ccan: import ccan/daemonize.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Makefile

@@ -47,6 +47,7 @@ CCAN_OBJS :=					\
 	ccan-crypto-sha256.o			\
 	ccan-crypto-shachain.o			\
 	ccan-crypto-siphash24.o			\
+	ccan-daemonize.o			\
 	ccan-err.o				\
 	ccan-fdpass.o				\
 	ccan-htable.o				\
@@ -97,6 +98,7 @@ CCAN_HEADERS :=						\
 	$(CCANDIR)/ccan/crypto/sha256/sha256.h		\
 	$(CCANDIR)/ccan/crypto/shachain/shachain.h	\
 	$(CCANDIR)/ccan/crypto/siphash24/siphash24.h	\
+	$(CCANDIR)/ccan/daemonize/daemonize.h		\
 	$(CCANDIR)/ccan/endian/endian.h			\
 	$(CCANDIR)/ccan/err/err.h			\
 	$(CCANDIR)/ccan/fdpass/fdpass.h			\
@@ -450,6 +452,8 @@ ccan-opt-parse.o: $(CCANDIR)/ccan/opt/parse.c
 	$(CC) $(CFLAGS) -c -o $@ $<
 ccan-opt-usage.o: $(CCANDIR)/ccan/opt/usage.c
 	$(CC) $(CFLAGS) -c -o $@ $<
+ccan-daemonize.o: $(CCANDIR)/ccan/daemonize/daemonize.c
+	$(CC) $(CFLAGS) -c -o $@ $<
 ccan-err.o: $(CCANDIR)/ccan/err/err.c
 	$(CC) $(CFLAGS) -c -o $@ $<
 ccan-noerr.o: $(CCANDIR)/ccan/noerr/noerr.c

ccan/ccan/daemonize/LICENSE

@@ -0,0 +1 @@
+../../licenses/BSD-MIT

ccan/ccan/daemonize/_info

@@ -0,0 +1,54 @@
+#include "config.h"
+#include <stdio.h>
+#include <string.h>
+
+/**
+ * daemonize - routine to turn a process into a well-behaved daemon.
+ *
+ * Daemons should detach themselves thoroughly from the process which launched
+ * them, and not prevent any filesystems from being unmounted.  daemonize()
+ * helps with the process.
+ *
+ * Example:
+ *	#include <ccan/daemonize/daemonize.h>
+ *	#include <ccan/str/str.h>
+ *	#include <err.h>
+ *	#include <unistd.h>
+ *	#include <stdlib.h>
+ *	
+ *	static void usage(const char *name)
+ *	{
+ *		errx(1, "Usage: %s [--daemonize]\n", name);
+ *	}
+ *	
+ *	// Wait for a minute, possibly as a daemon.
+ *	int main(int argc, char *argv[])
+ *	{
+ *		if (argc != 1) {
+ *			if (argc == 2 && streq(argv[1], "--daemonize")) {
+ *				if (!daemonize())
+ *					err(1, "Failed to become daemon");
+ *			} else
+ *				usage(argv[1]);
+ *		}
+ *		sleep(60);
+ *		exit(0);
+ *	}
+ *
+ * License: BSD-MIT
+ */
+int main(int argc, char *argv[])
+{
+	if (argc != 2)
+		return 1;
+
+	if (strcmp(argv[1], "depends") == 0) {
+		return 0;
+	}
+
+	if (strcmp(argv[1], "libs") == 0) {
+		return 0;
+	}
+
+	return 1;
+}

ccan/ccan/daemonize/daemonize.c

@@ -0,0 +1,45 @@
+/* Licensed under BSD-MIT - see LICENSE file for details */
+#include <ccan/daemonize/daemonize.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+/* This code is based on Stevens Advanced Programming in the UNIX
+ * Environment. */
+bool daemonize(void)
+{
+	pid_t pid;
+
+	/* Separate from our parent via fork, so init inherits us. */
+	if ((pid = fork()) < 0)
+		return false;
+	/* use _exit() to avoid triggering atexit() processing */
+	if (pid != 0)
+		_exit(0);
+
+	/* Don't hold files open. */
+	close(STDIN_FILENO);
+	close(STDOUT_FILENO);
+	close(STDERR_FILENO);
+
+	/* Many routines write to stderr; that can cause chaos if used
+	 * for something else, so set it here. */
+	if (open("/dev/null", O_WRONLY) != 0)
+		return false;
+	if (dup2(0, STDERR_FILENO) != STDERR_FILENO)
+		return false;
+	close(0);
+
+	/* Session leader so ^C doesn't whack us. */
+	if (setsid() == (pid_t)-1)
+	        return false;
+	/* Move off any mount points we might be in. */
+	if (chdir("/") != 0)
+		return false;
+
+	/* Discard our parent's old-fashioned umask prejudices. */
+	umask(0);
+	return true;
+}

