Add spawnd skeleton

.gitignore

@@ -0,0 +1,4 @@
+*.o
+config.mk
+spawn
+spawnd

Makefile

@@ -0,0 +1,15 @@
+CFLAGS += -std=c99 -Wall -Wextra -Wpedantic
+
+-include config.mk
+
+OBJS += daemon.o
+
+all: spawn spawnd
+
+spawnd: ${OBJS}
+	${CC} ${LDFLAGS} ${OBJS} ${LDLIBS} -o $@
+
+${OBJS}: daemon.h
+
+clean:
+	rm -f spawn spawnd ${OBJS}

daemon.c

@@ -0,0 +1,122 @@
+/* Copyright (C) 2020  C. McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sysexits.h>
+#include <unistd.h>
+
+#include "daemon.h"
+
+#ifndef RUNDIR
+#define RUNDIR "/var/run"
+#endif
+
+#ifndef ETCDIR
+#define ETCDIR "/usr/local/etc"
+#endif
+
+int restartInterval = 1000;
+struct Set256 stopExits;
+
+static void parseExits(char *list) {
+	setClear(&stopExits);
+	while (*list) {
+		byte exit = strtoul(list, &list, 10);
+		if (*list) {
+			if (*list != ',') errx(EX_USAGE, "invalid exit status %s", list);
+			list++;
+		}
+		setAdd(&stopExits, exit);
+	}
+}
+
+int main(int argc, char *argv[]) {
+	bool daemonize = true;
+
+	const char *pidPath = NULL;
+	const char *configPath = ETCDIR "/spawntab";
+	const char *fifoPath = RUNDIR "/spawnd.pipe";
+
+	const char *chdirPath = "/";
+	const char *user = NULL;
+	const char *group = NULL;
+
+	setAdd(&stopExits, 127);
+	setAdd(&stopExits, EX_USAGE);
+	setAdd(&stopExits, EX_DATAERR);
+	setAdd(&stopExits, EX_NOINPUT);
+	setAdd(&stopExits, EX_OSFILE);
+	setAdd(&stopExits, EX_CANTCREAT);
+	setAdd(&stopExits, EX_CONFIG);
+
+	for (int opt; 0 < (opt = getopt(argc, argv, "C:c:df:g:p:s:t:u:"));) {
+		switch (opt) {
+			break; case 'C': chdirPath = optarg;
+			break; case 'c': fifoPath = optarg;
+			break; case 'd': daemonize = false;
+			break; case 'f': configPath = optarg;
+			break; case 'g': group = optarg;
+			break; case 'p': pidPath = optarg;
+			break; case 's': parseExits(optarg);
+			break; case 't': restartInterval = strtoul(optarg, NULL, 10);
+			break; case 'u': user = optarg;
+			break; default:  return EX_USAGE;
+		}
+	}
+
+	int pidFile = -1;
+	if (pidPath) {
+		pidFile = open(
+			pidPath, O_WRONLY | O_CREAT | O_EXLOCK | O_CLOEXEC, 0600
+		);
+		if (pidFile < 0) err(EX_CANTCREAT, "%s", pidPath);
+	}
+
+	// TODO: Read config file.
+	
+	int error = access(chdirPath, X_OK);
+	if (error) err(EX_NOINPUT, "%s", chdirPath);
+
+	// TODO: Do user, group lookup.
+
+	// We can't lock a named pipe, so just warn if it already exists.
+	error = mkfifo(fifoPath, 0600);
+	if (error) {
+		if (errno != EEXIST) err(EX_CANTCREAT, "%s", fifoPath);
+		warn("%s", fifoPath);
+	}
+
+	int fifo = open(fifoPath, O_RDONLY | O_NONBLOCK | O_CLOEXEC);
+	if (fifo < 0) err(EX_CANTCREAT, "%s", fifoPath);
+
+	// TODO: Daemonize, write pid file.
+
+	// TODO: Main loop.
+	
+	close(fifo);
+	unlink(fifoPath);
+	if (pidPath) {
+		close(pidFile);
+		unlink(pidPath);
+	}
+}

daemon.h

@@ -0,0 +1,35 @@
+/* Copyright (C) 2020  C. McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+
+typedef unsigned char byte;
+
+struct Set256 {
+	uint32_t bits[8];
+};
+static inline void setClear(struct Set256 *set) {
+	for (int i = 0; i < 8; ++i) set->bits[i] = 0;
+}
+static inline void setAdd(struct Set256 *set, byte x) {
+	set->bits[x / 32] |= 1 << (uint32_t)(x & 31);
+}
+static inline uint32_t setTest(const struct Set256 *set, byte x) {
+	return set->bits[x / 32] & (1 << (uint32_t)(x & 31));
+}
+
+extern int restartInterval;
+extern struct Set256 stopExits;