Add helper library for cron configuration

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>

1 files changed, 503 insertions, 0 deletions

diff --git a/lib/cron/rdcron.c b/lib/cron/rdcron.c
new file mode 100644
index 0000000..42936ce
--- /dev/null
+++ b/lib/cron/rdcron.c
@@ -0,0 +1,503 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * Copyright (C) 2018 - David Oberhollenzer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdlib.h>
+#include <limits.h>
+#include <stdio.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <ctype.h>
+#include <pwd.h>
+#include <grp.h>
+
+#include "crontab.h"
+#include "libcfg.h"
+#include "util.h"
+
+
+static const enum_map_t weekday[] = {
+	{ "MON", 1 },
+	{ "TUE", 2 },
+	{ "WED", 3 },
+	{ "THU", 4 },
+	{ "FRI", 5 },
+	{ "SAT", 6 },
+	{ "SUN", 0 },
+};
+
+static const enum_map_t month[] = {
+	{ "JAN", 1 },
+	{ "FEB", 2 },
+	{ "MAR", 3 },
+	{ "APR", 4 },
+	{ "MAY", 5 },
+	{ "JUN", 6 },
+	{ "JUL", 7 },
+	{ "AUG", 8 },
+	{ "SEP", 9 },
+	{ "OCT", 10 },
+	{ "NOV", 11 },
+	{ "DEC", 12 },
+};
+
+static const struct {
+	const char *macro;
+	crontab_t tab;
+} intervals[] = {
+	{
+		.macro = "yearly",
+		.tab = {
+			.minute = 0x01,
+			.hour = 0x01,
+			.dayofmonth = 0x01,
+			.month = 0x01,
+			.dayofweek = 0xFF
+		},
+	}, {
+		.macro = "annually",
+		.tab = {
+			.minute = 0x01,
+			.hour = 0x01,
+			.dayofmonth = 0x01,
+			.month = 0x01,
+			.dayofweek = 0xFF
+		},
+	}, {
+		.macro = "monthly",
+		.tab = {
+			.minute = 0x01,
+			.hour = 0x01,
+			.dayofmonth = 0x01,
+			.month = 0xFFFF,
+			.dayofweek = 0xFF
+		},
+	}, {
+		.macro = "weekly",
+		.tab = {
+			.minute = 0x01,
+			.hour = 0x01,
+			.dayofmonth = 0xFFFFFFFF,
+			.month = 0xFFFF,
+			.dayofweek = 0x01
+		},
+	}, {
+		.macro = "daily",
+		.tab = {
+			.minute = 0x01,
+			.hour = 0x01,
+			.dayofmonth = 0xFFFFFFFF,
+			.month = 0xFFFF,
+			.dayofweek = 0xFF
+		},
+	}, {
+		.macro = "hourly",
+		.tab = {
+			.minute = 0x01,
+			.hour = 0xFFFFFFFF,
+			.dayofmonth = 0xFFFFFFFF,
+			.month = 0xFFFF,
+			.dayofweek = 0xFF
+		},
+	},
+};
+
+/*****************************************************************************/
+
+static int try_unescape(char *arg, rdline_t *rd)
+{
+	if (unescape(arg)) {
+		fprintf(stderr, "%s: %zu: malformed string constant\n",
+			rd->filename, rd->lineno);
+		return -1;
+	}
+	return 0;
+}
+
+static char *try_strdup(const char *str, rdline_t *rd)
+{
+	char *out = strdup(str);
+
+	if (out == NULL) {
+		fprintf(stderr, "%s: %zu: out of memory\n",
+			rd->filename, rd->lineno);
+	}
+	return out;
+}
+
+static char *readnum(char *line, int *out, int minval, int maxval,
+		     const enum_map_t *mnemonic, rdline_t *rd)
+{
+	int i, temp, value = 0;
+	const enum_map_t *ev;
+
+	if (!isdigit(*line)) {
+		if (!mnemonic)
+			goto fail_mn;
+
+		for (i = 0; isalnum(line[i]); ++i)
+			;
+		if (i == 0)
+			goto fail_mn;
+
+		temp = line[i];
+		line[i] = '\0';
+		ev = enum_by_name(mnemonic, line);
+		if (!ev) {
+			fprintf(stderr, "%s: %zu: unexpected '%s'",
+				rd->filename, rd->lineno, line);
+		}
+		line[i] = temp;
+		if (!ev)
+			return NULL;
+		*out = ev->value;
+		return line + i;
+	}
+
+	while (isdigit(*line)) {
+		i = ((*(line++)) - '0');
+		if (value > (maxval - i) / 10)
+			goto fail_of;
+		value = value * 10 + i;
