X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=miscutils%2Fcrond.c;h=88e7b47b3ff13c43001bdd98e31836e7d1cbc4b9;hb=52a515d18724bbb34e3ccbbb0218efcc4eccc0a8;hp=804fe0b292f0f1bf21eaad16048ce75da27fa844;hpb=551ffdccea39a9223ad451954db40fd7a6e20e79;p=oweals%2Fbusybox.git

diff --git a/miscutils/crond.c b/miscutils/crond.c
index 804fe0b29..88e7b47b3 100644
--- a/miscutils/crond.c
+++ b/miscutils/crond.c
@@ -1,72 +1,121 @@
 /* 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.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
+//config:config CROND
+//config:	bool "crond"
+//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 option -d to 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_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>
 
 /* glibc frees previous setenv'ed value when we do next setenv()
  * of the same variable. uclibc does not do this! */
 #if (defined(__GLIBC__) && !defined(__UCLIBC__)) /* || OTHER_SAFE_LIBC... */
-#define SETENV_LEAKS 0
+# define SETENV_LEAKS 0
 #else
-#define SETENV_LEAKS 1
+# define SETENV_LEAKS 1
 #endif
 
 
-#define TMPDIR          CONFIG_FEATURE_CROND_DIR
+#define CRON_DIR        CONFIG_FEATURE_CROND_DIR
 #define CRONTABS        CONFIG_FEATURE_CROND_DIR "/crontabs"
 #ifndef SENDMAIL
-#define SENDMAIL        "sendmail"
+# define SENDMAIL       "sendmail"
 #endif
 #ifndef SENDMAIL_ARGS
-#define SENDMAIL_ARGS   "-ti", "oem"
+# define SENDMAIL_ARGS  "-ti"
 #endif
 #ifndef CRONUPDATE
-#define CRONUPDATE      "cron.update"
+# define CRONUPDATE     "cron.update"
 #endif
 #ifndef MAXLINES
-#define MAXLINES        256	/* max lines in non-root crontabs */
+# 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                     */
-	smallint cf_Ready;              /* bool: one or more jobs ready */
-	smallint cf_Running;            /* bool: one or more jobs running */
-	smallint cf_Deleted;            /* marked for deletion, ignore  */
+	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_Shell;         /* shell command                        */
-	pid_t cl_Pid;           /* running pid, 0, or armed (-1)        */
+	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 */
 #if ENABLE_FEATURE_CROND_CALL_SENDMAIL
-	int cl_MailPos;         /* 'empty file' size                    */
-	smallint cl_MailFlag;   /* running pid is for mail              */
-	char *cl_MailTo;	/* whom to mail results                 */
+	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                                 */
+	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 DaemonUid 0
+#define DAEMON_UID 0
 
 
 enum {
@@ -78,224 +127,77 @@ enum {
 	OPT_c = (1 << 5),
 	OPT_d = (1 << 6) * ENABLE_FEATURE_CROND_D,
 };
-#if ENABLE_FEATURE_CROND_D
-#define DebugOpt (option_mask32 & OPT_d)
-#else
-#define DebugOpt 0
-#endif
-
 
 struct globals {
-	unsigned LogLevel; /* = 8; */
-	const char *LogFile;
-	const char *CDir; /* = CRONTABS; */
-	CronFile *FileBase;
+	unsigned log_level; /* = 8; */
+	time_t crontab_dir_mtime;
+	const char *log_filename;
+	const char *crontab_dir_name; /* = CRONTABS; */
+	CronFile *cron_files;
 #if SETENV_LEAKS
 	char *env_var_user;
 	char *env_var_home;
+	char *env_var_shell;
+	char *env_var_logname;
 #endif
-};
-#define G (*(struct globals*)&bb_common_bufsiz1)
-#define LogLevel           (G.LogLevel               )
-#define LogFile            (G.LogFile                )
-#define CDir               (G.CDir                   )
-#define FileBase           (G.FileBase               )
-#define env_var_user       (G.env_var_user           )
-#define env_var_home       (G.env_var_home           )
+} FIX_ALIASING;
+#define G (*(struct globals*)bb_common_bufsiz1)
 #define INIT_G() do { \
-	LogLevel = 8; \
-	CDir = CRONTABS; \
+	setup_common_bufsiz(); \
+	G.log_level = 8; \
+	G.crontab_dir_name = CRONTABS; \
 } while (0)
 
