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proc(4)								       proc(4)

NAME
       proc - /proc, the process file system

       /proc  is  a  file  system  that	 provides  access to the state of each
       process and light-weight	process	(lwp) in the system. The name of  each
       entry  in  the  /proc  directory	is a decimal number corresponding to a
       process-ID. These entries are  themselves  subdirectories.   Access  to
       process	state  is  provided  by	additional files contained within each
       subdirectory; the hierarchy is described	more completely	below. In this
       document,  ``/proc  file''  refers  to  a non-directory file within the
       hierarchy rooted	at /proc. The owner of each /proc file	and  subdirec-
       tory is determined by the user-ID of the	process.

       /proc  can  be  mounted on any mount point, in addition to the standard
       /proc mount point, and can be mounted  several  places  at  once.  Such
       additional mounts are allowed in	order to facilitate the	confinement of
       processes to subtrees of	the file system	via chroot(1M) and  yet	 allow
       such processes access to	commands like ps(1).

       Standard	 system	 calls	are  used  to  access  /proc  files:  open(2),
       close(2),  read(2),  and	 write(2)  (including	readv(2),   writev(2),
       pread(2),  and  pwrite(2)).  Most  files	describe process state and can
       only be opened for reading.  ctl	 and  lwpctl  (control)	 files	permit
       manipulation  of	 process  state	and can	only be	opened for writing. as
       (address	space) files contain the image of the running process and  can
       be  opened  for	both  reading  and writing. An open for	writing	allows
       process control;	a read-only open allows	inspection but not control. In
       this  document,	we refer to the	process	as open	for reading or writing
       if any of its associated	/proc files is open for	reading	or writing.

       In general, more	than one process can open the same /proc file  at  the
       same  time.  Exclusive  open is an advisory mechanism provided to allow
       controlling processes to	avoid collisions with each  other.  A  process
       can obtain exclusive control of a target	process, with respect to other
       cooperating processes, if it successfully opens any /proc file  in  the
       target  process for writing (the	as or ctl files, or the	lwpctl file of
       any lwp)	while specifying O_EXCL	in the open(2).	Such an	open will fail
       if  the	target process is already open for writing (that is, if	an as,
       ctl, or lwpctl file is already open for writing). There can be any num-
       ber of concurrent read-only opens; O_EXCL is ignored on opens for read-
       ing. It is recommended that the first open for writing by a controlling
       process	use  the  O_EXCL  flag;	multiple controlling processes usually
       result in chaos.

       If a process opens one of its own /proc files  for  writing,  the  open
       succeeds	 regardless  of	 O_EXCL	 and  regardless of whether some other
       process has the process open for	writing. Self-opens do not count  when
       another process attempts	an exclusive open. (A process cannot exclude a
       debugger	by opening itself for writing and the application of a	debug-
       ger  cannot  prevent a process from opening itself.) All	self-opens for
       writing are forced to be	close-on-exec (see the	F_SETFD	 operation  of
       fcntl(2)).

       Data  may  be transferred from or to any	locations in the address space
       of the traced process by	applying lseek(2) to position the as  file  at
       the  virtual address of interest	followed by read(2) or write(2)	(or by
       using pread(2) or pwrite(2) for the combined operation).	 The  address-
       map  file  /proc/pid/map	 can be	read to	determine the accessible areas
       (mappings) of the address space.	I/O transfers may span contiguous map-
       pings.  An  I/O request extending into an unmapped area is truncated at
       the boundary. A write request beginning at an unmapped virtual  address
       fails with EIO; a read request beginning	at an unmapped virtual address
       returns zero (an	end-of-file indication).

       Information and control	operations  are	 provided  through  additional
       files.  <procfs.h>  contains definitions	of data	structures and message
       formats used with these files. Some of these  definitions  involve  the
       use  of	sets  of flags.	The set	types sigset_t,	fltset_t, and sysset_t
       correspond, respectively, to signal, fault, and	system	call  enumera-
       tions  defined  in  <sys/signal.h>, <sys/fault.h>, and <sys/syscall.h>.
       Each set	type is	large enough to	hold flags for	its  own  enumeration.
       Although	 they are of different sizes, they have	a common structure and
       can be manipulated by these macros:

       prfillset(&set);		    /* turn on all flags in set	*/
       premptyset(&set);	    /* turn off	all flags in set */
       praddset(&set, flag);	    /* turn on the specified flag */
       prdelset(&set, flag);	    /* turn off	the specified flag */
       r = prismember(&set, flag);  /* != 0 iff	flag is	turned on */

       One of prfillset() or premptyset()  must	 be  used  to  initialize  set
       before  it is used in any other operation. flag must be a member	of the
       enumeration corresponding to set.

       Every process contains at least one light-weight	process, or lwp.  Each
       lwp  represents	a flow of execution that is independently scheduled by
       the operating system. All lwps in a process share its address space  as
       well as many other attributes.  Through the use of lwpctl and ctl files
       as described below, it is possible  to  affect  individual  lwps	 in  a
       process or to affect all	of them	at once, depending on the operation.

       When  the process has more than one lwp,	a representative lwp is	chosen
       by the system for certain process status	files and control  operations.
       The  representative  lwp	 is a stopped lwp only if all of the process's
       lwps are	stopped; is stopped on an event	of interest only if all	of the
       lwps are	so stopped (excluding PR_SUSPENDED lwps); is in	a PR_REQUESTED
       stop only if there are no other events of interest  to  be  found;  or,
       failing	everything  else, is in	a PR_SUSPENDED stop (implying that the
       process is deadlocked).	See the	description of	the  status  file  for
       definitions of stopped states. See the PCSTOP control operation for the
       definition of ``event of	interest''.

       The representative lwp remains fixed (it	will be	chosen	again  on  the
       next  operation)	 as  long  as all of the lwps are stopped on events of
       interest	or are in a PR_SUSPENDED stop and the PCRUN control  operation
       is not applied to any of	them.

       When applied to the process control file, every /proc control operation
       that must act on	an lwp uses the	same algorithm to choose which lwp  to
       act  upon. Together with	synchronous stopping (see PCSET), this enables
       a debugger to control a multiple-lwp process using  only	 the  process-
       level status and	control	files if it so chooses.	More fine-grained con-
       trol can	be achieved using the lwp-specific files.

       The system supports two process data  models,  the  traditional	32-bit
       data  model in which ints, longs	and pointers are all 32	bits wide (the
       ILP32 data model), and on some platforms	the 64-bit data	model in which
       longs  and  pointers, but not ints, are 64 bits in width	(the LP64 data
       model). In the LP64 data	model some system data types, notably  size_t,
       off_t, time_t and dev_t,	grow from 32 bits to 64	bits as	well.

       The  /proc  interfaces  described here are available to both 32-bit and
       64-bit controlling processes. However, many operations attempted	 by  a
       32-bit  controlling  process  on	a 64-bit target	process	will fail with
       EOVERFLOW because the address space range of a  32-bit  process	cannot
       encompass  a  64-bit  process or	because	the data in some 64-bit	system
       data type cannot	be compressed to fit  into  the	 corresponding	32-bit
       type  without loss of information. Operations that fail in this circum-
       stance include reading and  writing  the	 address  space,  reading  the
       address-map  file, and setting the target process's registers. There is
       no restriction on operations applied by a 64-bit	process	 to  either  a
       32-bit or a 64-bit target processes.

       The  format of the contents of any /proc	file depends on	the data model
       of the observer (the controlling	process), not on the data model	of the
       target process. A 64-bit	debugger does not have to translate the	infor-
       mation it reads from a /proc file for a 32-bit process from 32-bit for-
       mat  to	64-bit format. However,	it usually has to be aware of the data
       model of	the target process. The	pr_dmodel field	of  the	 status	 files
       indicates the target process's data model.

       To help deal with system	data structures	that are read from 32-bit pro-
       cesses, a 64-bit	controlling program can	be compiled with  the  C  pre-
       processor  symbol  _SYSCALL32  defined  before  system header files are
       included. This makes explicit 32-bit fixed-width	data structures	 (like
       cstruct stat32) visible to the 64-bit program. See types32.h(3HEAD).

DIRECTORY STRUCTURE
       At  the	top  level, the	directory /proc	contains entries each of which
       names an	existing process in the	system.	These entries  are  themselves
       directories.  Except  where  otherwise noted, the files described below
       can be opened for reading only. In addition, if	a  process  becomes  a
       zombie  (one  that  has exited but whose	parent has not yet performed a
       wait(3C)	upon it), most of its associated /proc	files  disappear  from
       the  hierarchy;	subsequent  attempts to	open them, or to read or write
       files opened before the process exited, will elicit the error ENOENT.

       Although	process	state and consequently the contents of /proc files can
       change  from  instant  to  instant, a single read(2) of a /proc file is
       guaranteed to return a sane representation of state; that is, the  read
       will  be	atomic with respect to the state of the	process. No such guar-
       antee applies to	successive reads applied to a /proc file for a running
       process.	 In  addition,	atomicity is not guaranteed for	I/O applied to
       the as (address-space) file for a running  process  or  for  a  process
       whose  address space contains memory shared by another running process.

       A number	of structure definitions are used to describe the files. These
       structures  may	grow  by the addition of elements at the end in	future
       releases	of the system and it is	not legitimate for a program to	assume
       that they will not.

STRUCTURE OF /proc/pid
       A  given	 directory /proc/pid contains the following entries. A process
       can use the invisible alias /proc/self if it wishes to open one of  its
       own /proc files (invisible in the sense that the	name ``self'' does not
       appear in a directory  listing  of  /proc  obtained  from  ls(1),  get-
       dents(2), or readdir(3C)).

   contracts
       A directory containing references to the	contracts held by the process.
       Each entry is a symlink to the contract's directory under  /system/con-
       tract. See contract(4).

   as
       Contains	 the  address-space image of the process; it can be opened for
       both reading and	writing. lseek(2) is used to position the file at  the
       virtual	address	of interest and	then the address space can be examined
       or changed through  read(2)  or	write(2)  (or  by  using  pread(2)  or
       pwrite(2) for the combined operation).

   ctl
       A  write-only  file  to which structured	messages are written directing
       the system to change some aspect	of the process's state or control  its
       behavior	 in  some way. The seek	offset is not relevant when writing to
       this file. Individual lwps also have associated lwpctl files in the lwp
       subdirectories.	A  control  message  may  be  written  either  to  the
       process's ctl file or to	a specific lwpctl file with operation-specific
       effects.	 The  effect  of a control message is immediately reflected in
       the state of the	process	visible	through	appropriate status and	infor-
       mation  files.  The  types  of control messages are described in	detail
       later. See CONTROL MESSAGES.

