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OpenSolaris 2009.06 - man page for intro (opensolaris section 2)

Intro(2)				   System Calls 				 Intro(2)

NAME
       Intro, intro - introduction to system calls and error numbers

SYNOPSIS
       #include <errno.h>

DESCRIPTION
       A  system  call	is  a C library function that requests a service from the system, such as
       getting the time of day. This request is performed in the kernel.  The  library	interface
       executes a trap into the kernel, which actually executes the system call code.

       Most  system calls return one or more error conditions. An error condition is indicated by
       an otherwise impossible return value. This is almost always -1 or the  null  pointer;  the
       individual descriptions specify the details. An error number is also made available in the
       external variable errno, which is not cleared on successful calls, so it should be  tested
       only after an error has been indicated.

       In the case of multithreaded applications, the -mt option must be specified on the command
       line at compilation time (see threads(5)). When the -mt option is specified, errno becomes
       a  macro  that  enables each thread to have its own errno. This errno macro can be used on
       either side of the assignment as though it were a variable.

       An error value listed as "will fail" describes a condition whose detection  and	reporting
       is  mandatory  for an implementation that conforms to the Single UNIX Specification (SUS).
       An application can rely on this condition being detected  and  reported.  An  error  value
       listed  as "may fail" describes a condition whose detection and reporting is  optional for
       an implementation that conforms to the SUS. An application should not rely this	condition
       being detected and reported. An application that relies on such behavior cannot be assured
       to be portable across conforming implementations. If more than one error  occurs  in  pro-
       cessing	a  function  call,  any  one of the possible errors might may be returned, as the
       order of detection is undefined. See standards(5) for additional information regarding the
       Single UNIX Specification.

       Each system call description attempts to list all possible error numbers. The following is
       a complete list of the error numbers and their names as defined in <errno.h>.

       1 EPERM		      Lacking appropriate privileges

			      Typically this error indicates an attempt to modify a file in  some
			      way  forbidden  except  to its owner or an appropriately privileged
			      process.	It is also returned for attempts  by  ordinary	users  to
			      perform  operations  allowed  only to processes with certain privi-
			      leges.

			      The manual pages for individual functions document which privileges
			      are needed to override the restriction.

       2 ENOENT 	      No such file or directory

			      A  file name is specified and the file should exist but doesn't, or
			      one of the directories in a path name does not exist.

       3 ESRCH		      No such process, LWP, or thread

			      No process can be found in the system that corresponds to the spec-
			      ified PID, LWPID_t, or thread_t.

       4 EINTR		      Interrupted system call

			      An  asynchronous signal (such as interrupt or quit), which the user
			      has elected to catch, occurred during a system service function. If
			      execution is resumed after processing the signal, it will appear as
			      if the interrupted function call returned this error condition.

			      In a multithreaded application,  EINTR  may  be  returned  whenever
			      another thread or LWP calls fork(2).

       5 EIO		      I/O error

			      Some  physical I/O error has occurred. This error may in some cases
			      occur on a call following the one to which it actually applies.

       6 ENXIO		      No such device or address

			      I/O on a special file refers to a subdevice which does  not  exist,
			      or  exists  beyond the limit of the device. It may also occur when,
			      for example, a tape drive is not on-line or no disk pack is  loaded
			      on a drive.

       7 E2BIG		      Arg list too long

			      An  argument list longer than  ARG_MAX bytes is presented to a mem-
			      ber of the exec family of functions  (see  exec(2)).  The  argument
			      list  limit  is  the  sum of the size of the argument list plus the
			      size of the environment's exported shell variables.

       8 ENOEXEC	      Exec format error

			      A request is made to execute a file  which,  although  it  has  the
			      appropriate  permissions,  does  not start with a valid format (see
			      a.out(4)).

       9 EBADF		      Bad file number

			      Either a file descriptor refers to  no  open  file,  or  a  read(2)
			      (respectively,   write(2))  request  is made to a file that is open
			      only for writing (respectively, reading).

       10 ECHILD	      No child processes

			      A wait(3C) function call was executed by	a  process  that  had  no
			      existing or unwaited-for child processes.

       11 EAGAIN	      No more processes, or no more LWPs

			      For  example,  the  fork(2)  function  failed  because the system's
			      process table is full or the user is not allowed to create any more
			      processes,  or a call failed because of insufficient memory or swap
			      space.

       12 ENOMEM	      Not enough space

			      During execution of brk() or sbrk() (see brk(2)),  or  one  of  the
			      exec  family  of	functions, a program asks for more space than the
			      system is able to supply. This is not a  temporary  condition;  the
			      maximum  size  is  a  system  parameter. On some architectures, the
			      error may also occur if the arrangement of text,	data,  and  stack
			      segments	requires  too many segmentation registers, or if there is
			      not enough swap space during the fork(2) function.

       13 EACCES	      Permission denied

			      An attempt was made to access a file in a way forbidden by the pro-
			      tection system.

			      The manual pages for individual functions document which privileges
			      are needed to override the protection system.

       14 EFAULT	      Bad address

			      The system encountered a hardware fault in  attempting  to  use  an
			      argument of a routine. For example, errno potentially may be set to
			      EFAULT any time a routine that takes a pointer argument  is  passed
			      an invalid address, if the system can detect the condition. Because
			      systems will differ in their  ability  to  reliably  detect  a  bad
			      address, on some implementations passing a bad address to a routine
			      will result in undefined behavior.

