bsd/man/man2/ktrace.2

   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: src/lib/libc/sys/ktrace.2,v 1.9.2.7 2001/12/14 18:34:01 ru Exp $
  34 .\"
  35 .Dd June 4, 1993
  36 .Dt KTRACE 2
  37 .Os
  38 .Sh NAME
  39 .Nm ktrace
  40 .Nd process tracing
  41 .Sh LIBRARY
  42 .Lb libc
  43 .Sh SYNOPSIS
  44 .In sys/param.h
  45 .In sys/time.h
  46 .In sys/uio.h
  47 .In sys/ktrace.h
  48 .Ft int
  49 .Fn ktrace "const char *tracefile" "int ops" "int trpoints" "int pid"
  50 .Sh DESCRIPTION
  51 The
  52 .Fn ktrace
  53 function enables or disables tracing of one or more processes.
  54 Users may only trace their own processes.
  55 Only the super-user can trace setuid or setgid programs.
  56 .Pp
  57 The
  58 .Fa tracefile
  59 gives the pathname of the file to be used for tracing.
  60 The file must exist and be a regular file writable by the calling process.
  61 All trace records are always appended to the file,
  62 so the file must be truncated to zero length to discard
  63 previous trace data.
  64 If tracing points are being disabled (see KTROP_CLEAR below),
  65 .Fa tracefile
  66 may be NULL.
  67 .Pp
  68 The
  69 .Fa ops
  70 parameter specifies the requested ktrace operation.
  71 The defined operations are:
  72 .Bl -column KTRFLAG_DESCENDXXX -offset indent
  73 .It "KTROP_SET  Enable trace points specified in"
  74 .Fa trpoints .
  75 .It "KTROP_CLEAR        Disable trace points specified in
  76 .Fa trpoints .
  77 .It "KTROP_CLEARFILE    Stop all tracing."
  78 .It "KTRFLAG_DESCEND    The tracing change should apply to the"
  79 specified process and all its current children.
  80 .El
  81 .Pp
  82 The
  83 .Fa trpoints
  84 parameter specifies the trace points of interest.
  85 The defined trace points are:
  86 .Bl -column KTRFAC_SYSCALLXXX -offset indent
  87 .It "KTRFAC_SYSCALL     Trace system calls."
  88 .It "KTRFAC_SYSRET      Trace return values from system calls."
  89 .It "KTRFAC_NAMEI       Trace name lookup operations."
  90 .It "KTRFAC_GENIO       Trace all I/O (note that this option can"
  91 generate much output).
  92 .It "KTRFAC_PSIG        Trace posted signals."
  93 .It "KTRFAC_CSW Trace context switch points."
  94 .It "KTRFAC_INHERIT     Inherit tracing to future children."
  95 .El
  96 .Pp
  97 Each tracing event outputs a record composed of a generic header
  98 followed by a trace point specific structure.
  99 The generic header is:
 100 .Bd -literal
 101 struct ktr_header {
 102         int     ktr_len;                /* length of buf */
 103         short   ktr_type;               /* trace record type */
 104         pid_t   ktr_pid;                /* process id */
 105         char    ktr_comm[MAXCOMLEN+1];  /* command name */
 106         struct  timeval ktr_time;       /* timestamp */
 107         caddr_t ktr_buf;
 108 };
 109 .Ed
 110 .Pp
 111 The
 112 .Va ktr_len
 113 field specifies the length of the
 114 .Va ktr_type
 115 data that follows this header.
 116 The
 117 .Va ktr_pid
 118 and
 119 .Va ktr_comm
 120 fields specify the process and command generating the record.
 121 The
 122 .Va ktr_time
 123 field gives the time (with microsecond resolution)
 124 that the record was generated.
 125 The
 126 .Va ktr_buf
 127 is an internal kernel pointer and is not useful.
 128 .Pp
 129 The generic header is followed by
 130 .Va ktr_len
 131 bytes of a
 132 .Va ktr_type
 133 record.
 134 The type specific records are defined in the
 135 .Aq Pa sys/ktrace.h
 136 include file.
 137 .Sh RETURN VALUES
 138 .Rv -std ktrace
 139 .Sh ERRORS
 140 .Fn Ktrace
 141 will fail if:
 142 .Bl -tag -width Er
 143 .It Bq Er ENOTDIR
 144 A component of the path prefix is not a directory.
 145 .It Bq Er ENAMETOOLONG
 146 A component of a pathname exceeded 255 characters,
 147 or an entire path name exceeded 1023 characters.
 148 .It Bq Er ENOENT
 149 The named tracefile does not exist.
 150 .It Bq Er EACCES
 151 Search permission is denied for a component of the path prefix.
 152 .It Bq Er ELOOP
 153 Too many symbolic links were encountered in translating the pathname.
 154 .It Bq Er EIO
 155 An I/O error occurred while reading from or writing to the file system.
 156 .It Bq Er ENOSYS
 157 The kernel was not compiled with
 158 .Nm
 159 support.
 160 .El
 161 .Sh SEE ALSO
 162 .Xr kdump 1 ,
 163 .Xr ktrace 1
 164 .Sh HISTORY
 165 A
 166 .Fn ktrace
 167 function call first appeared in
 168 .Bx 4.4 .