-
-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);
-
-
-#define LVL5  "\x05"
-#define LVL7  "\x07"
-#define LVL8  "\x08"
-#define LVL9  "\x09"
-#define WARN9 "\x49"
-#define DIE9  "\xc9"
-/* level >= 20 is "error" */
-#define ERR20 "\x14"
-
-static void crondlog(const char *ctl, ...)
+/* 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)
 {
-	va_list va;
-	int level = (ctl[0] & 0x1f);
-
-	va_start(va, ctl);
-	if (level >= (int)LogLevel) {
-		/* Debug mode: all to (non-redirected) stderr, */
-		/* Syslog mode: all to syslog (logmode = LOGMODE_SYSLOG), */
-		if (!DebugOpt && LogFile) {
-			/* Otherwise (log to file): we reopen log file at every write: */
-			int logfd = open3_or_warn(LogFile, O_WRONLY | O_CREAT | O_APPEND, 0666);
-			if (logfd >= 0)
-				xmove_fd(logfd, STDERR_FILENO);
-		}
-// TODO: ERR -> error, WARN -> warning, LVL -> info
-		bb_verror_msg(ctl + 1, va, /* strerr: */ NULL);
+	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).
+		 */
+		syslog_level = LOG_INFO;
+		bb_verror_msg(msg, va, /* strerr: */ NULL);
+		syslog_level = LOG_ERR;
 	}
-	va_end(va);
-	if (ctl[0] & 0x80)
-		exit(20);
 }
 
-int crond_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int crond_main(int argc UNUSED_PARAM, char **argv)
+static void log5(const char *msg, ...)
 {
-	unsigned opt;
-
-	INIT_G();
-
-	/* "-b after -f is ignored", and so on for every pair a-b */
-	opt_complementary = "f-b:b-f:S-L:L-S" USE_FEATURE_CROND_D(":d-l")
-			":l+:d+"; /* -l and -d have numeric param */
-	opt = getopt32(argv, "l:L:fbSc:" USE_FEATURE_CROND_D("d:"),
-			&LogLevel, &LogFile, &CDir
-			USE_FEATURE_CROND_D(,&LogLevel));
-	/* both -d N and -l N set the same variable: LogLevel */
-
-	if (!(opt & OPT_f)) {
-		/* close stdin, stdout, stderr.
-		 * close unused descriptors - don't need them. */
-		bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv);
-	}
-
-	if (!DebugOpt && LogFile == NULL) {
-		/* logging to syslog */
-		openlog(applet_name, LOG_CONS | LOG_PID, LOG_CRON);
-		logmode = LOGMODE_SYSLOG;
-	}
-
-	xchdir(CDir);
-	//signal(SIGHUP, SIG_IGN); /* ? original crond dies on HUP... */
-	xsetenv("SHELL", DEFAULT_SHELL); /* once, for all future children */
-	crondlog(LVL9 "crond (busybox "BB_VER") started, log level %d", LogLevel);
-	SynchronizeDir();
-
-	/* main loop - synchronize to 1 second after the minute, minimum sleep
-	 * of 1 second. */
-	{
-		time_t t1 = time(NULL);
-		time_t t2;
-		long dt;
-		int rescan = 60;
-		int sleep_time = 60;
-
-		write_pidfile("/var/run/crond.pid");
-		for (;;) {
-			sleep((sleep_time + 1) - (time(NULL) % sleep_time));
-
-			t2 = time(NULL);
-			dt = (long)t2 - (long)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 (DebugOpt)
-				crondlog(LVL5 "wakeup dt=%ld", dt);
-			if (dt < -60 * 60 || dt > 60 * 60) {
-				crondlog(WARN9 "time disparity of %d minutes detected", 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 */
+	va_list va;
+	va_start(va, msg);
+	crondlog(4, msg, va);
+	va_end(va);
 }
 
