (fgets(buf, sizeof(buf), fi) != NULL) {
SynchronizeFile(strtok(buf, " \t\r\n"));
}
fclose(fi);
}
}
static void SynchronizeDir(void)
{
/* Attempt to delete the database. */
for (;;) {
CronFile *file;
for (file = FileBase; file && file->cf_Deleted; file = file->cf_Next);
if (file == NULL) {
break;
}
DeleteFile(file->cf_User);
}
/*
* Remove cron update file
*
* Re-chdir, in case directory was renamed & deleted, or otherwise
* screwed up.
*
* scan directory and add associated users
*/
remove(CRONUPDATE);
if (chdir(CDir) < 0) {
crondlog("\311cannot find %s\n", CDir);
}
{
DIR *dir = opendir(".");
struct dirent *den;
if (dir) {
while ((den = readdir(dir))) {
if (strchr(den->d_name, '.') != NULL) {
continue;
}
if (getpwnam(den->d_name)) {
SynchronizeFile(den->d_name);
} else {
crondlog("\007ignoring %s\n", den->d_name);
}
}
closedir(dir);
} else {
crondlog("\311cannot open current dir!\n");
}
}
}
/*
* DeleteFile() - delete user database
*
* Note: multiple entries for same user may exist if we were unable to
* completely delete a database due to running processes.
*/
static void DeleteFile(const char *userName)
{
CronFile **pfile = &FileBase;
CronFile *file;
while ((file = *pfile) != NULL) {
if (strcmp(userName, file->cf_User) == 0) {
CronLine **pline = &file->cf_LineBase;
CronLine *line;
file->cf_Running = 0;
file->cf_Deleted = 1;
while ((line = *pline) != NULL) {
if (line->cl_Pid > 0) {
file->cf_Running = 1;
pline = &line->cl_Next;
} else {
*pline = line->cl_Next;
free(line->cl_Shell);
free(line);
}
}
if (file->cf_Running == 0) {
*pfile = file->cf_Next;
free(file->cf_User);
free(file);
} else {
pfile = &file->cf_Next;
}
} else {
pfile = &file->cf_Next;
}
}
}
/*
* TestJobs()
*
* 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 int TestJobs(time_t t1, time_t t2)
{
int nJobs = 0;
time_t t;
/* Find jobs > t1 and <= t2 */
for (t = t1 - t1 % 60; t <= t2; t += 60) {
if (t > t1) {
struct tm *tp = localtime(&t);
CronFile *file;
CronLine *line;
for (file = FileBase; file; file = file->cf_Next) {
#if ENABLE_DEBUG_CROND_OPTION
if (DebugOpt)
crondlog("\005FILE %s:\n", file->cf_User);
#endif
if (file->cf_Deleted)
continue;
for (line = file->cf_LineBase; line; line = line->cl_Next) {
#if ENABLE_DEBUG_CROND_OPTION
if (DebugOpt)
crondlog("\005 LINE %s\n", line->cl_Shell);
#endif
if (line->cl_Mins[tp->tm_min] && line->cl_Hrs[tp->tm_hour] &&
(line->cl_Days[tp->tm_mday] || line->cl_Dow[tp->tm_wday])
&& line->cl_Mons[tp->tm_mon]) {
#if ENABLE_DEBUG_CROND_OPTION
if (DebugOpt) {
crondlog("\005 JobToDo: %d %s\n",
line->cl_Pid, line->cl_Shell);
}
#endif
if (line->cl_Pid > 0) {
crondlog("\010 process already running: %s %s\n",
file->cf_User, line->cl_Shell);
} else if (line->cl_Pid == 0) {
line->cl_Pid = -1;
file->cf_Ready = 1;
++nJobs;
}
}
}
}
}
}
return nJobs;
}
static void RunJobs(void)
{
CronFile *file;
CronLine *line;
for (file = FileBase; file; file = file->cf_Next) {
if (file->cf_Ready) {
file->cf_Ready = 0;
for (line = file->cf_LineBase; line; line = line->cl_Next) {
if (line->cl_Pid < 0) {
RunJob(file->cf_User, line);
crondlog("\010USER %s pid %3d cmd %s\n",
file->cf_User, line->cl_Pid, line->cl_Shell);
if (line->cl_Pid < 0) {
file->cf_Ready = 1;
}
else if (line->cl_Pid > 0) {
file->cf_Running = 1;
}
}
}
}
}
}
/*
* CheckJobs() - check for job completion
*
* Check for job completion, return number of jobs still running after
* all done.
