1.\" $NetBSD: ktrace.2,v 1.13 2002/10/01 18:10:44 wiz 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 39.Sh NAME 40.Nm ktrace 41.Nd process tracing 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.Fd #include \*[Lt]sys/types.h\*[Gt] 46.Fd #include \*[Lt]sys/uio.h\*[Gt] 47.Fd #include \*[Lt]sys/ktrace.h\*[Gt] 48.Ft int 49.Fn ktrace "const char *tracefile" "int ops" "int trpoints" "pid_t pid" 50.Ft int 51.Fn fktrace "int fd" "int ops" "int trpoints" "pid_t pid" 52.Sh DESCRIPTION 53The 54.Fn ktrace 55function enables or disables tracing of one or more processes. 56Users may only trace their own processes. 57Only the super-user can trace setuid or setgid programs. 58.Pp 59The 60.Ar tracefile 61gives the pathname of the file to be used for tracing. 62The file must exist and be writable by the calling process. 63All trace records are always appended to the file, 64so the file must be truncated to zero length to discard 65previous trace data. 66If tracing points are being disabled (see KTROP_CLEAR below), 67.Ar tracefile 68may be NULL. 69If using 70.Fn fktrace 71then instead of passing a filename as 72.Ar tracefile , 73a file descriptor is passed as 74.Ar fd 75and behaviour is otherwise the same. 76.Pp 77The 78.Nm ops 79parameter specifies the requested ktrace operation. 80The defined operations are: 81.Bl -column KTRFLAG_DESCENDXXX -offset indent 82.It KTROP_SET Enable trace points specified in Ar trpoints . 83.It KTROP_CLEAR Disable trace points specified in Ar trpoints . 84.It KTROP_CLEARFILE Stop all tracing. 85.It KTRFLAG_DESCEND The tracing change should apply to the 86specified process and all its current children. 87.El 88.Pp 89The 90.Nm trpoints 91parameter specifies the trace points of interest. 92The defined trace points are: 93.Bl -column KTRFAC_SYSCALLXXX -offset indent 94.It KTRFAC_SYSCALL Trace system calls. 95.It KTRFAC_SYSRET Trace return values from system calls. 96.It KTRFAC_NAMEI Trace name lookup operations. 97.It KTRFAC_GENIO Trace all I/O (note that this option can 98generate much output). 99.It KTRFAC_PSIG Trace posted signals. 100.It KTRFAC_CSW Trace context switch points. 101.It KTRFAC_EMUL Trace emulation changes. 102.It KTRFAC_INHERIT Inherit tracing to future children. 103.El 104.Pp 105Each tracing event outputs a record composed of a generic header 106followed by a trace point specific structure. 107The generic header is: 108.Bd -literal 109struct ktr_header { 110 int ktr_len; /* length of buf */ 111 short ktr_type; /* trace record type */ 112 pid_t ktr_pid; /* process id */ 113 char ktr_comm[MAXCOMLEN+1]; /* command name */ 114 struct timeval ktr_time; /* timestamp */ 115 caddr_t ktr_buf; 116}; 117.Ed 118.Pp 119The 120.Nm ktr_len 121field specifies the length of the 122.Nm ktr_type 123data that follows this header. 124The 125.Nm ktr_pid 126and 127.Nm ktr_comm 128fields specify the process and command generating the record. 129The 130.Nm ktr_time 131field gives the time (with microsecond resolution) 132that the record was generated. 133The 134.Nm ktr_buf 135is an internal kernel pointer and is not useful. 136.Pp 137The generic header is followed by 138.Nm ktr_len 139bytes of a 140.Nm ktr_type 141record. 142The type specific records are defined in the 143.Pa \*[Lt]sys/ktrace.h\*[Gt] 144include file. 145.Sh RETURN VALUES 146On successful completion a value of 0 is returned. 147Otherwise, a value of -1 is returned and 148.Va errno 149is set to show the error. 150.Sh ERRORS 151.Fn ktrace 152will fail if: 153.Bl -tag -width ENAMETOOLONGAA 154.It Bq Er ENOTDIR 155A component of the path prefix is not a directory. 156.It Bq Er EINVAL 157The pathname contains a character with the high-order bit set. 158.It Bq Er ENAMETOOLONG 159A component of a pathname exceeded 255 characters, 160or an entire path name exceeded 1023 characters. 161.It Bq Er ENOENT 162The named tracefile does not exist. 163.It Bq Er EACCES 164Search permission is denied for a component of the path prefix. 165.It Bq Er ELOOP 166Too many symbolic links were encountered in translating the pathname. 167.It Bq Er EIO 168An I/O error occurred while reading from or writing to the file system. 169.El 170.Sh SEE ALSO 171.Xr kdump 1 , 172.Xr ktrace 1 173.Sh HISTORY 174A 175.Nm ktrace 176function call first appeared in 177.Bx 4.4 . 178