utrace(2) [netbsd man page]

UTRACE(2)						      BSD System Calls Manual							 UTRACE(2)

NAME

     utrace -- insert user record in ktrace log

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/types.h>
     #include <sys/param.h>
     #include <sys/time.h>
     #include <sys/uio.h>
     #include <sys/ktrace.h>

     int
     utrace(const char *label, void *addr, size_t len);

DESCRIPTION

     Adds a record to the process trace with information supplied by user.  The record is identified by label and contains len bytes from memory
     pointed to by addr.  This call only has an effect if the calling process is being traced.

RETURN VALUES

     Upon successful completion, a value of 0 is returned.  Otherwise, a value of -1 is returned and errno is set to indicate the error.

ERRORS

     [ENOSYS]		Currently running kernel was compiled without ktrace(2) support (option KTRACE).

     [EINVAL]		Specified data length len was bigger than KTR_USER_MAXLEN.

SEE ALSO

     kdump(1), ktrace(1), ktruss(1), fktrace(2), ktrace(2), options(4)

HISTORY

     The utrace() system call first appeared in FreeBSD 2.2.  It was added to NetBSD in NetBSD 1.6.  The label argument is a NetBSD extension.

BSD
								 December 28, 2000							       BSD

KTRACE(2)						      BSD System Calls Manual							 KTRACE(2)

NAME

     ktrace -- process tracing

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/param.h>
     #include <sys/time.h>
     #include <sys/uio.h>
     #include <sys/ktrace.h>

     int
     ktrace(const char *tracefile, int ops, int trpoints, int pid);

DESCRIPTION

     The ktrace() system call 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.

     The tracefile argument 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), tracefile may be NULL.

     The ops argument specifies the requested ktrace operation.  The defined operations are:

	   KTROP_SET		 Enable trace points specified in trpoints.
	   KTROP_CLEAR		 Disable trace points specified in trpoints.
	   KTROP_CLEARFILE	 Stop all tracing.
	   KTRFLAG_DESCEND	 The tracing change should apply to the specified process and all its current children.

     The trpoints argument specifies the trace points of interest.  The defined trace points are:

	   KTRFAC_SYSCALL	Trace system calls.
	   KTRFAC_SYSRET	Trace return values from system calls.
	   KTRFAC_NAMEI 	Trace name lookup operations.
	   KTRFAC_GENIO 	Trace all I/O (note that this option can generate much output).
	   KTRFAC_PSIG		Trace posted signals.
	   KTRFAC_CSW		Trace context switch points.
	   KTRFAC_INHERIT	Inherit tracing to future children.

     Each tracing event outputs a record composed of a generic header followed by a trace point specific structure.  The generic header is:

     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 */
	     intptr_t	     ktr_tid;	     /* was ktr_buffer */
     };

     The ktr_len field specifies the length of the ktr_type data that follows this header.  The ktr_pid and ktr_comm fields specify the process
     and command generating the record.  The ktr_time field gives the time (with microsecond resolution) that the record was generated.  The
     ktr_tid field holds a threadid.

     The generic header is followed by ktr_len bytes of a ktr_type record.  The type specific records are defined in the <sys/ktrace.h> include
     file.

SYSCTL TUNABLES

     The following sysctl(8) tunables influence the behaviour of ktrace():

     kern.ktrace.geniosize
	     bounds the amount of data a traced I/O request will log to the trace file.

     kern.ktrace.request_pool
	     bounds the number of trace events being logged at a time.

     Sysctl tunables that control process debuggability (as determined by p_candebug(9)) also affect the operation of ktrace().

RETURN VALUES

     The ktrace() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate
     the error.

ERRORS

     The ktrace() system call will fail if:

     [ENOTDIR]		A component of the path prefix is not a directory.

     [ENAMETOOLONG]	A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.

     [ENOENT]		The named tracefile does not exist.

     [EACCES]		Search permission is denied for a component of the path prefix.

     [ELOOP]		Too many symbolic links were encountered in translating the pathname.

     [EIO]		An I/O error occurred while reading from or writing to the file system.

     [ENOSYS]		The kernel was not compiled with ktrace support.

     A thread may be unable to log one or more tracing events due to a temporary shortage of resources.  This condition is remembered by the ker-
     nel, and the next tracing request that succeeds will have the flag KTR_DROP set in its ktr_type field.

SEE ALSO

     kdump(1), ktrace(1), utrace(2), sysctl(8), p_candebug(9)

HISTORY

     The ktrace() system call first appeared in 4.4BSD.

BSD
								   July 13, 2008							       BSD