       15 ENOTBLK	      Block device required

			      A non-block device or file was mentioned where a block  device  was
			      required (for example, in a call to the mount(2) function).

       16 EBUSY 	      Device busy

			      An  attempt  was made to mount a device that was already mounted or
			      an attempt was made to unmount a device on which there is an active
			      file  (open  file,  current directory, mounted-on file, active text
			      segment). It will also occur  if	an  attempt  is  made  to  enable
			      accounting  when	it  is already enabled. The device or resource is
			      currently unavailable.   EBUSY is also used by mutexes, semaphores,
			      condition  variables,  and  r/w  locks, to indicate that	a lock is
			      held,  and by the processor control function  P_ONLINE.

       17 EEXIST	      File exists

			      An existing file was mentioned in  an  inappropriate  context  (for
			      example, call to the link(2) function).

       18 EXDEV 	      Cross-device link

			      A hard link to a file on another device was attempted.

       19 ENODEV	      No such device

			      An attempt was made to apply an inappropriate operation to a device
			      (for example, read a write-only device).

       20 ENOTDIR	      Not a directory

			      A non-directory was specified where a directory  is  required  (for
			      example,	in  a path prefix or as an argument to the chdir(2) func-
			      tion).

       21 EISDIR	      Is a directory

			      An attempt was made to write on a directory.

       22 EINVAL	      Invalid argument

			      An invalid argument was specified (for example, unmounting  a  non-
			      mounted  device),  mentioning  an undefined signal in a call to the
			      signal(3C) or kill(2) function, or an unsupported operation related
			      to extended attributes was attempted.

       23 ENFILE	      File table overflow

			      The  system  file table is full (that is,  SYS_OPEN files are open,
			      and temporarily no more files can be opened).

       24 EMFILE	      Too many open files

			      No process may have more than  OPEN_MAX file descriptors open at	a
			      time.

       25 ENOTTY	      Inappropriate ioctl for device

			      A  call was made to the ioctl(2) function specifying a file that is
			      not a special character device.

       26 ETXTBSY	      Text file busy (obsolete)

			      An attempt was made to execute a	pure-procedure	program  that  is
			      currently  open for writing. Also an attempt to open for writing or
			      to remove a pure-procedure program that is  being  executed.  (This
			      message is obsolete.)

       27 EFBIG 	      File too large

			      The  size  of  the  file	exceeded  the limit specified by resource
			      RLIMIT_FSIZEn; the file size exceeds the maximum supported  by  the
			      file  system;  or  the  file size exceeds the offset maximum of the
			      file descriptor.	See the File Descriptor subsection of the DEFINI-
			      TIONS section below.

       28 ENOSPC	      No space left on device

			      While writing an ordinary file or creating a directory entry, there
			      is no free space left on the device. In the fcntl(2) function,  the
			      setting  or  removing  of  record  locks on a file cannot be accom-
			      plished because there are no more record entries left on	the  sys-
			      tem.

       29 ESPIPE	      Illegal seek

			      A call to the  lseek(2) function was issued to a pipe.

       30 EROFS 	      Read-only file system

			      An  attempt  to  modify  a  file	or directory was made on a device
			      mounted read-only.

       31 EMLINK	      Too many links

			      An  attempt  to  make  more  than  the  maximum  number  of  links,
			      LINK_MAX, to a file.

       32 EPIPE 	      Broken pipe

			      A  write	on a pipe for which there is no process to read the data.
			      This condition normally generates a signal; the error  is  returned
			      if the signal is ignored.

       33 EDOM		      Math argument out of domain of function

			      The  argument  of a function in the math package(3M) is out of the
			      domain of the function.

       34 ERANGE	      Math result not representable

			      The value of a function in the math  package(3M)  is  not  repre-
			      sentable within machine precision.

       35 ENOMSG	      No message of desired type

			      An  attempt  was	made to receive a message of a type that does not
			      exist on the specified message queue (see msgrcv(2)).

       36 EIDRM 	      Identifier removed

			      This error is returned to processes that resume  execution  due  to
			      the removal of an identifier from the file system's name space (see
			      msgctl(2), semctl(2), and shmctl(2)).

       37 ECHRNG	      Channel number out of range

       38 EL2NSYNC	      Level 2 not synchronized

       39 EL3HLT	      Level 3 halted

       40 EL3RST	      Level 3 reset

       41 ELNRNG	      Link number out of range

       42 EUNATCH	      Protocol driver not attached

       43 ENOCSI	      No CSI structure available

       44 EL2HLT	      Level 2 halted

       45 EDEADLK	      Deadlock condition

			      A deadlock situation was detected and avoided. This error  pertains
			      to  file	and  record  locking,  and also applies to mutexes, sema-
			      phores, condition variables, and r/w locks.

       46 ENOLCK	      No record locks available

			      There are no more locks available. The system lock  table  is  full
			      (see fcntl(2)).

       47 ECANCELED	      Operation canceled

			      The  associated  asynchronous operation was canceled before comple-
			      tion.

       48 ENOTSUP	      Not supported

			      This version of the system does not support  this  feature.  Future
			      versions of the system may provide support.

       49 EDQUOT	      Disc quota exceeded

			      A write(2) to an ordinary file, the creation of a directory or sym-
			      bolic link, or the creation of a directory entry failed because the
			      user's  quota of disk blocks was exhausted, or the allocation of an
			      inode for a newly created file failed because the user's	quota  of
			      inodes was exhausted.

