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- proc.p_filemon is added which is protected by PROC_LOCK. This improves performance and avoids double-fork issues, taking allproc_lock while in syscalls, and walking the process tree in syscalls. A particular proc.p_filemon can only be changed to NULL or another filemon, or the filemon inherited, while the filemon->lock is held. - Filemon are reference counted. On the last reference the log will be closed. - When closing the devfs file handle, the filemon will be detached from all processes and inheritance prevented. - Disallow attaching to a process already being traced since filemon is typically intended to be used on children only. This is allowed for curproc as bmake relies on this behavior for rare cases when combining .MAKE with .META. - Detach any previously tracked process on ioctl(FILEMON_SET_PID). - Handle error from devfs_set_cdevpriv() in filemon_open(). - The global filemon lock and lists are removed. - A free list is no longer kept. Previously this list was forever-expanding and never garbage cleaned. - No longer loses track of double-forks. If the process holding the filemon handle closes it will close the log rather than wait on a daemonized process, but it will log all activity until it closes its handle. The filemon will be removed from the process and not inherited. - A separate process count is kept only as an optimization for forced detachment to avoid taking allproc_lock and walking the entire process tree. - struct filemon access is protected by sx(9) filemon->lock as it was before. - Add more comments and KASSERTS. MFC after: 2 weeks Reviewed by: kib, mjg, markj (all on previous versions) Sponsored by: EMC / Isilon Storage Division Differential Revision: https://reviews.freebsd.org/D5520
222 lines
5.3 KiB
Groff
222 lines
5.3 KiB
Groff
.\" Copyright (c) 2012
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.\" David E. O'Brien <obrien@FreeBSD.org>. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgment:
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.\" This product includes software developed by David E. O'Brien and
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.\" contributors.
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.\" 4. Neither the name of the author nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANT ABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd March 21, 2016
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.Dt FILEMON 4
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.Os
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.Sh NAME
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.Nm filemon
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.Nd the filemon device
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.Sh SYNOPSIS
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.In dev/filemon/filemon.h
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.Sh DESCRIPTION
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The
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.Nm
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device allows a process to collect file operations data of its children.
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The device
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.Pa /dev/filemon
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responds to two
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.Xr ioctl 2
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calls.
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.Pp
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.Nm
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is not intended to be a security auditing tool.
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Many syscalls are not tracked and binaries of foreign ABI will not be fully
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audited.
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It is intended for auditing of processes for the purpose of determining its
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dependencies in an efficient and easily parsable format.
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An example of this is
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.Xr make 1
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which uses this module with
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.Sy .MAKE.MODE=meta
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to handle incremental builds more smartly.
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.Pp
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System calls are denoted using the following single letters:
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.Pp
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.Bl -tag -width indent -compact
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.It Ql C
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.Xr chdir 2
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.It Ql D
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.Xr unlink 2
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.It Ql E
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.Xr exec 2
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.It Ql F
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.Xr fork 2 ,
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.Xr vfork 2
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.It Ql L
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.Xr link 2 ,
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.Xr linkat 2 ,
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.Xr symlink 2 ,
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.Xr symlinkat 2
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.It Ql M
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.Xr rename 2
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.It Ql R
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.Xr open 2
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for read
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.It Ql S
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.Xr stat 2
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.It Ql W
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.Xr open 2
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for write
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.It Ql X
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.Xr _exit 2
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.El
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.Pp
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Note that
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.Ql R
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following
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.Ql W
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records can represent a single
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.Xr open 2
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for R/W,
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or two separate
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.Xr open 2
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calls, one for
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.Ql R
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and one for
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.Ql W .
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Note that only successful system calls are captured.
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.Sh IOCTLS
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User mode programs communicate with the
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.Nm
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driver through a number of ioctls which are described below.
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Each takes a single argument.
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.Bl -tag -width ".Dv FILEMON_SET_PID"
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.It Dv FILEMON_SET_FD
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Write the internal tracing buffer to the supplied open file descriptor.
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.It Dv FILEMON_SET_PID
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Child process ID to trace.
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This should normally be done under the control of a parent in the child after
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.Xr fork 2
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but before anything else.
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See the example below.
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.El
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.Sh RETURN VALUES
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.\" .Rv -std ioctl
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The
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.Fn ioctl
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function returns the value 0 if successful;
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otherwise the value \-1 is returned and the global variable
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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The
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.Fn ioctl
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system call
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with
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.Dv FILEMON_SET_FD
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EEXIST
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The
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.Nm
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handle is already associated with a file descriptor.
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.El
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.Pp
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The
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.Fn ioctl
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system call
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with
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.Dv FILEMON_SET_PID
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will fail if:
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.Bl -tag -width Er
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.It Bq Er ESRCH
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No process having the specified process ID exists.
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.It Bq Er EBUSY
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The process ID specified is already being traced and was not the current
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process.
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.El
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.Sh FILES
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.Bl -tag -width ".Pa /dev/filemon"
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.It Pa /dev/filemon
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.El
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.Sh EXAMPLES
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.Bd -literal
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <sys/ioctl.h>
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#include <dev/filemon/filemon.h>
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#include <fcntl.h>
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#include <err.h>
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#include <unistd.h>
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static void
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open_filemon(void)
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{
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pid_t child;
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int fm_fd, fm_log;
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if ((fm_fd = open("/dev/filemon", O_RDWR | O_CLOEXEC)) == -1)
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err(1, "open(\e"/dev/filemon\e", O_RDWR)");
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if ((fm_log = open("filemon.out",
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O_CREAT | O_WRONLY | O_TRUNC | O_CLOEXEC, DEFFILEMODE)) == -1)
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err(1, "open(filemon.out)");
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if (ioctl(fm_fd, FILEMON_SET_FD, &fm_log) == -1)
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err(1, "Cannot set filemon log file descriptor");
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if ((child = fork()) == 0) {
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child = getpid();
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if (ioctl(fm_fd, FILEMON_SET_PID, &child) == -1)
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err(1, "Cannot set filemon PID");
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/* Do something here. */
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} else {
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wait(&child);
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close(fm_fd);
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}
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}
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.Ed
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.Pp
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Creates a file named
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.Pa filemon.out
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and configures the
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.Nm
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device to write the
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.Nm
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buffer contents to it.
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.Sh SEE ALSO
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.Xr dtrace 1 ,
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.Xr ktrace 1 ,
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.Xr script 1 ,
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.Xr truss 1 ,
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.Xr ioctl 2
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.Sh HISTORY
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A
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.Nm
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device appeared in
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.Fx 9.1 .
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.Sh BUGS
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Unloading the module may panic the system, thus requires using
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.Ic kldunload -f .
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