   status
       Contains	state information about	the  process  and  the	representative
       lwp.  The  file contains	a pstatus structure which contains an embedded
       lwpstatus structure for the representative lwp, as follows:

       typedef struct pstatus {
	    int	pr_flags;	      /* flags (see below) */
	    int	pr_nlwp;	      /* number	of active lwps in the process */
	    int	pr_nzomb;	      /* number	of zombie lwps in the process */
	    pid_tpr_pid;	      /* process id */
	    pid_tpr_ppid;	      /* parent	process	id */
	    pid_tpr_pgid;	      /* process group id */
	    pid_tpr_sid;	      /* session id */
	    id_t pr_aslwpid;	      /* obsolete */
	    id_t pr_agentid;	      /* lwp-id	of the agent lwp, if any */
	    sigset_t pr_sigpend;      /* set of	process	pending	signals	*/
	    uintptr_t pr_brkbase;     /* virtual address of the	process	heap */
	    size_t pr_brksize;	      /* size of the process heap, in bytes */
	    uintptr_t pr_stkbase;     /* virtual address of the	process	stack */
	    size_tpr_stksize;	      /* size of the process stack, in bytes */
	    timestruc_t	pr_utime;     /* process user cpu time */
	    timestruc_t	pr_stime;     /* process system	cpu time */
	    timestruc_t	pr_cutime;    /* sum of	children's user	times */
	    timestruc_t	pr_cstime;    /* sum of	children's system times	*/
	    sigset_t pr_sigtrace;     /* set of	traced signals */
	    fltset_t pr_flttrace;     /* set of	traced faults */
	    sysset_t pr_sysentry;     /* set of	system calls traced on entry */
	    sysset_t pr_sysexit;      /* set of	system calls traced on exit */
	    char pr_dmodel;	      /* data model of the process */
	    taskid_t pr_taskid;	      /* task id */
	    projid_t pr_projid;	      /* project id */
	    zoneid_t pr_zoneid;	      /* zone id */
	    lwpstatus_t	pr_lwp;	      /* status	of the representative lwp */
       } pstatus_t;

       pr_flags	is a bit-mask holding the following process flags. For	conve-
       nience,	it  also  contains  the	 lwp flags for the representative lwp,
       described later.

       PR_ISSYS	       process is a system process (see	PCSTOP).

       PR_VFORKP       process is the parent of	a vforked child	(see PCWATCH).

       PR_FORK	       process has its inherit-on-fork mode set	(see PCSET).

       PR_RLC	       process has its run-on-last-close mode set (see PCSET).

       PR_KLC	       process	has  its  kill-on-last-close  mode  set	  (see
		       PCSET).

       PR_ASYNC	       process has its asynchronous-stop mode set (see PCSET).

       PR_MSACCT       Set by  default	in  all	 processes  to	indicate  that
		       microstate  accounting  is  enabled. However, this flag
		       has been	deprecated  and	 no  longer  has  any  effect.
		       Microstate  accounting may not be disabled; however, it
		       is still	possible to toggle the flag.

       PR_MSFORK       Set by  default	in  all	 processes  to	indicate  that
		       microstate  accounting  will  be	 enabled for processes
		       that this parent	forks(). However, this flag  has  been
		       deprecated and no longer	has any	effect.	It is possible
		       to toggle this flag; however, it	 is  not  possible  to
		       disable microstate accounting.

       PR_BPTADJ       process	has  its  breakpoint  adjustment mode set (see
		       PCSET).

       PR_PTRACE       process has  its	 ptrace-compatibility  mode  set  (see
		       PCSET).

       pr_nlwp	is the total number of active lwps in the process. pr_nzomb is
       the total number	of zombie lwps in the process. A zombie	lwp is a  non-
       detached	 lwp  that  has	 terminated  but  has  not  been  reaped  with
       thr_join(3C) or pthread_join(3C).

       pr_pid, pr_ppid,	pr_pgid, and pr_sid are, respectively, the process ID,
       the ID of the process's parent, the process's process group ID, and the
       process's session ID.

       pr_aslwpid is obsolete and is always zero.

       pr_agentid is the lwp-ID	for the	/proc agent lwp	(see the PCAGENT  con-
       trol operation).	It is zero if there is no agent	lwp in the process.

       pr_sigpend identifies asynchronous signals pending for the process.

       pr_brkbase is the virtual address of the	process	heap and pr_brksize is
       its size	in bytes. The address formed by	the sum	of these values	is the
       process	break  (see  brk(2)).  pr_stkbase  and pr_stksize are, respec-
       tively, the virtual address of the process stack	and its	size in	bytes.
       (Each  lwp  runs	on a separate stack; the distinguishing	characteristic
       of the process stack is that the	operating system  will	grow  it  when
       necessary.)

       pr_utime,  pr_stime,  pr_cutime,	 and  pr_cstime	are, respectively, the
       user CPU	and system CPU time consumed by	the process, and  the  cumula-
       tive  user  CPU and system CPU time consumed by the process's children,
       in seconds and nanoseconds.

       pr_sigtrace and pr_flttrace contain, respectively, the set  of  signals
       and  the	set of hardware	faults that are	being traced (see PCSTRACE and
       PCSFAULT).

       pr_sysentry and pr_sysexit contain, respectively, the  sets  of	system
       calls being traced on entry and exit (see PCSENTRY and PCSEXIT).

       pr_dmodel indicates the data model of the process. Possible values are:

       PR_MODEL_ILP32	       process data model is ILP32.

       PR_MODEL_LP64	       process data model is LP64.

       PR_MODEL_NATIVE	       process data model is native.

       The pr_taskid, pr_projid, and pr_zoneid	fields	contain	 respectively,
       the numeric IDs of the task, project, and zone in which the process was
       running.

       The constant PR_MODEL_NATIVE reflects the data model of the controlling
       process,	 that is, its value is PR_MODEL_ILP32 or PR_MODEL_LP64 accord-
       ing to whether the controlling process has been compiled	 as  a	32-bit
       program or a 64-bit program, respectively.

       pr_lwp contains the status information for the representative lwp:

       typedef struct lwpstatus	{
	   int pr_flags;	       /* flags	(see below) */
	   id_t	pr_lwpid;	       /* specific lwp identifier */
	   short pr_why;	       /* reason for lwp stop, if stopped */
	   short pr_what;	       /* more detailed	reason */
	   short pr_cursig;	       /* current signal, if any */
	   siginfo_t pr_info;	       /* info associated with signal or fault */
	   sigset_t pr_lwppend;	       /* set of signals pending to the	lwp */
	   sigset_t pr_lwphold;	       /* set of signals blocked by the	lwp */
	   struct sigaction pr_action; /* signal action	for current signal */
	   stack_t pr_altstack;	       /* alternate signal stack info */
	   uintptr_t pr_oldcontext;    /* address of previous ucontext */
	   short pr_syscall;	       /* system call number (if in syscall) */
	   short pr_nsysarg;	       /* number of arguments to this syscall */
	   int pr_errno;	       /* errno	for failed syscall */
	   long	pr_sysarg[PRSYSARGS];  /* arguments to this syscall */
	   long	pr_rval1;	       /* primary syscall return value */
	   long	pr_rval2;	       /* second syscall return	value, if any */
	   char	pr_clname[PRCLSZ];     /* scheduling class name	*/
	   timestruc_t pr_tstamp;      /* real-time time stamp of stop */
	   timestruc_t pr_utime;       /* lwp user cpu time */
	   timestruc_t pr_stime;       /* lwp system cpu time */
	   uintptr_t pr_ustack;	       /* stack	boundary data (stack_t)	address	*/
	   ulong_t pr_instr;	       /* current instruction */
	   prgregset_t pr_reg;	       /* general registers */
	   prfpregset_t	pr_fpreg;      /* floating-point registers */
       } lwpstatus_t;

       pr_flags	 is  a	bit-mask  holding  the following lwp flags. For	conve-
       nience, it also contains	the process flags, described previously.

       PR_STOPPED      The lwp is stopped.

       PR_ISTOP	       The lwp	is  stopped  on	 an  event  of	interest  (see
		       PCSTOP).

       PR_DSTOP	       The lwp has a stop directive in effect (see PCSTOP).

       PR_STEP	       The  lwp	 has  a	 single-step  directive	in effect (see
		       PCRUN).

       PR_ASLEEP       The lwp is in an	interruptible sleep  within  a	system
		       call.

       PR_PCINVAL      The  lwp's current instruction (pr_instr) is undefined.

       PR_DETACH       This is a  detached  lwp	 (see  pthread_create(3C)  and
		       pthread_join(3C)).

       PR_DAEMON       This is a daemon	lwp (see pthread_create(3C)).

       PR_ASLWP	       This flag is obsolete and is never set.

       PR_AGENT	       This is the /proc agent lwp for the process.

       pr_lwpid	names the specific lwp.

       pr_why and pr_what together describe, for a stopped lwp,	the reason for
       the stop. Possible values of pr_why and the associated pr_what are:

       PR_REQUESTED    indicates that the stop occurred	in response to a  stop
		       directive,  normally  because  PCSTOP  was  applied  or
		       because another lwp stopped on an event of interest and
		       the  asynchronous-stop flag (see	PCSET) was not set for
		       the process. pr_what is unused in this case.

       PR_SIGNALLED    indicates that the lwp stopped on receipt of  a	signal
		       (see  PCSTRACE);	 pr_what  holds	the signal number that
		       caused the stop (for  a	newly-stopped  lwp,  the  same
		       value is	in pr_cursig).

       PR_FAULTED      indicates  that the lwp stopped on incurring a hardware
		       fault (see PCSFAULT); pr_what holds  the	 fault	number
		       that caused the stop.

       PR_SYSENTRY     indicate	 a stop	on entry to or exit from a system call
       PR_SYSEXIT      (see PCSENTRY and PCSEXIT); pr_what  holds  the	system
		       call number.

       PR_JOBCONTROL   indicates  that	the  lwp  stopped  due	to the default
		       action of a job control stop signal (see	sigaction(2));
		       pr_what holds the stopping signal number.