+	}
+
+	if (value < minval)
+		goto fail_uf;
+
+	*out = value;
+	return line;
+fail_of:
+	fprintf(stderr, "%s: %zu: value exceeds maximum (%d > %d)\n",
+		rd->filename, rd->lineno, value, maxval);
+	return NULL;
+fail_uf:
+	fprintf(stderr, "%s: %zu: value too small (%d < %d)\n",
+		rd->filename, rd->lineno, value, minval);
+	return NULL;
+fail_mn:
+	fprintf(stderr, "%s: %zu: expected numeric value",
+		rd->filename, rd->lineno);
+	return NULL;
+}
+
+static char *readfield(char *line, uint64_t *out, int minval, int maxval,
+		       const enum_map_t *mnemonic, rdline_t *rd)
+{
+	int value, endvalue, step;
+	uint64_t v = 0;
+next:
+	if (*line == '*') {
+		++line;
+		value = minval;
+		endvalue = maxval;
+	} else {
+		line = readnum(line, &value, minval, maxval, mnemonic, rd);
+		if (!line)
+			goto fail;
+
+		if (*line == '-') {
+			line = readnum(line + 1, &endvalue, minval, maxval,
+				       mnemonic, rd);
+			if (!line)
+				goto fail;
+		} else {
+			endvalue = value;
+		}
+	}
+
+	if (endvalue < value)
+		goto fail;
+
+	if (*line == '/') {
+		line = readnum(line + 1, &step, 1, maxval + 1, NULL, rd);
+		if (!line)
+			goto fail;
+	} else {
+		step = 1;
+	}
+
+	while (value <= endvalue) {
+		v |= 1UL << (unsigned long)(value - minval);
+		value += step;
+	}
+
+	if (*line == ',' || *line == ' ') {
+		++line;
+		goto next;
+	}
+
+	if (*line != '\0')
+		goto fail;
+
+	*out = v;
+	return line;
+fail:
+	fprintf(stderr, "%s: %zu: invalid time range expression\n",
+		rd->filename, rd->lineno);
+	return NULL;
+}
+
+/*****************************************************************************/
+
+static int cron_exec(void *user, char *arg, rdline_t *rd, int flags)
+{
+	crontab_t *cron = user;
+	exec_t *e, *end;
+	(void)flags;
+
+	e = calloc(1, sizeof(*e) + strlen(arg) + 1);
+	if (e == NULL) {
+		fprintf(stderr, "%s: %zu: out of memory\n",
+			rd->filename, rd->lineno);
+		return -1;
+	}
+
+	strcpy(e->args, arg);
+
+	e->argc = pack_argv(e->args);
+	if (e->argc < 0) {
+		fprintf(stderr, "%s: %zu: malformed string constant\n",
+			rd->filename, rd->lineno);
+		return -1;
+	}
+
+	if (cron->exec == NULL) {
+		cron->exec = e;
+	} else {
+		for (end = cron->exec; end->next != NULL; end = end->next)
+			;
+		end->next = e;
+	}
+	return 0;
+}
+
+static int cron_hour(void *user, char *arg, rdline_t *rd, int flags)
+{
+	crontab_t *cron = user;
+	uint64_t value;
+	(void)flags;
+
+	if (!readfield(arg, &value, 0, 23, NULL, rd))
+		return -1;
+
+	cron->hour = value;
+	return 0;
+}
+
+static int cron_minute(void *user, char *arg, rdline_t *rd, int flags)
+{
+	crontab_t *cron = user;
+	uint64_t value;
+	(void)flags;
+
+	if (!readfield(arg, &value, 0, 59, NULL, rd))
+		return -1;
+
+	cron->minute = value;
+	return 0;
+}
+
+static int cron_dayofmonth(void *user, char *arg, rdline_t *rd, int flags)
+{
+	crontab_t *cron = user;
+	uint64_t value;
+	(void)flags;
+
+	if (!readfield(arg, &value, 1, 31, NULL, rd))
+		return -1;
+
+	cron->dayofmonth = value;
+	return 0;
+}
+
+static int cron_dayofweek(void *user, char *arg, rdline_t *rd, int flags)
+{
+	crontab_t *cron = user;
+	uint64_t value;
+	(void)flags;
+
+	if (!readfield(arg, &value, 0, 6, weekday, rd))
+		return -1;
+
+	cron->dayofweek = value;
+	return 0;
+}
+
