1.\" $OpenBSD: ktrace.2,v 1.9 2000/04/25 16:40:37 millert Exp $ 2.\" $NetBSD: ktrace.2,v 1.2 1995/02/27 12:33:58 cgd Exp $ 3.\" 4.\" Copyright (c) 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)ktrace.2 8.1 (Berkeley) 6/4/93 36.\" 37.Dd June 4, 1993 38.Dt KTRACE 2 39.Os 40.Sh NAME 41.Nm ktrace 42.Nd process tracing 43.Sh SYNOPSIS 44.Fd #include <sys/types.h> 45.Fd #include <sys/param.h> 46.Fd #include <sys/uio.h> 47.Fd #include <sys/ktrace.h> 48.Ft int 49.Fn ktrace "const char *tracefile" "int ops" "int trpoints" "int pid" 50.Sh DESCRIPTION 51The 52.Fn ktrace 53function enables or disables tracing of one or more processes. 54Users may only trace their own processes. 55Only the superuser can trace setuid or setgid programs. 56.Pp 57.Fa tracefile 58gives the pathname of the file to be used for tracing. 59The file must exist, be writable by the calling process, and 60not be a symbolic link. 61All trace records are always appended to the file, 62so the file must be truncated to zero length to discard 63previous trace data. 64If tracing points are being disabled (see 65.Dv KTROP_CLEAR 66below), 67.Ar tracefile 68may be 69.Dv NULL . 70.Pp 71The 72.Fa ops 73parameter specifies the requested ktrace operation. 74The defined operations are: 75.Bl -column KTRFLAG_DESCENDXXX -offset indent 76.It Dv KTROP_SET Enable trace points specified in Ar trpoints . 77.It Dv KTROP_CLEAR Disable trace points specified in Ar trpoints . 78.It Dv KTROP_CLEARFILE Stop all tracing. 79.It Dv KTRFLAG_DESCEND The tracing change should apply to the 80specified process and all its current children. 81.El 82.Pp 83The 84.Fa trpoints 85parameter specifies the trace points of interest. 86The defined trace points are: 87.Bl -column KTRFAC_SYSCALLXXX -offset indent 88.It Dv KTRFAC_SYSCALL Trace system calls. 89.It Dv KTRFAC_SYSRET Trace return values from system calls. 90.It Dv KTRFAC_NAMEI Trace name lookup operations. 91.It Dv KTRFAC_GENIO Trace all I/O (note that this option can 92generate much output). 93.It Dv KTRFAC_PSIG Trace posted signals. 94.It Dv KTRFAC_CSW Trace context switch points. 95.It Dv KTRFAC_INHERIT Inherit tracing to future children. 96.El 97.Pp 98Each tracing event outputs a record composed of a generic header 99followed by a trace point specific structure. 100The generic header is: 101.Bd -literal 102struct ktr_header { 103 int ktr_len; /* length of buf */ 104 short ktr_type; /* trace record type */ 105 pid_t ktr_pid; /* process id */ 106 char ktr_comm[MAXCOMLEN+1]; /* command name */ 107 struct timeval ktr_time; /* timestamp */ 108 caddr_t ktr_buf; 109}; 110.Ed 111.Pp 112The 113.Fa ktr_len 114field specifies the length of the 115.Fa ktr_type 116data that follows this header. 117The 118.Fa ktr_pid 119and 120.Fa ktr_comm 121fields specify the process and command generating the record. 122The 123.Fa ktr_time 124field gives the time (with microsecond resolution) 125that the record was generated. 126The 127.Fa ktr_buf 128is an internal kernel pointer and is not useful. 129.Pp 130The generic header is followed by 131.Fa ktr_len 132bytes of a 133.Fa ktr_type 134record. 135The type specific records are defined in the 136.Pa <sys/ktrace.h> 137include file. 138.Sh RETURN VALUES 139On successful completion a value of 0 is returned. 140Otherwise, a value of \-1 is returned and 141.Va errno 142is set to show the error. 143.Sh ERRORS 144.Fn ktrace 145will fail if: 146.Bl -tag -width ENAMETOOLONGAA 147.It Bq Er ENOTDIR 148A component of the path prefix is not a directory. 149.It Bq Er EINVAL 150The pathname contains a character with the high-order bit set. 151.It Bq Er ENAMETOOLONG 152A component of a pathname exceeded 255 characters, 153or an entire path name exceeded 1023 characters. 154.It Bq Er ENOENT 155The named tracefile does not exist. 156.It Bq Er EACCES 157Search permission is denied for a component of the path prefix or the 158path refers to a symbolic link. 159.It Bq Er ELOOP 160Too many symbolic links were encountered in translating the pathname. 161.It Bq Er EIO 162An I/O error occurred while reading from or writing to the file system. 163.El 164.Sh SEE ALSO 165.Xr kdump 1 , 166.Xr ktrace 1 167.Sh HISTORY 168A 169.Fn ktrace 170function call first appeared in 171.Bx 4.4 . 172