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39 .Nd the filemon device
41 .In dev/filemon/filemon.h
45 device allows a process to collect file operations data of its children.
53 is not intended to be a security auditing tool.
54 Many system calls are not tracked and binaries using a non-native ABI may not
56 It is intended for auditing of processes for the purpose of determining their
57 dependencies using an efficient and easily parsable format.
60 which uses this module with
62 to handle incremental builds more smartly.
64 System calls are denoted using the following single letters:
66 .Bl -tag -width indent -compact
69 The next log entry may be lacking an absolute path or be inaccurate.
103 records can represent a single
112 Note that only successful system calls are captured.
114 User mode programs communicate with the
116 driver through a number of ioctls which are described below.
117 Each takes a single argument.
118 .Bl -tag -width ".Dv FILEMON_SET_PID"
119 .It Dv FILEMON_SET_FD
120 Write the internal tracing buffer to the supplied open file descriptor.
121 .It Dv FILEMON_SET_PID
122 Child process ID to trace.
123 This should normally be done under the control of a parent in the child after
125 but before anything else.
126 See the example below.
132 function returns the value 0 if successful;
133 otherwise the value \-1 is returned and the global variable
135 is set to indicate the error.
147 handle is already associated with a file descriptor.
149 The file descriptor has an invalid type and cannot be used for
152 The file descriptor is invalid or not opened for writing.
163 No process having the specified process ID exists.
165 The process ID specified is already being traced and was not the current
171 system call on the filemon file descriptor may fail with the errors from
173 if any error is encountered while writing the log.
177 An invalid address was used for a traced system call argument, resulting in
178 no log entry for the system call.
179 .It Bq Er ENAMETOOLONG
180 An argument for a traced system call was too long, resulting in
181 no log entry for the system call.
184 .Bl -tag -width ".Pa /dev/filemon"
189 #include <sys/types.h>
190 #include <sys/stat.h>
191 #include <sys/wait.h>
192 #include <sys/ioctl.h>
193 #include <dev/filemon/filemon.h>
202 pid_t child, wait_rv;
205 if ((fm_fd = open("/dev/filemon", O_RDWR | O_CLOEXEC)) == -1)
206 err(1, "open(\e"/dev/filemon\e", O_RDWR)");
207 if ((fm_log = open("filemon.out",
208 O_CREAT | O_WRONLY | O_TRUNC | O_CLOEXEC, DEFFILEMODE)) == -1)
209 err(1, "open(filemon.out)");
211 if (ioctl(fm_fd, FILEMON_SET_FD, &fm_log) == -1)
212 err(1, "Cannot set filemon log file descriptor");
214 if ((child = fork()) == 0) {
216 if (ioctl(fm_fd, FILEMON_SET_PID, &child) == -1)
217 err(1, "Cannot set filemon PID");
218 /* Do something here. */
219 } else if (child == -1)
220 err(1, "Cannot fork child");
222 while ((wait_rv = wait(&child)) == -1 &&
226 err(1, "cannot wait for child");
238 buffer contents to it.
251 Unloading the module may panic the system, thus requires using