1.\" Copyright (c) 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)ktrace.2 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd June 4, 1993 36.Dt KTRACE 2 37.Os BSD 4 38.Sh NAME 39.Nm ktrace 40.Nd process tracing 41.Sh SYNOPSIS 42.Fd #include <sys/param.h> 43.Fd #include <sys/time.h> 44.Fd #include <sys/uio.h> 45.Fd #include <sys/ktrace.h> 46.Ft int 47.Fn ktrace "const char *tracefile" "int ops" "int trpoints" "int pid" 48.Sh DESCRIPTION 49The 50.Fn ktrace 51function enables or disables tracing of one or more processes. 52Users may only trace their own processes. 53Only the super-user can trace setuid or setgid programs. 54.Pp 55The 56.Ar tracefile 57gives the pathname of the file to be used for tracing. 58The file must exist and be a regular file writable by the calling process. 59All trace records are always appended to the file, 60so the file must be truncated to zero length to discard 61previous trace data. 62If tracing points are being disabled (see KTROP_CLEAR below), 63.Ar tracefile 64may be NULL. 65.Pp 66The 67.Nm ops 68parameter specifies the requested ktrace operation. 69The defined operations are: 70.Bl -column KTRFLAG_DESCENDXXX -offset indent 71.It KTROP_SET Enable trace points specified in Ar trpoints . 72.It KTROP_CLEAR Disable trace points specified in Ar trpoints . 73.It KTROP_CLEARFILE Stop all tracing. 74.It KTRFLAG_DESCEND The tracing change should apply to the 75specified process and all its current children. 76.El 77.Pp 78The 79.Nm trpoints 80parameter specifies the trace points of interest. 81The defined trace points are: 82.Bl -column KTRFAC_SYSCALLXXX -offset indent 83.It KTRFAC_SYSCALL Trace system calls. 84.It KTRFAC_SYSRET Trace return values from system calls. 85.It KTRFAC_NAMEI Trace name lookup operations. 86.It KTRFAC_GENIO Trace all I/O (note that this option can 87generate much output). 88.It KTRFAC_PSIG Trace posted signals. 89.It KTRFAC_CSW Trace context switch points. 90.It KTRFAC_INHERIT Inherit tracing to future children. 91.El 92.Pp 93Each tracing event outputs a record composed of a generic header 94followed by a trace point specific structure. 95The generic header is: 96.Bd -literal 97struct ktr_header { 98 int ktr_len; /* length of buf */ 99 short ktr_type; /* trace record type */ 100 pid_t ktr_pid; /* process id */ 101 char ktr_comm[MAXCOMLEN+1]; /* command name */ 102 struct timeval ktr_time; /* timestamp */ 103 caddr_t ktr_buf; 104}; 105.Ed 106.Pp 107The 108.Nm ktr_len 109field specifies the length of the 110.Nm ktr_type 111data that follows this header. 112The 113.Nm ktr_pid 114and 115.Nm ktr_comm 116fields specify the process and command generating the record. 117The 118.Nm ktr_time 119field gives the time (with microsecond resolution) 120that the record was generated. 121The 122.Nm ktr_buf 123is an internal kernel pointer and is not useful. 124.Pp 125The generic header is followed by 126.Nm ktr_len 127bytes of a 128.Nm ktr_type 129record. 130The type specific records are defined in the 131.Pa <sys/ktrace.h> 132include file. 133.Sh RETURN VALUES 134On successful completion a value of 0 is returned. 135Otherwise, a value of -1 is returned and 136.Va errno 137is set to show the error. 138.Sh ERRORS 139.Fn Ktrace 140will fail if: 141.Bl -tag -width ENAMETOOLONGAA 142.It Bq Er ENOTDIR 143A component of the path prefix is not a directory. 144.It Bq Er ENAMETOOLONG 145A component of a pathname exceeded 255 characters, 146or an entire path name exceeded 1023 characters. 147.It Bq Er ENOENT 148The named tracefile does not exist. 149.It Bq Er EACCES 150Search permission is denied for a component of the path prefix. 151.It Bq Er ELOOP 152Too many symbolic links were encountered in translating the pathname. 153.It Bq Er EIO 154An I/O error occurred while reading from or writing to the file system. 155.It Bq Er ENOSYS 156The kernel was not compiled with 157.Nm 158support. 159.El 160.Sh SEE ALSO 161.Xr kdump 1 , 162.Xr ktrace 1 163.Sh HISTORY 164A 165.Fn ktrace 166function call first appeared in 167.Bx 4.4 . 168