1 files changed, 375 insertions, 0 deletions
diff --git a/lib/libutil/pidfile.c b/lib/libutil/pidfile.c
new file mode 100644
index 000000000000..4c365a55842c
--- /dev/null
+++ b/lib/libutil/pidfile.c
@@ -0,0 +1,375 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
+ * All rights reserved.
+ *
+ * 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 AUTHORS 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 AUTHORS 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 <sys/types.h>
+#include <sys/capsicum.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <libgen.h>
+#include <libutil.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+struct pidfh {
+	int	pf_dirfd;
+	int	pf_fd;
+	char	pf_dir[MAXPATHLEN + 1];
+	char	pf_filename[MAXPATHLEN + 1];
+	dev_t	pf_dev;
+	ino_t	pf_ino;
+};
+
+static int _pidfile_remove(struct pidfh *pfh, int freeit);
+
+static int
+pidfile_verify(const struct pidfh *pfh)
+{
+	struct stat sb;
+
+	if (pfh == NULL || pfh->pf_fd == -1)
+		return (EDOOFUS);
+	/*
+	 * Check remembered descriptor.
+	 */
+	if (fstat(pfh->pf_fd, &sb) == -1)
+		return (errno);
+	if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino)
+		return (EDOOFUS);
+	return (0);
+}
+
+static int
+pidfile_read_impl(int dirfd, const char *filename, pid_t *pidptr)
+{
+	char buf[16], *endptr;
+	int error, fd, i;
+
+	fd = openat(dirfd, filename, O_RDONLY | O_CLOEXEC);
+	if (fd == -1)
+		return (errno);
+
+	i = read(fd, buf, sizeof(buf) - 1);
+	error = errno;	/* Remember errno in case close() wants to change it. */
+	close(fd);
+	if (i == -1)
+		return (error);
+	else if (i == 0)
+		return (EAGAIN);
+	buf[i] = '\0';
+
+	*pidptr = strtol(buf, &endptr, 10);
+	if (endptr != &buf[i])
+		return (EINVAL);
+
+	return (0);
+}
+
+static int
+pidfile_read(int dirfd, const char *filename, pid_t *pidptr)
+{
+	struct timespec rqtp;
+	int count;
+
+	count = 20;
+	rqtp.tv_sec = 0;
+	rqtp.tv_nsec = 5000000;
+	for (;;) {
+		errno = pidfile_read_impl(dirfd, filename, pidptr);
+		if (errno != EAGAIN || --count == 0)
+			break;
+		nanosleep(&rqtp, 0);
+	}
+	if (errno == EAGAIN)
+		*pidptr = -1;
+	return (errno);
+}
+
+struct pidfh *
+pidfile_open(const char *pathp, mode_t mode, pid_t *pidptr)
+{
+	char path[MAXPATHLEN];
+	struct pidfh *pfh;
+	struct stat sb;
+	int error, fd, dirfd, dirlen, filenamelen;
+	cap_rights_t caprights;
+
+	pfh = malloc(sizeof(*pfh));
+	if (pfh == NULL)
+		return (NULL);
+
+	if (pathp == NULL) {
+		dirlen = snprintf(pfh->pf_dir, sizeof(pfh->pf_dir),
+		    "/var/run/");
+		filenamelen = snprintf(pfh->pf_filename,
+		    sizeof(pfh->pf_filename), "%s.pid", getprogname());
+	} else {
+		if (strlcpy(path, pathp, sizeof(path)) >= sizeof(path)) {
+			free(pfh);
+			errno = ENAMETOOLONG;
+			return (NULL);
+		}
+		dirlen = strlcpy(pfh->pf_dir, dirname(path),
+		    sizeof(pfh->pf_dir));
+		(void)strlcpy(path, pathp, sizeof(path));
+		filenamelen = strlcpy(pfh->pf_filename, basename(path),
+		    sizeof(pfh->pf_filename));
+	}
+
+	if (dirlen >= (int)sizeof(pfh->pf_dir) ||
+	    filenamelen >= (int)sizeof(pfh->pf_filename)) {
+		free(pfh);
+		errno = ENAMETOOLONG;
+		return (NULL);
+	}
+
+	dirfd = open(pfh->pf_dir, O_CLOEXEC | O_DIRECTORY | O_NONBLOCK);
+	if (dirfd == -1) {
+		error = errno;
+		free(pfh);
+		errno = error;
+		return (NULL);
+	}
+
+	/*
+	 * Open the PID file and obtain exclusive lock.
+	 * We truncate PID file here only to remove old PID immediately,
+	 * PID file will be truncated again in pidfile_write(), so
+	 * pidfile_write() can be called multiple times.
+	 */
+	fd = flopenat(dirfd, pfh->pf_filename,
+	    O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NONBLOCK, mode);
+	if (fd == -1) {
+		if (errno == EWOULDBLOCK) {
+			if (pidptr == NULL) {
+				errno = EEXIST;
+			} else {
+				errno = pidfile_read(dirfd,
+				    pfh->pf_filename, pidptr);
+				if (errno == 0 || errno == EAGAIN)
+					errno = EEXIST;
+			}
+		}
+		error = errno;
+		close(dirfd);
+		free(pfh);
+		errno = error;
+		return (NULL);
+	}
+
+	/*
+	 * Remember file information, so in pidfile_write() we are sure we write
+	 * to the proper descriptor.
