mirror of https://github.com/mkerrisk/man-pages
Formatting & lang clean-ups; added data structure defns
This commit is contained in:
Michael Kerrisk
parent
f998edca67
commit
70d0e5ef63
116
man2/msgctl.2
116
man2/msgctl.2
|
|
@ -26,8 +26,11 @@
|
|||
.\" Added notes on CAP_IPC_OWNER requirement
|
||||
.\" Modified, 17 Jun 2004, Michael Kerrisk <mtk-manpages@gmx.net>
|
||||
.\" Added notes on CAP_SYS_ADMIN requirement for IPC_SET and IPC_RMID
|
||||
.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk-manpages@gmx.net>
|
||||
.\" Language and formatting clean-ups
|
||||
.\" Added msqid_ds and ipc_perm structure definitions
|
||||
.\"
|
||||
.TH MSGCTL 2 2004-06-17 "Linux 2.6.7" "Linux Programmer's Manual"
|
||||
.TH MSGCTL 2 2004-11-10 "Linux 2.6.9" "Linux Programmer's Manual"
|
||||
.SH NAME
|
||||
msgctl \- message control operations
|
||||
.SH SYNOPSIS
|
||||
|
|
@ -44,74 +47,115 @@ msgctl \- message control operations
|
|||
.BI "int " cmd ,
|
||||
.BI "struct msqid_ds *" buf );
|
||||
.SH DESCRIPTION
|
||||
This function performs the control operation specified by
|
||||
.B msgctl
|
||||
performs the control operation specified by
|
||||
.I cmd
|
||||
on the message queue with identifier
|
||||
.IR msqid .
|
||||
Legal values for
|
||||
.PP
|
||||
The
|
||||
.I msqid_ds
|
||||
data structure is defined in <sys/msg.h> as follows:
|
||||
.nf
|
||||
.in +4n
|
||||
|
||||
struct msqid_ds {
|
||||
struct ipc_perm msg_perm; /* Ownership and permissions
|
||||
time_t msg_stime; /* Time of last msgsnd() */
|
||||
time_t msg_rtime; /* Time of last msgrcv() */
|
||||
time_t msg_ctime; /* Time of last change */
|
||||
unsigned long __msg_cbytes; /* Current number of bytes in
|
||||
queue (non-standard) */
|
||||
msgqnum_t msg_qnum; /* Current number of messages
|
||||
in queue */
|
||||
msglen_t msg_qbytes; /* Maximum number of bytes
|
||||
allowed in queue */
|
||||
pid_t msg_lspid; /* PID of last msgsnd() */
|
||||
pid_t msg_lrpid; /* PID of last msgrcv() */
|
||||
|
||||
};
|
||||
.in -4n
|
||||
.fi
|
||||
.PP
|
||||
The
|
||||
.I ipc_perm
|
||||
structure is defined in <sys/ipc.h> as follows
|
||||
(the highlighted fields are settable using
|
||||
.BR IPC_SET ):
|
||||
.PP
|
||||
.nf
|
||||
.in +4n
|
||||
struct ipc_perm {
|
||||
key_t key; /* Key supplied to msgget() */
|
||||
uid_t \fBuid\fP; /* Effective UID of owner */
|
||||
gid_t \fBgid\fP; /* Effective GID of owner */
|
||||
uid_t cuid; /* Effective UID of creator */
|
||||
gid_t cgid; /* Effective GID of creator */
|
||||
unsigned short \fBmode\fP; /* Permissions */
|
||||
unsigned short seq; /* Sequence number */
|
||||
};
|
||||
.in -4n
|
||||
.fi
|
||||
.PP
|
||||
Valid values for
|
||||
.I cmd
|
||||
are:
|
||||
.TP
|
||||
.B IPC_STAT
|
||||
Copy info from the message queue data structure associated with
|
||||
Copy information from the kernel data structure associated with
|
||||
.I msqid
|
||||
into the structure pointed to by
|
||||
into the
|
||||
.I msqid_ds
|
||||
structure pointed to by
|
||||
.IR buf .
|
||||
The caller must have read permission on the message queue.