-#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)
+static void log7(const char *msg, ...)
 {
-	char *var_val = *pvar_val;
-
-	if (var_val) {
-		bb_unsetenv(var_val);
-		free(var_val);
-	}
-	*pvar_val = xasprintf("%s=%s", var, val);
-	putenv(*pvar_val);
+	va_list va;
+	va_start(va, msg);
+	crondlog(7, msg, va);
+	va_end(va);
 }
-#endif
 
-static void SetEnv(struct passwd *pas)
+static void log8(const char *msg, ...)
 {
-#if SETENV_LEAKS
-	safe_setenv(&env_var_user, "USER", pas->pw_name);
-	safe_setenv(&env_var_home, "HOME", pas->pw_dir);
-	/* if we want to set user's shell instead: */
-	/*safe_setenv(env_var_user, "SHELL", pas->pw_shell);*/
-#else
-	xsetenv("USER", pas->pw_name);
-	xsetenv("HOME", pas->pw_dir);
-#endif
-	/* currently, we use constant one: */
-	/*setenv("SHELL", DEFAULT_SHELL, 1); - done earlier */
+	va_list va;
+	va_start(va, msg);
+	crondlog(8, msg, va);
+	va_end(va);
 }
 
-static void ChangeUser(struct passwd *pas)
-{
-	/* careful: we're after vfork! */
-	change_identity(pas); /* - initgroups, setgid, setuid */
-	if (chdir(pas->pw_dir) < 0) {
-		crondlog(LVL9 "can't chdir(%s)", pas->pw_dir);
-		if (chdir(TMPDIR) < 0) {
-			crondlog(DIE9 "can't chdir(%s)", TMPDIR); /* exits */
-		}
-	}
-}
 
 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 void ParseField(char *user, char *ary, int modvalue, int off,
@@ -315,16 +217,18 @@ static void ParseField(char *user, char *ary, int modvalue, int off,
 
 		/* Handle numeric digit or symbol or '*' */
 		if (*ptr == '*') {
-			n1 = 0;		/* everything will be filled */
+			n1 = 0;  /* everything will be filled */
 			n2 = modvalue - 1;
 			skip = 1;
 			++ptr;
 		} else if (isdigit(*ptr)) {
+			char *endp;
 			if (n1 < 0) {
-				n1 = strtol(ptr, &ptr, 10) + off;
+				n1 = strtol(ptr, &endp, 10) + off;
 			} else {
-				n2 = strtol(ptr, &ptr, 10) + off;
+				n2 = strtol(ptr, &endp, 10) + off;
 			}
+			ptr = endp; /* gcc likes temp var for &endp */
 			skip = 1;
 		} else if (names) {
 			int i;
@@ -361,7 +265,9 @@ static void ParseField(char *user, char *ary, int modvalue, int off,
 			n2 = n1;
 		}
 		if (*ptr == '/') {
-			skip = strtol(ptr + 1, &ptr, 10);
+			char *endp;
+			skip = strtol(ptr + 1, &endp, 10);
+			ptr = endp; /* gcc likes temp var for &endp */
 		}
 
 		/*
@@ -384,7 +290,6 @@ static void ParseField(char *user, char *ary, int modvalue, int off,
 					goto err;
 				}
 			} while (n1 != n2);
-
 		}
 		if (*ptr != ',') {
 			break;
@@ -396,16 +301,16 @@ static void ParseField(char *user, char *ary, int modvalue, int off,
 
 	if (*ptr) {
  err:
-		crondlog(WARN9 "user %s: parse error at %s", user, base);
+		bb_error_msg("user %s: parse error at %s", user, base);
 		return;
 	}
 
