1.\" $NetBSD: ktrace.2,v 1.2 1995/02/27 12:33:58 cgd Exp $ 2.\" 3.\" Copyright (c) 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)ktrace.2 8.1 (Berkeley) 6/4/93 35.\" 36.Dd June 4, 1993 37.Dt KTRACE 2 38.Os BSD 4 39.Sh NAME 40.Nm ktrace 41.Nd process tracing 42.Sh SYNOPSIS 43.Fd #include <sys/types.h> 44.Fd #include <sys/ktrace.h> 45.Ft int 46.Fn ktrace "const char *tracefile" "int ops" "int trpoints" "int pid" 47.Sh DESCRIPTION 48The 49.Fn ktrace 50function enables or disables tracing of one or more processes. 51Users may only trace their own processes. 52Only the super-user can trace setuid or setgid programs. 53.Pp 54The 55.Ar tracefile 56gives the pathname of the file to be used for tracing. 57The file must exist and be writable by the calling process. 58All trace records are always appended to the file, 59so the file must be truncated to zero length to discard 60previous trace data. 61If tracing points are being disabled (see KTROP_CLEAR below), 62.Ar tracefile 63may be NULL. 64.Pp 65The 66.Nm ops 67parameter specifies the requested ktrace operation. 68The defined operations are: 69.Bl -column KTRFLAG_DESCENDXXX -offset indent 70.It KTROP_SET Enable trace points specified in Ar trpoints . 71.It KTROP_CLEAR Disable trace points specified in Ar trpoints . 72.It KTROP_CLEARFILE Stop all tracing. 73.It KTRFLAG_DESCEND The tracing change should apply to the 74specified process and all its current children. 75.El 76.Pp 77The 78.Nm trpoints 79parameter specifies the trace points of interest. 80The defined trace points are: 81.Bl -column KTRFAC_SYSCALLXXX -offset indent 82.It KTRFAC_SYSCALL Trace system calls. 83.It KTRFAC_SYSRET Trace return values from system calls. 84.It KTRFAC_NAMEI Trace name lookup operations. 85.It KTRFAC_GENIO Trace all I/O (note that this option can 86generate much output). 87.It KTRFAC_PSIG Trace posted signals. 88.It KTRFAC_CSW Trace context switch points. 89.It KTRFAC_INHERIT Inherit tracing to future children. 90.El 91.Pp 92Each tracing event outputs a record composed of a generic header 93followed by a trace point specific structure. 94The generic header is: 95.Bd -literal 96struct ktr_header { 97 int ktr_len; /* length of buf */ 98 short ktr_type; /* trace record type */ 99 pid_t ktr_pid; /* process id */ 100 char ktr_comm[MAXCOMLEN+1]; /* command name */ 101 struct timeval ktr_time; /* timestamp */ 102 caddr_t ktr_buf; 103}; 104.Ed 105.Pp 106The 107.Nm ktr_len 108field specifies the length of the 109.Nm ktr_type 110data that follows this header. 111The 112.Nm ktr_pid 113and 114.Nm ktr_comm 115fields specify the process and command generating the record. 116The 117.Nm ktr_time 118field gives the time (with microsecond resolution) 119that the record was generated. 120The 121.Nm ktr_buf 122is an internal kernel pointer and is not useful. 123.Pp 124The generic header is followed by 125.Nm ktr_len 126bytes of a 127.Nm ktr_type 128record. 129The type specific records are defined in the 130.Pa <sys/ktrace.h> 131include file. 132.Sh RETURN VALUES 133On successful completion a value of 0 is returned. 134Otherwise, a value of -1 is returned and 135.Va errno 136is set to show the error. 137.Sh ERRORS 138.Fn Ktrace 139will fail if: 140.Bl -tag -width ENAMETOOLONGAA 141.It Bq Er ENOTDIR 142A component of the path prefix is not a directory. 143.It Bq Er EINVAL 144The pathname contains a character with the high-order bit set. 145.It Bq Er ENAMETOOLONG 146A component of a pathname exceeded 255 characters, 147or an entire path name exceeded 1023 characters. 148.It Bq Er ENOENT 149The named tracefile does not exist. 150.It Bq Er EACCES 151Search permission is denied for a component of the path prefix. 152.It Bq Er ELOOP 153Too many symbolic links were encountered in translating the pathname. 154.It Bq Er EIO 155An I/O error occurred while reading from or writing to the file system. 156.El 157.Sh SEE ALSO 158.Xr ktrace 1 , 159.Xr kdump 1 160.Sh HISTORY 161A 162.Nm ktrace 163function call first appeared in 164.Bx 4.4 . 165