Add special times support to crond
Denys Vlasenko
vda.linux at googlemail.com
Sat Jul 8 18:52:34 UTC 2017
On Thu, Jun 22, 2017 at 8:24 PM, Jonathan Kolb <kolbyjack at gmail.com> wrote:
> I recently started using Alpine Linux, and ran into an issue where my
> user could no longer use the @reboot cron feature to define its own
> startup jobs. Attached is a patch to add support for the named times
> found here: https://linux.die.net/man/5/crontab.
>
> size -A -d miscutils/crond.o change:
> section original patch
> .rodata.str1.1 693 775
> .text.start_jobs 0 382
> .text.load_crontab 804 1031
> .text.crond_main 1535 1363
> .rodata 0 50
> .rodata.SpecAry 0 144
> Total 4953 5666
The patch does not apply.
flag_reboot_jobs() is redundant, you can flag reboot jobs as wanting to start
as you create them. This also makes ->cl_Reboot field redundant.
+ if (access(CRON_REBOOT, R_OK | W_OK) == -1) {
+ close(open(CRON_REBOOT, O_WRONLY | O_CREAT, 0000));
No need to access(). Just open(O_EXCL) it. If you get >= 0,
the file did not exist.
+ { "yearly", "0\0" "0\0" "1\0" "1\0" "*" },
+ { "annually", "0\0" "0\0" "1\0" "1\0" "*" },
+ { "monthly", "0\0" "0\0" "1\0" "*\0" "*" },
+ { "weekly", "0\0" "0\0" "*\0" "*\0" "0" },
+ { "daily", "0\0" "0\0" "*\0" "*\0" "*" },
+ { "midnight", "0\0" "0\0" "*\0" "*\0" "*" },
+ { "hourly", "0\0" "*\0" "*\0" "*\0" "*" },
You need not specify "minutes" field, it is "0" for all of them.
+ for (int i = 0; i < 5; ++i)
+ tokens[i] = (char *)e->tokens + 2 * i;
How about:
+ 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;
+ tokens[5] =
parser->data + strspn(parser->data, DELIMS);
+ tokens[5] +=
strcspn(tokens[5], DELIMS);
+ tokens[5] +=
strspn(tokens[5], DELIMS);
Oh no...
How about doing it like in attached patch? I did not test it...
-------------- next part --------------
diff --git a/miscutils/crond.c b/miscutils/crond.c
index 88e7b47..8a39944 100644
--- a/miscutils/crond.c
+++ b/miscutils/crond.c
@@ -35,6 +35,22 @@
//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"
@@ -74,6 +90,7 @@
#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
@@ -101,6 +118,8 @@ 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 */
@@ -452,6 +471,59 @@ static void load_crontab(const char *fileName)
shell = xstrdup(&tokens[0][6]);
continue;
}
+#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,
+ * find the entire command in unmodified string:
+ */
+ tokens[5] = strstr(
+ skip_non_whitespace(skip_whitespace(parser->data)),
+ /* ^^^^ avoids mishandling e.g. "@daily aily PARAM" */
+ tokens[1]
+ );
+ 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
//TODO: handle HOME= too? "man crontab" says:
//name = value
//
@@ -468,18 +540,30 @@ static void load_crontab(const char *fileName)
/* check if a minimum of tokens is specified */
if (n < 6)
continue;
+ IF_FEATURE_CROND_SPECIAL_TIMES(
+ got_it:
+ )
*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_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);
@@ -664,7 +748,7 @@ fork_job(const char *user, int mailFd, CronLine *line, bool run_sendmail)
return pid;
}
-static void start_one_job(const char *user, CronLine *line)
+static pid_t start_one_job(const char *user, CronLine *line)
{
char mailFile[128];
int mailFd = -1;
@@ -698,6 +782,8 @@ static void start_one_job(const char *user, CronLine *line)
free(mailFile2);
}
}
+
+ return line->cl_pid;
}
/*
@@ -748,7 +834,7 @@ static void process_finished_job(const char *user, CronLine *line)
#else /* !ENABLE_FEATURE_CROND_CALL_SENDMAIL */
-static void start_one_job(const char *user, CronLine *line)
+static pid_t start_one_job(const char *user, CronLine *line)
{
const char *shell;
struct passwd *pas;
@@ -782,6 +868,7 @@ static void start_one_job(const char *user, CronLine *line)
pid = 0;
}
line->cl_pid = pid;
+ return pid;
}
#define process_finished_job(user, line) ((line)->cl_pid = 0)
@@ -825,7 +912,7 @@ static void flag_starting_jobs(time_t t1, time_t t2)
log8("user %s: process already running: %s",
file->cf_username, line->cl_cmd);
} else if (line->cl_pid == 0) {
- line->cl_pid = -1;
+ line->cl_pid = START_ME_NORMAL;
file->cf_wants_starting = 1;
}
}
@@ -834,7 +921,20 @@ static void flag_starting_jobs(time_t t1, time_t t2)
}
}
-static void start_jobs(void)
+#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;
@@ -846,11 +946,10 @@ static void start_jobs(void)
file->cf_wants_starting = 0;
for (line = file->cf_lines; line; line = line->cl_next) {
pid_t pid;
- if (line->cl_pid >= 0)
+ if (line->cl_pid != wants_start)
continue;
- start_one_job(file->cf_username, line);
- pid = line->cl_pid;
+ 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) {
@@ -950,6 +1049,10 @@ int crond_main(int argc UNUSED_PARAM, char **argv)
log8("crond (busybox "BB_VER") started, log level %d", G.log_level);
rescan_crontab_dir();
write_pidfile(CONFIG_PID_FILE_PATH "/crond.pid");
+#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);
@@ -1002,7 +1105,7 @@ int crond_main(int argc UNUSED_PARAM, char **argv)
} else if (dt > 0) {
/* Usual case: time advances forward, as expected */
flag_starting_jobs(t1, t2);
- start_jobs();
+ start_jobs(START_ME_NORMAL);
sleep_time = 60;
if (check_completions() > 0) {
/* some jobs are still running */
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