       PR_SUSPENDED    indicates that the lwp stopped due to internal synchro-
		       nization	of lwps	within the process. pr_what is	unused
		       in this case.

       pr_cursig  names	 the  current  signal,	that is, the next signal to be
       delivered to the	lwp, if	any. pr_info, when the lwp  is	in  a  PR_SIG-
       NALLED or PR_FAULTED stop, contains additional information pertinent to
       the particular signal or	fault (see <sys/siginfo.h>).

       pr_lwppend identifies any synchronous or	directed signals  pending  for
       the  lwp.  pr_lwphold  identifies those signals whose delivery is being
       blocked by the lwp (the signal mask).

       pr_action contains the signal action information	pertaining to the cur-
       rent  signal  (see sigaction(2)); it is undefined if pr_cursig is zero.
       pr_altstack contains the	alternate signal stack information for the lwp
       (see sigaltstack(2)).

       pr_oldcontext,  if not zero, contains the address on the	lwp stack of a
       ucontext	structure describing  the  previous  user-level	 context  (see
       ucontext.h(3HEAD)).  It is non-zero only	if the lwp is executing	in the
       context of a signal handler.

       pr_syscall is the number	of the system call, if any, being executed  by
       the  lwp; it is non-zero	if and only if the lwp is stopped on PR_SYSEN-
       TRY or PR_SYSEXIT, or is	asleep within a	system	call  (	 PR_ASLEEP  is
       set).  If pr_syscall is non-zero, pr_nsysarg is the number of arguments
       to the system call and pr_sysarg	contains the actual arguments.

       pr_rval1, pr_rval2, and pr_errno	are defined only if the	lwp is stopped
       on  PR_SYSEXIT  or  if  the PR_VFORKP flag is set. If pr_errno is zero,
       pr_rval1	and pr_rval2 contain the return	values from the	 system	 call.
       Otherwise,  pr_errno  contains  the error number	for the	failing	system
       call (see <sys/errno.h>).

       pr_clname contains the name of the lwp's	scheduling class.

       pr_tstamp, if the lwp is	stopped, contains a time  stamp	 marking  when
       the  lwp	 stopped,  in real time	seconds	and nanoseconds	since an arbi-
       trary time in the past.

       pr_utime	is the amount of user level CPU	time used by this LWP.

       pr_stime	is the amount of system	level CPU time used by this LWP.

       pr_ustack is the	virtual	address	of the stack_t that contains the stack
       boundaries for this LWP.	See getustack(2) and _stack_grow(3C).

       pr_instr	 contains  the	machine	instruction to which the lwp's program
       counter refers. The amount  of  data  retrieved	from  the  process  is
       machine-dependent.  On  SPARC  based  machines, it is a 32-bit word. On
       -based machines,	it is a	single byte. In	general, the size is  that  of
       the  machine's  smallest	instruction. If	PR_PCINVAL is set, pr_instr is
       undefined; this occurs whenever the lwp is not stopped or when the pro-
       gram counter refers to an invalid virtual address.

       pr_reg is an array holding the contents of a stopped lwp's general reg-
       isters.

       SPARC

	   On SPARC-based machines, the	predefined constants  R_G0  ...	 R_G7,
	   R_O0	 ...  R_O7, R_L0 ... R_L7, R_I0	... R_I7, R_PC,	R_nPC, and R_Y
	   can be used as indices to refer  to	the  corresponding  registers;
	   previous register windows can be read from their overflow locations
	   on  the  stack   (however,	see   the   gwindows   file   in   the
	   /proc/pid/lwp/lwpid subdirectory).

       SPARC V8	(32-bit)

	   For	SPARC  V8  (32-bit) controlling	processes, the predefined con-
	   stants R_PSR, R_WIM,	and R_TBR can be used as indices to  refer  to
	   the	corresponding  special	registers.  For	SPARC V9 (64-bit) con-
	   trolling processes, the  predefined	constants  R_CCR,  R_ASI,  and
	   R_FPRS can be used as indices to refer to the corresponding special
	   registers.

	(32-bit)

	   For 32-bit  processes, the predefined constants listed belowcan  be
	   used	as indices to refer to the corresponding registers.

	   SS
	   UESP
	   EFL
	   CS
	   EIP
	   ERR
	   TRAPNO
	   EAX
	   ECX
	   EDX
	   EBX
	   ESP
	   EBP
	   ESI
	   EDI
	   DS
	   ES
	   GS

	   The preceding constants are listed in <sys/regset.h>.

	   Note	 that a	32-bit process can run on an  64-bit system, using the
	   constants listed above.

	(64-bit)

	   To read the registers of a  32-  or	a  64-bit  process,  a	64-bit
	   process should use the predefined constants listed below.

	   REG_GSBASE
	   REG_FSBASE
	   REG_DS
	   REG_ES
	   REG_GS
	   REG_FS
	   REG_SS
	   REG_RSP
	   REG_RFL
	   REG_CS
	   REG_RIP
	   REG_ERR
	   REG_TRAPNO
	   REG_RAX
	   REG_RCX
	   REG_RDX
	   REG_RBX
	   REG_RBP
	   REG_RSI
	   REG_RDI
	   REG_R8
	   REG_R9
	   REG_R10
	   REG_R11
	   REG_R12
	   REG_R13
	   REG_R14
	   REG_R15

	   The preceding constants are listed in <sys/regset.h>.

       pr_fpreg	is a structure holding the contents of the floating-point reg-
       isters.

       SPARC registers,	both general and floating-point, as seen by  a	64-bit
       controlling  process  are the V9	versions of the	registers, even	if the
       target process is a 32-bit (V8) process.	V8 registers are a  subset  of
       the V9 registers.

       If the lwp is not stopped, all register values are undefined.

   psinfo
       Contains	 miscellaneous information about the process and the represen-
       tative lwp needed by the	ps(1) command. psinfo remains accessible after
       a  process becomes a zombie. The	file contains a	psinfo structure which
       contains	an embedded lwpsinfo structure for the representative lwp,  as
       follows:

       typedef struct psinfo {
	   int pr_flag;		     /*	process	flags (DEPRECATED: see below) */
	   int pr_nlwp;		     /*	number of active lwps in the process */
	   int pr_nzomb;	     /*	number of zombie lwps in the process */
	   pid_t pr_pid;	     /*	process	id */
	   pid_t pr_ppid;	     /*	process	id of parent */
	   pid_t pr_pgid;	     /*	process	id of process group leader */
	   pid_t pr_sid;	     /*	session	id */
	   uid_t pr_uid;	     /*	real user id */
	   uid_t pr_euid;	     /*	effective user id */
	   gid_t pr_gid;	     /*	real group id */
	   gid_t pr_egid;	     /*	effective group	id */
	   uintptr_t pr_addr;	     /*	address	of process */
	   size_t pr_size;	     /*	size of	process	image in Kbytes	*/
	   size_t pr_rssize;	     /*	resident set size in Kbytes */
	   dev_t pr_ttydev;	     /*	controlling tty	device (or PRNODEV) */
	   ushort_t pr_pctcpu;	     /*	% of recent cpu	time used by all lwps */
	   ushort_t pr_pctmem;	     /*	% of system memory used	by process */
	   timestruc_t pr_start;     /*	process	start time, from the epoch */
	   timestruc_t pr_time;	     /*	cpu time for this process */
	   timestruc_t pr_ctime;     /*	cpu time for reaped children */
	   char	pr_fname[PRFNSZ];    /*	name of	exec'ed	file */
	   char	pr_psargs[PRARGSZ];  /*	initial	characters of arg list */
	   int pr_wstat;	     /*	if zombie, the wait() status */
	   int pr_argc;		     /*	initial	argument count */
	   uintptr_t pr_argv;	     /*	address	of initial argument vector */
	   uintptr_t pr_envp;	     /*	address	of initial environment vector */
	   char	pr_dmodel;	     /*	data model of the process */
	   lwpsinfo_t pr_lwp;	     /*	information for	representative lwp */
	   taskid_t pr_taskid;	     /*	task id	*/
	   projid_t pr_projid;	     /*	project	id */
	   poolid_t pr_poolid;	     /*	pool id	*/
	   zoneid_t pr_zoneid;	     /*	zone id	*/
	   ctid_t pr_contract;	     /*	process	contract id */
       } psinfo_t;

       Some  of	the entries in psinfo, such as pr_addr,	refer to internal ker-
       nel data	structures and should not be expected to retain	their meanings
       across different	versions of the	operating system.

       psinfo_t.pr_flag	 is  a	deprecated  interface that should no longer be
       used. Applications currently relying on the SSYS	bit in pr_flag	should
       migrate to checking PR_ISSYS in the pstatus structure's pr_flags	field.

       pr_pctcpu and pr_pctmem are 16-bit binary fractions in the range	0.0 to
       1.0  with  the  binary point to the right of the	high-order bit (1.0 ==
       0x8000).	pr_pctcpu is the summation over	all lwps in the	process.

       pr_lwp contains the ps(1) information for the  representative  lwp.  If
       the  process  is	 a  zombie, pr_nlwp, pr_nzomb, and pr_lwp.pr_lwpid are
       zero and	the other fields of pr_lwp are undefined:

       typedef struct lwpsinfo {
	   int pr_flag;		     /*	lwp flags (DEPRECATED: see below) */
	   id_t	pr_lwpid;	     /*	lwp id */
	   uintptr_t pr_addr;	     /*	internal address of lwp	*/
	   uintptr_t pr_wchan;	     /*	wait addr for sleeping lwp */
	   char	pr_stype;	     /*	synchronization	event type */
	   char	pr_state;	     /*	numeric	lwp state */
	   char	pr_sname;	     /*	printable character for	pr_state */
	   char	pr_nice;	     /*	nice for cpu usage */
	   short pr_syscall;	     /*	system call number (if in syscall) */
	   char	pr_oldpri;	     /*	pre-SVR4, low value is high priority */
	   char	pr_cpu;		     /*	pre-SVR4, cpu usage for	scheduling */
	   int pr_pri;		     /*	priority, high value = high priority */
	   ushort_t pr_pctcpu;	     /*	% of recent cpu	time used by this lwp */
	   timestruc_t pr_start;     /*	lwp start time,	from the epoch */
	   timestruc_t pr_time;	     /*	cpu time for this lwp */
	   char	pr_clname[PRCLSZ];   /*	scheduling class name */
	   char	pr_name[PRFNSZ];     /*	name of	system lwp */
	   processorid_t pr_onpro;   /*	processor which	last ran this lwp */
	   processorid_t pr_bindpro; /*	processor to which lwp is bound	*/
	   psetid_t pr_bindpset;     /*	processor set to which lwp is bound */
       } lwpsinfo_t;

       Some of the entries in lwpsinfo,	such as	pr_addr,  pr_wchan,  pr_stype,
       pr_state,  and  pr_name,	 refer	to internal kernel data	structures and
       should not be expected to retain	their meanings across  different  ver-
       sions of	the operating system.

       lwpsinfo_t.pr_flag  is  a deprecated interface that should no longer be
       used.

       pr_pctcpu is a 16-bit binary fraction, as described  above.  It	repre-
       sents  the  CPU	time  used  by	the specific lwp. On a multi-processor
       machine,	the maximum value is 1/N, where	N is the number	of CPUs.

       pr_contract is the id of	the process contract of	which the process is a
       member. See contract(4) and process(4).

   cred
       Contains	a description of the credentials associated with the process:

       typedef struct prcred {
	    uid_t pr_euid;	/* effective user id */
	    uid_t pr_ruid;	/* real	user id	*/
	    uid_t pr_suid;	/* saved user id (from exec) */
	    gid_t pr_egid;	/* effective group id */
	    gid_t pr_rgid;	/* real	group id */
	    gid_t pr_sgid;	/* saved group id (from	exec) */
	    int	pr_ngroups;	/* number of supplementary groups */
	    gid_t pr_groups[1];	/* array of supplementary groups */
       } prcred_t;

       The  array  of associated supplementary groups in pr_groups is of vari-
       able length; the	cred file contains all of  the	supplementary  groups.
       pr_ngroups  indicates the number	of supplementary groups. (See also the
       PCSCRED and PCSCREDX control operations.)

   priv
       Contains	a description of the privileges	associated with	the process:

       typedef struct prpriv {
	    uint32_t	    pr_nsets;	   /* number of	privilege set */
	    uint32_t	    pr_setsize;	   /* size of privilege	set */
	    uint32_t	    pr_infosize;   /* size of supplementary data */
	    priv_chunk_t    pr_sets[1];	   /* array of sets */
       } prpriv_t;

       The actual dimension of the pr_sets[] field is

       pr_sets[pr_nsets][pr_setsize]

       which is	followed by additional information  about  the	process	 state
       pr_infosize bytes in size.

