FILEMON(4) BSD Kernel Interfaces Manual FILEMON(4)
NAME
filemon -- the filemon device
SYNOPSIS
#include <dev/filemon/filemon.h>
DESCRIPTION
The filemon device allows a process to collect file operations data of its children. The device /dev/filemon responds to two ioctl(2) calls.
System calls are denoted using the following single letters:
'C' chdir(2)
'D' unlink(2)
'E' exec(2)
'F' fork(2), vfork(2)
'L' link(2), linkat(2), symlink(2), symlinkat(2)
'M' rename(2)
'R' open(2) for read
'S' stat(2)
'W' open(2) for write
'X' _exit(2)
Note that 'R' following 'W' records can represent a single open(2) for R/W, or two separate open(2) calls, one for 'R' and one for 'W'. Note
that only successful system calls are captured.
IOCTLS
User mode programs communicate with the filemon driver through a number of ioctls which are described below. Each takes a single argument.
FILEMON_SET_FD Write the internal tracing buffer to the supplied open file descriptor.
FILEMON_SET_PID Child process ID to trace.
RETURN VALUES
The ioctl() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate
the error.
FILES
/dev/filemon
EXAMPLES
#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>
#include <unistd.h>
static void
open_filemon(void)
{
pid_t child;
int fm_fd, fm_log;
if ((fm_fd = open("/dev/filemon", O_RDWR | O_CLOEXEC)) == -1)
err(1, "open("/dev/filemon", O_RDWR)");
if ((fm_log = open("filemon.out",
O_CREAT | O_WRONLY | O_TRUNC | O_CLOEXEC, 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");
if ((child = fork()) == 0) {
child = getpid();
if (ioctl(fm_fd, FILEMON_SET_PID, &child) == -1)
err(1, "Cannot set filemon PID");
/* Do something here. */
} else {
wait(&child);
close(fm_fd);
}
}
Creates a file named filemon.out and configures the filemon device to write the filemon buffer contents to it.
SEE ALSO
dtrace(1), ktrace(1), script(1), truss(1), ioctl(2)
HISTORY
A filemon device appeared in FreeBSD 9.1.
BSD
June 14, 2013 BSD