|
||||
.TP
|
||||
.B IPC_SET
|
||||
Write the values of some members of the
|
||||
.B msqid_ds
|
||||
.I msqid_ds
|
||||
structure pointed to by
|
||||
.I buf
|
||||
to the message queue data structure, updating also its
|
||||
.B msg_ctime
|
||||
to the kernel data structure associated with this message queue,
|
||||
updating also its
|
||||
.I msg_ctime
|
||||
member.
|
||||
The following members of the structure can be updated:
|
||||
.nf
|
||||
.sp
|
||||
.ft B
|
||||
msg_perm.uid
|
||||
msg_perm.gid
|
||||
msg_perm.mode \fR/* only lowest 9-bits */\fP
|
||||
msg_qbytes
|
||||
.fi
|
||||
.ft R
|
||||
.sp
|
||||
The calling process must have appropriate (probably, root) privileges
|
||||
or its effective user\-ID must be that of the creator
|
||||
.RI ( msg_perm.cuid )
|
||||
or owner
|
||||
The following members of the structure are updated:
|
||||
.IR msg_qbytes ,
|
||||
.IR msg_perm.uid ,
|
||||
.IR msg_perm.gid ,
|
||||
and (the least significant 9 bits of)
|
||||
.IR msg_perm.mode .
|
||||
The effective UID of the calling process must match the owner
|
||||
.RI ( msg_perm.uid )
|
||||
of the message queue.
|
||||
or creator
|
||||
.RI ( msg_perm.cuid )
|
||||
of the message queue, or the caller must be privileged.
|
||||
Appropriate privilege (Linux: the
|
||||
.B CAP_IPC_RESOURCE
|
||||
capability) is required to raise the
|
||||
.B msg_qbytes
|
||||
.I msg_qbytes
|
||||
value beyond the system parameter
|
||||
.BR MSGMNB .
|
||||
.TP
|
||||
.B IPC_RMID
|
||||
Immediately remove the message queue and its associated data structure,
|
||||
Immediately remove the message queue,
|
||||
awakening all waiting reader and writer processes (with an error
|
||||
return and
|
||||
.B errno
|
||||
.I errno
|
||||
set to
|
||||
.BR EIDRM ).
|
||||
The calling process must have appropriate (probably, root) privileges
|
||||
The calling process must have appropriate privileges
|
||||
or its effective user\-ID must be either that of the creator or owner
|
||||
of the message queue.
|
||||
.SH "RETURN VALUE"
|
||||
On success, the return value will be
|
||||
.BR 0 ,
|
||||
otherwise
|
||||
.B \-1
|
||||
On success, the return value will be 0
|
||||
otherwise \-1
|
||||
with
|
||||
.B errno
|
||||
.I errno
|
||||
indicating the error.
|
||||
.SH ERRORS
|
||||
On failure,
|
||||
.B errno
|
||||
.I errno
|
||||
is set to one of the following:
|
||||
.TP 11
|
||||
.B EACCES
|
||||
|
|
@ -165,10 +209,10 @@ and the process is not privileged (Linux: it does not have the
|
|||
.B CAP_SYS_ADMIN
|
||||
capability).
|
||||
.SH NOTES
|
||||
Various fields in a \fIstruct msqid_ds\fP were shorts under Linux 2.2
|
||||
Various fields in the \fIstruct msqid_ds\fP were shorts under Linux 2.2
|
||||
and have become longs under Linux 2.4. To take advantage of this,
|
||||
a recompilation under glibc-2.1.91 or later should suffice.
|
||||
(The kernel distinguishes old and new calls by a IPC_64 flag in
|
||||
(The kernel distinguishes old and new calls by an IPC_64 flag in
|
||||
.IR cmd .)
|
||||
.SH "CONFORMING TO"
|
||||
SVr4, SVID. SVID does not document the EIDRM error condition.