       The    full   size   of	 the   structure   can	 be   computed	 using
       PRIV_PRPRIV_SIZE(prpriv_t *).

   sigact
       Contains	an array of sigaction structures describing the	current	dispo-
       sitions	of  all	signals	associated with	the traced process (see	sigac-
       tion(2)).  Signal numbers are displaced by 1  from  array  indices,  so
       that  the  action  for  signal  number n	appears	in position n-1	of the
       array.

   auxv
       Contains	the initial values of the process's aux	vector in an array  of
       auxv_t  structures  (see	 <sys/auxv.h>).	The values are those that were
       passed by the operating system as startup information  to  the  dynamic
       linker.

   ldt
       This  file  exists only on -based machines. It is non-empty only	if the
       process has established a local descriptor table	(LDT).	If  non-empty,
       the file	contains the array of currently	active LDT entries in an array
       of elements of type struct ssd, defined in <sys/sysi86.h>, one  element
       for each	active LDT entry.

   map
       Contains	 information about the virtual address map of the process. The
       file contains an	array of prmap structures, each	of which  describes  a
       contiguous  virtual  address  region in the address space of the	traced
       process:

       typedef struct prmap {
	    uintptr_tpr_vaddr;	       /* virtual address of mapping */
	    size_t pr_size;	       /* size of mapping in bytes */
	    char pr_mapname[PRMAPSZ];  /* name in /proc/pid/object */
	    offset_t pr_offset;	       /* offset into mapped object, if	any */
	    int	pr_mflags;	       /* protection and attribute flags */
	    int	pr_pagesize;	       /* pagesize for this mapping in bytes */
	    int	pr_shmid;	       /* SysV shared memory identifier	*/
       } prmap_t;

       pr_vaddr	is the virtual	address	 of  the  mapping  within  the	traced
       process	and  pr_size  is its size in bytes. pr_mapname,	if it does not
       contain a null string, contains the name	of a file in the object	direc-
       tory (see below)	that can be opened read-only to	obtain a file descrip-
       tor for the mapped file associated with the  mapping.  This  enables  a
       debugger	 to  find object file symbol tables without having to know the
       real path names of the executable file  and  shared  libraries  of  the
       process.	pr_offset is the 64-bit	offset within the mapped file (if any)
       to which	the virtual address is mapped.

       pr_mflags is a bit-mask of protection and attribute flags:

       MA_READ	       mapping is readable by the traced process.

       MA_WRITE	       mapping is writable by the traced process.

       MA_EXEC	       mapping is executable by	the traced process.

       MA_SHARED       mapping changes are shared by the mapped	object.

       MA_ISM	       mapping	is  intimate   shared	memory	 (shared   MMU
		       resources)

       MAP_NORESERVE   mapping	does not have swap space reserved (mapped with
		       MAP_NORESERVE)

       MA_SHM	       mapping System V	shared memory

       A contiguous area of the	 address  space	 having	 the  same  underlying
       mapped  object  may  appear  as	multiple mappings due to varying read,
       write, and execute attributes. The underlying mapped  object  does  not
       change  over  the range of a single mapping. An I/O operation to	a map-
       ping marked MA_SHARED fails if applied at a virtual address not	corre-
       sponding	 to a valid page in the	underlying mapped object. A write to a
       MA_SHARED mapping that is not marked MA_WRITE fails. Reads  and	writes
       to  private  mappings  always  succeed.	Reads  and  writes to unmapped
       addresses fail.

       pr_pagesize is the page size for	the mapping, currently always the sys-
       tem pagesize.

       pr_shmid	 is the	shared memory identifier, if any, for the mapping. Its
       value is	-1  if	the  mapping  is  not  System  V  shared  memory.  See
       shmget(2).

   rmap
       Contains	 information about the reserved	address	ranges of the process.
       The file	contains an array of prmap structures, as  defined  above  for
       the  map	 file.	Each  structure	describes a contiguous virtual address
       region in the address space of the traced process that is  reserved  by
       the system in the sense that an mmap(2) system call that	does not spec-
       ify MAP_FIXED will not use any part of it for the new mapping. Examples
       of  such	 reservations  include	the  address  ranges  reserved for the
       process stack and the individual	 thread	 stacks	 of  a	multi-threaded
       process.

   cwd
       A  symbolic  link  to  the  process's  current  working	directory. See
       chdir(2). A readlink(2) of /proc/pid/cwd	yields a null string. However,
       it  can	be opened, listed, and searched	as a directory,	and can	be the
       target of chdir(2).

   root
       A symbolic link to the process's	 root  directory.  /proc/pid/root  can
       differ  from  the  system  root	directory if the process or one	of its
       ancestors executed chroot(2) as super user. It has the  same  semantics
       as /proc/pid/cwd.

   fd
       A  directory  containing	 references  to	the open files of the process.
       Each entry is a decimal number corresponding to an open file descriptor
       in the process.

       If an entry refers to a regular file, it	can be opened with normal file
       system semantics	but, to	ensure that  the  controlling  process	cannot
       gain  greater  access  than the controlled process, with	no file	access
       modes other than	its read/write open modes in the  controlled  process.
       If  an  entry  refers  to a directory, it can be	accessed with the same
       semantics as /proc/pid/cwd. An attempt to open any other	type of	 entry
       fails with EACCES.

   object
       A  directory containing read-only files with names corresponding	to the
       pr_mapname entries in the map and pagedata files. Opening such  a  file
       yields a	file descriptor	for the	underlying mapped file associated with
       an address-space	mapping	in the process.	The file name a.out appears in
       the directory as	an alias for the process's executable file.

       The  object  directory  makes  it possible for a	controlling process to
       gain access to the object file and any  shared  libraries  (and	conse-
       quently the symbol tables) without having to know the actual path names
       of the executable files.

   path
       A directory containing symbolic links to	files opened by	 the  process.
       The  directory  includes	one entry for cwd and root. The	directory also
       contains	a numerical entry for each file	descriptor in  the  fd	direc-
       tory,  and  entries  matching  those  in	 the object directory. If this
       information is not avilable, any	attempt	to read	the  contents  of  the
       symbolic	 link  will  fail.  This  is most common for files that	do not
       exist in	the filesystem namespace (such as FIFOs	and sockets), but  can
       also  happen  for  regular  files. For the file descriptor entries, the
       path may	be different from the one used by  the	process	 to  open  the
       file.

   pagedata
       Opening the page	data file enables tracking of address space references
       and modifications on a per-page basis.

       A read(2) of the	page data file descriptor returns structured page data
       and atomically clears the page data maintained for the file by the sys-
       tem. That is to say, each read returns data collected  since  the  last
       read;  the first	read returns data collected since the file was opened.
       When the	call completes,	the read buffer	contains the following	struc-
       ture  as	 its header and	thereafter contains a number of	section	header
       structures and associated byte arrays that must be accessed by  walking
       linearly	through	the buffer.

       typedef struct prpageheader {
	   timestruc_t pr_tstamp; /* real time stamp, time of read() */
	   ulong_t pr_nmap;	  /* number of address space mappings */
	   ulong_t pr_npage;	  /* total number of pages */
       } prpageheader_t;

       The  header  is	followed  by pr_nmap prasmap structures	and associated
       data arrays. The	prasmap	structure contains the following elements:

       typedef struct prasmap {
	   uintptr_t pr_vaddr;	      /* virtual address of mapping */
	   ulong_t pr_npage;	      /* number	of pages in mapping */
	   char	pr_mapname[PRMAPSZ];  /* name in /proc/pid/object */
	   offset_t pr_offset;	      /* offset	into mapped object, if any */
	   int pr_mflags;	      /* protection and	attribute flags	*/
	   int pr_pagesize;	      /* pagesize for this mapping in bytes */
	   int pr_shmid;	      /* SysV shared memory identifier */
       } prasmap_t;

       Each section header is followed by pr_npage bytes, one  byte  for  each
       page  in	 the  mapping, plus 0-7	null bytes at the end so that the next
       prasmap structure begins	on an eight-byte aligned boundary.  Each  data
       byte may	contain	these flags:

       PG_REFERENCED	       page has	been referenced.

       PG_MODIFIED	       page has	been modified.

       If the read buffer is not large enough to contain all of	the page data,
       the read	fails with E2BIG  and  the  page  data	is  not	 cleared.  The
       required	 size  of  the read buffer can be determined through fstat(2).
       Application of lseek(2) to the page data	file  descriptor  is  ineffec-
       tive;  every  read  starts  from	the beginning of the file. Closing the
       page data file descriptor terminates  the  system  overhead  associated
       with collecting the data.

       More  than  one	page  data file	descriptor for the same	process	can be
       opened, up to a system-imposed limit per	traced process.	A read of  one
       does  not affect	the data being collected by the	system for the others.
       An open of the page data	file will fail	with  ENOMEM  if  the  system-
       imposed limit would be exceeded.

   watch
       Contains	 an  array  of	prwatch	 structures, one for each watched area
       established by the PCWATCH control operation. See PCWATCH for  details.

   usage
       Contains	 process  usage	 information  described	by a prusage structure
       which contains at least the following fields:

       typedef struct prusage {
	   id_t	pr_lwpid;	    /* lwp id.	0: process or defunct */
	   int pr_count;	    /* number of contributing lwps */
	   timestruc_t pr_tstamp;   /* real time stamp,	time of	read() */
	   timestruc_t pr_create;   /* process/lwp creation time stamp */
	   timestruc_t pr_term;	    /* process/lwp termination time stamp */
	   timestruc_t pr_rtime;    /* total lwp real (elapsed)	time */
	   timestruc_t pr_utime;    /* user level CPU time */
	   timestruc_t pr_stime;    /* system call CPU time */
	   timestruc_t pr_ttime;    /* other system trap CPU time */
	   timestruc_t pr_tftime;   /* text page fault sleep time */
	   timestruc_t pr_dftime;   /* data page fault sleep time */
	   timestruc_t pr_kftime;   /* kernel page fault sleep time */
	   timestruc_t pr_ltime;    /* user lock wait sleep time */
	   timestruc_t pr_slptime;  /* all other sleep time */
	   timestruc_t pr_wtime;    /* wait-cpu	(latency) time */
	   timestruc_t pr_stoptime; /* stopped time */
	   ulong_t pr_minf;	    /* minor page faults */
	   ulong_t pr_majf;	    /* major page faults */
	   ulong_t pr_nswap;	    /* swaps */
	   ulong_t pr_inblk;	    /* input blocks */
	   ulong_t pr_oublk;	    /* output blocks */
	   ulong_t pr_msnd;	    /* messages	sent */
	   ulong_t pr_mrcv;	    /* messages	received */
	   ulong_t pr_sigs;	    /* signals received	*/
	   ulong_t pr_vctx;	    /* voluntary context switches */
	   ulong_t pr_ictx;	    /* involuntary context switches */
	   ulong_t pr_sysc;	    /* system calls */
	   ulong_t pr_ioch;	    /* chars read and written */
       } prusage_t;

