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man pages section 2: System Calls     Oracle Solaris 11 Information Library
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Document Information

Preface

Introduction

System Calls

access(2)

acct(2)

acl(2)

adjtime(2)

alarm(2)

brk(2)

chdir(2)

chmod(2)

chown(2)

chroot(2)

close(2)

creat(2)

dup(2)

exec(2)

execl(2)

execle(2)

execlp(2)

execv(2)

execve(2)

execvex(2)

execvp(2)

_Exit(2)

_exit(2)

exit(2)

faccessat(2)

facl(2)

fchdir(2)

fchmod(2)

fchmodat(2)

fchown(2)

fchownat(2)

fchroot(2)

fcntl(2)

fexecve(2)

fgetlabel(2)

fork1(2)

fork(2)

forkall(2)

forkallx(2)

forkx(2)

fpathconf(2)

fstat(2)

fstatat(2)

fstatvfs(2)

futimens(2)

futimesat(2)

getacct(2)

getcontext(2)

getdents(2)

getegid(2)

geteuid(2)

getgid(2)

getgroups(2)

getisax(2)

getitimer(2)

getlabel(2)

getmsg(2)

getpflags(2)

getpgid(2)

getpgrp(2)

getpid(2)

getpmsg(2)

getppid(2)

getppriv(2)

getprojid(2)

getrctl(2)

getrlimit(2)

getsid(2)

gettaskid(2)

getuid(2)

getustack(2)

ioctl(2)

issetugid(2)

kill(2)

lchown(2)

link(2)

linkat(2)

llseek(2)

lseek(2)

lstat(2)

_lwp_cond_broadcast(2)

_lwp_cond_reltimedwait(2)

_lwp_cond_signal(2)

_lwp_cond_timedwait(2)

_lwp_cond_wait(2)

_lwp_continue(2)

_lwp_info(2)

_lwp_kill(2)

_lwp_mutex_lock(2)

_lwp_mutex_trylock(2)

_lwp_mutex_unlock(2)

_lwp_self(2)

_lwp_sema_init(2)

_lwp_sema_post(2)

_lwp_sema_trywait(2)

_lwp_sema_wait(2)

_lwp_suspend(2)

memcntl(2)

meminfo(2)

mincore(2)

mkdir(2)

mkdirat(2)

mknod(2)

mknodat(2)

mmap(2)

mmapobj(2)

mount(2)

mprotect(2)

msgctl(2)

msgget(2)

msgids(2)

msgrcv(2)

msgsnap(2)

msgsnd(2)

munmap(2)

nice(2)

ntp_adjtime(2)

ntp_gettime(2)

open(2)

openat(2)

pathconf(2)

pause(2)

pcsample(2)

pipe(2)

poll(2)

p_online(2)

ppoll(2)

pread(2)

priocntl(2)

priocntlset(2)

processor_bind(2)

processor_info(2)

profil(2)

pset_assign(2)

pset_bind(2)

pset_create(2)

pset_destroy(2)

pset_getattr(2)

pset_info(2)

pset_list(2)

pset_setattr(2)

putacct(2)

putmsg(2)

putpmsg(2)

pwrite(2)

read(2)

readlink(2)

readlinkat(2)

readv(2)

rename(2)

renameat(2)

resolvepath(2)

rmdir(2)

sbrk(2)

semctl(2)

semget(2)

semids(2)

semop(2)

semtimedop(2)

setcontext(2)

setegid(2)

seteuid(2)

setgid(2)

setgroups(2)

setitimer(2)

setpflags(2)

setpgid(2)

setpgrp(2)

setppriv(2)

setrctl(2)

setregid(2)

setreuid(2)

setrlimit(2)

setsid(2)

settaskid(2)

setuid(2)

setustack(2)

shmadv(2)

shmat(2)

shmctl(2)

shmdt(2)

shmget(2)

shmids(2)

shmop(2)

sigaction(2)

sigaltstack(2)

sigpending(2)

sigprocmask(2)

sigsend(2)

sigsendset(2)

sigsuspend(2)

sigwait(2)

__sparc_utrap_install(2)

stat(2)

statvfs(2)

stime(2)

swapctl(2)

symlink(2)

symlinkat(2)

sync(2)

sysfs(2)

sysinfo(2)

time(2)

times(2)

uadmin(2)

ulimit(2)

umask(2)

umount(2)

umount2(2)

uname(2)

unlink(2)

unlinkat(2)

ustat(2)

utime(2)

utimensat(2)

utimes(2)

uucopy(2)

vfork(2)

vforkx(2)

vhangup(2)

waitid(2)

wracct(2)

write(2)

writev(2)

yield(2)

msgrcv

- message receive operation

Synopsis

#include <sys/msg.h>

ssize_t msgrcv(int msqid, void *msgp, size_t msgsz,
     long int msgtyp, int msgflg);

Description

The msgrcv() function reads a message from the queue associated with the message queue identifier specified by msqid and places it in the user-defined buffer pointed to by msgp.

The msgp argument points to a user-defined buffer that must contain first a field of type long int that will specify the type of the message, and then a data portion that will hold the data bytes of the message. The structure below is an example of what this user-defined buffer might look like:

struct mymsg {
        long int    mtype;     /* message type */
        char        mtext[1];  /* message text */
}      

The mtype member is the received message's type as specified by the sending process.

The mtext member is the text of the message.

The msgsz argument specifies the size in bytes of mtext. The received message is truncated to msgsz bytes if it is larger than msgsz and (msgflg&MSG_NOERROR) is non-zero. The truncated part of the message is lost and no indication of the truncation is given to the calling process.

The msgtyp argument specifies the type of message requested as follows:

The msgflg argument specifies which of the following actions is to be taken if a message of the desired type is not on the queue:

Upon successful completion, the following actions are taken with respect to the data structure associated with msqid (see Intro(2)):

Return Values

Upon successful completion, msgrcv() returns a value equal to the number of bytes actually placed into the buffer mtext. Otherwise, -1 is returned, no message is received, and errno is set to indicate the error.

Errors

The msgrcv() function will fail if:

E2BIG

The value of mtext is greater than msgsz and (msgflg&MSG_NOERROR) is 0.

EACCES

Operation permission is denied to the calling process. See Intro(2).

EIDRM

The message queue identifier msqid is removed from the system.

EINTR

The msgrcv() function was interrupted by a signal.

EINVAL

The msqid argument is not a valid message queue identifier.

ENOMSG

The queue does not contain a message of the desired type and (msgflg&IPC_NOWAIT) is non-zero.

The msgrcv() function may fail if:

EFAULT

The msgp argument points to an illegal address.

Usage

The value passed as the msgp argument should be converted to type void *.

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
Standard

See Also

Intro(2), msgctl(2), msgget(2), msgsnd(2), sigaction(2), attributes(5), standards(5)