+	 */
+	if (fstat(fd, &sb) == -1) {
+		goto failed;
+	}
+
+	if (cap_rights_limit(dirfd,
+	    cap_rights_init(&caprights, CAP_UNLINKAT)) < 0 && errno != ENOSYS) {
+		goto failed;
+	}
+
+	if (cap_rights_limit(fd, cap_rights_init(&caprights, CAP_PWRITE,
+	    CAP_FSTAT, CAP_FTRUNCATE, CAP_EVENT)) < 0 &&
+	    errno != ENOSYS) {
+		goto failed;
+	}
+
+	pfh->pf_dirfd = dirfd;
+	pfh->pf_fd = fd;
+	pfh->pf_dev = sb.st_dev;
+	pfh->pf_ino = sb.st_ino;
+
+	return (pfh);
+
+failed:
+	error = errno;
+	unlinkat(dirfd, pfh->pf_filename, 0);
+	close(dirfd);
+	close(fd);
+	free(pfh);
+	errno = error;
+	return (NULL);
+}
+
+int
+pidfile_write(struct pidfh *pfh)
+{
+	char pidstr[16];
+	int error, fd;
+
+	/*
+	 * Check remembered descriptor, so we don't overwrite some other
+	 * file if pidfile was closed and descriptor reused.
+	 */
+	errno = pidfile_verify(pfh);
+	if (errno != 0) {
+		/*
+		 * Don't close descriptor, because we are not sure if it's ours.
+		 */
+		return (-1);
+	}
+	fd = pfh->pf_fd;
+
+	/*
+	 * Truncate PID file, so multiple calls of pidfile_write() are allowed.
+	 */
+	if (ftruncate(fd, 0) == -1) {
+		error = errno;
+		_pidfile_remove(pfh, 0);
+		errno = error;
+		return (-1);
+	}
+
+	snprintf(pidstr, sizeof(pidstr), "%u", getpid());
+	if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) {
+		error = errno;
+		_pidfile_remove(pfh, 0);
+		errno = error;
+		return (-1);
+	}
+
+	return (0);
+}
+
+int
+pidfile_close(struct pidfh *pfh)
+{
+	int error;
+
+	error = pidfile_verify(pfh);
+	if (error != 0) {
+		errno = error;
+		return (-1);
+	}
+
+	if (close(pfh->pf_fd) == -1)
+		error = errno;
+	if (close(pfh->pf_dirfd) == -1 && error == 0)
+		error = errno;
+
+	free(pfh);
+	if (error != 0) {
+		errno = error;
+		return (-1);
+	}
+	return (0);
+}
+
+static int
+_pidfile_remove(struct pidfh *pfh, int freeit)
+{
+	int error;
+
+	error = pidfile_verify(pfh);
+	if (error != 0) {
+		errno = error;
+		return (-1);
+	}
+
+	if (funlinkat(pfh->pf_dirfd, pfh->pf_filename, pfh->pf_fd, 0) == -1) {
+		if (errno == EDEADLK)
+			return (-1);
+		error = errno;
+	}
+	if (close(pfh->pf_fd) == -1 && error == 0)
+		error = errno;
+	if (close(pfh->pf_dirfd) == -1 && error == 0)
+		error = errno;
+	if (freeit)
+		free(pfh);
+	else
+		pfh->pf_fd = -1;
+	if (error != 0) {
+		errno = error;
+		return (-1);
+	}
+	return (0);
+}
+
+int
+pidfile_remove(struct pidfh *pfh)
+{
+
+	return (_pidfile_remove(pfh, 1));
+}
+
+int
+pidfile_fileno(const struct pidfh *pfh)
+{
+
+	if (pfh == NULL || pfh->pf_fd == -1) {
+		errno = EDOOFUS;
+		return (-1);
+	}
+	return (pfh->pf_fd);
+}
+
+int
+pidfile_signal(const char *pathp, int sig, pid_t *pidptr)
+{
+	pid_t pid;
+	int fd;
+
+	fd = flopenat(AT_FDCWD, pathp,
+	    O_RDONLY | O_CLOEXEC | O_NONBLOCK);
+	if (fd >= 0) {
+		/*
+		 * The file exists but is not locked,
+		 * so the daemon is dead. Nothing to do.
+		 */
+		close(fd);
+		errno = ENOENT;
+		return (errno);
+	}
+	if (errno != EWOULDBLOCK) {
+		return (errno);
+	}
+	errno = pidfile_read(AT_FDCWD, pathp, &pid);
+	if (errno != 0)
+		return (errno);
+	/*
+	 * Refuse to send broadcast or group signals, this has
+	 * happened due to the bugs in pidfile(3).
+	 */
+	if (pid <= 0)
+		return (EDOM);
+	kill(pid, sig);
+	if (pidptr != NULL)
+		*pidptr = pid;
+	return (errno);
+}