|
||||
|
|
|
|||
228
man2/semctl.2
228
man2/semctl.2
|
|
@ -29,8 +29,12 @@
|
|||
.\" Added notes on CAP_IPC_OWNER requirement
|
||||
.\" Modified 17 Jun 2004, Michael Kerrisk <mtk-manpages@gmx.net>
|
||||
.\" Added notes on CAP_SYS_ADMIN requirement for IPC_SET and IPC_RMID
|
||||
.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk-manpages@gmx.net>
|
||||
.\" Language and formatting clean-ups
|
||||
.\" Rewrote semun text
|
||||
.\" Added semid_ds and ipc_perm structure definitions
|
||||
.\"
|
||||
.TH SEMCTL 2 2004-06-17 "Linux 2.6.7" "Linux Programmer's Manual"
|
||||
.TH SEMCTL 2 2004-11-10 "Linux 2.6.9" "Linux Programmer's Manual"
|
||||
.SH NAME
|
||||
semctl \- semaphore control operations
|
||||
.SH SYNOPSIS
|
||||
|
|
@ -42,7 +46,6 @@ semctl \- semaphore control operations
|
|||
.BI "int semctl(int " semid ", int " semnum ", int " cmd ", ...);"
|
||||
.fi
|
||||
.SH DESCRIPTION
|
||||
The function
|
||||
.B semctl
|
||||
performs the control operation specified by
|
||||
.I cmd
|
||||
|
|
@ -51,81 +54,110 @@ on the semaphore set identified by
|
|||
or on the
|
||||
.IR semnum -th
|
||||
semaphore of that set.
|
||||
(Semaphores are numbered starting at 0.)
|
||||
(The semaphores in a set are numbered starting at 0.)
|
||||
.PP
|
||||
This function has three or four arguments. When there
|
||||
are four, the call is
|
||||
.BI semctl( semid , semnum , cmd , arg );
|
||||
where the fourth argument
|
||||
.I arg
|
||||
has a type
|
||||
.B union semun
|
||||
defined as follows:
|
||||
This function has three or four arguments, depending on
|
||||
.IR cmd .
|
||||
When there are four, the fourth has the type
|
||||
.IR "union semun" .
|
||||
The \fIcalling program\fP must define this union as follows:
|
||||
|
||||
.nf
|
||||
#if defined(__GNU_LIBRARY__) && !defined(_SEM_SEMUN_UNDEFINED)
|
||||
/* union semun is defined by including <sys/sem.h> */
|
||||
#else
|
||||
/* according to X/OPEN we have to define it ourselves */
|
||||
.in +4n
|
||||
union semun {
|
||||
int val; /* value for SETVAL */
|
||||
struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
|
||||
unsigned short *array; /* array for GETALL, SETALL */
|
||||
/* Linux specific part: */
|
||||
struct seminfo *__buf; /* buffer for IPC_INFO */
|
||||
int val; /* Value for SETVAL */
|
||||
struct semid_ds *buf; /* Buffer for IPC_STAT, IPC_SET */
|
||||
unsigned short *array; /* Array for GETALL, SETALL */
|
||||
struct seminfo *__buf; /* Buffer for IPC_INFO
|
||||
(Linux specific) */
|
||||
};
|
||||
#endif
|
||||
.in -4n
|
||||
.fi
|
||||
.PP
|
||||
Legal values for
|
||||
The
|
||||
.I semid_ds
|
||||
data structure is defined in <sys/sem.h> as follows:
|
||||
.nf
|
||||
.in +4n
|
||||
|
||||
struct semid_ds {
|
||||
struct ipc_perm sem_perm; /* Ownership and permissions
|
||||
time_t sem_otime; /* Last semop time */
|
||||
time_t sem_ctime; /* Last change time */
|
||||
unsigned short sem_nsems; /* No. of semaphores in set */
|
||||
};
|
||||
.in -4n
|
||||
.fi
|
||||
.PP
|
||||
The
|
||||
.I ipc_perm
|
||||
structure is defined in <sys/ipc.h> as follows
|
||||
(the highlighted fields are settable using
|
||||
.BR IPC_SET ):
|
||||
.PP
|
||||
.nf
|
||||
.in +4n
|
||||
struct ipc_perm {
|
||||
key_t key; /* Key supplied to semget() */
|
||||
uid_t \fBuid\fP; /* Effective UID of owner */
|
||||
gid_t \fBgid\fP; /* Effective GID of owner */
|
||||
uid_t cuid; /* Effective UID of creator */
|
||||
gid_t cgid; /* Effective GID of creator */
|
||||
unsigned short \fBmode\fP; /* Permissions */
|
||||
unsigned short seq; /* Sequence number */
|
||||
};
|
||||
.in -4n
|
||||
.fi
|
||||
.PP
|
||||
Valid values for
|
||||
.I cmd
|
||||
are:
|
||||
.TP 12
|
||||
.B IPC_STAT
|
||||
Copy info from the semaphore set data structure
|
||||
into the structure pointed to by
|
||||
.IB arg .buf \fR.
