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about msgget troble
Post 12353 by subrain on Thursday 27th of December 2001 09:42:37 PM
12-27-2001
about msgget troble
hi,all
i have in trouble about msgget.
i create a queue and the program like blow:
openMsg( pid_t key )
{
....
int msgid;
....
msgid=msgget(key,IPC_CREAT|IPC_EXCL|0666)
if( msgid<=0 ){
fprintf( stdout,"%s,%d",strerror(errno),errno );
return -1;
}
else{
return msgid;
}
}
when i open my computer and run this program first ,the answer always is "Invalid argument" .
use ipc to see the queue stat, i found a queue is already exist just like this
"Message Queues
q 0 0x00000835 --rw-rw-rw- iccard informix
"
when i delete the queue ,and restart my program ,everything right.
so why? please tell me.
thank you.
i have in trouble about msgget.
i create a queue and the program like blow:
openMsg( pid_t key )
{
....
int msgid;
....
msgid=msgget(key,IPC_CREAT|IPC_EXCL|0666)
if( msgid<=0 ){
fprintf( stdout,"%s,%d",strerror(errno),errno );
return -1;
}
else{
return msgid;
}
}
when i open my computer and run this program first ,the answer always is "Invalid argument" .
use ipc to see the queue stat, i found a queue is already exist just like this
"Message Queues
q 0 0x00000835 --rw-rw-rw- iccard informix
"
when i delete the queue ,and restart my program ,everything right.
so why? please tell me.
thank you.
Last edited by Perderabo; 03-17-2005 at 11:10 AM.. Reason: Remove email
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LEARN ABOUT FREEBSD
msgget
MSGGET(2) BSD System Calls Manual MSGGET(2) NAME
msgget -- get message queue LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <sys/types.h> #include <sys/ipc.h> #include <sys/msg.h> int msgget(key_t key, int msgflg); DESCRIPTION
The msgget() function returns the message queue identifier associated with key. A message queue identifier is a unique integer greater than zero. A message queue is created if either key is equal to IPC_PRIVATE, or key does not have a message queue identifier associated with it, and the IPC_CREAT bit is set in msgflg. If a new message queue is created, the data structure associated with it (the msqid_ds structure, see msgctl(2)) is initialized as follows: o msg_perm.cuid and msg_perm.uid are set to the effective uid of the calling process. o msg_perm.gid and msg_perm.cgid are set to the effective gid of the calling process. o msg_perm.mode is set to the lower 9 bits of msgflg. o msg_cbytes, msg_qnum, msg_lspid, msg_lrpid, msg_rtime, and msg_stime are set to 0. o msg_qbytes is set to the system wide maximum value for the number of bytes in a queue (MSGMNB). o msg_ctime is set to the current time. RETURN VALUES
Upon successful completion a positive message queue identifier is returned. Otherwise, -1 is returned and the global variable errno is set to indicate the error. ERRORS
[EACCES] A message queue is already associated with key and the caller has no permission to access it. [EEXIST] Both IPC_CREAT and IPC_EXCL are set in msgflg, and a message queue is already associated with key. [ENOSPC] A new message queue could not be created because the system limit for the number of message queues has been reached. [ENOENT] IPC_CREAT was not set in msgflg and no message queue associated with key was found. SEE ALSO
msgctl(2), msgrcv(2), msgsnd(2) HISTORY
Message queues appeared in the first release of AT&T System V UNIX. BSD
July 9, 2009 BSD