ccan/ccan/daemonize/daemonize.h

@@ -0,0 +1,21 @@
+/* Licensed under BSD-MIT - see LICENSE file for details */
+#ifndef CCAN_DAEMONIZE_H
+#define CCAN_DAEMONIZE_H
+#include <stdbool.h>
+
+/**
+ * daemonize - turn this process into a daemon.
+ *
+ * This routine forks us off to become a daemon.  It returns false on failure
+ * (eg. fork(), chdir or open failed) and sets errno.
+ *
+ * Side effects for programmers to be aware of:
+ *  - PID changes (our parent exits, we become child of init)
+ *  - stdin and stdout file descriptors are closed
+ *  - stderr is reopened to /dev/null so you don't reuse it
+ *  - Current working directory changes to /
+ *  - Umask is set to 0.
+ */
+bool daemonize(void);
+
+#endif /* CCAN_DAEMONIZE_H */

ccan/ccan/daemonize/test/run.c

@@ -0,0 +1,76 @@
+#include <ccan/daemonize/daemonize.h>
+#include <ccan/daemonize/daemonize.c>
+#include <ccan/tap/tap.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <err.h>
+#include <errno.h>
+#include <string.h>
+
+struct child_data {
+	pid_t pid;
+	pid_t ppid;
+	bool in_root_dir;
+	int read_from_stdin, write_to_stdout, write_to_stderr;
+};
+
+int main(int argc, char *argv[])
+{
+	int fds[2];
+	struct child_data daemonized;
+	pid_t pid;
+
+	plan_tests(5);
+
+	if (pipe(fds) != 0)
+		err(1, "Failed pipe");
+
+	/* Since daemonize forks and parent exits, we need to fork
+	 * that parent. */
+	pid = fork();
+	if (pid == -1)
+		err(1, "Failed fork");
+
+	if (pid == 0) {
+		char buffer[2];
+		pid = getpid();
+		daemonize();
+		/* Keep valgrind happy about uninitialized bytes. */
+		memset(&daemonized, 0, sizeof(daemonized));
+		daemonized.pid = getpid();
+		daemonized.in_root_dir = (getcwd(buffer, 2) != NULL);
+		daemonized.read_from_stdin
+			= read(STDIN_FILENO, buffer, 1) == -1 ? errno : 0;
+		daemonized.write_to_stdout
+			= write(STDOUT_FILENO, buffer, 1) == -1 ? errno : 0;
+		if (write(STDERR_FILENO, buffer, 1) != 1) {
+			daemonized.write_to_stderr = errno;
+			if (daemonized.write_to_stderr == 0)
+				daemonized.write_to_stderr = -1;
+		} else
+			daemonized.write_to_stderr = 0;
+
+		/* Make sure parent exits. */
+		while (getppid() == pid)
+			sleep(1);
+		daemonized.ppid = getppid();
+		if (write(fds[1], &daemonized, sizeof(daemonized))
+		    != sizeof(daemonized))
+			exit(1);
+		exit(0);
+	}
+
+	if (read(fds[0], &daemonized, sizeof(daemonized)) != sizeof(daemonized))
+		err(1, "Failed read");
+
+	ok1(daemonized.pid != pid);
+#if 0	/* Believe it or not, this fails under Ubuntu 13.10 (Upstart) */
+	ok1(daemonized.ppid == 1);
+#endif
+	ok1(daemonized.in_root_dir);
+	ok1(daemonized.read_from_stdin == EBADF);
+	ok1(daemonized.write_to_stdout == EBADF);
+	ok1(daemonized.write_to_stderr == 0);
+
+	return exit_status();
+}