消息队列工作机制 msgsnd: Invalid argument

女爷i 2022-03-26 18:52 231阅读 0赞

msgsnd: Invalid argument

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 最近写个一个小程序 测试System V的消息队列工作机制，写完代码后编译通过但是运行出现这个错误msgsnd: Invalid argument 于是去Google ，可惜没有找到满意的结果，后来仔细检查代码发现 没有对消息类型赋值，花了我2个小时，终于搞定，以此告诫程序员要细心啊，呵呵 
 这是代码 
 /* 发送*/ 
 #include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; #include &lt;unistd.h&gt; #include &lt;string.h&gt; #include &lt;sys/types.h&gt; #include &lt;sys/msg.h&gt; #include &lt;sys/ipc.h&gt; 
 #define MAX_TEXT 512 
 struct my_msg_st { &nbsp;&nbsp; long my_msg_type;&nbsp;&nbsp;&nbsp;//消息类型 &nbsp;&nbsp; char msg_text[MAX_TEXT]; }; 
 int main(int argc,char ** argv) { int running = 1; struct my_msg_st some_data; int msgid; char buffer[MAX_TEXT]; if( (msgid = msgget((key_t)12345,0666|IPC_CREAT) )== -1 ) { &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; perror("msgget"); &nbsp;&nbsp;&nbsp; exit(EXIT_FAILURE); } printf("msgid:%d\t\n",msgid); while(running ) { &nbsp;&nbsp;&nbsp; printf("Enter the message to send:"); &nbsp;&nbsp;&nbsp; fgets( buffer,MAX_TEXT,stdin); &nbsp;&nbsp; //some_data.my_msg_type =1;&nbsp;&nbsp; //这一句为后来加上的,加上这一句就没有问题了 &nbsp;&nbsp;&nbsp; strcpy(some_data.msg_text,buffer); 
 &nbsp;&nbsp;&nbsp; if( msgsnd(msgid,(void*)&amp;some_data,MAX_TEXT,IPC_NOWAIT) == -1 ) &nbsp;&nbsp;&nbsp; {&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; perror("msgsnd"); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; exit(EXIT_FAILURE); &nbsp;&nbsp;&nbsp; } &nbsp;&nbsp; &nbsp;&nbsp; if(strncmp(buffer,"end",3)==0) &nbsp;&nbsp; { &nbsp;&nbsp;&nbsp;&nbsp; running=0; &nbsp;&nbsp; } } return 0; } 
 /*接收*/ 
 #include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; #include &lt;unistd.h&gt; #include &lt;string.h&gt; #include &lt;sys/types.h&gt; #include &lt;sys/msg.h&gt; #include &lt;sys/ipc.h&gt; 
 
 struct my_msg_st { &nbsp;&nbsp; long my_msg_type;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;//消息类型 &nbsp;&nbsp; char msg_text[BUFSIZ]; }; 
 int main(int argc,char ** argv) { int running = 1; struct my_msg_st some_data; int msgid; int msg_to_receive =0; if( (msgid = msgget((key_t)12345,0666|IPC_CREAT) )== -1 ) { 
 &nbsp;&nbsp;&nbsp; perror("msgget"); &nbsp;&nbsp;&nbsp; exit(EXIT_FAILURE); } printf("msgid:%d\t\n",msgid); while(running ) { &nbsp;&nbsp; if( msgrcv(msgid,(void*)&amp;some_data,BUFSIZ,msg_to_receive,0)==-1) &nbsp;&nbsp;&nbsp; { &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; perror("msgrcv"); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; exit(EXIT_FAILURE); &nbsp;&nbsp;&nbsp; } &nbsp;&nbsp;&nbsp; printf("receiver message:%s",some_data.msg_text); &nbsp;&nbsp;&nbsp; if(strncmp(some_data.msg_text,"end",3)==0) &nbsp;&nbsp;&nbsp; { &nbsp;&nbsp;&nbsp;&nbsp; running=0; &nbsp;&nbsp;&nbsp; } } if(msgctl(msgid,IPC_RMID,0)==-1) { &nbsp;&nbsp;&nbsp; fprintf(stderr,"msgctl(IPC_RMID) feiled\n"); &nbsp;&nbsp;&nbsp; exit(EXIT_FAILURE); } return 0; } 
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