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$FreeBSD$
.Dd May 30, 2012 .Dt FILEMON 4 .Os .Sh NAME .Nm filemon .Nd the filemon device .Sh SYNOPSIS n dev/filemon/filemon.h .Sh DESCRIPTION The .Nm device allows a process to collect file operations data of its children. The device
a /dev/filemon responds to two .Xr ioctl 2 calls.
p System calls are denoted using the following single letters:
p l -tag -width indent -compact t Ql C .Xr chdir 2 t Ql D .Xr unlink 2 t Ql E .Xr exec 2 t Ql F .Xr fork 2 , .Xr vfork 2 t Ql L .Xr link 2 , .Xr linkat 2 , .Xr symlink 2 , .Xr symlinkat 2 t Ql M .Xr rename 2 t Ql R .Xr open 2 for read t Ql S .Xr stat 2 t Ql W .Xr open 2 for write t Ql X .Xr _exit 2 .El
p
Note that
.Ql R
following
.Ql W
records can represent a single
.Xr open 2
for R/W,
or two seperate
.Xr open 2
calls, one for
.Ql R
and one for
.Ql W .
.Sh IOCTLS
User mode programs communicate with the
.Nm
driver through a number of ioctls which are described below.
Each takes a single argument.
l -tag -width ".Dv FILEMON_SET_PID" t Dv FILEMON_SET_FD Write the internal tracing buffer to the supplied open file descriptor.
t Dv FILEMON_SET_PID Child process ID to trace.
.El
.Sh RETURN VALUES
.Rv -std ioctl
The
.Fn ioctl
function returns the value 0 if successful;
otherwise the value -1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh FILES
l -tag -width ".Pa /dev/filemon" t Pa /dev/filemon .El
.Sh EXAMPLES
d -literal #include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <dev/filemon/filemon.h>
#include <fcntl.h>
#include <err.h>
static void
open_filemon(void)
{
pid_t child;
int fm_fd, fm_log;
if ((fm_fd = open("/dev/filemon", O_RDWR)) == -1)
err(1, "open(\e"/dev/filemon\e", O_RDWR)");
if ((fm_log = open("filemon.out",
O_CREAT | O_WRONLY | O_TRUNC, DEFFILEMODE)) == -1)
err(1, "open(filemon.out)");
if (ioctl(fm_fd, FILEMON_SET_FD, &fm_log) == -1)
err(1, "Cannot set filemon log file descriptor");
/* Set up these two fd's to close on exec. */
(void)fcntl(fm_fd, F_SETFD, FD_CLOEXEC);
(void)fcntl(fm_log, F_SETFD, FD_CLOEXEC);
if ((child = fork()) == 0) {
child = getpid();
if (ioctl(fm_fd, FILEMON_SET_PID, &child) == -1)
err(1, "Cannot set filemon PID");
/* Do something here. */
return 0;
} else {
wait(&child);
close(fm_fd);
}
return 0;
}
.Ed
p Creates a file named
a filemon.out and configures the .Nm device to write the .Nm buffer contents to it. .Sh SEE ALSO .Xr dtrace 1 , .Xr ktrace 1 , .Xr truss 1 .Sh HISTORY A .Nm device appeared in .Fx 9.1 .