-	if (DebugOpt && (LogLevel <= 5)) { /* like LVL5 */
-		/* can't use crondlog, it inserts '\n' */
+	/* 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]);
-		fputc('\n', stderr);
+		bb_putchar_stderr('\n');
 	}
 }
 
@@ -435,7 +340,60 @@ static void FixDayDow(CronLine *line)
 	}
 }
 
-static void SynchronizeFile(const char *fileName)
+/*
+ * 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;
@@ -444,55 +402,79 @@ static void SynchronizeFile(const char *fileName)
 #if ENABLE_FEATURE_CROND_CALL_SENDMAIL
 	char *mailTo = NULL;
 #endif
+	char *shell = NULL;
 
-	if (!fileName)
+	delete_cronfile(fileName);
+
+	if (!getpwnam(fileName)) {
+		log7("ignoring file '%s' (no such user)", fileName);
 		return;
+	}
 
-	DeleteFile(fileName);
 	parser = config_open(fileName);
 	if (!parser)
 		return;
 
 	maxLines = (strcmp(fileName, "root") == 0) ? 65535 : MAXLINES;
 
-	if (fstat(fileno(parser->fp), &sbuf) == 0 && sbuf.st_uid == DaemonUid) {
+	if (fstat(fileno(parser->fp), &sbuf) == 0 && sbuf.st_uid == DAEMON_UID) {
 		CronFile *file = xzalloc(sizeof(CronFile));
 		CronLine **pline;
 		int n;
 
-		file->cf_User = xstrdup(fileName);
-		pline = &file->cf_LineBase;
+		file->cf_username = xstrdup(fileName);
+		pline = &file->cf_lines;
 
 		while (1) {
 			CronLine *line;
 
-			if (!--maxLines)
+			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;
 
-			if (DebugOpt)
-				crondlog(LVL5 "user:%s entry:%s", fileName, parser->data);
+			log5("user:%s entry:%s", fileName, parser->data);
 
 			/* check if line is setting MAILTO= */
-			if (0 == strncmp(tokens[0], "MAILTO=", 7)) {
+			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.
+
 			/* check if a minimum of tokens is specified */
 			if (n < 6)
 				continue;
 			*pline = line = xzalloc(sizeof(*line));
 			/* parse date ranges */
-			ParseField(file->cf_User, line->cl_Mins, 60, 0, NULL, tokens[0]);
-			ParseField(file->cf_User, line->cl_Hrs, 24, 0, NULL, tokens[1]);
-			ParseField(file->cf_User, line->cl_Days, 32, 0, NULL, tokens[2]);
-			ParseField(file->cf_User, line->cl_Mons, 12, -1, MonAry, tokens[3]);
-			ParseField(file->cf_User, line->cl_Dow, 7, 0, DowAry, tokens[4]);
+			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
@@ -500,29 +482,27 @@ static void SynchronizeFile(const char *fileName)
 			FixDayDow(line);
 #if ENABLE_FEATURE_CROND_CALL_SENDMAIL
 			/* copy mailto (can be NULL) */
-			line->cl_MailTo = xstrdup(mailTo);
+			line->cl_mailto = xstrdup(mailTo);
 #endif
+			line->cl_shell = xstrdup(shell);
 			/* copy command */
-			line->cl_Shell = xstrdup(tokens[5]);
-			if (DebugOpt) {
-				crondlog(LVL5 " command:%s", tokens[5]);
-			}
-			pline = &line->cl_Next;
+			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 = FileBase;
-		FileBase = file;
-
-		if (maxLines == 0) {
-			crondlog(WARN9 "user %s: too many lines", fileName);
-		}
+		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 CheckUpdates(void)
+static void process_cron_update_file(void)
 {
 	FILE *fi;
 	char buf[256];
@@ -532,275 +512,147 @@ static void CheckUpdates(void)
 		unlink(CRONUPDATE);
 		while (fgets(buf, sizeof(buf), fi) != NULL) {
 			/* use first word only */
-			SynchronizeFile(strtok(buf, " \t\r\n"));
+			skip_non_whitespace(buf)[0] = '\0';
+			load_crontab(buf);
 		}
 		fclose(fi);
 	}
 }
 