       Microstate accounting is	now continuously enabled. While	this  informa-
       tion  was  previously  an  estimate,  if	microstate accounting were not
       enabled,	the current information	is now never  an  estimate  represents
       time the	process	has spent in various states.

   lstatus
       Contains	 a prheader structure followed by an array of lwpstatus	struc-
       tures,  one  for	 each  active	lwp   in   the	 process   (see	  also
       /proc/pid/lwp/lwpid/lwpstatus, below). The prheader structure describes
       the number and size of the array	entries	that follow.

       typedef struct prheader {
	   long	pr_nent;	/* number of entries */
	   size_t pr_entsize;	/* size	of each	entry, in bytes	*/
       } prheader_t;

       The lwpstatus structure may grow	by the addition	of elements at the end
       in  future  releases of the system. Programs must use pr_entsize	in the
       file header to index through the	array. These  comments	apply  to  all
       /proc  files  that  include  a  prheader	structure (lpsinfo and lusage,
       below).

   lpsinfo
       Contains	a prheader structure followed by an array of  lwpsinfo	struc-
       tures,  one  for	 eachactive  and  zombie  lwp in the process. See also
       /proc/pid/lwp/lwpid/lwpsinfo, below.

   lusage
       Contains	a prheader structure followed by an array  of  prusage	struc-
       tures,  one for each active lwp in the process, plus an additional ele-
       ment at the beginning that contains the summation over all defunct lwps
       (lwps  that once	existed	but no longer exist in the process). Excluding
       the pr_lwpid, pr_tstamp,	pr_create, and pr_term entries,	the  entry-by-
       entry  summation	 over  all  these  structures is the definition	of the
       process usage information obtained  from	 the  usage  file.  (See  also
       /proc/pid/lwp/lwpid/lwpusage, below.)

   lwp
       A  directory containing entries each of which names an active or	zombie
       lwp within the process. These entries are themselves  directories  con-
       taining	additional  files  as  described below.	Only the lwpsinfo file
       exists in the directory of a zombie lwp.

STRUCTURE OF /proc/pid/lwp/ lwpid
       A given directory /proc/pid/lwp/lwpid contains the following entries:

   lwpctl
       Write-only control file.	The messages written to	this file  affect  the
       specific	lwp rather than	the representative lwp,	as is the case for the
       process's ctl file.

   lwpstatus
       lwp-specific state information. This file contains the lwpstatus	struc-
       ture for	the specific lwp as described above for	the representative lwp
       in the process's	status file.

   lwpsinfo
       lwp-specific ps(1) information. This file contains the lwpsinfo	struc-
       ture for	the specific lwp as described above for	the representative lwp
       in the process's	psinfo file.  The  lwpsinfo  file  remains  accessible
       after an	lwp becomes a zombie.

   lwpusage
       This  file  contains  the  prusage  structure  for  the specific	lwp as
       described above for the process's usage file.

   gwindows
       This file exists	only on	SPARC based machines. If it is	non-empty,  it
       contains	 a  gwindows_t	structure, defined in <sys/regset.h>, with the
       values of those SPARC register windows that could not be	stored on  the
       stack when the lwp stopped. Conditions under which register windows are
       not stored on the stack are: the	stack pointer  refers  to  nonexistent
       process	memory	or the stack pointer is	improperly aligned. If the lwp
       is not stopped or if there are no register windows that	could  not  be
       stored on the stack, the	file is	empty (the usual case).

   xregs
       Extra  state  registers.	 The  extra state register set is architecture
       dependent; this file is empty if	the  system  does  not	support	 extra
       state  registers. If the	file is	non-empty, it contains an architecture
       dependent structure of type prxregset_t,	defined	 in  <procfs.h>,  with
       the  values  of	the  lwp's  extra  state  registers. If	the lwp	is not
       stopped,	all register values are	undefined. See also the	 PCSXREG  con-
       trol operation, below.

   asrs
       This  file  exists  only	 for 64-bit SPARC V9 processes.	It contains an
       asrset_t	structure, defined in <sys/regset.h>, containing the values of
       the  lwp's  platform-dependent ancillary	state registers. If the	lwp is
       not stopped, all	register values	are undefined. See  also  the  PCSASRS
       control operation, below.

   templates
       A  directory  which contains references to the active templates for the
       lwp, named by the contract type.	Changes	made  to  an  active  template
       descriptor  do  not  affect  the	original template which	was activated,
       though they do affect the active	template. It is	not possible to	 acti-
       vate an active template descriptor. See contract(4).

CONTROL	MESSAGES
       Process	state  changes	are  effected  through	messages  written to a
       process's ctl file or to	an individual lwp's lwpctl file.  All  control
       messages	 consist  of a long that names the specific operation followed
       by additional data containing the operand, if any.

       Multiple	control	messages may be	combined  in  a	 single	 write(2)  (or
       writev(2)) to a control file, but no partial writes are permitted. That
       is, each	control	message, operation code	plus operand, if any, must  be
       presented  in  its entirety to the write(2) and not in pieces over sev-
       eral system calls. If a control operation fails,	no  subsequent	opera-
       tions contained in the same write(2) are	attempted.

       Descriptions  of	 the  allowable	control	messages follow. In all	cases,
       writing a message to a control file for a process or lwp	that has  ter-
       minated elicits the error ENOENT.

   PCSTOP PCDSTOP PCWSTOP PCTWSTOP
       When  applied  to  the process control file, PCSTOP directs all lwps to
       stop and	waits for them to stop,	PCDSTOP	directs	all lwps to stop with-
       out  waiting for	them to	stop, and PCWSTOP simply waits for all lwps to
       stop. When applied to an	lwp control file, PCSTOP directs the  specific
       lwp  to	stop  and waits	until it has stopped, PCDSTOP directs the spe-
       cific lwp to stop without waiting for it	to stop,  and  PCWSTOP	simply
       waits  for  the	specific  lwp  to stop.	When applied to	an lwp control
       file, PCSTOP and	PCWSTOP	complete when the lwp stops  on	 an  event  of
       interest,  immediately  if  already  so	stopped;  when	applied	to the
       process control file, they complete when	every lwp has  stopped	either
       on an event of interest or on a PR_SUSPENDED stop.

       PCTWSTOP	 is  identical to PCWSTOP except that it enables the operation
       to time out, to avoid waiting forever for a process  or	lwp  that  may
       never stop on an	event of interest. PCTWSTOP takes a long operand spec-
       ifying a	number of milliseconds;	the wait will  terminate  successfully
       after  the  specified number of milliseconds even if the	process	or lwp
       has not stopped;	a timeout value	of zero	makes the operation  identical
       to PCWSTOP.

       An  ``event  of interest'' is either a PR_REQUESTED stop	or a stop that
       has been	specified in the process's tracing  flags  (set	 by  PCSTRACE,
       PCSFAULT,  PCSENTRY, and	PCSEXIT). PR_JOBCONTROL	and PR_SUSPENDED stops
       are specifically	not events of interest.	(An lwp	may stop twice due  to
       a  stop	signal,	first showing PR_SIGNALLED if the signal is traced and
       again showing PR_JOBCONTROL if the lwp is set running without  clearing
       the signal.) If PCSTOP or PCDSTOP is applied to an lwp that is stopped,
       but not on an event of interest,	the stop directive takes  effect  when
       the  lwp	is restarted by	the competing mechanism. At that time, the lwp
       enters a	PR_REQUESTED stop before executing any user-level code.

       A write of a control message that blocks	is interruptible by  a	signal
       so  that,  for example, an alarm(2) can be set to avoid waiting forever
       for a process or	lwp that may never stop	on an event  of	 interest.  If
       PCSTOP  is  interrupted,	 the lwp stop directives remain	in effect even
       though the write(2) returns an error. (Use of PCTWSTOP with a  non-zero
       timeout is recommended over PCWSTOP with	an alarm(2).)

       A  system  process  (indicated  by the PR_ISSYS flag) never executes at
       user level, has no user-level address space visible through /proc,  and
       cannot be stopped. Applying one of these	operations to a	system process
       or any of its lwps elicits the error EBUSY.

   PCRUN
       Make an lwp runnable again after	a stop.	This operation	takes  a  long
       operand containing zero or more of the following	flags:

       PRCSIG	       clears the current signal, if any (see PCCSIG).

       PRCFAULT	       clears the current fault, if any	(see PCCFAULT).

       PRSTEP	       directs	the  lwp  to execute a single machine instruc-
		       tion. On	completion of the instruction,	a  trace  trap
		       occurs.	If  FLTTRACE  is  being	traced,	the lwp	stops;
		       otherwise, it is	sent  SIGTRAP.	If  SIGTRAP  is	 being
		       traced  and is not blocked, the lwp stops. When the lwp
		       stops on	an event of interest, the  single-step	direc-
		       tive  is	 cancelled, even if the	stop occurs before the
		       instruction is executed.	This operation requires	 hard-
		       ware and	operating system support and may not be	imple-
		       mented on all processors. It is	implemented  on	 SPARC
		       and -based machines.

       PRSABORT	       is  meaningful only if the lwp is in a PR_SYSENTRY stop
		       or is marked PR_ASLEEP; it instructs the	lwp  to	 abort
		       execution   of	the  system  call  (see	 PCSENTRY  and
		       PCSEXIT).

       PRSTOP	       directs the lwp to stop again as	soon as	possible after
		       resuming	execution (see PCDSTOP). In particular,	if the
		       lwp is stopped on PR_SIGNALLED or PR_FAULTED, the  next
		       stop  will  show	 PR_REQUESTED, no other	stop will have
		       intervened, and the lwp	will  not  have	 executed  any
		       user-level code.

       When  applied  to  an  lwp  control  file, PCRUN	clears any outstanding
       directed-stop request and makes the specific lwp	runnable.  The	opera-
       tion fails with EBUSY if	the specific lwp is not	stopped	on an event of
       interest	or has not been	directed to stop or if the  agent  lwp	exists
       and this	is not the agent lwp (see PCAGENT).

