1 files changed, 271 insertions, 0 deletions
diff --git a/compat/pidfile.c b/compat/pidfile.c
new file mode 100644
index 000000000000..9dfd9c468a7a
--- /dev/null
+++ b/compat/pidfile.c
@@ -0,0 +1,271 @@
+/*	$NetBSD: pidfile.c,v 1.14 2016/04/12 20:40:43 roy Exp $	*/
+
+/*-
+ * Copyright (c) 1999, 2016 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Jason R. Thorpe, Matthias Scheler, Julio Merino and Roy Marples.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+ */
+
+#include <sys/param.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <paths.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/file.h>	/* for flock(2) */
+#include "config.h"
+#include "defs.h"
+
+static pid_t pidfile_pid;
+static char pidfile_path[PATH_MAX];
+static int pidfile_fd = -1;
+
+/* Closes pidfile resources.
+ *
+ * Returns 0 on success, otherwise -1. */
+static int
+pidfile_close(void)
+{
+	int error;
+
+	pidfile_pid = 0;
+	error = close(pidfile_fd);
+	pidfile_fd = -1;
+	pidfile_path[0] = '\0';
+	return error;
+}
+
+/* Truncate, close and unlink an existent pidfile,
+ * if and only if it was created by this process.
+ * The pidfile is truncated because we may have dropped permissions
+ * or entered a chroot and thus unable to unlink it.
+ *
+ * Returns 0 on truncation success, otherwise -1. */
+int
+pidfile_clean(void)
+{
+	int error;
+
+	if (pidfile_fd == -1) {
+		errno = EBADF;
+		return -1;
+	}
+
+	if (pidfile_pid != getpid())
+		error = EPERM;
+	else if (ftruncate(pidfile_fd, 0) == -1)
+		error = errno;
+	else {
+#ifndef HAVE_PLEDGE /* Avoid a pledge violating segfault. */
+		(void)unlink(pidfile_path);
+#endif
+		error = 0;
+	}
+
+	(void) pidfile_close();
+
+	if (error != 0) {
+		errno = error;
+		return -1;
+	}
+	return 0;
+}
+
+/* atexit shim for pidfile_clean */
+static void
+pidfile_cleanup(void)
+{
+
+	pidfile_clean();
+}
+
+/* Constructs a name for a pidfile in the default location (/var/run).
+ * If 'bname' is NULL, uses the name of the current program for the name of
+ * the pidfile.
+ *
+ * Returns 0 on success, otherwise -1. */
+static int
+pidfile_varrun_path(char *path, size_t len, const char *bname)
+{
+
+	if (bname == NULL)
+		bname = PACKAGE;
+
+	/* _PATH_VARRUN includes trailing / */
+	if ((size_t)snprintf(path, len, "%s%s.pid", _PATH_VARRUN, bname) >= len)
+	{
+		errno = ENAMETOOLONG;
+		return -1;
+	}
+	return 0;
+}
+
+/* Returns the process ID inside path on success, otherwise -1.
+ * If no path is given, use the last pidfile path, othewise the default one. */
+pid_t
+pidfile_read(const char *path)
+{
+	char dpath[PATH_MAX], buf[16], *eptr;
+	int fd, error;
+	ssize_t n;
+	pid_t pid;
+
+	if (path == NULL && pidfile_path[0] != '\0')
+		path = pidfile_path;
+	if (path == NULL || strchr(path, '/') == NULL) {
+		if (pidfile_varrun_path(dpath, sizeof(dpath), path) == -1)
+			return -1;
+		path = dpath;
+	}
+
+	if ((fd = open(path, O_RDONLY | O_NONBLOCK)) == -1)
+		return  -1;
+	n = read(fd, buf, sizeof(buf) - 1);
+	error = errno;
+	(void) close(fd);
+	if (n == -1) {
+		errno = error;
+		return -1;
+	}
+	buf[n] = '\0';
+	pid = (pid_t)strtoi(buf, &eptr, 10, 1, INT_MAX, &error);
+	if (error && !(error == ENOTSUP && *eptr == '\n')) {
+		errno = error;
+		return -1;
+	}
+	return pid;
+}
+
+/* Locks the pidfile specified by path and writes the process pid to it.
+ * The new pidfile is "registered" in the global variables pidfile_fd,
+ * pidfile_path and pidfile_pid so that any further call to pidfile_lock(3)
+ * can check if we are recreating the same file or a new one.
+ *
+ * Returns 0 on success, otherwise the pid of the process who owns the
+ * lock if it can be read, otherwise -1. */
+pid_t
+pidfile_lock(const char *path)
+{
+	char dpath[PATH_MAX];
+	static bool registered_atexit = false;
+
+	/* Register for cleanup with atexit. */
+	if (!registered_atexit) {
+		if (atexit(pidfile_cleanup) == -1)
+			return -1;
+		registered_atexit = true;
+	}
+
+	if (path == NULL || strchr(path, '/') == NULL) {
+		if (pidfile_varrun_path(dpath, sizeof(dpath), path) == -1)
+			return -1;
+		path = dpath;
+	}
+
+	/* If path has changed (no good reason), clean up the old pidfile. */
+	if (pidfile_fd != -1 && strcmp(pidfile_path, path) != 0)
+		pidfile_clean();
+
+	if (pidfile_fd == -1) {
+		int fd, opts;
+
+		opts = O_WRONLY | O_CREAT | O_NONBLOCK;
+#ifdef O_CLOEXEC
+		opts |= O_CLOEXEC;
+#endif
+#ifdef O_EXLOCK
+		opts |=	O_EXLOCK;
+#endif
+		if ((fd = open(path, opts, 0644)) == -1)
+			goto return_pid;
+#ifndef O_CLOEXEC
+		if ((opts = fcntl(fd, F_GETFD)) == -1 ||
+		    fcntl(fd, F_SETFL, opts | FD_CLOEXEC) == -1)
+		{
+			int error = errno;
+
+			(void) close(fd);
+			errno = error;
+			return -1;
+		}
+#endif
+#ifndef O_EXLOCK
+		if (flock(fd, LOCK_EX | LOCK_NB) == -1) {
+			int error = errno;
+
+			(void) close(fd);
+			if (error != EAGAIN) {
+				errno = error;
+				return -1;
+			}
+			fd = -1;
+		}
+#endif
+
+return_pid:
+		if (fd == -1) {
+			pid_t pid;
+
+			if (errno == EAGAIN) {
+				/* The pidfile is locked, return the process ID
+				 * it contains.
+				 * If sucessful, set errno to EEXIST. */
+				if ((pid = pidfile_read(path)) != -1)
+					errno = EEXIST;
+			} else
+				pid = -1;
+
+			return pid;
+		}
+		pidfile_fd = fd;
+		strlcpy(pidfile_path, path, sizeof(pidfile_path));
+	}
+
+	pidfile_pid = getpid();
+
+	/* Truncate the file, as we could be re-writing it.
+	 * Then write the process ID. */
+	if (ftruncate(pidfile_fd, 0) == -1 ||
+	    lseek(pidfile_fd, 0, SEEK_SET) == -1 ||
+	    dprintf(pidfile_fd, "%d\n", pidfile_pid) == -1)
+	{
+		int error = errno;
+
+		pidfile_cleanup();
+		errno = error;
+		return -1;
+	}
+
+	/* Hold the fd open to persist the lock. */
+	return 0;
+}