地址错误,带有mq_open [英] Bad address with mq_open
问题描述
我正在尝试使用mq_open打开一个简单的队列,但我不断收到错误消息:
"Error while opening ...
Bad address: Bad address"
我也不知道为什么.
int main(int argc, char **argv) {
struct mq_attr attr;
//max size of a message
attr.mq_msgsize = MSG_SIZE;
attr.mq_flags = 0;
//maximum of messages on queue
attr.mq_maxmsg = 1024 ;
dRegister = mq_open("/serverQRegister",O_RDONLY | O_CREAT, S_IRUSR | S_IWUSR,0664, &attr);
if(dRegister == -1)
{
perror("mq_open() failed");
exit(1);
}
}
我已按照建议更新代码,但仍然出现错误(无效参数"):
#include <stdio.h>
#include <stdlib.h>
#include <mqueue.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
#include "serverDefinitions.h"
mqd_t dRegister;
int main(int argc, char **argv) {
struct mq_attr attr;
//setting all attributes to 0
memset(&attr, 0, sizeof attr);
//max size of a message
attr.mq_msgsize = MSG_SIZE; //MSG_SIZE = 4096
attr.mq_flags = 0;
//maximum of messages on queue
attr.mq_maxmsg = 1024;
dRegister = mq_open("/serverQRegister", O_RDONLY | O_CREAT, 0664, &attr);
if (dRegister == -1) {
perror("mq_open() failed");
exit(1);
}
return 0;
}
此呼叫
... = mq_open("/serverQRegister",O_RDONLY | O_CREAT, S_IRUSR | S_IWUSR,0664, &attr);
指定了太多参数. mode
似乎已被指定两次.
应该是
... = mq_open("/serverQRegister",O_RDONLY | O_CREAT, S_IRUSR | S_IWUSR, &attr);
或
... = mq_open("/serverQRegister",O_RDONLY | O_CREAT, 0664, &attr);
关于EINVAL, man mq_open
指出:
EINVAL
在oflag中指定了O_CREAT ,并且attr不为NULL,但是 attr-> mq_maxmsg 或 attr-> mq_msqsize 无效.这两个字段都必须大于零.在没有特权的过程中(没有 CAP_SYS_RESOURCE 功能), attr-> mq_maxmsg 必须小于或等于 msg_max 限制,并且 attr-> mq_msgsize 必须小于或等于msgsize_max限制.此外,即使在特权进程中, attr-> mq_maxmsg 也不能超过 HARD_MAX 限制. (有关这些限制的详细信息,请参见mq_overview(7).)
attr
的初始化达到了mq_maxmsg
或/和mq_msgsize
之一或两者的限制.阅读 man 7 mq_overview
有关如何找出限制的信息. /p>
I am trying to open a simple queue using mq_open but I keep getting error:
"Error while opening ...
Bad address: Bad address"
And I have no idea why.
int main(int argc, char **argv) {
struct mq_attr attr;
//max size of a message
attr.mq_msgsize = MSG_SIZE;
attr.mq_flags = 0;
//maximum of messages on queue
attr.mq_maxmsg = 1024 ;
dRegister = mq_open("/serverQRegister",O_RDONLY | O_CREAT, S_IRUSR | S_IWUSR,0664, &attr);
if(dRegister == -1)
{
perror("mq_open() failed");
exit(1);
}
}
I updated code as suggested but still getting error ("invalid argument"):
#include <stdio.h>
#include <stdlib.h>
#include <mqueue.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
#include "serverDefinitions.h"
mqd_t dRegister;
int main(int argc, char **argv) {
struct mq_attr attr;
//setting all attributes to 0
memset(&attr, 0, sizeof attr);
//max size of a message
attr.mq_msgsize = MSG_SIZE; //MSG_SIZE = 4096
attr.mq_flags = 0;
//maximum of messages on queue
attr.mq_maxmsg = 1024;
dRegister = mq_open("/serverQRegister", O_RDONLY | O_CREAT, 0664, &attr);
if (dRegister == -1) {
perror("mq_open() failed");
exit(1);
}
return 0;
}
This call
... = mq_open("/serverQRegister",O_RDONLY | O_CREAT, S_IRUSR | S_IWUSR,0664, &attr);
specifies too many parameters. The mode
seems to have been specified twice.
It should be
... = mq_open("/serverQRegister",O_RDONLY | O_CREAT, S_IRUSR | S_IWUSR, &attr);
or
... = mq_open("/serverQRegister",O_RDONLY | O_CREAT, 0664, &attr);
Regarding EINVAL, the man mq_open
states:
EINVAL
O_CREAT was specified in oflag, and attr was not NULL, but attr->mq_maxmsg or attr->mq_msqsize was invalid. Both of these fields must be greater than zero. In a process that is unprivileged (does not have the CAP_SYS_RESOURCE capability), attr->mq_maxmsg must be less than or equal to the msg_max limit, and attr->mq_msgsize must be less than or equal to the msgsize_max limit. In addition, even in a privileged process, attr->mq_maxmsg cannot exceed the HARD_MAX limit. (See mq_overview(7) for details of these limits.)
The initialisation of attr
hits the limits for either one or both of mq_maxmsg
or/and mq_msgsize
. Read man 7 mq_overview
on how to find out the limits.
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