|
||||
Copy information from the kernel data structure associated with
|
||||
.I semid
|
||||
into the
|
||||
.I semid_ds
|
||||
structure pointed to by
|
||||
.IR arg.buf .
|
||||
The argument
|
||||
.I semnum
|
||||
is ignored.
|
||||
The calling process must have read access privileges on the semaphore set.
|
||||
The calling process must have read permission on the semaphore set.
|
||||
.TP
|
||||
.B IPC_SET
|
||||
Write the values of some members of the
|
||||
.B semid_ds
|
||||
.I semid_ds
|
||||
structure pointed to by
|
||||
.IB arg .buf
|
||||
to the semaphore set data structure, updating also its
|
||||
.B sem_ctime
|
||||
.I arg.buf
|
||||
to the kernel data structure associated with this semaphore set,
|
||||
updating also its
|
||||
.I sem_ctime
|
||||
member.
|
||||
Considered members from the user supplied
|
||||
.B "struct semid_ds"
|
||||
pointed to by
|
||||
.IB arg .buf
|
||||
are
|
||||
.nf
|
||||
.sp
|
||||
.ft B
|
||||
sem_perm.uid
|
||||
sem_perm.gid
|
||||
sem_perm.mode \fR/* only lowest 9-bits */\fP
|
||||
.fi
|
||||
.ft R
|
||||
.sp
|
||||
The effective user\-ID of the calling process must be that of the
|
||||
super\-user, or match the creator or owner of the semaphore set.
|
||||
The following members of the structure are updated:
|
||||
.IR sem_perm.uid ,
|
||||
.IR sem_perm.gid ,
|
||||
and (the least significant 9 bits of)
|
||||
.IR sem_perm.mode .
|
||||
The effective UID of the calling process must match the owner
|
||||
.RI ( sem_perm.uid )
|
||||
or creator
|
||||
.RI ( sem_perm.cuid )
|
||||
of the semaphore set, or the caller must be privileged.
|
||||
The argument
|
||||
.I semnum
|
||||
is ignored.
|
||||
.TP
|
||||
.B IPC_RMID
|
||||
Immediately remove the semaphore set and its data structures
|
||||
awakening all waiting processes (with an error return and
|
||||
.B errno
|
||||
Immediately remove the semaphore set,
|
||||
awakening all processes blocked in
|
||||
.BR semop ()
|
||||
calls on the set (with an error return and
|
||||
.I errno
|
||||
set to
|
||||
.BR EIDRM ).
|
||||
The effective user\-ID of the calling process must be that of the
|
||||
super\-user, or match the creator or owner of the semaphore set.
|
||||
superuser, or match the creator or owner of the semaphore set.
|
||||
The argument
|
||||
.I semnum
|
||||
is ignored.
|
||||
|
|
@ -133,17 +165,19 @@ is ignored.
|
|||
.B GETALL
|
||||
Return
|
||||
.B semval
|
||||
(i.e., the current value)
|
||||
for all semaphores of the set into
|
||||
.IB arg .array \fR.
|
||||
.IB arg.array .
|
||||
The argument
|
||||
.I semnum
|
||||
is ignored.
|
||||
The calling process must have read access privileges on the semaphore set.
|
||||
The calling process must have read permission on the semaphore set.
|
||||
.TP
|
||||
.B GETNCNT
|
||||
The system call returns the value of
|
||||
.B semncnt
|
||||
for the
|
||||
(i.e., the number of processes waiting for the value of
|
||||
this semaphore to increase) for the
|
||||
.IR semnum \-th
|
||||
semaphore of the set
|
||||
(i.e. the number of processes waiting for an increase of
|
||||
|
|
@ -151,7 +185,7 @@ semaphore of the set
|
|||
for the
|
||||
.IR semnum \-th
|
||||
semaphore of the set).
|
||||
The calling process must have read access privileges on the semaphore set.
|
||||
The calling process must have read permission on the semaphore set.
|
||||
.TP
|
||||
.B GETPID
|
||||
The system call returns the value of
|
||||
|
|
@ -159,12 +193,12 @@ The system call returns the value of
|
|||
for the
|
||||
.IR semnum \-th
|
||||
semaphore of the set
|
||||
(i.e. the pid of the process that executed the last
|
||||
.B semop
|
||||
(i.e. the PID of the process that executed the last
|
||||
.BR semop ()
|
||||
call for the
|
||||
.IR semnum \-th
|
||||
semaphore of the set).
|
||||
The calling process must have read access privileges on the semaphore set.
|
||||
The calling process must have read permission on the semaphore set.
|
||||
.TP
|
||||
.B GETVAL
|
||||
The system call returns the value of
|
||||
|
|
@ -172,12 +206,13 @@ The system call returns the value of
|
|||
for the
|
||||
.IR semnum \-th
|
||||
semaphore of the set.
|
||||
The calling process must have read access privileges on the semaphore set.
|
||||
The calling process must have read permission on the semaphore set.
|
||||
.TP
|
||||
.B GETZCNT
|
||||
The system call returns the value of
|
||||
.B semzcnt
|
||||
for the
|
||||
(i.e., the number of processes waiting for the value of
|
||||
this semaphore to become zero) for the
|
||||
.IR semnum \-th
|
||||
semaphore of the set
|
||||
(i.e. the number of processes waiting for
|
||||
|
|
@ -185,51 +220,53 @@ semaphore of the set
|
|||
of the
|
||||
.IR semnum \-th
|
||||
semaphore of the set to become 0).
|
||||
The calling process must have read access privileges on the semaphore set.
|
||||
The calling process must have read permission on the semaphore set.
|
||||
.TP
|
||||
.B SETALL
|
||||
Set
|
||||
.B semval
|
||||
for all semaphores of the set using
|
||||
.IB arg .array ,
|
||||
.IB arg.array ,
|
||||
updating also the
|
||||
.B sem_ctime
|
||||
.I sem_ctime
|
||||
member of the
|
||||
.B semid_ds
|
||||
structure associated to the set.
|
||||
Undo entries are cleared for altered semaphores in all processes.
|
||||
Processes sleeping on the wait queue are awakened if some
|
||||
.B semval
|
||||
becomes 0 or increases.
|
||||
.I semid_ds
|
||||
structure associated with the set.
|
||||
Undo entries (see
|
||||
.BR semop (2))
|
||||
are cleared for altered semaphores in all processes.
|
||||
If the changes to semaphore values would permit blocked
|
||||
.BR semop ()
|
||||
calls in other processes to proceed, then those processes are woken up.
|
||||
The argument
|
||||
.I semnum
|
||||
is ignored.
|
||||
The calling process must have alter access privileges on the semaphore set.
|
||||
The calling process must have alter (write) permission on
|
||||
the semaphore set.
|
||||
.TP
|
||||
.B SETVAL
|
||||
Set the value of
|
||||
.B semval
|
||||
to
|
||||
.IB arg .val
|
||||
.IB arg.val
|
||||
for the
|
||||
.IR semnum \-th
|
||||
semaphore of the set, updating also the
|
||||
.B sem_ctime
|
||||
.I sem_ctime
|
||||
member of the
|
||||
.B semid_ds
|
||||
structure associated to the set.
|
||||
.I semid_ds
|
||||
structure associated with the set.
|
||||
Undo entries are cleared for altered semaphores in all processes.
|
||||
Processes sleeping on the wait queue are awakened if
|
||||
.B semval
|
||||
becomes 0 or increases.
|
||||
The calling process must have alter access privileges on the semaphore set.
