zte's code,first commit

Change-Id: I9a04da59e459a9bc0d67f101f700d9d7dc8d681b
diff --git a/ap/app/busybox/src/miscutils/crond.c b/ap/app/busybox/src/miscutils/crond.c
new file mode 100644
index 0000000..582dc99
--- /dev/null
+++ b/ap/app/busybox/src/miscutils/crond.c
@@ -0,0 +1,954 @@
+/* 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 GPLv2 or later, see file LICENSE in this source tree.
+ */
+
+//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	Set log level. 0 is the most verbose, default 8"
+//usage:	IF_FEATURE_CROND_D(
+//usage:     "\n	-d	Set log level, log to stderr"
+//usage:	)
+//usage:     "\n	-L	Log to file"
+//usage:     "\n	-c	Working dir"
+
+#include "libbb.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
+#else
+# define SETENV_LEAKS 1
+#endif
+
+
+#define TMPDIR          CONFIG_FEATURE_CROND_DIR
+#define CRONTABS        CONFIG_FEATURE_CROND_DIR "/crontabs"
+#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 */
+#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
+	/* 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,
+};
+#if ENABLE_FEATURE_CROND_D
+# define DebugOpt (option_mask32 & OPT_d)
+#else
+# define DebugOpt 0
+#endif
+
+
+struct globals {
+	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;
+#endif
+} FIX_ALIASING;
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define INIT_G() do { \
+	G.log_level = 8; \
+	G.crontab_dir_name = CRONTABS; \
+} while (0)
+
+
+/* 0 is the most verbose, default 8 */
+#define LVL5  "\x05"
+#define LVL7  "\x07"
+#define LVL8  "\x08"
+#define WARN9 "\x49"
+#define DIE9  "\xc9"
+/* level >= 20 is "error" */
+#define ERR20 "\x14"
+
+static void crondlog(const char *ctl, ...) __attribute__ ((format (printf, 1, 2)));
+static void crondlog(const char *ctl, ...)
+{
+	va_list va;
+	int level = (ctl[0] & 0x1f);
+
+	va_start(va, ctl);
+	if (level >= (int)G.log_level) {
+		/* Debug mode: all to (non-redirected) stderr, */
+		/* Syslog mode: all to syslog (logmode = LOGMODE_SYSLOG), */
+		if (!DebugOpt && G.log_filename) {
+			/* Otherwise (log to file): we reopen log file at every write: */
+			int logfd = open_or_warn(G.log_filename, O_WRONLY | O_CREAT | O_APPEND);
+			if (logfd >= 0)
+				xmove_fd(logfd, STDERR_FILENO);
+		}
+		/* When we log to syslog, level > 8 is logged at LOG_ERR
+		 * syslog level, level <= 8 is logged at LOG_INFO. */
+		if (level > 8) {
+			bb_verror_msg(ctl + 1, va, /* strerr: */ NULL);
+		} else {
+			char *msg = NULL;
+			vasprintf(&msg, ctl + 1, va);
+			bb_info_msg("%s: %s", applet_name, msg);
+			free(msg);
+		}
+	}
+	va_end(va);
+	if (ctl[0] & 0x80)
+		exit(20);
+}
+
+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,
+				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:
+		crondlog(WARN9 "user %s: parse error at %s", user, base);
+		return;
+	}
+
+	if (DebugOpt && (G.log_level <= 5)) { /* like LVL5 */
+		/* can't use crondlog, it inserts '\n' */
+		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
+
+	delete_cronfile(fileName);
+
+	if (!getpwnam(fileName)) {
+		crondlog(LVL7 "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)
+				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);
+
+			/* check if line is setting MAILTO= */
+			if (0 == strncmp(tokens[0], "MAILTO=", 7)) {
+#if ENABLE_FEATURE_CROND_CALL_SENDMAIL
+				free(mailTo);
+				mailTo = (tokens[0][7]) ? xstrdup(&tokens[0][7]) : NULL;
+#endif /* otherwise just ignore such lines */
+				continue;
+			}
+			/* check if a minimum of tokens is specified */
+			if (n < 6)
+				continue;
+			*pline = line = xzalloc(sizeof(*line));
+			/* 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
+			/* copy command */
+			line->cl_cmd = xstrdup(tokens[5]);
+			if (DebugOpt) {
+				crondlog(LVL5 " command:%s", 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;
+
+		if (maxLines == 0) {
+			crondlog(WARN9 "user %s: too many lines", fileName);
+		}
+	}
+	config_close(parser);
+}
+
+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 */
+	if (chdir(G.crontab_dir_name) < 0) {
+		crondlog(DIE9 "chdir(%s)", G.crontab_dir_name);
+	}
+
+	/* Scan directory and add associated users */
+	{
+		DIR *dir = opendir(".");
+		struct dirent *den;
+
+		if (!dir)
+			crondlog(DIE9 "chdir(%s)", "."); /* exits */
+		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)
+{
+#if SETENV_LEAKS
+	safe_setenv(&G.env_var_user, "USER", pas->pw_name);
+	safe_setenv(&G.env_var_home, "HOME", pas->pw_dir);
+	/* if we want to set user's shell instead: */
+	/*safe_setenv(G.env_var_shell, "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 */
+}
+
+static void change_user(struct passwd *pas)
+{
+	/* careful: we're after vfork! */