-static void SynchronizeDir(void)
+static void rescan_crontab_dir(void)
 {
 	CronFile *file;
-	/* Attempt to delete the database. */
+
+	/* Delete all files until we only have ones with running jobs (or none) */
  again:
-	for (file = FileBase; file; file = file->cf_Next) {
-		if (!file->cf_Deleted) {
-			DeleteFile(file->cf_User);
+	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
-	 *
-	 * Re-chdir, in case directory was renamed & deleted, or otherwise
-	 * screwed up.
-	 *
-	 * scan directory and add associated users
-	 */
+	/* Remove cron update file */
 	unlink(CRONUPDATE);
-	if (chdir(CDir) < 0) {
-		crondlog(DIE9 "can't chdir(%s)", CDir);
-	}
+	/* 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)
-			crondlog(DIE9 "can't chdir(%s)", "."); /* exits */
+			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;
 			}
-			if (getpwnam(den->d_name)) {
-				SynchronizeFile(den->d_name);
-			} else {
-				crondlog(LVL7 "ignoring %s", den->d_name);
-			}
+			load_crontab(den->d_name);
 		}
 		closedir(dir);
 	}
 }
 
-/*
- *  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)
+#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)
 {
-	int nJobs = 0;
-	time_t t;
-
-	/* Find jobs > t1 and <= t2 */
-
-	for (t = t1 - t1 % 60; t <= t2; t += 60) {
-		struct tm *tp;
-		CronFile *file;
-		CronLine *line;
-
-		if (t <= t1)
-			continue;
+	char *var_val = *pvar_val;
 
-		tp = localtime(&t);
-		for (file = FileBase; file; file = file->cf_Next) {
-			if (DebugOpt)
-				crondlog(LVL5 "file %s:", file->cf_User);
-			if (file->cf_Deleted)
-				continue;
-			for (line = file->cf_LineBase; line; line = line->cl_Next) {
-				if (DebugOpt)
-					crondlog(LVL5 " line %s", line->cl_Shell);
-				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 (DebugOpt) {
-						crondlog(LVL5 " job: %d %s",
-							(int)line->cl_Pid, line->cl_Shell);
-					}
-					if (line->cl_Pid > 0) {
-						crondlog(LVL8 "user %s: process already running: %s",
-							file->cf_User, line->cl_Shell);
-					} else if (line->cl_Pid == 0) {
-						line->cl_Pid = -1;
-						file->cf_Ready = 1;
-						++nJobs;
-					}
-				}
-			}
-		}
+	if (var_val) {
+		bb_unsetenv_and_free(var_val);
 	}
-	return nJobs;
+	*pvar_val = xasprintf("%s=%s", var, val);
+	putenv(*pvar_val);
 }
+#endif
 
-static void RunJobs(void)
+static void set_env_vars(struct passwd *pas, const char *shell)
 {
-	CronFile *file;
-	CronLine *line;
-
-	for (file = FileBase; file; file = file->cf_Next) {
-		if (!file->cf_Ready)
-			continue;
-
-		file->cf_Ready = 0;
-		for (line = file->cf_LineBase; line; line = line->cl_Next) {
-			if (line->cl_Pid >= 0)
-				continue;
-
-			RunJob(file->cf_User, line);
-			crondlog(LVL8 "USER %s pid %3d cmd %s",
-				file->cf_User, (int)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;
-			}
-		}
-	}
+	/* 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
 }
 
-/*
- * CheckJobs() - check for job completion
- *
- * Check for job completion, return number of jobs still running after
- * all done.
- */
-static int CheckJobs(void)
+static void change_user(struct passwd *pas)
 {
-	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) {
-				int status, r;
-				if (line->cl_Pid <= 0)
-					continue;
-
-				r = waitpid(line->cl_Pid, &status, WNOHANG);
-				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;
+	/* 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);
 	}
-	return nStillRunning;
 }
 