*/
static int CheckJobs(void)
{
CronFile *file;
CronLine *line;
int nStillRunning = 0;
for (file = FileBase; file; file = file->cf_Next) {
if (file->cf_Running) {
file->cf_Running = 0;
for (line = file->cf_LineBase; line; line = line->cl_Next) {
if (line->cl_Pid > 0) {
int status;
int r = wait4(line->cl_Pid, &status, WNOHANG, NULL);
if (r < 0 || r == line->cl_Pid) {
EndJob(file->cf_User, line);
if (line->cl_Pid) {
file->cf_Running = 1;
}
} else if (r == 0) {
file->cf_Running = 1;
}
}
}
}
nStillRunning += file->cf_Running;
}
return nStillRunning;
}
#if ENABLE_FEATURE_CROND_CALL_SENDMAIL
static void
ForkJob(const char *user, CronLine * line, int mailFd,
const char *prog, const char *cmd, const char *arg, const char *mailf)
{
/* Fork as the user in question and run program */
pid_t pid = fork();
line->cl_Pid = pid;
if (pid == 0) {
/* CHILD */
/* Change running state to the user in question */
if (ChangeUser(user) < 0) {
exit(0);
}
#if ENABLE_DEBUG_CROND_OPTION
if (DebugOpt) {
crondlog("\005Child Running %s\n", prog);
}
#endif
if (mailFd >= 0) {
dup2(mailFd, mailf != NULL);
dup2((mailf ? mailFd : 1), 2);
close(mailFd);
}
execl(prog, prog, cmd, arg, NULL);
crondlog("\024cannot exec, user %s cmd %s %s %s\n", user, prog, cmd, arg);
if (mailf) {
fdprintf(1, "Exec failed: %s -c %s\n", prog, arg);
}
exit(0);
} else if (pid < 0) {
/* FORK FAILED */
crondlog("\024cannot fork, user %s\n", user);
line->cl_Pid = 0;
if (mailf) {
remove(mailf);
}
} else if (mailf) {
/* PARENT, FORK SUCCESS
* rename mail-file based on pid of process
*/
char mailFile2[128];
snprintf(mailFile2, sizeof(mailFile2), TMPDIR "/cron.%s.%d", user, pid);
rename(mailf, mailFile2);
}
/*
* 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);
}
}
static void RunJob(const char *user, CronLine * line)
{
char mailFile[128];
int mailFd;
line->cl_Pid = 0;
line->cl_MailFlag = 0;
/* open mail file - owner root so nobody can screw with it. */
snprintf(mailFile, sizeof(mailFile), TMPDIR "/cron.%s.%d", user, getpid());
mailFd = open(mailFile, O_CREAT | O_TRUNC | O_WRONLY | O_EXCL | O_APPEND, 0600);
if (mailFd >= 0) {
line->cl_MailFlag = 1;
fdprintf(mailFd, "To: %s\nSubject: cron: %s\n\n", user,
line->cl_Shell);
line->cl_MailPos = lseek(mailFd, 0, SEEK_CUR);
} else {
crondlog("\024cannot create mail file user %s file %s, output to /dev/null\n", user, mailFile);
}
ForkJob(user, line, mailFd, DEFAULT_SHELL, "-c", line->cl_Shell, mailFile);
}
/*
* EndJob - called when job terminates and when mail terminates
*/
static void EndJob(const char *user, CronLine * line)
{
int mailFd;
char mailFile[128];
struct stat sbuf;
/* No job */
if (line->cl_Pid <= 0) {
line->cl_Pid = 0;
return;
}
/*
* End of job and no mail file
* End of sendmail job
*/
snprintf(mailFile, sizeof(mailFile), TMPDIR "/cron.%s.%d", user, line->cl_Pid);
line->cl_Pid = 0;
if (line->cl_MailFlag != 1) {
return;
}
line->cl_MailFlag = 0;
/*
* End of primary job - check for mail file. If size has increased and
* the file is still valid, we sendmail it.
*/
mailFd = open(mailFile, O_RDONLY);
remove(mailFile);
if (mailFd < 0) {
return;
}
if (fstat(mailFd, &sbuf) < 0 || sbuf.st_uid != DaemonUid
|| sbuf.st_nlink != 0 || sbuf.st_size == line->cl_MailPos
|| !S_ISREG(sbuf.st_mode)
) {
close(mailFd);
return;
}
ForkJob(user, line, mailFd, SENDMAIL, SENDMAIL_ARGS, NULL);
}
#else
/* crond without sendmail */
static void RunJob(const char *user, CronLine * line)
{
/* Fork as the user in question and run program */
pid_t pid = fork();
if (pid == 0) {
/* CHILD */
/* Change running state to the user in question */
if (ChangeUser(user) < 0) {
exit(0);
}
#if ENABLE_DEBUG_CROND_OPTION
if (DebugOpt) {
crondlog("\005Child Running %s\n", DEFAULT_SHELL);
}
#endif
execl(DEFAULT_SHELL, DEFAULT_SHELL, "-c", line->cl_Shell, NULL);
crondlog("\024cannot exec, user %s cmd %s -c %s\n", user,
DEFAULT_SHELL, line->cl_Shell);
exit(0);
} else if (pid < 0) {
/* FORK FAILED */
crondlog("\024cannot, user %s\n", user);
pid = 0;
}
line->cl_Pid = pid;
}
#endif /* ENABLE_FEATURE_CROND_CALL_SENDMAIL */
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