From cb589475e89a2cc44f1d7a42a4a5f31e18e4019b Mon Sep 17 00:00:00 2001 From: mpp Date: Mon, 12 Feb 1996 07:03:24 +0000 Subject: Added man pages for msgctl(3), msgget(3), msgrcv(3) and msgsnd(3). Obtained from: NetBSD --- lib/libc/gen/Makefile.inc | 4 +- lib/libc/gen/msgctl.3 | 201 ++++++++++++++++++++++++++++++++++++++++++++++ lib/libc/gen/msgget.3 | 126 +++++++++++++++++++++++++++++ lib/libc/gen/msgrcv.3 | 181 +++++++++++++++++++++++++++++++++++++++++ lib/libc/gen/msgsnd.3 | 145 +++++++++++++++++++++++++++++++++ 5 files changed, 656 insertions(+), 1 deletion(-) create mode 100644 lib/libc/gen/msgctl.3 create mode 100644 lib/libc/gen/msgget.3 create mode 100644 lib/libc/gen/msgrcv.3 create mode 100644 lib/libc/gen/msgsnd.3 (limited to 'lib') diff --git a/lib/libc/gen/Makefile.inc b/lib/libc/gen/Makefile.inc index 542028c..95e773b 100644 --- a/lib/libc/gen/Makefile.inc +++ b/lib/libc/gen/Makefile.inc @@ -46,7 +46,9 @@ MAN3+= gen/alarm.3 gen/clock.3 gen/confstr.3 gen/config_open.3 \ gen/getmntinfo.3 gen/getnetgrent.3 gen/getpagesize.3 gen/getpass.3 \ gen/getpwent.3 gen/getttyent.3 gen/getvfsent.3 gen/getusershell.3 \ gen/glob.3 \ - gen/initgroups.3 gen/isinf.3 gen/ldexp.3 gen/modf.3 gen/nice.3 \ + gen/initgroups.3 gen/isinf.3 gen/ldexp.3 \ + gen/msgctl.3 gen/msgget.3 gen/msgrcv.3 gen/msgsnd.3 \ + gen/modf.3 gen/nice.3 \ gen/nlist.3 gen/pause.3 gen/popen.3 gen/psignal.3 gen/pwcache.3 \ gen/raise.3 gen/rand48.3 gen/scandir.3 gen/setjmp.3 gen/setmode.3 \ gen/siginterrupt.3 gen/signal.3 gen/sigsetops.3 gen/sleep.3 \ diff --git a/lib/libc/gen/msgctl.3 b/lib/libc/gen/msgctl.3 new file mode 100644 index 0000000..27da57c --- /dev/null +++ b/lib/libc/gen/msgctl.3 @@ -0,0 +1,201 @@ +.\" $NetBSD: msgctl.2,v 1.1 1995/10/16 23:49:15 jtc Exp $ +.\" +.\" Copyright (c) 1995 Frank van der Linden +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed for the NetBSD Project +.\" by Frank van der Linden +.\" 4. The name of the author may not be used to endorse or promote products +.\" derived from this software without specific prior written permission +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR +.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES +.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. +.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, +.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT +.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF +.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +.\"/ +.Dd August 17, 1995 +.Dt MSGCTL 3 +.Os NetBSD +.Sh NAME +.Nm msgctl +.Nd message control operations +.Sh SYNOPSIS +.Fd #include +.Fd #include +.Fd #include +.Ft int +.Fn msgctl "int msqid" "int cmd" "struct msqid_ds *buf" +.Sh DESCRIPTION +The +.Fn msgctl +system call performs some control operations on the message queue specified +by +.Fa msqid . + +Each message queue has a data structure associated with it, parts of which +may be altered by +.Fn msgctl +and parts of which determine the actions of +.Fn msgctl . +The data structure is defined in +.Aq Pa sys/msg.h +and contains (amongst others) the following members: +.Bd -literal +struct msqid_ds { + struct ipc_perm msg_perm; /* msg queue permission bits */ + u_long msg_cbytes; /* # of bytes in use on the queue */ + u_long msg_qnum; /* # of msgs in the queue */ + u_long msg_qbytes; /* max # of bytes on the queue */ + pid_t msg_lspid; /* pid of last msgsnd() */ + pid_t msg_lrpid; /* pid of last msgrcv() */ + time_t msg_stime; /* time of last msgsnd() */ + time_t msg_rtime; /* time of last msgrcv() */ + time_t msg_ctime; /* time of last msgctl() */ +}; +.Ed + +The +.Bf -literal +ipc_perm +.Ef +structure used inside the +.Bf -literal +shmid_ds +.Ef +structure is defined in +.Aq Pa sys/ipc.h +and looks like this: +.Bd -literal +struct ipc_perm { + ushort cuid; /* creator user id */ + ushort cgid; /* creator group id */ + ushort uid; /* user id */ + ushort gid; /* group id */ + ushort mode; /* permission (9 bits, see chmod(2)) */ + ushort seq; /* sequence # (to generate unique id) */ + key_t key; /* user specified msg/sem/shm key */ +}; +.Ed + +The operation to be performed by +.Fn msgctl +is specified in +.Fa cmd +and is one of: +.Bl -tag -width IPC_RMIDX +.It Dv IPC_STAT +Gather information about the message queue and place it in the +structure pointed to by +.Fa buf . +.It Dv IPC_SET +Set the value of the +.Va msg_perm.uid , +.Va msg_perm.gid , +.Va msg_perm.mode +and +.Va msg_qbytes +fields in the structure associated with +.Fa msqid . +The values are taken from the corresponding fields in the structure +pointed to by +.Fa buf . +This operation can only be executed by the super-user, or a process that +has an effective user id equal to either +.Va msg_perm.cuid +or +.Va msg_perm.uid +in the data structure associated with the message queue. +The value of +.Va msg_qbytes +can only be increased by the super-user. Values for +.Va msg_qbytes +that exceed the system limit (MSGMNB from +.Aq Pa sys/msg.h ) +are silently truncated to that limit. + +.It Dv IPC_RMID +Remove the message queue specified by +.Fa msqid +and destroy the data associated with it. Only the super-user or a process +with an effective uid equal to the +.Va msg_perm.cuid +or +.Va msg_perm.uid +values in the data structure associated with the queue can do this. +.El + +The permission to read from or write to a message queue (see +.Xr msgsnd 3 +and +.Xr msgrcv 3 ) +is determined by the +.Va msg_perm.mode +field in the same way as is +done with files (see +.Xr chmod 2 ), +but the effective uid can match either the +.Va msg_perm.cuid +field or the +.Va msg_perm.uid +field, and the +effective gid can match either +.Va msg_perm.cgid +or +.Va msg_perm.gid . +.Sh RETURN VALUES +Upon successful completion, a value of 0 is returned. Otherwise, -1 is +returned and the global variable +.Va errno +is set to indicate the error. +.Sh ERRORS +.Fn msgctl +will fail if: +.Bl -tag -width Er +.It Bq Er EPERM +.Fa cmd +is equal to IPC_SET or IPC_RMID and the caller is not the super-user, nor does +the effective uid match either the +.Va msg_perm.uid +or +.Va msg_perm.cuid +fields of the data structure associated with the message queue. + +An attempt is made to increase the value of +.Va msg_qbytes +through IPC_SET +but the caller is not the super-user. +.It Bq Er EACCESS +The command is IPC_STAT +and the caller has no read permission for this message queue. +.It Bq Er EINVAL +.Fa msqid +is not a valid message queue identifier. + +.Va cmd +is not a valid command. +.It Bq Er EFAULT +.Fa buf +specifies an invalid address. +.El +.Sh SEE ALSO +.Xr msgsnd 3 , +.Xr msgrcv 3 , +.Xr msgget 3 +.Sh HISTORY +Message queues appeared in the first release of AT&T Unix System V. diff --git a/lib/libc/gen/msgget.3 b/lib/libc/gen/msgget.3 new file mode 100644 index 0000000..41a7202 --- /dev/null +++ b/lib/libc/gen/msgget.3 @@ -0,0 +1,126 @@ +.\" $NetBSD: msgget.2,v 1.1 1995/10/16 23:49:19 jtc Exp $ +.\" +.\" Copyright (c) 1995 Frank van der Linden +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed for the NetBSD Project +.\" by Frank van der Linden +.\" 4. The name of the author may not be used to endorse or promote products +.\" derived from this software without specific prior written permission +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR +.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES +.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. +.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, +.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT +.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF +.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +.\"/ +.Dd August 17, 1995 +.Dt MSGGET 3 +.Os NetBSD +.Sh NAME +.Nm msgget +.Nd get message queue +.Sh SYNOPSIS +.Fd #include +.Fd #include +.Fd #include +.Ft int +.Fn msgget "key_t key" "int msgflg" +.Sh DESCRIPTION +.Fn msgget +returns the message queue identifier associated with +.Fa key . +A message queue identifier is a unique integer greater than zero. + +A message queue is created if either +.Fa key +is equal to IPC_PRIVATE, or +.Fa key +does not have a message queue identifier associated with it, and the IPC_CREAT +bit is set in +.Fa msgflg. + +If a new message queue is created, the data structure associated with it (the +.Va msqid_ds +structure, see +.Xr msgctl 3 ) +is initialized as follows: +.Bl -bullet +.It +.Va msg_perm.cuid +and +.Va msg_perm.uid +are set to the effective uid of the calling process. +.It +.Va msg_perm.gid +and +.Va msg_perm.cgid +are set to the effective gid of the calling process. +.It +.Va msg_perm.mode +is set to the lower 9 bits of +.Fa msgflg . +.It +.Va msg_cbytes , +.Va msg_qnum , +.Va msg_lspid , +.Va msg_lrpid , +.Va msg_rtime , +and +.Va msg_stime +are set to 0 +.It +.Va msg_qbytes +is set to the system wide maximum value for the number of bytes in a queue +(MSGMNB). +.It +.Va msg_ctime +is set to the current time. +.El +.Sh RETURN VALUES +Upon successful completion a positive message queue identifier is returned. +Otherwise, -1 is returned and the global variable +.Va errno +is set to indicate the error. +.Sh ERRORS +.Bl -tag -width Er +.It Bq Er EACESS +A message queue is already associated with +.Fa key +and the caller has no permission to access it. +.It Bq Er EEXIST +Both IPC_CREAT and IPC_EXCL are set in +.Fa msgflg , +and a message queue is already associated with +.Fa key . +.It Bq Er ENOSPC +A new message queue could not be created because the system limit for +the number of message queues has been reached. +.It Bq Er ENOENT +IPC_CREAT was not set in +.Fa msgflg +and no message queue associated with +.Fa key +was found. +.El +.Sh SEE ALSO +.Xr msgctl 3 , +.Xr msgrcv 3 , +.Xr msgsnd 3 +.Sh HISTORY +Message queues appeared in the first release of AT&T Unix System V. diff --git a/lib/libc/gen/msgrcv.3 b/lib/libc/gen/msgrcv.3 new file mode 100644 index 0000000..db61fab --- /dev/null +++ b/lib/libc/gen/msgrcv.3 @@ -0,0 +1,181 @@ +.\" $NetBSD: msgrcv.2,v 1.1 1995/10/16 23:49:20 jtc Exp $ +.\" +.\" Copyright (c) 1995 Frank van der Linden +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed for the NetBSD Project +.\" by Frank van der Linden +.\" 4. The name of the author may not be used to endorse or promote products +.\" derived from this software without specific prior written permission +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR +.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES +.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. +.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, +.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT +.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF +.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +.\"/ +.Dd August 17, 1995 +.Dt MSGRCV 3 +.Os NetBSD +.Sh NAME +.Nm msgrcv +.Nd receive a message from a message queue +.Sh SYNOPSIS +.Fd #include +.Fd #include +.Fd #include +.Ft int +.Fn msgrcv "int msqid" "void *msgp" "size_t msgsz" "long msgtyp" "int msgflg" +.Sh DESCRIPTION +The +.Fn msgrcv +function receives a message from the message queue specified in +.Fa msqid , +and places it into the structure pointed to by +.Fa msgp . +This structure should consist of the following members: +.Bd -literal + long mtype; /* message type */ + char mtext[1]; /* body of message */ +.Ed + +.Va mtype +is an integer greater than 0 that can be used for selecting messages, +.Va mtext +is an array of bytes, with a size up to that of the system limit (MSGMAX). + +The value of +.Fa msgtyp +has one of the following meanings: +.Bl -bullet +.It +.Fa msgtyp +is greater than 0. The first message of type +.Fa msgtyp +will be received. +.It +.Fa msgtyp +is equal to 0. The first message on the queue will be received. +.It +.Fa msgtyp +is less than 0. The first message of the lowest message type that is +less than or equal to the absolute value of +.Fa msgtyp +will be received. +.El + +.Fa msgsz +specifies the maximum length of the requested message. If the received +message has a length greater than +.Fa msgsz +it will be silently truncated if the MSG_NOERROR flag is set in +.Fa msgflg , +otherwise an error will be returned. + +If no matching message is present on the message queue specified by +.Fa msqid , +the behavior of +.Fn msgrcv +depends on whether the IPC_NOWAIT flag is set in +.Fa msgflg +or not. If IPC_NOWAIT is set, +.Fn msgrcv +will immediately return a value of -1, and set +.Va errno +to EAGAIN. If IPC_NOWAIT is not set, the calling process will be blocked +until: +.Bl -bullet +.It +A message of the requested type becomes available on the message queue. +.It +The message queue is removed, in which case -1 will be returned, and +.Va errno +set to EINVAL. +.It +A signal is received and caught. -1 is returned, and +.Va errno +set to EINTR. +.El + +If a message is successfully received, the data structure associated with +.Fa msqid +is updated as follows: +.Bl -bullet +.It +.Va msg_cbytes +is decremented by the size of the message. +.It +.Va msg_lrpid +is set to the pid of the caller. +.It +.Va msg_lrtime +is set to the current time. +.It +.Va msg_qnum +is decremented by 1. +.Sh RETURN VALUES +Upon successful completion, +.Fn msgrcv +returns the number of bytes received into the +.Va mtext +field of the structure pointed to by +.Fa msgp . +Otherwise, -1 is returned, and +.Va errno +set to indicate the error. +.Sh ERRORS +.Fn msgrcv +will fail if: +.Bl -tag -width Er +.It Bq Er EINVAL +.Fa msqid +is not a valid message queue identifier + +The message queue was removed while +.Fn msgrcv +was waiting for a message of the requested type to become available on it. + +.Fa msgsz +is less than 0. +.It Bq Er E2BIG +A matching message was received, but its size was greater than +.Fa msgsz +and the MSG_NOERROR flag was not set in +.Fa msgflg . +.It Bq Er EACCESS +The calling process does not have read access to the message queue. +.It Bq Er EFAULT +.Fa msgp +points to an invalid address. +.It Bq Er EINTR +The system call was interrupted by the delivery of a signal. +.It Bq Er EAGAIN +There is no message of the requested type available on the message queue, +and IPC_NOWAIT is set in +.Fa msgflg . +.Sh SEE ALSO +.Xr msgsnd 3 , +.Xr msgctl 3 , +.Xr msgget 3 +.Sh BUGS +NetBSD and FreeBSD do not define the EIDRM error value, which should be used in +the case of a removed message queue, nor the ENOMSG value, which +should be used when no suitable message is available and IPC_NOWAIT +is set. +.Sh HISTORY +Message queues appeared in the first release of AT&T Unix System V. diff --git a/lib/libc/gen/msgsnd.3 b/lib/libc/gen/msgsnd.3 new file mode 100644 index 0000000..b97a313 --- /dev/null +++ b/lib/libc/gen/msgsnd.3 @@ -0,0 +1,145 @@ +.\" $NetBSD: msgsnd.2,v 1.1 1995/10/16 23:49:24 jtc Exp $ +.