-#if ENABLE_FEATURE_CROND_CALL_SENDMAIL
-
 // TODO: sendmail should be _run-time_ option, not compile-time!
+#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 *mail_filename)
+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) {
-		crondlog(LVL9 "can't get uid for %s", user);
+		bb_error_msg("can't get uid for %s", user);
 		goto err;
 	}
-	SetEnv(pas);
 
+	shell = line->cl_shell ? line->cl_shell : DEFAULT_SHELL;
+	prog = run_sendmail ? SENDMAIL : shell;
+
+	set_env_vars(pas, shell);
+
+	sv_logmode = logmode;
 	pid = vfork();
 	if (pid == 0) {
 		/* CHILD */
-		/* change running state to the user in question */
-		ChangeUser(pas);
-		if (DebugOpt) {
-			crondlog(LVL5 "child running %s", prog);
-		}
+		/* initgroups, setgid, setuid, and chdir to home or CRON_DIR */
+		change_user(pas);
+		log5("child running %s", prog);
 		if (mailFd >= 0) {
-			xmove_fd(mailFd, mail_filename ? 1 : 0);
+			xmove_fd(mailFd, run_sendmail ? 0 : 1);
 			dup2(1, 2);
 		}
 		/* crond 3.0pl1-100 puts tasks in separate process groups */
 		bb_setpgrp();
-		execlp(prog, prog, cmd, arg, (char *) NULL);
-		crondlog(ERR20 "can't exec, user %s cmd %s %s %s", user, prog, cmd, arg);
-		if (mail_filename) {
-			fdprintf(1, "Exec failed: %s -c %s\n", prog, arg);
-		}
-		_exit(EXIT_SUCCESS);
+		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;
 
-	line->cl_Pid = pid;
 	if (pid < 0) {
-		/* FORK FAILED */
-		crondlog(ERR20 "can't vfork");
+		bb_perror_msg("vfork");
  err:
-		line->cl_Pid = 0;
-		if (mail_filename) {
-			unlink(mail_filename);
-		}
-	} else if (mail_filename) {
-		/* PARENT, FORK SUCCESS
-		 * rename mail-file based on pid of process
-		 */
-		char mailFile2[128];
-
-		snprintf(mailFile2, sizeof(mailFile2), "%s/cron.%s.%d", TMPDIR, user, pid);
-		rename(mail_filename, mailFile2); // TODO: xrename?
-	}
+		pid = 0;
+	} /* else: PARENT, FORK SUCCESS */
 
 	/*
 	 * Close the mail file descriptor.. we can't just leave it open in
@@ -809,121 +661,356 @@ ForkJob(const char *user, CronLine *line, int mailFd,
 	if (mailFd >= 0) {
 		close(mailFd);
 	}
+	return pid;
 }
 
-static void RunJob(const char *user, CronLine *line)
+static void start_one_job(const char *user, CronLine *line)
 {
 	char mailFile[128];
 	int mailFd = -1;
 
-	line->cl_Pid = 0;
-	line->cl_MailFlag = 0;
+	line->cl_pid = 0;
+	line->cl_empty_mail_size = 0;
 
-	if (line->cl_MailTo) {
-		/* open mail file - owner root so nobody can screw with it. */
-		snprintf(mailFile, sizeof(mailFile), "%s/cron.%s.%d", TMPDIR, user, getpid());
+	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) {
-			line->cl_MailFlag = 1;
-			fdprintf(mailFd, "To: %s\nSubject: cron: %s\n\n", line->cl_MailTo,
-				line->cl_Shell);
-			line->cl_MailPos = lseek(mailFd, 0, SEEK_CUR);
+			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 {
-			crondlog(ERR20 "cannot create mail file %s for user %s, "
+			bb_error_msg("can't create mail file %s for user %s, "
 					"discarding output", mailFile, user);
 		}
 	}
 
-	ForkJob(user, line, mailFd, DEFAULT_SHELL, "-c", line->cl_Shell, mailFile);
+	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);
+		}
+	}
 }
 
