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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.
52 System calls are denoted using the following single letters:
54 .Bl -tag -width indent -compact
87 records can represent a single
97 User mode programs communicate with the
99 driver through a number of ioctls which are described below.
100 Each takes a single argument.
101 .Bl -tag -width ".Dv FILEMON_SET_PID"
102 .It Dv FILEMON_SET_FD
103 Write the internal tracing buffer to the supplied open file descriptor.
104 .It Dv FILEMON_SET_PID
105 Child process ID to trace.
111 function returns the value 0 if successful;
112 otherwise the value \-1 is returned and the global variable
114 is set to indicate the error.
116 .Bl -tag -width ".Pa /dev/filemon"
121 #include <sys/types.h>
122 #include <sys/stat.h>
123 #include <sys/wait.h>
124 #include <sys/ioctl.h>
125 #include <dev/filemon/filemon.h>
135 if ((fm_fd = open("/dev/filemon", O_RDWR)) == -1)
136 err(1, "open(\e"/dev/filemon\e", O_RDWR)");
137 if ((fm_log = open("filemon.out",
138 O_CREAT | O_WRONLY | O_TRUNC, DEFFILEMODE)) == -1)
139 err(1, "open(filemon.out)");
141 if (ioctl(fm_fd, FILEMON_SET_FD, &fm_log) == -1)
142 err(1, "Cannot set filemon log file descriptor");
143 /* Set up these two fd's to close on exec. */
144 (void)fcntl(fm_fd, F_SETFD, FD_CLOEXEC);
145 (void)fcntl(fm_log, F_SETFD, FD_CLOEXEC);
147 if ((child = fork()) == 0) {
149 if (ioctl(fm_fd, FILEMON_SET_PID, &child) == -1)
150 err(1, "Cannot set filemon PID");
151 /* Do something here. */
167 buffer contents to it.