|
||||
If the changes to semaphore values would permit blocked
|
||||
.BR semop ()
|
||||
calls in other processes to proceed, then those processes are woken up.
|
||||
The calling process must have alter permission on the semaphore set.
|
||||
.SH "RETURN VALUE"
|
||||
On failure
|
||||
.B semctl
|
||||
returns
|
||||
.B \-1
|
||||
returns \-1
|
||||
with
|
||||
.B errno
|
||||
.I errno
|
||||
indicating the error.
|
||||
Otherwise the system call returns a nonnegative value depending on
|
||||
.I cmd
|
||||
|
|
@ -256,7 +293,7 @@ All other
|
|||
values return 0 on success.
|
||||
.SH ERRORS
|
||||
On failure,
|
||||
.B errno
|
||||
.I errno
|
||||
will be set to one of the following:
|
||||
.TP 11
|
||||
.B EACCES
|
||||
|
|
@ -280,9 +317,9 @@ capability.
|
|||
.TP
|
||||
.B EFAULT
|
||||
The address pointed to by
|
||||
.IB arg .buf
|
||||
.IB arg.buf
|
||||
or
|
||||
.IB arg .array
|
||||
.IB arg.array
|
||||
isn't accessible.
|
||||
.TP
|
||||
.B EIDRM
|
||||
|
|
@ -297,11 +334,11 @@ or
|
|||
.B EPERM
|
||||
The argument
|
||||
.I cmd
|
||||
has value
|
||||
has the value
|
||||
.B IPC_SET
|
||||
or
|
||||
.B IPC_RMID
|
||||
but the but the effective user ID of the calling process is not the creator
|
||||
but the effective user ID of the calling process is not the creator
|
||||
(as found in
|
||||
.IR sem_perm.cuid )
|
||||
or the owner
|
||||
|
|
@ -315,14 +352,14 @@ capability.
|
|||
.B ERANGE
|
||||
The argument
|
||||
.I cmd
|
||||
has value
|
||||
has the value
|
||||
.B SETALL
|
||||
or
|
||||
.B SETVAL
|
||||
and the value to which
|
||||
.B semval
|
||||
has to be set (for some semaphore of the set) is less than 0
|
||||
or greater than the implementation value
|
||||
is to be set (for some semaphore of the set) is less than 0
|
||||
or greater than the implementation limit
|
||||
.BR SEMVMX .
|
||||
.SH NOTES
|
||||
The
|
||||
|
|
@ -333,15 +370,24 @@ and
|
|||
control calls are used by the
|
||||
.BR ipcs (8)
|
||||
program to provide information on allocated resources.
|
||||
In the future these can be modified as needed or moved to a proc file system
|
||||
In the future these may modified or moved to a /proc file system
|
||||
interface.
|
||||
.LP
|
||||
Various fields in a \fIstruct semid_ds\fP were shorts under Linux 2.2
|
||||
and have become longs under Linux 2.4. To take advantage of this,
|
||||
a recompilation under glibc-2.1.91 or later should suffice.
|
||||
(The kernel distinguishes old and new calls by a IPC_64 flag in
|
||||
(The kernel distinguishes old and new calls by an IPC_64 flag in
|
||||
.IR cmd .)
|
||||
.PP
|
||||
In some earlier versions of glibc, the
|
||||
.I semun
|
||||
union was defined in <sys/sem.h>, but POSIX.1-2001 requires
|
||||
that the caller define this union.
|
||||
On versions of glibc where this union is \fInot\fP defined,
|
||||
the macro
|
||||
.B _SEM_SEMUN_UNDEFINED
|
||||
is defined in <sys/sem.h>.
|
||||
.PP
|
||||
The following system limit on semaphore sets affects a
|
||||
.B semctl
|
||||
call:
|
||||
|
|
@ -355,7 +401,7 @@ For greater portability it is best to always call
|
|||
.B semctl
|
||||
with four arguments.
|
||||
.LP
|
||||
Under Linux, the function
|
||||
Under Linux,
|
||||
.B semctl
|
||||
is not a system call, but is implemented via the system call
|
||||
.BR ipc (2).
|
||||
|
|
|
|||
Loading…
Reference in New Issue