       58-59		      Reserved

       60 ENOSTR	      Device not a stream

			      A  putmsg(2)  or	getmsg(2) call was attempted on a file descriptor
			      that is not a STREAMS device.

       61 ENODATA	      No data available

       62 ETIME 	      Timer expired

			      The timer set for a STREAMS ioctl(2) call has expired. The cause of
			      this  error is device-specific and could indicate either a hardware
			      or software failure, or perhaps a timeout value that is  too  short
			      for  the specific operation. The status of the ioctl() operation is
			      indeterminate.   This   is   also   returned   in   the	case   of
			      _lwp_cond_timedwait(2) or cond_timedwait(3C).

       63 ENOSR 	      Out of stream resources

			      During  a   STREAMS  open(2)  call, either no  STREAMS queues or no
			      STREAMS head data structures were available. This  is  a	temporary
			      condition;  one  may  recover  from  it  if other processes release
			      resources.

       65 ENOPKG	      Package not installed

			      This error occurs when users attempt to use a call from  a  package
			      which has not been installed.

       71 EPROTO	      Protocol error

			      Some  protocol  error occurred.  This error is device-specific, but
			      is generally not related to a hardware failure.

       77 EBADMSG	      Not a data message

			      During a read(2), getmsg(2), or ioctl(2) I_RECVFD call to a STREAMS
			      device, something has come to the head of the queue that can not be
			      processed.  That something depends on the call:

			      read():	   control information or passed file descriptor.

			      getmsg():    passed file descriptor.

			      ioctl():	   control or data information.

       78 ENAMETOOLONG	      File name too long

			      The length of the path argument exceeds  PATH_MAX, or the length of
			      a  path  component  exceeds  NAME_MAX  while  _POSIX_NO_TRUNC is in
			      effect; see limits.h(3HEAD).

       79 EOVERFLOW	      Value too large for defined data type.

       80 ENOTUNIQ	      Name not unique on network

			      Given log name not unique.

       81 EBADFD	      File descriptor in bad state

			      Either a file descriptor refers to no open file or a  read  request
			      was made to a file that is open only for writing.

       82 EREMCHG	      Remote address changed

       83 ELIBACC	      Cannot access a needed share library

			      Trying  to  exec an a.out that requires a static shared library and
			      the static shared library does not exist or the user does not  have
			      permission to use it.

       84 ELIBBAD	      Accessing a corrupted shared library

			      Trying  to  exec an a.out that requires a static shared library (to
			      be linked in) and exec could not load the  static  shared  library.
			      The static shared library is probably corrupted.

       85 ELIBSCN	      .lib section in a.out corrupted

			      Trying  to  exec an a.out that requires a static shared library (to
			      be linked in) and there was erroneous data in the .lib  section  of
			      the a.out. The .lib section tells exec what static shared libraries
			      are needed. The a.out is probably corrupted.

       86 ELIBMAX	      Attempting to link in more shared libraries than system limit

			      Trying to exec an a.out that requires more static shared	libraries
			      than  is	allowed  on  the current configuration of the system. See
			      System Administration Guide: IP Services

       87 ELIBEXEC	      Cannot exec a shared library directly

			      Attempting to exec a shared library directly.

       88 EILSEQ	      Error 88

			      Illegal byte sequence. Handle multiple characters as a single char-
			      acter.

       89 ENOSYS	      Operation not applicable

       90 ELOOP 	      Number  of  symbolic  links  encountered during path name traversal
			      exceeds MAXSYMLINKS

       91 ESTART	      Restartable system call

			      Interrupted system call should be restarted.

       92 ESTRPIPE	      If pipe/FIFO, don't sleep in stream head

			      Streams pipe error (not externally visible).

       93 ENOTEMPTY	      Directory not empty

       94 EUSERS	      Too many users

       95 ENOTSOCK	      Socket operation on non-socket

       96 EDESTADDRREQ	      Destination address required

			      A required address was omitted from an  operation  on  a	transport
			      endpoint. Destination address required.

       97 EMGSIZE	      Message too long

			      A message sent on a transport provider was larger than the internal
			      message buffer or some other network limit.

       98 EPROTOTYPE	      Protocol wrong type for socket

			      A protocol was specified that does not support the semantics of the
			      socket type requested.

       99 ENOPROTOOPT	      Protocol not available

			      A bad option or level was specified when getting or setting options
			      for a protocol.

       120 EPROTONOSUPPORT    Protocol not supported

			      The protocol has not been configured into the system or  no  imple-
			      mentation for it exists.

       121 ESOCKTNOSUPPORT    Socket type not supported

			      The  support  for  the socket type has not been configured into the
			      system or no implementation for it exists.

       122 EOPNOTSUPP	      Operation not supported on transport endpoint

			      For example, trying to accept a connection on a datagram	transport
			      endpoint.

       123 EPFNOSUPPORT       Protocol family not supported

			      The  protocol  family has not been configured into the system or no
			      implementation for it exists. Used for the Internet protocols.

       124 EAFNOSUPPORT       Address family not supported by protocol family

			      An address incompatible with the requested protocol was used.

       125 EADDRINUSE	      Address already in use

			      User attempted to use an address already in use, and  the  protocol
			      does not allow this.

       126 EADDRNOTAVAIL      Cannot assign requested address

			      Results  from  an  attempt  to  create a transport endpoint with an
			      address not on the current machine.

       127 ENETDOWN	      Network is down

			      Operation encountered a dead network.

       128 ENETUNREACH	      Network is unreachable

			      Operation was attempted to an unreachable network.

       129 ENETRESET	      Network dropped connection because of reset

			      The host you were connected to crashed and rebooted.

       130 ECONNABORTED       Software caused connection abort

			      A connection abort was caused internal to your host machine.

       131 ECONNRESET	      Connection reset by peer

			      A connection was forcibly closed by a peer. This	normally  results
			      from  a  loss of the connection on the remote host due to a timeout
			      or a reboot.

       132 ENOBUFS	      No buffer space available

			      An operation on a transport endpoint  or	pipe  was  not	performed
			      because  the  system  lacked  sufficient	buffer space or because a
			      queue was full.

       133 EISCONN	      Transport endpoint is already connected

			      A connect request was made on an already connected  transport  end-
			      point;  or, a sendto(3SOCKET) or sendmsg(3SOCKET) request on a con-
			      nected transport endpoint specified a destination when already con-
			      nected.

       134 ENOTCONN	      Transport endpoint is not connected

			      A request to send or receive data was disallowed because the trans-
			      port endpoint is not connected and (when	sending  a  datagram)  no
			      address was supplied.

       143 ESHUTDOWN	      Cannot send after transport endpoint shutdown

			      A  request  to  send data was disallowed because the transport end-
			      point has already been shut down.

       144 ETOOMANYREFS       Too many references: cannot splice

       145 ETIMEDOUT	      Connection timed out

			      A  connect(3SOCKET) or  send(3SOCKET) request  failed  because  the
			      connected party did not properly respond after a period of time; or
			      a write(2) or  fsync(3C) request failed because a  file  is  on  an
			      NFS file system mounted with the	soft option.

       146 ECONNREFUSED       Connection refused

			      No  connection  could  be  made because the target machine actively
			      refused it. This usually results from trying to connect to  a  ser-
			      vice that is inactive on the remote host.

       147 EHOSTDOWN	      Host is down

			      A  transport provider operation failed because the destination host
			      was down.

       148 EHOSTUNREACH       No route to host

			      A transport provider operation  was  attempted  to  an  unreachable
			      host.

       149 EALREADY	      Operation already in progress

			      An  operation  was  attempted on a non-blocking object that already
			      had an operation in progress.

       150 EINPROGRESS	      Operation now in progress

			      An operation that takes a long time to complete  (such  as  a  con-
			      nect()) was attempted on a non-blocking object.

       151 ESTALE	      Stale NFS file handle

DEFINITIONS
   Background Process Group
       Any  process  group that is not the foreground process group  of a session that has estab-
       lished a connection with a controlling terminal.

   Controlling Process
       A session leader that established a connection to a controlling terminal.

   Controlling Terminal
       A terminal that is associated with a session.  Each session may have, at  most,	one  con-
       trolling  terminal  associated  with  it and a controlling terminal may be associated with
       only one session.  Certain input sequences from the controlling terminal cause signals  to
       be  sent  to  process  groups in the session associated with the controlling terminal; see
       termio(7I).

   Directory
       Directories organize files into a hierarchical system where directories are the	nodes  in
       the  hierarchy.	A directory is a file that catalogs the list of files, including directo-
       ries (sub-directories), that are directly beneath it in the hierarchy. Entries in a direc-
       tory  file  are called links. A link associates a file identifier with a filename. By con-
       vention, a directory contains at least two links, .  (dot)  and	..  (dot-dot).	The  link
       called  dot  refers  to the directory itself while dot-dot refers to its parent directory.
       The root directory, which is the top-most node of the hierarchy, has itself as its  parent
       directory.  The	pathname  of the root directory is / and the parent directory of the root
       directory is /.

   Downstream
       In a stream, the direction from stream head to driver.

   Driver
       In a stream, the driver provides the interface between peripheral hardware and the stream.
       A  driver  can also be a pseudo-driver, such as a multiplexor or log driver (see log(7D)),
       which is not associated with a hardware device.

   Effective User ID and Effective Group ID
       An active process has an effective user ID and an effective group  ID  that  are  used  to
       determine  file	access permissions (see below). The effective user ID and effective group
       ID are equal to the process's real user ID and real group  ID,  respectively,  unless  the
       process	or one of its ancestors evolved from a file that had the  set-user-ID bit or set-
       group-ID bit set  (see exec(2)).

   File Access Permissions
       Read, write, and execute/search permissions for a file are granted to a process if one  or
       more of the following are true:

	   o	  The  effective  user	ID of the process matches the user ID of the owner of the
		  file and the appropriate access bit of the "owner" portion(0700) of	the  file
		  mode is set.

	   o	  The  effective  user	ID of the process does not match the user ID of the owner
		  of the file, but either the effective group ID  or  one  of  the  supplementary
		  group   IDs  of the process match the group  ID of the file and the appropriate
		  access bit of the "group" portion(0070) of the file mode is set.

	   o	  The effective user ID of the process does not match the user ID of the owner of
		  the file, and neither the effective group ID nor any of the supplementary group
		  IDs of the process match the group ID of the file, but the  appropriate  access
		  bit of the "other" portion(0007) of the file mode is set.

	   o	  The read, write, or execute mode bit is not set but the process has the discre-
		  tionary  file  access  override  privilege  for  the	corresponding  mode  bit:
		  {PRIV_FILE_DAC_READ}	for the read bit {PRIV_FILE_DAC_WRITE} for the write bit,
		  {PRIV_FILE_DAC_SEARCH}   for	 the   execute	 bit	on    directories,    and
		  {PRIV_FILE_DAC_EXECUTE} for the executable bit on plain files.

       Otherwise, the corresponding permissions are denied.

   File Descriptor
       A  file	descriptor  is a small integer used to perform I/O on a file. The value of a file
       descriptor is from 0 to (NOFILES-1). A  process	may  have  no  more  than   NOFILES  file
       descriptors   open  simultaneously. A file descriptor is returned by calls such as open(2)
       or pipe(2). The file descriptor is used as an argument by calls such as read(2), write(2),
       ioctl(2), and close(2).

       Each  file  descriptor  has  a  corresponding  offset maximum. For regular files that were
       opened without setting the O_LARGEFILE flag, the offset maximum is 2 Gbyte - 1 byte  (2^31
       -1  bytes).  For  regular files that were opened with the O_LARGEFILE flag set, the offset
       maximum is 2^63 -1 bytes.

   File Name
       Names consisting of 1 to  NAME_MAX characters may be used to name an ordinary  file,  spe-
       cial file or directory.

       These  characters may be selected from the set of all character values excluding \0 (null)
       and the ASCII code for / (slash).

       Note that it is generally unwise to use *, ?, [, or ] as part of file names because of the
       special meaning attached to these characters by the shell (see sh(1), csh(1), and ksh(1)).
       Although permitted, the use of unprintable characters in file names should be avoided.

       A file name is sometimes referred to as a pathname component.   The  interpretation  of	a
       pathname  component is dependent on the values of NAME_MAX and  _POSIX_NO_TRUNC associated
       with the path prefix of that component.	If any pathname component is longer than NAME_MAX
       and  _POSIX_NO_TRUNC  is in effect for the path prefix of that component (see fpathconf(2)
       and limits.h(3HEAD)), it shall be considered an error condition in   that  implementation.
       Otherwise,  the	implementation	shall use the first NAME_MAX bytes of the pathname compo-
       nent.

   Foreground Process Group
       Each session that has established a connection with a controlling  terminal  will  distin-
       guish  one process group of the session as the foreground process group of the controlling
       terminal.  This group has certain privileges when accessing its controlling terminal  that
       are denied to background process groups.

   {IOV_MAX}
       Maximum number of entries in a struct iovec array.

   {LIMIT}
       The  braces  notation,  {LIMIT},  is  used to denote a magnitude limitation imposed by the
       implementation. This indicates a value which may be  defined by a header file (without the
       braces),  or  the  actual value may be obtained at runtime  by a call to the configuration
       inquiry pathconf(2) with the name argument  _PC_LIMIT.

   Masks
       The file mode creation mask of the process used during any create function calls  to  turn
       off  permission	bits  in  the  mode  argument  supplied.  Bit  positions  that are set in
       umask(cmask) are cleared in the mode of the created file.

   Message
       In a stream, one or more blocks of data or information, with  associated  STREAMS  control
       structures. Messages can be of several defined types, which identify the message contents.
       Messages are the only means of transferring data and communicating within a stream.

   Message Queue
       In a stream, a linked list of messages awaiting processing by a module or driver.

   Message Queue Identifier
       A message queue identifier (msqid) is a unique positive integer	created  by  a	msgget(2)
       call.  Each  msqid  has	a message queue and a data structure associated with it. The data
       structure is referred to as msqid_ds and contains the following members:

	 struct     ipc_perm msg_perm;
	 struct     msg *msg_first;
	 struct     msg *msg_last;
	 ulong_t    msg_cbytes;
	 ulong_t    msg_qnum;
	 ulong_t    msg_qbytes;
	 pid_t	    msg_lspid;
	 pid_t	    msg_lrpid;
	 time_t     msg_stime;
	 time_t     msg_rtime;
	 time_t     msg_ctime;

       The following are descriptions of the msqid_ds structure members:

       The msg_perm member is an ipc_perm structure that specifies the message operation  permis-
       sion (see below). This structure includes the following members:

	 uid_t	  cuid;   /* creator user id */
	 gid_t	  cgid;   /* creator group id */
	 uid_t	  uid;	  /* user id */
	 gid_t	  gid;	  /* group id */
	 mode_t   mode;   /* r/w permission */
	 ulong_t  seq;	  /* slot usage sequence # */
	 key_t	  key;	  /* key */

       The *msg_first member is a pointer to the first message on the queue.

       The *msg_last member is a pointer to the last message on the queue.

       The msg_cbytes member is the current number of bytes on the queue.

       The msg_qnum member is the number of messages currently on the queue.

       The msg_qbytes member is the maximum number of bytes allowed on the queue.

       The msg_lspid member is the process ID of the last process that performed a msgsnd() oper-
       ation.

       The msg_lrpid member is the process id of the last process that performed a msgrcv() oper-
       ation.

       The msg_stime member is the time of the last msgsnd() operation.

       The msg_rtime member is the time of the last msgrcv() operation.

       The  msg_ctime  member is the time of the last msgctl() operation that changed a member of
       the above structure.

   Message Operation Permissions
       In the msgctl(2), msgget(2), msgrcv(2), and msgsnd(2) function descriptions,  the  permis-
       sion  required for an operation is given as {token}, where token is the type of permission
       needed, interpreted as follows:

	 00400	 READ by user
	 00200	 WRITE by user
	 00040	 READ by group
	 00020	 WRITE by group
	 00004	 READ by others
	 00002	 WRITE by others

       Read and write permissions for a msqid are granted to a process if one or more of the fol-
       lowing are true:

	   o	  The  {PRIV_IPC_DAC_READ}  or	{PRIV_IPC_DAC_WRITE}  privilege is present in the
		  effective set.

	   o	  The effective user ID of the process matches msg_perm.cuid or  msg_perm.uid  in
		  the  data structure associated with msqid and the appropriate bit of the "user"
		  portion(0600) of msg_perm.mode is set.

	   o	  Any group ID in the  process	credentials  from  the	set  (cr_gid,  cr_groups)
		  matches  msg_perm.cgid  or  msg_perm.gid and the appropriate bit of the "group"
		  portion(060) of msg_perm.mode is set.

	   o	  The appropriate bit of the "other" portion(006) of msg_perm.mode is set."

       Otherwise, the corresponding permissions are denied.

   Module
       A module is an entity containing processing routines for input and output data. It  always
       exists  in the middle of a stream, between the stream's head and a driver. A module is the
       STREAMS counterpart to the commands in a shell pipeline except that a  module  contains	a
       pair  of  functions  which  allow independent bidirectional (downstream and upstream) data
       flow and processing.

   Multiplexor
       A multiplexor is a driver that allows streams associated with several user processes to be
       connected to a single driver, or several drivers to be connected to a single user process.
       STREAMS does not provide a general multiplexing driver, but does  provide  the  facilities
       for constructing them and for connecting multiplexed configurations of streams.

   Offset Maximum
       An  offset  maximum  is	an attribute of an open file description representing the largest
       value that can be used as a file offset.

   Orphaned Process Group
       A process group in which the parent of every member in the group is either itself a member
       of the group, or is not a member of the process group's session.

   Path Name
       A  path	name  is  a null-terminated character string starting with an optional slash (/),
       followed by zero or more directory names separated by slashes, optionally  followed  by	a
       file name.

       If  a  path name begins with a slash, the path search begins at the root directory. Other-
       wise, the search begins from the current working directory.

       A slash by itself names the root directory.

       Unless specifically stated otherwise, the null path name is treated as if it named a  non-
       existent file.

   Privileged User
       Solaris software implements a set of privileges that provide fine-grained control over the
       actions of processes. The possession of of a certain privilege allows a process to perform
       a  specific  set of restricted operations. Prior to the Solaris 10 release, a process run-
       ning with uid 0 was granted all privileges. See privileges(5) for the  semantics  and  the
       degree of backward compatibility awarded to processes with an effective uid of 0.

   Process ID
       Each  process in the system is uniquely identified during its lifetime by a positive inte-
       ger called a process ID. A process ID cannot be reused by the  system  until  the  process
       lifetime,  process  group  lifetime, and session lifetime ends for any process ID, process
       group ID, and session ID equal to that process ID. There are threads within a process with
       thread IDs thread_t and LWPID_t. These threads are not visible to the outside process.

   Parent Process ID
       A  new  process is created by a currently active process (see fork(2)). The parent process
       ID of a process is the process ID of its creator.

   Privilege
       Having appropriate privilege means having the capability to override system restrictions.

   Process Group
       Each process in the system is a member of a process group that is identified by a  process
       group  ID.   Any process that is not a process group leader may create a new process group
       and become its leader. Any process that is not a process group leader may join an existing
       process	group that shares the same session as the process.  A newly created process joins
       the process group of its parent.

   Process Group Leader
       A process group leader is a process whose process ID is the same as its process group ID.

   Process Group ID
       Each active process is a member of a process group and is identified by a positive integer
       called  the process group ID. This ID is the process ID of the group leader. This grouping
       permits the signaling of related processes (see kill(2)).

   Process Lifetime
       A process lifetime begins when the process is forked and ends after  it	exits,	when  its
       termination has been acknowledged by its parent process. See wait(3C).

   Process Group Lifetime
       A  process  group  lifetime  begins when the process group is created by its process group
       leader, and ends when the lifetime of the last process in the group ends or when the  last
       process in the group leaves the group.

   Processor Set ID
       The processors in a system may be divided into subsets, known as processor sets. A process
       bound to one of these sets will run only on processors in that set, and the processors  in
       the set will normally run only processes that have been bound to the set. Each active pro-
       cessor set is identified by a positive integer. See pset_create(2).

   Read Queue
       In a stream, the message queue in a module or driver containing messages moving upstream.

   Real User ID and Real Group ID
       Each user allowed on the system is  identified by a positive integer (0 to  MAXUID) called
       a real user ID.

       Each  user  is  also  a	member	of a group. The group is identified by a positive integer
       called the real group ID.

       An active process has a real user ID and real group ID that are set to the  real  user  ID
       and real group ID, respectively, of the user responsible for the creation of the process.

   Root Directory and Current Working Directory
       Each  process  has  associated with it a concept of a root directory and a current working
       directory for the purpose of resolving path name searches. The root directory of a process
       need not be the root directory of the root file system.