+static int cron_month(void *user, char *arg, rdline_t *rd, int flags)
+{
+	crontab_t *cron = user;
+	uint64_t value;
+	(void)flags;
+
+	if (!readfield(arg, &value, 1, 12, month, rd))
+		return -1;
+
+	cron->month = value;
+	return 0;
+}
+
+static int cron_interval(void *user, char *arg, rdline_t *rd, int flags)
+{
+	crontab_t *cron = user;
+	size_t i;
+	(void)flags;
+
+	for (i = 0; i < ARRAY_SIZE(intervals); ++i) {
+		if (!strcmp(intervals[i].macro, arg)) {
+			cron->minute = intervals[i].tab.minute;
+			cron->hour = intervals[i].tab.hour;
+			cron->dayofmonth = intervals[i].tab.dayofmonth;
+			cron->month = intervals[i].tab.month;
+			cron->dayofweek = intervals[i].tab.dayofweek;
+			return 0;
+		}
+	}
+
+	fprintf(stderr, "%s: %zu: unknown interval '%s'\n",
+		rd->filename, rd->lineno, arg);
+	return -1;
+}
+
+static int cron_user(void *user, char *arg, rdline_t *rd, int flags)
+{
+	crontab_t *cron = user;
+	struct passwd *pwd;
+	bool isnumeric;
+	char *ptr;
+	int value;
+	(void)flags;
+
+	for (ptr = arg; isdigit(*ptr); ++ptr)
+		;
+
+	isnumeric = (*ptr == '\0');
+	pwd = getpwnam(arg);
+
+	if (pwd == NULL && !isnumeric) {
+		fprintf(stderr, "%s: %zu: unknown user '%s'\n",
+			rd->filename, rd->lineno, arg);
+		return -1;
+	}
+
+	if (pwd != NULL) {
+		cron->uid = pwd->pw_uid;
+	} else {
+		if (readnum(arg, &value, 0, INT_MAX, NULL, rd))
+			return -1;
+		cron->uid = value;
+	}
+	return 0;
+}
+
+static int cron_group(void *user, char *arg, rdline_t *rd, int flags)
+{
+	crontab_t *cron = user;
+	struct group *group;
+	bool isnumeric;
+	char *ptr;
+	int value;
+	(void)flags;
+
+	for (ptr = arg; isdigit(*ptr); ++ptr)
+		;
+
+	isnumeric = (*ptr == '\0');
+	group = getgrnam(arg);
+
+	if (group == NULL && !isnumeric) {
+		fprintf(stderr, "%s: %zu: unknown group '%s'\n",
+			rd->filename, rd->lineno, arg);
+		return -1;
+	}
+
+	if (group != NULL) {
+		cron->gid = group->gr_gid;
+	} else {
+		if (readnum(arg, &value, 0, INT_MAX, NULL, rd))
+			return -1;
+		cron->gid = value;
+	}
+	return 0;
+}
+
+static int cron_tty(void *user, char *arg, rdline_t *rd, int flags)
+{
+	crontab_t *cron = user;
+	(void)flags;
+
+	if (strncmp(arg, "truncate", 8) == 0 && isspace(arg[8])) {
+		cron->tty_truncate = 1;
+		arg += 8;
+		while (isspace(*arg))
+			++arg;
+	}
+
+	if (try_unescape(arg, rd))
+		return -1;
+
+	cron->ctty = try_strdup(arg, rd);
+	return cron->ctty == NULL ? -1 : 0;
+}
+
+
+
+static const cfg_param_t cron_params[] = {
+	{ "hour", 0, cron_hour },
+	{ "minute", 0, cron_minute },
+	{ "dayofmonth", 0, cron_dayofmonth },
+	{ "dayofweek", 0, cron_dayofweek },
+	{ "month", 0, cron_month },
+	{ "interval", 0, cron_interval },
+	{ "user", 0, cron_user },
+	{ "group", 0, cron_group },
+	{ "tty", 0, cron_tty },
+	{ "exec", 1, cron_exec },
+};
+
+crontab_t *rdcron(int dirfd, const char *filename)
+{
+	crontab_t *cron;
+	rdline_t rd;
+	int fd, ret;
+
+	fd = openat(dirfd, filename, O_RDONLY);
+	if (fd < 0) {
+		perror(filename);
+		return NULL;
+	}
+
+	cron = calloc(1, sizeof(*cron));
+	if (cron == NULL) {
+		fputs("out of memory\n", stderr);
+		goto out;
+	}
+
+	cron->pid = -1;
+
+	rdline_init(&rd, fd, filename, 0, NULL);
+	ret = rdcfg(cron, &rd, cron_params, ARRAY_SIZE(cron_params), 0);
+	if (ret) {
+		delcron(cron);
+		cron = NULL;
+	}
+out:
+	close(fd);
+	return cron;
+}