       When  applied to	the process control file, a representative lwp is cho-
       sen for the operation as	described for /proc/pid/status.	The  operation
       fails  with  EBUSY if the representative	lwp is not stopped on an event
       of interest or has not been directed  to	 stop  or  if  the  agent  lwp
       exists.	If  PRSTEP  or PRSTOP was requested, the representative	lwp is
       made runnable and its outstanding  directed-stop	 request  is  cleared;
       otherwise all outstanding directed-stop requests	are cleared and, if it
       was stopped on an event of interest, the	representative lwp  is	marked
       PR_REQUESTED. If, as a consequence, all lwps are	in the PR_REQUESTED or
       PR_SUSPENDED  stop  state,  all	lwps  showing  PR_REQUESTED  are  made
       runnable.

   PCSTRACE
       Define a	set of signals to be traced in the process. The	receipt	of one
       of these	signals	by an lwp causes the lwp to stop. The set  of  signals
       is  defined using an operand sigset_t contained in the control message.
       Receipt of SIGKILL cannot be  traced;  if  specified,  it  is  silently
       ignored.

       If  a  signal  that is included in an lwp's held	signal set (the	signal
       mask) is	sent to	the lwp, the signal is not received and	does not cause
       a  stop until it	is removed from	the held signal	set, either by the lwp
       itself or by setting the	held signal set	with PCSHOLD.

   PCCSIG
       The current signal, if any, is cleared from the specific	or representa-
       tive lwp.

   PCSSIG
       The  current  signal and	its associated signal information for the spe-
       cific or	representative lwp are set according to	the  contents  of  the
       operand	siginfo	structure (see <sys/siginfo.h>). If the	specified sig-
       nal number is zero, the current signal is  cleared.  The	 semantics  of
       this  operation	are different from those of kill(2) in that the	signal
       is delivered to the lwp immediately after execution is resumed (even if
       it  is  being  blocked)	and  an	 additional PR_SIGNALLED stop does not
       intervene even if the signal is traced. Setting the current  signal  to
       SIGKILL terminates the process immediately.

   PCKILL
       If applied to the process control file, a signal	is sent	to the process
       with semantics identical	to those of kill(2). If	applied	to an lwp con-
       trol file, a directed signal is sent to the specific lwp. The signal is
       named in	a long operand contained in the	message. Sending SIGKILL  ter-
       minates the process immediately.

   PCUNKILL
       A  signal  is  deleted,	that is, it is removed from the	set of pending
       signals.	If applied to the process control file,	the signal is  deleted
       from  the process's pending signals. If applied to an lwp control file,
       the signal is deleted from the lwp's pending signals. The current  sig-
       nal  (if	 any)  is unaffected. The signal is named in a long operand in
       the control message. It is an  error  (EINVAL)  to  attempt  to	delete
       SIGKILL.

   PCSHOLD
       Set  the	 set  of  held	signals	for the	specific or representative lwp
       (signals	whose delivery will be blocked if sent to the lwp). The	set of
       signals	is specified with a sigset_t operand. SIGKILL and SIGSTOP can-
       not be held; if specified, they are silently ignored.

   PCSFAULT
       Define a	set of hardware	faults to be traced in the process. On	incur-
       ring  one of these faults, an lwp stops.	The set	is defined via the op-
       erand fltset_t structure. Fault names are defined in <sys/fault.h>  and
       include	the  following.	Some of	these may not occur on all processors;
       there may be processor-specific faults in addition to these.

       FLTILL	       illegal instruction

       FLTPRIV	       privileged instruction

       FLTBPT	       breakpoint trap

       FLTTRACE	       trace trap (single-step)

       FLTWATCH	       watchpoint trap

       FLTACCESS       memory access fault (bus	error)

       FLTBOUNDS       memory bounds violation

       FLTIOVF	       integer overflow

       FLTIZDIV	       integer zero divide

       FLTFPE	       floating-point exception

       FLTSTACK	       unrecoverable stack fault

       FLTPAGE	       recoverable page	fault

       When not	traced,	a fault	normally results in the	posting	of a signal to
       the lwp that incurred the fault.	If an lwp stops	on a fault, the	signal
       is posted to the	lwp when execution is  resumed	unless	the  fault  is
       cleared	by  PCCFAULT or	by the PRCFAULT	option of PCRUN. FLTPAGE is an
       exception; no signal is posted. The  pr_info  field  in	the  lwpstatus
       structure  identifies  the  signal to be	sent and contains machine-spe-
       cific information about the fault.

   PCCFAULT
       The current fault, if any, is cleared; the associated signal  will  not
       be sent to the specific or representative lwp.

   PCSENTRY PCSEXIT
       These  control  operations instruct the process's lwps to stop on entry
       to or exit from specified system	calls. The set of system calls	to  be
       traced is defined via an	operand	sysset_t structure.

       When  entry to a	system call is being traced, an	lwp stops after	having
       begun the call to the system but	before the system call arguments  have
       been  fetched  from  the	 lwp.  When  exit  from	a system call is being
       traced, an lwp stops on completion of the system	 call  just  prior  to
       checking	 for  signals  and returning to	user level. At this point, all
       return values have been stored into the lwp's registers.

       If an lwp is stopped on entry to	a system call  (PR_SYSENTRY)  or  when
       sleeping	 in an interruptible system call (PR_ASLEEP is set), it	may be
       instructed to go	 directly  to  system  call  exit  by  specifying  the
       PRSABORT	 flag  in a PCRUN control message. Unless exit from the	system
       call is being traced, the lwp returns to	user level showing EINTR.

   PCWATCH
       Set or clear a watched area in the controlled process  from  a  prwatch
       structure operand:

       typedef struct prwatch {
	   uintptr_t pr_vaddr;	/* virtual address of watched area */
	   size_t pr_size;	/* size	of watched area	in bytes */
	   int pr_wflags;	/* watch type flags */
       } prwatch_t;

       pr_vaddr	 specifies  the	 virtual  address  of  an area of memory to be
       watched in the controlled process. pr_size specifies the	 size  of  the
       area,  in  bytes.  pr_wflags  specifies the type	of memory access to be
       monitored as a bit-mask of the following	flags:

       WA_READ		       read access

       WA_WRITE		       write access

       WA_EXEC		       execution access

       WA_TRAPAFTER	       trap after the instruction completes

       If pr_wflags is non-empty, a watched area is established	for  the  vir-
       tual  address  range specified by pr_vaddr and pr_size. If pr_wflags is
       empty, any previously-established watched area starting at  the	speci-
       fied virtual address is cleared;	pr_size	is ignored.

       A  watchpoint  is  triggered  when an lwp in the	traced process makes a
       memory reference	that covers at least one byte of a  watched  area  and
       the memory reference is as specified in pr_wflags. When an lwp triggers
       a watchpoint, it	incurs a watchpoint trap. If FLTWATCH is being traced,
       the  lwp	 stops;	 otherwise, it is sent a SIGTRAP signal; if SIGTRAP is
       being traced and	is not blocked,	the lwp	stops.

       The watchpoint trap occurs  before  the	instruction  completes	unless
       WA_TRAPAFTER  was specified, in which case it occurs after the instruc-
       tion completes. If it occurs before completion, the memory is not modi-
       fied.  If  it  occurs  after completion,	the memory is modified (if the
       access is a write access).

       Physical	i/o is an exception for	watchpoint traps.  In  this  instance,
       there  is  no guarantee that memory before the watched area has already
       been modified (or in the	case of	WA_TRAPAFTER, that the memory  follow-
       ing  the	 watched  area has not been modified) when the watchpoint trap
       occurs and the lwp stops.

       pr_info in the lwpstatus	structure contains  information	 pertinent  to
       the watchpoint trap. In particular, the si_addr field contains the vir-
       tual address of the memory reference that triggered the watchpoint, and
       the   si_code  field  contains  one  of	TRAP_RWATCH,  TRAP_WWATCH,  or
       TRAP_XWATCH, indicating read, write, or execute	access,	 respectively.
       The  si_trapafter  field	 is  zero unless WA_TRAPAFTER is in effect for
       this watched area; non-zero indicates that the current  instruction  is
       not  the	instruction that incurred the watchpoint trap. The si_pc field
       contains	the virtual address of the instruction that incurred the trap.

       A  watchpoint  trap may be triggered while executing a system call that
       makes reference to the traced process's memory. The lwp that is execut-
       ing  the	system call incurs the watchpoint trap while still in the sys-
       tem call. If it stops as	a result, the lwpstatus	structure contains the
       system  call  number and	its arguments. If the lwp does not stop, or if
       it is set running again without clearing	the signal or fault, the  sys-
       tem  call  fails	with EFAULT. If	WA_TRAPAFTER was specified, the	memory
       reference will have completed and the memory will  have	been  modified
       (if the access was a write access) when the watchpoint trap occurs.

       If  more	 than one of WA_READ, WA_WRITE,	and WA_EXEC is specified for a
       watched area, and a single instruction incurs  more  than  one  of  the
       specified  types, only one is reported when the watchpoint trap occurs.
       The precedence is WA_EXEC, WA_READ, WA_WRITE (WA_EXEC and WA_READ  take
       precedence  over	WA_WRITE), unless WA_TRAPAFTER was specified, in which
       case it is WA_WRITE, WA_READ, WA_EXEC (WA_WRITE takes precedence).

       PCWATCH fails with EINVAL if an attempt is made to specify  overlapping
       watched areas or	if pr_wflags contains flags other than those specified
       above. It fails with ENOMEM if an attempt is  made  to  establish  more
       watched areas than the system can support (the system can support thou-
       sands).

       The child of a vfork(2) borrows the  parent's  address  space.  When  a
       vfork(2)	is executed by a traced	process, all watched areas established
       for the parent are suspended until the child terminates or performs  an
       exec(2).	 Any  watched areas established	independently in the child are
       cancelled when the parent resumes  after	 the  child's  termination  or
       exec(2).	 PCWATCH  fails	 with  EBUSY  if  applied  to  the parent of a
       vfork(2)	before the child has terminated	or performed an	 exec(2).  The
       PR_VFORKP  flag	is  set	 in  the  pstatus  structure for such a	parent
       process.

       Certain accesses	of the traced process's	address	space by the operating
       system  are immune to watchpoints. The initial construction of a	signal
       stack frame when	a signal is delivered to an lwp	 will  not  trigger  a
       watchpoint  trap	 even  if  the	new  frame covers watched areas	of the
       stack. Once the signal handler is entered, watchpoint traps occur  nor-
       mally.  On SPARC	based machines,	register window	overflow and underflow
       will not	trigger	watchpoint traps, even if  the	register  window  save
       areas cover watched areas of the	stack.

       Watched	areas are not inherited	by child processes, even if the	traced
       process's inherit-on-fork mode, PR_FORK,	is set (see PCSET, below). All
       watched areas are cancelled when	the traced process performs a success-
       ful exec(2).

   PCSET PCUNSET
       PCSET sets one or more modes of operation for the traced	process. PCUN-
       SET  unsets  these modes. The modes to be set or	unset are specified by
       flags in	an operand long	in the control message:

       PR_FORK	       (inherit-on-fork):  When	 set,  the  process's  tracing
		       flags and its inherit-on-fork mode are inherited	by the
		       child of	a fork(2), fork1(2), or	vfork(2). When	unset,
		       child processes start with all tracing flags cleared.