   Saved Resource Limits
       Saved  resource	limits is an attribute of a process that provides some flexibility in the
       handling of unrepresentable resource limits, as described in the exec family of	functions
       and setrlimit(2).

   Saved User ID and Saved Group ID
       The  saved  user ID and saved group ID are the values of the  effective user ID and effec-
       tive group ID just after an exec of a file whose set user or set group file mode  bit  has
       been set (see exec(2)).

   Semaphore Identifier
       A  semaphore identifier (semid) is a unique positive  integer created by a semget(2) call.
       Each semid has a set of semaphores and a data  structure  associated  with  it.	The  data
       structure is referred to as semid_ds and contains the following members:

	 struct ipc_perm   sem_perm;	/* operation permission struct */
	 struct sem	   *sem_base;	/* ptr to first semaphore in set */
	 ushort_t	   sem_nsems;	/* number of sems in set */
	 time_t 	   sem_otime;	/* last operation time */
	 time_t 	   sem_ctime;	/* last change time */
					/* Times measured in secs since */
					/* 00:00:00 GMT, Jan. 1, 1970 */

       The following are descriptions of the semid_ds structure members:

       The  sem_perm  member is an ipc_perm structure that specifies the semaphore operation per-
       mission (see below). This structure includes the following members:

	 uid_t	   uid;    /* user id */
	 gid_t	   gid;    /* group id */
	 uid_t	   cuid;   /* creator user id */
	 gid_t	   cgid;   /* creator group id */
	 mode_t    mode;   /* r/a permission */
	 ulong_t   seq;    /* slot usage sequence number */
	 key_t	   key;    /* key */

       The sem_nsems member is equal to the number of semaphores in the set.  Each  semaphore  in
       the  set  is  referenced by a nonnegative integer referred to as a sem_num. sem_num values
       run sequentially from 0 to the value of sem_nsems minus 1.

       The sem_otime member is the time of the last semop(2) operation.

       The sem_ctime member is the time of the last semctl(2) operation that changed a member  of
       the above structure.

       A semaphore is a data structure called sem that contains the following members:

	 ushort_t   semval;    /* semaphore value */
	 pid_t	    sempid;    /* pid of last operation  */
	 ushort_t   semncnt;   /* # awaiting semval > cval */
	 ushort_t   semzcnt;   /* # awaiting semval = 0 */

       The following are descriptions of the sem structure members:

       The semval member is a non-negative integer that is the actual value of the semaphore.

       The  sempid  member  is equal to the process ID of the last process that performed a sema-
       phore operation on this semaphore.

       The semncnt member is a count of the number of  processes  that	are  currently	suspended
       awaiting this semaphore's semval to become greater than its current value.

       The  semzcnt  member  is  a  count of the number of processes that are currently suspended
       awaiting this semaphore's semval to become 0.

   Semaphore Operation Permissions
       In the semop(2) and semctl(2) function descriptions, the permission required for an opera-
       tion is given as {token}, where token is the type of permission needed interpreted as fol-
       lows:

	 00400	     READ by user
	 00200	 ALTER by user
	 00040	 READ by group
	 00020	 ALTER by group
	 00004	 READ by others
	 00002	 ALTER by others

       Read and alter permissions for a semid are granted to a process if one or more of the fol-
       lowing are true:

	   o	  The  {PRIV_IPC_DAC_READ}  or	{PRIV_IPC_DAC_WRITE}  privilege is present in the
		  effective set.

	   o	  The effective user ID of the process matches sem_perm.cuid or  sem_perm.uid  in
		  the  data structure associated with semid and the appropriate bit of the "user"
		  portion(0600) of sem_perm.mode is set.

	   o	  The effective group ID of the process matches sem_perm.cgid or sem_perm.gid and
		  the appropriate bit of the "group" portion(060) of sem_perm.mode is set.

	   o	  The appropriate bit of the "other" portion(06) of sem_perm.mode is set.

       Otherwise, the corresponding permissions are denied.

   Session
       A  session is a group of processes identified by a common ID called a session  ID, capable
       of establishing a connection with a controlling terminal.   Any	process  that  is  not	a
       process	group  leader  may  create a new session  and process group, becoming the session
       leader of the session and process group leader of the  process  group.	A  newly  created
       process joins the session of its creator.

   Session ID
       Each session in the system is uniquely identified during its lifetime by  a positive inte-
       ger called a session ID, the process ID of its session leader.

   Session Leader
       A session leader is a process whose session ID is the same as  its   process  and  process
       group ID.

   Session Lifetime
       A session lifetime begins when the session is created by its session leader, and ends when
       the lifetime of the last process that is a member  of the session ends, or when	the  last
       process that is a member in the session leaves the session.

