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  12 .\" Copyright 2015 Joyent, Inc.
  13 .\"
  14 .Dd May 11, 2016
  15 .Dt PFAULT 3PROC
  16 .Os
  17 .Sh NAME
  18 .Nm Pfault
  19 .Nd enable and disable the tracing of faults
  20 .Sh SYNOPSIS
  21 .Lb libproc
  22 .In libproc.h
  23 .Ft "int"
  24 .Fo Pfault
  25 .Fa "struct ps_prochandle *P"
  26 .Fa "int which"
  27 .Fa "int stop"
  28 .Fc
  29 .Sh DESCRIPTION
  30 The
  31 .Fn Pfault
  32 function controls what the process
  33 .Fa P
  34 should do on faults.
  35 .Pp
  36 A fault is a hardware event that occurs in the context of a running
  37 process and thread.
  38 A hardware fault may occur because an illegal instruction was executed,
  39 a breakpoint or watchpoint was encountered, or an arithmetic exception occurred,
  40 among others.
  41 The full list of faults is available in both
  42 .Xr proc 4
  43 and
  44 .In sys/fault.h .
  45 .Pp
  46 For each hardware fault, a process may be configured to stop the thread
  47 that encountered it when it occurs.
  48 The value of the
  49 .Fa stop
  50 parameter controls whether or not the listed fault in
  51 .Fa which
  52 will cause the thread to trap.
  53 A value of 1 indicates the thread should stop; a value of 0 indicates it should
  54 not.
  55 .Pp
  56 The value of
  57 .Fa which
  58 indicates which hardware fault the change applies to.
  59 However, if the value of
  60 .Fa which
  61 is zero, then it applies to all faults.
  62 .Pp
  63 The
  64 .Fn Pfault
  65 function only applies to actively running processes.
  66 It does not function on handles that refer to core files, zombie processes, or
  67 ELF objects.
  68 .Sh RETURN VALUES
  69 Upon successful completion, the
  70 .Fn Pfault
  71 function returns the old disposition of the fault --
  72 .Sy 0
  73 if it was not set to stop and
  74 .Sy 1
  75 if it was --
  76 and the fault state is updated.
  77 Otherwise,
  78 .Sy -1
  79 is returned,
  80 .Dv errno
  81 is updated with the error that occurred, and the fault state is not
  82 updated.
  83 .Sh ERRORS
  84 The
  85 .Fn Pfault
  86 function will fail if:
  87 .Bl -tag -width Er
  88 .It Er EINVAL
  89 The value of
  90 .Fa which
  91 is invalid, e.g. it is less than zero or greater than the largest defined
  92 fault.
  93 .It Er ENOENT
  94 The handle
  95 .Fa P
  96 refers to a process that is a zombie, a core file, or a file.
  97 .El
  98 .Sh INTERFACE STABILITY
  99 .Sy Uncommitted
 100 .Sh MT-LEVEL
 101 See
 102 .Sy LOCKING
 103 in
 104 .Xr libproc 3LIB .
 105 .Sh SEE ALSO
 106 .Xr libproc 3LIB ,
 107 .Xr proc 4