       PR_RLC	       (run-on-last-close):  When  set	and  the last writable
		       /proc file descriptor referring to the  traced  process
		       or  any	of  its	 lwps  is closed, all of the process's
		       tracing flags and watched areas are cleared,  any  out-
		       standing	 stop directives are canceled, and if any lwps
		       are stopped on events of	interest, they are set running
		       as  though  PCRUN had been applied to them. When	unset,
		       the process's  tracing  flags  and  watched  areas  are
		       retained	and lwps are not set running on	last close.

       PR_KLC	       (kill-on-last-close):  When  set	 and the last writable
		       /proc file descriptor referring to the  traced  process
		       or any of its lwps is closed, the process is terminated
		       with SIGKILL.

       PR_ASYNC	       (asynchronous-stop): When set, a	stop on	 an  event  of
		       interest	 by one	lwp does not directly affect any other
		       lwp in the process. When	unset and an lwp stops	on  an
		       event  of  interest  other than PR_REQUESTED, all other
		       lwps in the process are directed	to stop.

       PR_MSACCT       (microstate accounting):	Microstate accounting  is  now
		       continuously  enabled.  This  flag is deprecated	and no
		       longer  has  any	 effect	 upon  microstate  accounting.
		       Applications  may toggle	this flag; however, microstate
		       accounting will remain enabled regardless.

       PR_MSFORK       (inherit	 microstate  accounting):  All	processes  now
		       inherit	microstate  accounting,	 as it is continuously
		       enabled.	This flag has been deprecated and its  use  no
		       longer  has  any	effect upon the	behavior of microstate
		       accounting.

       PR_BPTADJ       (breakpoint trap	pc adjustment):	On -based machines,  a
		       breakpoint  trap	 leaves	 the program counter (the EIP)
		       referring to  the  breakpointed	instruction  plus  one
		       byte.   When  PR_BPTADJ	is set,	the system will	adjust
		       the program counter back	to the location	of the	break-
		       pointed instruction when	the lwp	stops on a breakpoint.
		       This flag has no	effect on SPARC	based machines,	 where
		       breakpoint traps	leave the program counter referring to
		       the breakpointed	instruction.

       PR_PTRACE       (ptrace-compatibility): When set, a stop	on an event of
		       interest	 by the	traced process is reported to the par-
		       ent of the traced process by wait(3C), SIGTRAP is  sent
		       to  the	traced	process	 when it executes a successful
		       exec(2),	setuid/setgid flags are	not honored for	 execs
		       performed  by the traced	process, any exec of an	object
		       file that the traced process cannot read	fails, and the
		       process	dies when its parent dies. This	mode is	depre-
		       cated; it is provided only to allow  ptrace(3C)	to  be
		       implemented as a	library	function using /proc.

       It  is  an  error  (EINVAL) to specify flags other than those described
       above or	to apply these operations to a	system	process.  The  current
       modes  are  reported  in	 the  pr_flags	field  of /proc/pid/status and
       /proc/pid/lwp/lwp/lwpstatus.

   PCSREG
       Set the general	registers  for	the  specific  or  representative  lwp
       according to the	operand	prgregset_t structure.

       On  SPARC based systems,	only the condition-code	bits of	the processor-
       status register (R_PSR) of SPARC	V8 (32-bit) processes can be  modified
       by PCSREG. Other	privileged registers cannot be modified	at all.

       On -based systems, only certain bits of the flags register (EFL)	can be
       modified	by PCSREG: these include the condition	codes,	direction-bit,
       and overflow-bit.

       PCSREG fails with EBUSY if the lwp is not stopped on an event of	inter-
       est.

   PCSVADDR
       Set the address at which	execution will resume for the specific or rep-
       resentative lwp from the	operand	long. On SPARC based systems, both %pc
       and %npc	are set, with %npc set to the instruction following  the  vir-
       tual  address. On -based	systems, only %eip is set. PCSVADDR fails with
       EBUSY if	the lwp	is not stopped on an event of interest.

   PCSFPREG
       Set the floating-point registers	for the	specific or representative lwp
       according  to the operand prfpregset_t structure.  An error (EINVAL) is
       returned	if the system does not support floating-point  operations  (no
       floating-point  hardware	and the	system does not	emulate	floating-point
       machine instructions). PCSFPREG fails with EBUSY	 if  the  lwp  is  not
       stopped on an event of interest.

   PCSXREG
       Set  the	 extra	state registers	for the	specific or representative lwp
       according to the	architecture-dependent operand prxregset_t  structure.
       An  error  (EINVAL)  is	returned  if the system	does not support extra
       state registers.	PCSXREG	fails with EBUSY if the	lwp is not stopped  on
       an event	of interest.

   PCSASRS
       Set  the	 ancillary  state registers for	the specific or	representative
       lwp according to	 the  SPARC  V9	 platform-dependent  operand  asrset_t
       structure.  An  error (EINVAL) is returned if either the	target process
       or the controlling process is not a 64-bit SPARC	V9  process.  Most  of
       the  ancillary  state registers are privileged registers	that cannot be
       modified. Only those that can be	 modified  are	set;  all  others  are
       silently	ignored. PCSASRS fails with EBUSY if the lwp is	not stopped on
       an event	of interest.

   PCAGENT
       Create an agent lwp in the controlled process with register values from
       the operand prgregset_t structure (see PCSREG, above). The agent	lwp is
       created in the stopped state showing PR_REQUESTED  and  with  its  held
       signal  set  (the  signal  mask)	 having	all signals except SIGKILL and
       SIGSTOP blocked.

       The PCAGENT operation fails with	EBUSY  unless  the  process  is	 fully
       stopped	via  /proc, that is, unless all	of the lwps in the process are
       stopped either on events	of interest or on PR_SUSPENDED,	or are stopped
       on  PR_JOBCONTROL and have been directed	to stop	via PCDSTOP.  It fails
       with EBUSY if an	agent lwp already exists. It fails with	ENOMEM if sys-
       tem resources for creating new lwps have	been exhausted.

       Any  PCRUN operation applied to the process control file	or to the con-
       trol file of an lwp other than the agent	lwp fails with EBUSY  as  long
       as  the	agent lwp exists. The agent lwp	must be	caused to terminate by
       executing the SYS_lwp_exit system call trap before the process  can  be
       restarted.

       Once  the  agent	lwp is created,	its lwp-ID can be found	by reading the
       process status file. To facilitate opening the agent lwp's control  and
       status  files,  the directory name /propc/pid/lwp/agent is accepted for
       lookup operations as an invisible alias for /proc/pid/lwp/lwpid,	 lwpid
       being the lwp-ID	of the agent lwp (invisible in the sense that the name
       ``agent'' does not appear  in  a	 directory  listing  of	 /proc/pid/lwp
       obtained	from ls(1), getdents(2), or readdir(3C)).

       The purpose of the agent	lwp is to perform operations in	the controlled
       process on behalf of the	controlling process: to	gather information not
       directly	 available  via	/proc files, or	in general to make the process
       change state in ways not	directly available via	/proc  control	opera-
       tions.  To  make	 use  of an agent lwp, the controlling process must be
       capable	of  making  it	execute	 system	  calls	  (specifically,   the
       SYS_lwp_exit  system call trap).	The register values given to the agent
       lwp on creation are typically the registers of the representative  lwp,
       so that the agent lwp can use its stack.

       The  agent  lwp is not allowed to execute any variation of the SYS_fork
       or SYS_exec system call traps. Attempts to do so	yield ENOTSUP  to  the
       agent lwp.

       Symbolic	 constants  for	system call trap numbers like SYS_lwp_exit and
       SYS_lwp_create can be found in the header file <sys/syscall.h>.

   PCREAD PCWRITE
       Read or write the target	process's address space	via a  priovec	struc-
       ture operand:

       typedef struct priovec {
	   void	*pio_base;	/* buffer in controlling process */
	   size_t pio_len;	/* size	of read/write request in bytes */
	   off_t pio_offset;	/* virtual address in target process */
       } priovec_t;

       These  operations  have	the  same  effect  as  pread(2)	and pwrite(2),
       respectively, of	the target process's address space file.  The  differ-
       ence  is	 that more than	one PCREAD or PCWRITE control operation	can be
       written to the control file at once, and	they can be interspersed  with
       other control operations	in a single write to the control file. This is
       useful, for example, when planting many breakpoint instructions in  the
       process's  address space, or when stepping over a breakpointed instruc-
       tion. Unlike pread(2) and pwrite(2), no provision is made  for  partial
       reads  or  writes;  if the operation cannot be performed	completely, it
       fails with EIO.

   PCNICE
       The traced process's nice(2) value is incremented by the	amount in  the
       operand	long.  Only  a process with the	{PRIV_PROC_PRIOCNTL} privilege
       asserted	in its effective set can better	a process's priority  in  this
       way,  but  any user may lower the priority. This	operation is not mean-
       ingful for all scheduling classes.

   PCSCRED
       Set the target process credentials  to  the  values  contained  in  the
       prcred_t	 structure  operand (see /proc/pid/cred). The effective, real,
       and saved user-IDs and group-IDs	of the target  process	are  set.  The
       target  process's  supplementary	groups are not changed;	the pr_ngroups
       and pr_groups members of	the structure operand are  ignored.  Only  the
       privileged  processes  can  perform  this  operation; for all others it
       fails with EPERM.

   PCSCREDX
       Operates	like PCSCRED but  also	sets  the  supplementary  groups;  the
       length  of  the	data  written  with  this  control operation should be
       "sizeof (prcred_t) + sizeof (gid_t) * (#groups -	1)".

   PCSPRIV
       Set the target  process	privilege  to  the  values  contained  in  the
       prpriv_t	operand	(see /proc/pid/priv). The effective, permitted,	inher-
       itable, and limit sets are all changed. Privilege  flags	 can  also  be
       set. The	process	is made	privilege aware	unless it can relinquish priv-
       ilege awareness.	See privileges(5).

       The limit set of	the target process cannot be grown. The	 other	privi-
       lege  sets  must	be subsets of the intersection of the effective	set of
       the calling process with	the new	limit set of  the  target  process  or
       subsets of the original values of the sets in the target	process.

       If any of the above restrictions	are not	met, EPERM is returned.	If the
       structure written is improperly formatted, EINVAL is returned.

PROGRAMMING NOTES
       For security reasons, except for	the psinfo,  usage,  lpsinfo,  lusage,
       lwpsinfo,  and lwpusage files, which are	world-readable,	and except for
       privileged processes, an	open of	a /proc	file  fails  unless  both  the
       user-ID	and  group-ID  of the caller match those of the	traced process
       and the process's object	file is	readable by the	caller.	The  effective
       set of the caller is a superset of both the inheritable and the permit-
       ted set of the target process. The limit	set of the caller is a	super-
       set  of the limit set of	the target process. Except for the world-read-
       able files just mentioned, files	corresponding  to  setuid  and	setgid
       processes can be	opened only by the appropriately privileged process.