   Shared Memory Identifier
       A  shared  memory  identifier  (shmid) is a unique positive integer created by a shmget(2)
       call. Each shmid has a segment of memory (referred to as a shared memory  segment)  and	a
       data structure associated with it. (Note that these shared memory segments must be explic-
       itly removed by the user after the last reference to them is removed.) The data	structure
       is referred to as shmid_ds and contains the following members:

	 struct ipc_perm   shm_perm;	 /* operation permission struct */
	 size_t 	   shm_segsz;	 /* size of segment */
	 struct anon_map   *shm_amp;	 /* ptr to region structure */
	 char		   pad[4];	 /* for swap compatibility */
	 pid_t		   shm_lpid;	 /* pid of last operation */
	 pid_t		   shm_cpid;	 /* creator pid */
	 shmatt_t	   shm_nattch;	 /* number of current attaches */
	 ulong_t	   shm_cnattch;  /* used only for shminfo */
	 time_t 	   shm_atime;	 /* last attach time */
	 time_t 	   shm_dtime;	 /* last detach time */
	 time_t 	   shm_ctime;	 /* last change time */
					 /* Times measured in secs since */
					 /* 00:00:00 GMT, Jan. 1, 1970 */

       The following are descriptions of the shmid_ds structure members:

       The  shm_perm  member  is an ipc_perm structure that specifies the shared memory operation
       permission (see below). This structure includes the following members:

	 uid_t	   cuid;   /* creator user id */
	 gid_t	   cgid;   /* creator group id */
	 uid_t	   uid;    /* user id */
	 gid_t	   gid;    /* group id */
	 mode_t    mode;   /* r/w permission */
	 ulong_t   seq;    /* slot usage sequence # */
	 key_t	   key;    /* key */

       The shm_segsz member specifies the size of the shared memory segment in bytes.

       The shm_cpid member is the process ID of the process that created the shared memory  iden-
       tifier.

       The  shm_lpid  member  is  the  process ID of the last process that performed a shmat() or
       shmdt() operation (see shmop(2)).

       The shm_nattch member is  the  number  of  processes  that  currently  have  this  segment
       attached.

       The shm_atime member is the time of the last shmat() operation (see shmop(2)).

       The shm_dtime member is the time of the last shmdt() operation (see shmop(2)).

       The  shm_ctime  member is the time of the last shmctl(2) operation that changed one of the
       members of the above structure.

   Shared Memory Operation Permissions
       In the shmctl(2), shmat(), and shmdt() (see shmop(2)) function descriptions,  the  permis-
       sion  required for an operation is given as {token}, where token is the type of permission
       needed interpreted as follows:

	 00400	 READ by user
	 00200	 WRITE by user
	 00040	 READ by group
	 00020	 WRITE by group
	 00004	 READ by others
	 00002	 WRITE by others

       Read and write permissions for a shmid are granted to a process if one or more of the fol-
       lowing are true:

	   o	  The  {PRIV_IPC_DAC_READ}  or	{PRIV_IPC_DAC_WRITE}  privilege is present in the
		  effective set.

	   o	  The effective user ID of the process matches shm_perm.cuid or  shm_perm.uid  in
		  the  data structure associated with shmid and the appropriate bit of the "user"
		  portion(0600) of shm_perm.mode is set.

	   o	  The effective group ID of the process matches shm_perm.cgid or shm_perm.gid and
		  the appropriate bit of the "group" portion(060) of shm_perm.mode is set.

	   o	  The appropriate bit of the "other" portion(06) of shm_perm.mode is set.

       Otherwise, the corresponding permissions are denied.

   Special Processes
       The process with ID 0 and the process with ID 1 are special processes referred to as proc0
       and proc1; see kill(2). proc0 is  the  process  scheduler.  proc1  is  the  initialization
       process	(init); proc1 is the ancestor of every other process in the system and is used to
       control the process structure.

   STREAMS
       A set of kernel mechanisms that support the development of network services and data  com-
       munication  drivers.  It defines interface standards for character input/output within the
       kernel and between the kernel and user level processes. The STREAMS mechanism is  composed
       of utility routines, kernel facilities and a set of data structures.

   Stream
       A  stream  is a full-duplex data path within the kernel	between a user process and driver
       routines. The primary components are a stream head, a driver, and  zero	or  more  modules
       between the stream head and driver. A stream is analogous to a shell pipeline, except that
       data flow and processing are bidirectional.

   Stream Head
       In a stream, the stream head is the end of the stream that provides the interface  between
       the  stream  and a user process. The principal functions of the stream head are processing
       STREAMS-related system calls and passing data and information between a user  process  and
       the stream.

   Upstream
       In a stream, the direction from driver to stream head.

   Write Queue
       In  a  stream,  the  message  queue in a module or driver containing messages moving down-
       stream.

ACKNOWLEDGMENTS
       Sun Microsystems, Inc. gratefully acknowledges The Open Group for permission to	reproduce
       portions  of its copyrighted documentation. Original documentation from The Open Group can
       be obtained online at http://www.opengroup.org/bookstore/.

       The Institute of Electrical and Electronics Engineers and The Open Group,  have	given  us
       permission to reprint portions of their documentation.

       In the following statement, the phrase ``this text'' refers to portions of the system doc-
       umentation.

       Portions of this text are reprinted and reproduced in electronic form in the SunOS  Refer-
       ence  Manual,  from  IEEE Std 1003.1, 2004 Edition, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base Specifications	Issue  6,
       Copyright  (C) 2001-2004 by the Institute of Electrical and Electronics Engineers, Inc and
       The Open Group.	In the event of any discrepancy between these versions and  the  original
       IEEE  and  The  Open  Group Standard, the original IEEE and The Open Group Standard is the
       referee document.  The original	Standard  can  be  obtained  online  at  http://www.open-
       group.org/unix/online.html.

       This notice shall appear on any product containing this material.

SEE ALSO
       standards(5), threads(5)

SunOS 5.11				   17 Nov 2008					 Intro(2)


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