1 files changed, 142 insertions, 0 deletions
diff --git a/sys/contrib/openzfs/cmd/zed/zed_file.c b/sys/contrib/openzfs/cmd/zed/zed_file.c
new file mode 100644
index 000000000000..c706398cdf99
--- /dev/null
+++ b/sys/contrib/openzfs/cmd/zed/zed_file.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: CDDL-1.0
+/*
+ * This file is part of the ZFS Event Daemon (ZED).
+ *
+ * Developed at Lawrence Livermore National Laboratory (LLNL-CODE-403049).
+ * Copyright (C) 2013-2014 Lawrence Livermore National Security, LLC.
+ * Refer to the OpenZFS git commit log for authoritative copyright attribution.
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License Version 1.0 (CDDL-1.0).
+ * You can obtain a copy of the license from the top-level file
+ * "OPENSOLARIS.LICENSE" or at <http://opensource.org/licenses/CDDL-1.0>.
+ * You may not use this file except in compliance with the license.
+ */
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include "zed_file.h"
+#include "zed_log.h"
+
+/*
+ * Set an exclusive advisory lock on the open file descriptor [fd].
+ * Return 0 on success, 1 if a conflicting lock is held by another process,
+ * or -1 on error (with errno set).
+ */
+int
+zed_file_lock(int fd)
+{
+	struct flock lock;
+
+	if (fd < 0) {
+		errno = EBADF;
+		return (-1);
+	}
+	lock.l_type = F_WRLCK;
+	lock.l_whence = SEEK_SET;
+	lock.l_start = 0;
+	lock.l_len = 0;
+
+	if (fcntl(fd, F_SETLK, &lock) < 0) {
+		if ((errno == EACCES) || (errno == EAGAIN))
+			return (1);
+
+		return (-1);
+	}
+	return (0);
+}
+
+/*
+ * Release an advisory lock held on the open file descriptor [fd].
+ * Return 0 on success, or -1 on error (with errno set).
+ */
+int
+zed_file_unlock(int fd)
+{
+	struct flock lock;
+
+	if (fd < 0) {
+		errno = EBADF;
+		return (-1);
+	}
+	lock.l_type = F_UNLCK;
+	lock.l_whence = SEEK_SET;
+	lock.l_start = 0;
+	lock.l_len = 0;
+
+	if (fcntl(fd, F_SETLK, &lock) < 0)
+		return (-1);
+
+	return (0);
+}
+
+/*
+ * Test whether an exclusive advisory lock could be obtained for the open
+ * file descriptor [fd].
+ * Return 0 if the file is not locked, >0 for the PID of another process
+ * holding a conflicting lock, or -1 on error (with errno set).
+ */
+pid_t
+zed_file_is_locked(int fd)
+{
+	struct flock lock;
+
+	if (fd < 0) {
+		errno = EBADF;
+		return (-1);
+	}
+	lock.l_type = F_WRLCK;
+	lock.l_whence = SEEK_SET;
+	lock.l_start = 0;
+	lock.l_len = 0;
+
+	if (fcntl(fd, F_GETLK, &lock) < 0)
+		return (-1);
+
+	if (lock.l_type == F_UNLCK)
+		return (0);
+
+	return (lock.l_pid);
+}
+
+
+#if __APPLE__
+#define	PROC_SELF_FD "/dev/fd"
+#else /* Linux-compatible layout */
+#define	PROC_SELF_FD "/proc/self/fd"
+#endif
+
+/*
+ * Close all open file descriptors greater than or equal to [lowfd].
+ * Any errors encountered while closing file descriptors are ignored.
+ */
+void
+zed_file_close_from(int lowfd)
+{
+	int errno_bak = errno;
+	int maxfd = 0;
+	int fd;
+	DIR *fddir;
+	struct dirent *fdent;
+
+	if ((fddir = opendir(PROC_SELF_FD)) != NULL) {
+		while ((fdent = readdir(fddir)) != NULL) {
+			fd = atoi(fdent->d_name);
+			if (fd > maxfd && fd != dirfd(fddir))
+				maxfd = fd;
+		}
+		(void) closedir(fddir);
+	} else {
+		maxfd = sysconf(_SC_OPEN_MAX);
+	}
+	for (fd = lowfd; fd < maxfd; fd++)
+		(void) close(fd);
+
+	errno = errno_bak;
+}