       A  process  that	is missing the basic privilege {PRIV_PROC_INFO}	cannot
       see any processes under /proc that it cannot send a signal to.

       A process that has {PRIV_PROC_OWNER} asserted in	its effective set  can
       open any	file for reading. To manipulate	or control a process, the con-
       trolling	process	must have at least as many privileges in its effective
       set  as	the target process has in its effective, inheritable, and per-
       mitted sets. The	limit set of the controlling process must be a	super-
       set  of	the  limit  set	of the target process. Additional restrictions
       apply if	any of the uids	of  the	 target	 process  are  0.  See	privi-
       leges(5).

       Even  if	 held  by  a  privileged  process, an open process or lwp file
       descriptor (other than file descriptors for the	world-readable	files)
       becomes	invalid	 if  the  traced  process  performs  an	 exec(2)  of a
       setuid/setgid object file or an object file  that  the  traced  process
       cannot  read.  Any  operation  performed	on an invalid file descriptor,
       except close(2),	fails with EAGAIN. In this situation, if  any  tracing
       flags  are  set	and the	process	or any lwp file	descriptor is open for
       writing,	the process will have been directed to stop  and  its  run-on-
       last-close flag will have been set (see PCSET). This enables a control-
       ling process (if	it has permission) to reopen the /proc	files  to  get
       new  valid  file	descriptors, close the invalid file descriptors, unset
       the run-on-last-close flag (if desired),	and proceed. Just closing  the
       invalid	file descriptors causes	the traced process to resume execution
       with all	tracing	flags cleared. Any  process  not  currently  open  for
       writing via /proc, but that has left-over tracing flags from a previous
       open, and that executes a setuid/setgid or unreadable object file, will
       not be stopped but will have all	its tracing flags cleared.

       To wait for one or more of a set	of processes or	lwps to	stop or	termi-
       nate, /proc file	descriptors (other than	those obtained by opening  the
       cwd  or root directories	or by opening files in the fd or object	direc-
       tories) can be used in  a  poll(2)  system  call.  When	requested  and
       returned,  either of the	polling	events POLLPRI or POLLWRNORM indicates
       that the	process	or lwp stopped on an event of interest.	Although  they
       cannot  be requested, the polling events	POLLHUP, POLLERR, and POLLNVAL
       may be returned.	POLLHUP	indicates that the process or lwp  has	termi-
       nated.  POLLERR	indicates that the file	descriptor has become invalid.
       POLLNVAL	is returned immediately	if POLLPRI or POLLWRNORM is  requested
       on  a  file  descriptor referring to a system process (see PCSTOP). The
       requested events	may be empty to	wait simply for	termination.

       /proc

	   directory (list of processes)

       /proc/pid

	   specific process directory

       /proc/self

	   alias for a process's own directory

       /proc/pid/as

	   address space file

       /proc/pid/ctl

	   process control file

       /proc/pid/status

	   process status

       /proc/pid/lstatus

	   array of lwp	status structs

       /proc/pid/psinfo

	   process ps(1) info

       /proc/pid/lpsinfo

	   array of lwp	ps(1) info structs

       /proc/pid/map

	   address space map

       /proc/pid/rmap

	   reserved address map

       /proc/pid/cred

	   process credentials

       /proc/pid/priv

	   process privileges

       /proc/pid/sigact

	   process signal actions

       /proc/pid/auxv

	   process aux vector

       /proc/pid/ldt

	   process LDT ( only)

       /proc/pid/usage

	   process usage

       /proc/pid/lusage

	   array of lwp	usage structs

       /proc/pid/path

	   symbolic links to process open files

       /proc/pid/pagedata

	   process page	data

       /proc/pid/watch

	   active watchpoints

       /proc/pid/cwd

	   alias for the current working directory

       /proc/pid/root

	   alias for the root directory

       /proc/pid/fd

	   directory (list of open files)

       /proc/pid/fd/*

	   aliases for process's open files

       /proc/pid/object

	   directory (list of mapped files)

       /proc/pid/object/a.out

	   alias for process's executable file

       /proc/pid/object/*

	   aliases for other mapped files

       /proc/pid/lwp

	   directory (list of lwps)

       /proc/pid/lwp/lwpid

	   specific lwp	directory

       /proc/pid/lwp/agent

	   alias for the agent lwp directory

       /proc/pid/lwp/lwpid/lwpctl

	   lwp control file

       /proc/pid/lwp/lwpid/lwpstatus

	   lwp status

       /proc/pid/lwp/lwpid/lwpsinfo

	   lwp ps(1) info

       /proc/pid/lwp/lwpid/lwpusage

	   lwp usage

       /proc/pid/lwp/lwpid/gwindows

	   register windows (SPARC only)

       /proc/pid/lwp/lwpid/xregs

	   extra state registers

       /proc/pid/lwp/lwpid/asrs

	   ancillary state registers (SPARC V9 only)

       ls(1),  ps(1),  chroot(1M),  alarm(2),  brk(2),	chdir(2),   chroot(2),
       close(2),  creat(2),  dup(2),  exec(2),	fcntl(2),  fork(2),  fork1(2),
       fstat(2),  getdents(2),	getustack(2),  kill(2),	  lseek(2),   mmap(2),
       nice(2),	 open(2),  poll(2),  pread(2), ptrace(3C), pwrite(2), read(2),
       readlink(2),   readv(2),	  shmget(2),   sigaction(2),   sigaltstack(2),
       vfork(2),    write(2),	 writev(2),    _stack_grow(3C),	  readdir(3C),
       pthread_create(3C),    pthread_join(3C),	    siginfo.h(3HEAD),	  sig-
       nal.h(3HEAD),  thr_create(3C),  thr_join(3C),  types32.h(3HEAD),	 ucon-
       text.h(3HEAD), wait(3C),	contract(4), process(4), lfcompile(5),	privi-
       leges(5)

       Errors  that  can  occur	 in addition to	the errors normally associated
       with file system	access:

       E2BIG	       Data to be returned in a	read(2)	of the page data  file
		       exceeds	the  size  of  the read	buffer provided	by the
		       caller.

       EACCES	       An attempt was made to examine a	process	that ran under
		       a  different  uid  than	the  controlling  process  and
		       {PRIV_PROC_OWNER} was not  asserted  in	the  effective
		       set.

       EAGAIN	       The  traced  process  has  performed  an	 exec(2)  of a
		       setuid/setgid object file or of an object file that  it
		       cannot  read;  all further operations on	the process or
		       lwp  file  descriptor  (except  close(2))  elicit  this
		       error.

       EBUSY	       PCSTOP,	PCDSTOP, PCWSTOP, or PCTWSTOP was applied to a
		       system process; an exclusive open(2) was	attempted on a
		       /proc  file  for	 a  process  already open for writing;
		       PCRUN,  PCSREG,	PCSVADDR,  PCSFPREG,  or  PCSXREG  was
		       applied	to a process or	lwp not	stopped	on an event of
		       interest; an attempt was	made to	mount  /proc  when  it
		       was  already  mounted; PCAGENT was applied to a process
		       that was	not fully stopped or that already had an agent
		       lwp.

       EINVAL	       In  general,  this means	that some invalid argument was
		       supplied	to a system call.  A  non-exhaustive  list  of
		       conditions  eliciting  this  error  includes: a control
		       message operation code is  undefined;  an  out-of-range
		       signal  number  was  specified  with PCSSIG, PCKILL, or
		       PCUNKILL; SIGKILL was specified with PCUNKILL; PCSFPREG
		       was applied on a	system that does not support floating-
		       point operations; PCSXREG was applied on	a system  that
		       does not	support	extra state registers.

       EINTR	       A  signal was received by the controlling process while
		       waiting for the traced  process	or  lwp	 to  stop  via
		       PCSTOP, PCWSTOP,	or PCTWSTOP.

       EIO	       A  write(2)  was	attempted at an	illegal	address	in the
		       traced process.

       ENOENT	       The traced process or lwp has  terminated  after	 being
		       opened.	The  basic  privilege  {PRIV_PROC_INFO}	is not
		       asserted	in the effective set of	 the  calling  process
		       and  the	 calling  process  cannot send a signal	to the
		       target process.

       ENOMEM	       The system-imposed limit	on the	number	of  page  data
		       file   descriptors   was	  reached   on	 an   open  of
		       /proc/pid/pagedata; an attempt was made with PCWATCH to
		       establish  more	watched	areas than the system can sup-
		       port; the PCAGENT operation was issued when the	system
		       was out of resources for	creating lwps.

       ENOSYS	       An attempt was made to perform an unsupported operation
		       (such as	creat(2), link(2), or unlink(2)) on  an	 entry
		       in /proc.

       EOVERFLOW       A 32-bit	controlling process attempted to read or write
		       the as file or attempted	to  read  the  map,  rmap,  or
		       pagedata	file of	a 64-bit target	process. A 32-bit con-
		       trolling	process	attempted to apply one of the  control
		       operations PCSREG, PCSXREG, PCSVADDR, PCWATCH, PCAGENT,
		       PCREAD, PCWRITE to a 64-bit target process.

       EPERM	       The process that	issued the PCSCRED or PCSCREDX	opera-
		       tion  did  not  have  the  {PRIV_PROC_SETID}  privilege
		       asserted	in its effective  set,	or  the	 process  that
		       issued	the   PCNICE   operation   did	not  have  the
		       {PRIV_PROC_PRIOCNTL} in its effective set.

		       An attempt was made to control a	process	of  which  the
		       E,  P,  and  I  privilege sets were not a subset	of the
		       effective set of	the controlling	process	or  the	 limit
		       set  of	the  controlling  process is not a superset of
		       limit set of the	controlled process.

		       Any of the uids of the  target  process	are  0	or  an
		       attempt	was  made to change any	of the uids to 0 using
		       PCSCRED and  the	 security  policy  imposed  additional
		       restrictions. See privileges(5).

       Descriptions  of	 structures  in	this document include only interesting
       structure elements, not filler and padding fields, and  may  show  ele-
       ments  out of order for descriptive clarity. The	actual structure defi-
       nitions are contained in	<procfs.h>.

       Because the old ioctl(2)-based version of /proc is currently  supported
       for binary compatibility	with old applications, the top-level directory
       for a process, /proc/pid, is  not  world-readable,  but	it  is	world-
       searchable.  Thus,  anyone  can open /proc/pid/psinfo even though ls(1)
       applied to /proc/pid will fail for anyone but the owner or an appropri-
       ately privileged	process. Support for the old ioctl(2)-based version of
       /proc will be dropped in	a future release, at which time	the  top-level
       directory for a process will be made world-readable.

       On  SPARC based machines, the types gregset_t and fpregset_t defined in
       <sys/regset.h> are similar to but not the same as the types prgregset_t
       and prfpregset_t	defined	in <procfs.h>.

				  24 May 2005			       proc(4)

NAME | DIRECTORY STRUCTURE | CONTROL MESSAGES | PROGRAMMING NOTES

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