+	change_identity(pas); /* - initgroups, setgid, setuid */
+	if (chdir(pas->pw_dir) < 0) {
+		crondlog(WARN9 "chdir(%s)", pas->pw_dir);
+		if (chdir(TMPDIR) < 0) {
+			crondlog(DIE9 "chdir(%s)", TMPDIR); /* exits */
+		}
+	}
+}
+
+// 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,
+		const char *prog,
+		const char *shell_cmd /* if NULL, we run sendmail */
+) {
+	struct passwd *pas;
+	pid_t pid;
+
+	/* prepare things before vfork */
+	pas = getpwnam(user);
+	if (!pas) {
+		crondlog(WARN9 "can't get uid for %s", user);
+		goto err;
+	}
+	set_env_vars(pas);
+
+	pid = vfork();
+	if (pid == 0) {
+		/* CHILD */
+		/* initgroups, setgid, setuid, and chdir to home or TMPDIR */
+		change_user(pas);
+		if (DebugOpt) {
+			crondlog(LVL5 "child running %s", prog);
+		}
+		if (mailFd >= 0) {
+			xmove_fd(mailFd, shell_cmd ? 1 : 0);
+			dup2(1, 2);
+		}
+		/* crond 3.0pl1-100 puts tasks in separate process groups */
+		bb_setpgrp();
+		execlp(prog, prog, (shell_cmd ? "-c" : SENDMAIL_ARGS), shell_cmd, (char *) NULL);
+		crondlog(ERR20 "can't execute '%s' for user %s", prog, user);
+		if (shell_cmd) {
+			fdprintf(1, "Exec failed: %s -c %s\n", prog, shell_cmd);
+		}
+		_exit(EXIT_SUCCESS);
+	}
+
+	if (pid < 0) {
+		/* FORK FAILED */
+		crondlog(ERR20 "can't 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 void 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", TMPDIR, 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 {
+			crondlog(ERR20 "can't create mail file %s for user %s, "
+					"discarding output", mailFile, user);
+		}
+	}
+
+	line->cl_pid = fork_job(user, mailFd, DEFAULT_SHELL, line->cl_cmd);
+	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", TMPDIR, user, (int)line->cl_pid);
+			rename(mailFile, mailFile2); // TODO: xrename?
+			free(mailFile2);
+		}
+	}
+}
+
+/*
+ * 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", TMPDIR, 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, SENDMAIL, NULL);
+}
+
+#else /* !ENABLE_FEATURE_CROND_CALL_SENDMAIL */
+
+static void start_one_job(const char *user, CronLine *line)
+{
+	struct passwd *pas;
+	pid_t pid;
+
+	pas = getpwnam(user);
+	if (!pas) {
+		crondlog(WARN9 "can't get uid for %s", user);
+		goto err;
+	}
+
+	/* Prepare things before vfork */
+	set_env_vars(pas);
+
+	/* Fork as the user in question and run program */
+	pid = vfork();
+	if (pid == 0) {
+		/* CHILD */
+		/* initgroups, setgid, setuid, and chdir to home or TMPDIR */
+		change_user(pas);
+		if (DebugOpt) {
+			crondlog(LVL5 "child running %s", DEFAULT_SHELL);
+		}
+		/* crond 3.0pl1-100 puts tasks in separate process groups */
+		bb_setpgrp();
+		execl(DEFAULT_SHELL, DEFAULT_SHELL, "-c", line->cl_cmd, (char *) NULL);
+		crondlog(ERR20 "can't execute '%s' for user %s", DEFAULT_SHELL, user);
+		_exit(EXIT_SUCCESS);
+	}
+	if (pid < 0) {
+		/* FORK FAILED */
+		crondlog(ERR20 "can't vfork");
+ err:
+		pid = 0;
+	}
+	line->cl_pid = 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) {
+			if (DebugOpt)
+				crondlog(LVL5 "file %s:", file->cf_username);
+			if (file->cf_deleted)
+				continue;
+			for (line = file->cf_lines; line; line = line->cl_next) {
+				if (DebugOpt)
+					crondlog(LVL5 " 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]
+				) {
+					if (DebugOpt) {
+						crondlog(LVL5 " job: %d %s",
+							(int)line->cl_pid, line->cl_cmd);
+					}
+					if (line->cl_pid > 0) {
+						crondlog(LVL8 "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;
+			crondlog(LVL8 "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;
+}
+
+int crond_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int crond_main(int argc UNUSED_PARAM, char **argv)
+{
+	time_t t2;
+	int rescan;
+	int 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;
+	}
+
+	xchdir(G.crontab_dir_name);
+	//signal(SIGHUP, SIG_IGN); /* ? original crond dies on HUP... */
+	xsetenv("SHELL", DEFAULT_SHELL); /* once, for all future children */
+	crondlog(LVL8 "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;
+
+		t1 = t2;
+
+		/* Synchronize to 1 minute, minimum 1 second */
+		sleep(sleep_time - (time(NULL) % sleep_time) + 1);
+
+		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 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();
+		if (DebugOpt)
+			crondlog(LVL5 "wakeup dt=%ld", dt);
+		if (dt < -60 * 60 || dt > 60 * 60) {
+			crondlog(WARN9 "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();
+			if (check_completions() > 0) {
+				/* some jobs are still running */
+				sleep_time = 10;
+			} else {
+				sleep_time = 60;
+			}
+		}
+		/* else: time jumped back, do not run any jobs */
+	} /* for (;;) */
+
+	return 0; /* not reached */
+}