[apple/xnu.git] / bsd / man / man2 / ktrace.2

.\" Copyright (c) 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)ktrace.2	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/sys/ktrace.2,v 1.9.2.7 2001/12/14 18:34:01 ru Exp $
.\"
.Dd June 4, 1993
.Dt KTRACE 2
.Os
.Sh NAME
.Nm ktrace
.Nd process tracing
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/param.h
.In sys/time.h
.In sys/uio.h
.In sys/ktrace.h
.Ft int
.Fn ktrace "const char *tracefile" "int ops" "int trpoints" "int pid"
.Sh DESCRIPTION
The
.Fn ktrace
function enables or disables tracing of one or more processes.
Users may only trace their own processes.
Only the super-user can trace setuid or setgid programs.
.Pp
The
.Fa tracefile
gives the pathname of the file to be used for tracing.
The file must exist and be a regular file writable by the calling process.
All trace records are always appended to the file,
so the file must be truncated to zero length to discard
previous trace data.
If tracing points are being disabled (see KTROP_CLEAR below),
.Fa tracefile
may be NULL.
.Pp
The
.Fa ops
parameter specifies the requested ktrace operation.
The defined operations are:
.Bl -column KTRFLAG_DESCENDXXX -offset indent
.It "KTROP_SET	Enable trace points specified in"
.Fa trpoints .
.It "KTROP_CLEAR	Disable trace points specified in
.Fa trpoints .
.It "KTROP_CLEARFILE	Stop all tracing."
.It "KTRFLAG_DESCEND	The tracing change should apply to the"
specified process and all its current children.
.El
.Pp
The
.Fa trpoints
parameter specifies the trace points of interest.
The defined trace points are:
.Bl -column KTRFAC_SYSCALLXXX -offset indent
.It "KTRFAC_SYSCALL	Trace system calls."
.It "KTRFAC_SYSRET	Trace return values from system calls."
.It "KTRFAC_NAMEI	Trace name lookup operations."
.It "KTRFAC_GENIO	Trace all I/O (note that this option can"
generate much output).
.It "KTRFAC_PSIG	Trace posted signals."
.It "KTRFAC_CSW	Trace context switch points."
.It "KTRFAC_INHERIT	Inherit tracing to future children."
.El
.Pp
Each tracing event outputs a record composed of a generic header
followed by a trace point specific structure.
The generic header is:
.Bd -literal
struct ktr_header {
	int	ktr_len;		/* length of buf */
	short	ktr_type;		/* trace record type */
	pid_t	ktr_pid;		/* process id */
	char	ktr_comm[MAXCOMLEN+1];	/* command name */
	struct	timeval ktr_time;	/* timestamp */
	caddr_t	ktr_buf;
};
.Ed
.Pp
The
.Va ktr_len
field specifies the length of the
.Va ktr_type
data that follows this header.
The
.Va ktr_pid
and
.Va ktr_comm
fields specify the process and command generating the record.
The
.Va ktr_time
field gives the time (with microsecond resolution)
that the record was generated.
The
.Va ktr_buf
is an internal kernel pointer and is not useful.
.Pp
The generic header is followed by
.Va ktr_len
bytes of a
.Va ktr_type
record.
The type specific records are defined in the
.Aq Pa sys/ktrace.h
include file.
.Sh RETURN VALUES
.Rv -std ktrace
.Sh ERRORS
.Fn Ktrace
will fail if:
.Bl -tag -width Er
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded 255 characters,
or an entire path name exceeded 1023 characters.
.It Bq Er ENOENT
The named tracefile does not exist.
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EIO
An I/O error occurred while reading from or writing to the file system.
.It Bq Er ENOSYS
The kernel was not compiled with
.Nm
support.
.El
.Sh SEE ALSO
.Xr kdump 1 ,
.Xr ktrace 1
.Sh HISTORY
A
.Fn ktrace
function call first appeared in
.Bx 4.4 .
Commit	Line	Data
9bccf70c A	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 .