\" +.\" Copyright (c) 1995 Frank van der Linden +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed for the NetBSD Project +.\" by Frank van der Linden +.\" 4. The name of the author may not be used to endorse or promote products +.\" derived from this software without specific prior written permission +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR +.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES +.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. +.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, +.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT +.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF +.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +.\"/ +.Dd August 17, 1995 +.Dt MSGSND 3 +.Os NetBSD +.Sh NAME +.Nm msgsnd +.Nd send a message to a message queue +.Sh SYNOPSIS +.Fd #include +.Fd #include +.Fd #include +.Ft int +.Fn msgsnd "int msqid" "void *msgp" "size_t msgsz" "int msgflg" +.Sh DESCRIPTION +The +.Fn msgsnd +function sends a message from the message queue specified in +.Fa msqid . +.Fa msgp +points to a structure containing the message. This structure should +consist of the following members: +.Bd -literal + long mtype; /* message type */ + char mtext[1]; /* body of message */ +.Ed + +.Va mtype +is an integer greater than 0 that can be used for selecting messages (see +.Xr msgrcv 3 ) , +.Va mtext +is an array of bytes, with a size up to that of the system limit (MSGMAX). + +If the number of bytes already on the message queue plus +.Fa msgsz +is bigger than the maximum number of bytes on the message queue ( +.Va msg_qbytes , +see +.Xr msgctl 3 ) , +or the number of messages on all queues system-wide is already equal to +the system limit, +.Fa msgflg +determines the action of +.Fn msgsnd . +If +.Fa msgflg +has IPC_NOWAIT mask set in it, the call will return immediately. If +.Fa msgflg +does not have IPC_NOWAIT set in it, the call will block until: +.Bl -bullet +.It +The condition which caused the call to block does no longer exist. +The message will be sent. +.It +The message queue is removed, in which case -1 will be returned, and +.Va errno +is set to EINVAL. +.It +The caller catches a signal. The call returns with +.Va errno +set to EINTR. +.El + +After a successful call, the data structure associated with the message +queue is updated in the following way: +.Bl -bullet +.It +.Va msg_cbytes +is incremented by the size of the message. +.It +.Va msg_qnum +is incremented by 1. +.It +.Va msg_lspid +is set to the pid of the calling process. +.It +.Va msg_stime +is set to the current time. +.El +.Sh RETURN VALUES +Upon successful completion, 0 is returned. Otherwise, -1 is returned and +.Va errno +is set to indicate the error. +.Sh ERRORS +.Fn msgsnd +will fail if: +.Bl -tag -width Er +.It Bq Er EINVAL +.Fa msqid +is not a valid message queue identifier + +The message queue was removed while +.Fn msgsnd +was waiting for a resource to become available in order to deliver the +message. + +.Fa msgsz +is less than 0, or greater than +.Va msg_qbytes . +.It Bq Er EACCESS +The calling process does not have write access to the message queue. +.It Bq Er EAGAIN +There was no space for this message either on the queue, or in the whole +system, and IPC_NOWAIT was set in +.Fa msgflg . +.It Bq Er EFAULT +.Fa msgp +points to an invalid address. +.It Bq Er EINTR +The system call was interrupted by the delivery of a signal. +.El +.Sh BUGS +NetBSD and FreeBSD do not define the EIDRM error value, which should be used +in the case of a removed message queue. +.Sh HISTORY +Message queues appeared in the first release of AT&T Unix System V. -- cgit v1.1