 /*
- * EndJob - called when job terminates and when mail terminates
+ * process_finished_job - called when job terminates and when mail terminates
  */
-static void EndJob(const char *user, CronLine *line)
+static void process_finished_job(const char *user, CronLine *line)
 {
+	pid_t pid;
 	int mailFd;
 	char mailFile[128];
 	struct stat sbuf;
 
-	/* No job */
-	if (line->cl_Pid <= 0) {
-		line->cl_Pid = 0;
+	pid = line->cl_pid;
+	line->cl_pid = 0;
+	if (pid <= 0) {
+		/* No job */
 		return;
 	}
-
-	/*
-	 * End of job and no mail file
-	 * End of sendmail job
-	 */
-	snprintf(mailFile, sizeof(mailFile), "%s/cron.%s.%d", TMPDIR, user, line->cl_Pid);
-	line->cl_Pid = 0;
-
-	if (line->cl_MailFlag == 0) {
+	if (line->cl_empty_mail_size <= 0) {
+		/* End of job and no mail file, or end of sendmail job */
 		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.
+	 * 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 != DaemonUid
-	 || sbuf.st_nlink != 0 || sbuf.st_size == line->cl_MailPos
+	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;
 	}
-	if (line->cl_MailTo)
-		ForkJob(user, line, mailFd, SENDMAIL, SENDMAIL_ARGS, NULL);
+	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 /* crond without sendmail */
+#else /* !ENABLE_FEATURE_CROND_CALL_SENDMAIL */
 
-static void RunJob(const char *user, CronLine *line)
+static void start_one_job(const char *user, CronLine *line)
 {
+	const char *shell;
 	struct passwd *pas;
 	pid_t pid;
 
-	/* prepare things before vfork */
 	pas = getpwnam(user);
 	if (!pas) {
-		crondlog(LVL9 "can't get uid for %s", user);
+		bb_error_msg("can't get uid for %s", user);
 		goto err;
 	}
-	SetEnv(pas);
 
-	/* fork as the user in question and run program */
+	/* Prepare things before vfork */
+	shell = line->cl_shell ? line->cl_shell : DEFAULT_SHELL;
+	set_env_vars(pas, shell);
+
+	/* Fork as the user in question and run program */
 	pid = vfork();
 	if (pid == 0) {
 		/* CHILD */
-		/* change running state to the user in question */
-		ChangeUser(pas);
-		if (DebugOpt) {
-			crondlog(LVL5 "child running %s", DEFAULT_SHELL);
-		}
+		/* 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(DEFAULT_SHELL, DEFAULT_SHELL, "-c", line->cl_Shell, (char *) NULL);
-		crondlog(ERR20 "can't exec, user %s cmd %s %s %s", user,
-				 DEFAULT_SHELL, "-c", line->cl_Shell);
-		_exit(EXIT_SUCCESS);
+		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) {
-		/* FORK FAILED */
-		crondlog(ERR20 "can't vfork");
+		bb_perror_msg("vfork");
  err:
 		pid = 0;
 	}
-	line->cl_Pid = pid;
+	line->cl_pid = pid;
 }
 
-#endif /* ENABLE_FEATURE_CROND_CALL_SENDMAIL */
+#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 = -1;
+						file->cf_wants_starting = 1;
+					}
+				}
+			}
+		}
+	}
+}
+
+static void start_jobs(void)
+{
+	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 >= 0)
+				continue;
+
+			start_one_job(file->cf_username, line);
+			pid = line->cl_pid;
+			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();
+
+	/* "-b after -f is ignored", and so on for every pair a-b */
+	opt_complementary = "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+");
+	opts = getopt32(argv, "l:L:fbSc:" 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);
+	log8("crond (busybox "BB_VER") started, log level %d", G.log_level);
+	rescan_crontab_dir();
+	write_pidfile(CONFIG_PID_FILE_PATH "/crond.pid");
+
+	/* 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_error_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();
+			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 */
+}