add basic bit of daemon-with-notify (mostly just from the Drizzle tree)

ccan/daemon-with-notify/LICENSE

+../../licenses/BSD
\ No newline at end of file

ccan/daemon-with-notify/_info

+#include <stdio.h>
+#include <string.h>
+#include "config.h"
+
+/**
+ * daemon-with-notify - turn a process into a daemon with parent exiting when
+ *                      child has decided that it has started correctly.
+ *
+ * Daemons should detach themselves thoroughly from the process which launched
+ * them, and not prevent any filesystems from being unmounted.  daemonize()
+ * helps with the process.
+ *
+ * Daemon-with-notify is different in that the child can send a SIGUSR1 to
+ * the parent to indicate it has started (e.g. after memory allocation and
+ * other things that may fail) so that the parent can return a success or
+ * failing exit code and init scripts can pick this up easily.
+ *
+ * Example:
+ *	#include <ccan/daemon-with-notify/daemon.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(1, 1, 1))
+ *					err(1, "Failed to become daemon");
+ *			} else
+ *				usage(argv[1]);
+ *		}
+ *		sleep(10); /* do some init here */
+ *		daemon_is_ready();
+ *		sleep(20); /* will be done in child, detached from parent */
+ *		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/daemon-with-notify/daemon.c

+/*    $Header: /cvsroot/wikipedia/willow/src/bin/willow/daemon.c,v 1.1 2005/05/02 19:15:21 kateturner Exp $    */
+/*    $NetBSD: daemon.c,v 1.9 2003/08/07 16:42:46 agc Exp $    */
+/*-
+ * Copyright (c) 1990, 1993
+ *    The Regents of the University of California.  All rights reserved.
+ * Copyright (c) 2010
+ *    Stewart Smith
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#if defined __SUNPRO_C || defined __DECC || defined __HP_cc
+# pragma ident "@(#)$Header: /cvsroot/wikipedia/willow/src/bin/willow/daemon.c,v 1.1 2005/05/02 19:15:21 kateturner Exp $"
+# pragma ident "$NetBSD: daemon.c,v 1.9 2003/08/07 16:42:46 agc Exp $"
+#endif
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include <unistd.h>
+#include <sys/select.h>
+
+int daemonize(int nochdir, int noclose, int wait_sigusr1);
+int daemon_is_ready(void);
+void sigusr1_handler(int sig);
+
+pid_t parent_pid;
+
+void sigusr1_handler(int sig)
+{
+  if (sig == SIGUSR1)
+    _exit(EXIT_SUCCESS);
+}
+
+int daemon_is_ready()
+{
+  kill(parent_pid, SIGUSR1);
+  return 0;
+}
+
+int daemonize(int nochdir, int noclose, int wait_sigusr1)
+{
+    int fd;
+    pid_t child= -1;
+
+    parent_pid= getpid();
+    signal(SIGUSR1, sigusr1_handler);
+
+    child= fork();
+
+    switch (child)
+    {
+    case -1:
+        return (-1);
+    case 0:
+        break;
+    default:
+      if (wait_sigusr1)
+      {
+        /* parent */
+        int exit_code= -1;
+        int status;
+        while (waitpid(child, &status, 0) != child);
+        if (WIFEXITED(status))
+        {
+          exit_code= WEXITSTATUS(status);
+        }
+        if (WIFSIGNALED(status))
+        {
+          exit_code= -1;
+        }
+        _exit(exit_code);
+      }
+      else
+      {
+        _exit(EXIT_SUCCESS);
+      }
+    }
+
+    /* child */
+    if (setsid() == -1)
+        return (-1);
+
+    if (nochdir == 0) {
+        if(chdir("/") != 0) {
+            perror("chdir");
+            return (-1);
+        }
+    }
+
+    if (noclose == 0 && (fd = open("/dev/null", O_RDWR, 0)) != -1) {
+        if(dup2(fd, STDIN_FILENO) < 0) {
+            perror("dup2 stdin");
+            return (-1);
+        }
+        if(dup2(fd, STDOUT_FILENO) < 0) {
+            perror("dup2 stdout");
+            return (-1);
+        }
+        if(dup2(fd, STDERR_FILENO) < 0) {
+            perror("dup2 stderr");
+            return (-1);
+        }
+
+        if (fd > STDERR_FILENO) {
+            if(close(fd) < 0) {
+                perror("close");
+                return (-1);
+            }
+        }
+    }
+    return (0);
+}

ccan/daemon-with-notify/test/run.c

+#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(6);
+
+	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);
+	ok1(daemonized.ppid == 1);
+	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();
+}

licenses/BSD

+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+3. Neither the name of the University nor the names of its contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGE.