'\" te
.\" Copyright (C) 2003, Sun Microsystems, Inc. All Rights Reserved.
.TH pctx_set_events 3CPC "13 May 2003" "SunOS 5.11" "CPU Performance Counters Library Functions"
.SH NAME
pctx_set_events \- associate callbacks with process events
.SH SYNOPSIS
.LP
.nf
cc [ \fIflag\fR... ] \fIfile\fR... \(milpctx [ \fIlibrary\fR... ]
#include <libpctx.h>

typedef	enum {
        PCTX_NULL_EVENT = 0,
        PCTX_SYSC_EXEC_EVENT,
        PCTX_SYSC_FORK_EVENT,
        PCTX_SYSC_EXIT_EVENT,
        PCTX_SYSC_LWP_CREATE_EVENT,
        PCTX_INIT_LWP_EVENT,
        PCTX_FINI_LWP_EVENT,
        PCTX_SYSC_LWP_EXIT_EVENT
} pctx_event_t;

\fBtypedef int\fR \fBpctx_sysc_execfn_t\fR(\fBpctx_t *\fR\fIpctx\fR, \fBpid_t\fR \fIpid\fR, \fBid_t\fR \fIlwpid\fR,
     \fBchar *\fR\fIcmd\fR, \fBvoid *\fR\fIarg\fR);
.fi

.LP
.nf
\fBtypedef void\fR \fBpctx_sysc_forkfn_t\fR(\fBpctx_t *\fR\fIpctx\fR,
     \fBpid_t\fR \fIpid\fR, \fBid_t\fR \fIlwpid\fR, \fBpid_t\fR \fIchild\fR, \fBvoid *\fR\fIarg\fR);
.fi

.LP
.nf
\fBtypedef void\fR \fBpctx_sysc_exitfn_t\fR(\fBpctx_t *\fR\fIpctx\fR, \fBpid_t\fR \fIpid\fR, \fBid_t\fR \fIlwpid\fR,
     \fBvoid *\fR\fIarg\fR);
.fi

.LP
.nf
\fBtypedef int\fR \fBpctx_sysc_lwp_createfn_t\fR(\fBpctx_t *\fR\fIpctx\fR, \fBpid_t\fR \fIpid\fR, \fBid_t\fR \fIlwpid\fR,
     \fBvoid *\fR\fIarg\fR);
.fi

.LP
.nf
\fBtypedef int\fR \fBpctx_init_lwpfn_t\fR(\fBpctx_t *\fR\fIpctx\fR, \fBpid_t\fR \fIpid\fR, \fBid_t\fR \fIlwpid\fR,
     \fBvoid *\fR\fIarg\fR);
.fi

.LP
.nf
\fBtypedef int\fR \fBpctx_fini_lwpfn_t\fR(\fBpctx_t *\fR\fIpctx\fR, \fBpid_t\fR \fIpid\fR, \fBid_t\fR \fIlwpid\fR,
     \fBvoid *\fR\fIarg\fR);
.fi

.LP
.nf
\fBtypedef int\fR \fBpctx_sysc_lwp_exitfn_t\fR(\fBpctx_t *\fR\fIpctx\fR, \fBpid_t\fR \fIpid\fR, \fBid_t\fR \fIlwpid\fR,
     \fBvoid *\fR\fIarg\fR);
.fi

.LP
.nf
\fBint\fR \fBpctx_set_events\fR(\fBpctx_t *\fR\fIpctx\fR...);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBpctx_set_events()\fR function allows the caller (the controlling process) to express interest in various events in the controlled process.  See \fBpctx_capture\fR(3CPC) for information about how the controlling process is able to create, capture and manipulate the controlled process.
.sp
.LP
The \fBpctx_set_events()\fR function takes a \fBpctx_t\fR handle, followed by a variable length list of pairs of \fBpctx_event_t\fR tags and their corresponding handlers, terminated by a \fBPCTX_NULL_EVENT\fR tag.
.sp
.LP
Most of the events correspond closely to various classes of system calls, though two additional pseudo-events (\fIinit_lwp\fR and \fIfini_lwp\fR) are provided to allow callers to perform various housekeeping tasks.  The \fIinit_lwp\fR handler is called as soon as the library identifies a new \fBLWP\fR, while \fIfini_lwp\fR is called just before the \fBLWP\fR disappears. Thus the classic "hello world" program would see an \fIinit_lwp\fR event, a  \fIfini_lwp\fR event and (process) \fIexit\fR event, in that order.   The table below displays the interactions between the states of the controlled process and the handlers executed by users of the library.
.sp

.sp
.TS
tab() box;
cw(1.02i) |cw(1.14i) |cw(3.34i) 
cw(1.02i) |cw(1.14i) |cw(3.34i) 
.
System Calls and pctx Handlers
_
System callHandlerComments
_
\fBexec\fR,\fBexecve\fR\fIfini_lwp\fRT{
Invoked serially on all lwps in the process.
T}
\fIexec\fRT{
Only invoked if the \fBexec()\fR system call succeeded.
T}
\fIinit_lwp\fRT{
If the exec succeeds, only invoked on lwp 1. If the exec fails, invoked serially on all lwps in the process.
T}
_
\fBfork\fR, \fBvfork\fR, \fBfork1\fR\fIfork\fRT{
Only invoked if the \fBfork()\fR system call succeeded.
T}
_
\fBexit\fR\fIfini_lwp\fRInvoked on all lwps in the process.
\fIexit\fRInvoked on the exiting lwp.
.TE

.sp
.LP
Each of the handlers is passed the caller's opaque handle, a \fBpctx_t\fR handle, the pid, and lwpid of the process and lwp generating the event. The \fIlwp_exit\fR, and (process) \fBexit\fR events are delivered \fIbefore\fR the underlying system calls begin, while the \fBexec\fR, \fIfork\fR, and \fIlwp_create\fR events are only delivered after the relevant system calls complete successfully. The \fBexec\fR handler is passed a string that describes the command being executed. Catching the \fIfork\fR event causes the calling process to \fBfork\fR(2), then capture the child of the controlled process using \fBpctx_capture\fR(\|) before handing control to the \fIfork\fR handler.  The process is released on return from the handler.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, \fBpctx_set_events\fR(\|) returns 0.  Otherwise, the function returns -1.
.SH EXAMPLES
.LP
\fBExample 1 \fRHandleExec example.
.sp
.LP
This example captures an existing process whose process identifier is \fIpid\fR, and arranges to call the \fIHandleExec\fR routine when the process performs an \fBexec\fR(2). 

.sp
.in +2
.nf
static void
HandleExec(pctx_t *pctx, pid_t pid, id_t lwpid, char *cmd, void *arg)
{
     (void) printf("pid %d execed '%s'\en", (int)pid, cmd);
}
int
main()
{
     ...
     pctx = pctx_capture(pid, NULL, 1, NULL);
     (void) pctx_set_events(pctx,
           PCTX_SYSC_EXEC_EVENT, HandleExec,
           ...
           PCTX_NULL_EVENT);
     (void) pctx_run(pctx, 0, 0, NULL);
     pctx_release(pctx);
}
.fi
.in -2

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
tab() box;
cw(2.75i) |cw(2.75i) 
lw(2.75i) |lw(2.75i) 
.
ATTRIBUTE TYPEATTRIBUTE VALUE
_
Interface StabilityCommitted
_
MT-LevelUnsafe
.TE

.SH SEE ALSO
.sp
.LP
\fBexec\fR(2), \fBexit\fR(2), \fBfork\fR(2), \fBvfork\fR(2), \fBfork1\fR(2), \fBcpc\fR(3CPC), \fBlibpctx\fR(3LIB), \fBproc\fR(4), \fBattributes\fR(5)