PSARC/2009/444 daemon() in libc

4471189 should have 4.4BSD's daemon() utility function

1 files changed, 103 insertions, 0 deletions

diff --git a/usr/src/lib/libc/port/gen/daemon.c b/usr/src/lib/libc/port/gen/daemon.c
new file mode 100644
index 0000000000..f1e6926c91
--- /dev/null
+++ b/usr/src/lib/libc/port/gen/daemon.c
@@ -0,0 +1,103 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#include "lint.h"
+#include "file64.h"
+#include "mtlib.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#include "stdiom.h"
+
+/*
+ * Use fork/setsid/fork to go into background and permanently remove
+ * controlling terminal.
+ */
+int
+daemon(int nochdir, int noclose)
+{
+	int retv, fd;
+
+	/*
+	 * By the first fork+setsid, we disconnect from our current controlling
+	 * terminal and become a session group leader.
+	 */
+	retv = fork();
+	if (retv == -1)
+		return (-1);
+	if (retv != 0)
+		_exit(EXIT_SUCCESS);
+	if (setsid() == -1)
+		return (-1);
+	/*
+	 * By forking again without calling setsid again, we make certain
+	 * that we are not the session group leader and can never reacquire
+	 * a controlling terminal.
+	 */
+	retv = fork();
+	if (retv == -1)
+		return (-1);
+	if (retv != 0)
+		_exit(EXIT_SUCCESS);
+
+	if (nochdir == 0)
+		(void) chdir("/");
+
+	if (noclose == 0) {
+		/*
+		 * Missing the PRIV_FILE_READ privilege may be one of the
+		 * reasons that prevent the opening of /dev/null to succeed.
+		 */
+		if ((fd = open("/dev/null", O_RDWR)) == -1)
+			return (-1);
+
+		/*
+		 * Also, if any of the descriptor redirects fails we should
+		 * return with error to signal to the caller that his request
+		 * cannot be fulfilled properly. It is up to the caller to
+		 * do the cleanup.
+		 */
+		if ((fd != STDIN_FILENO) && (dup2(fd, STDIN_FILENO) < 0)) {
+			(void) close(fd);
+			return (-1);
+		}
+		if ((fd != STDOUT_FILENO) && (dup2(fd, STDOUT_FILENO) < 0)) {
+			(void) close(fd);
+			return (-1);
+		}
+		if ((fd != STDERR_FILENO) && (dup2(fd, STDERR_FILENO) < 0)) {
+			(void) close(fd);
+			return (-1);
+		}
+
+		if (fd > STDERR_FILENO)
+			(void) close(fd);
+	}
+	return (0);
+}