创建自定义属性的POSIX消息队列

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51

#include <stdio.h> #include <fcntl.h> #include <errno.h> #include <string.h> #include <stdlib.h> #include <unistd.h> #include <mqueue.h>   struct mq_attr attr; const int maxline=4096;   int main(int argc, char **argv) {     int c, flags;     mqd_t mqd;     char errbuff[maxline];       flags=O_RDWR | O_CREAT;     while((c=getopt(argc, argv, "em:z:"))!=-1) {         switch(c) {             case 'e':                 flags|=O_EXCL;                 break;             case 'm':                 attr.mq_maxmsg=atol(optarg);                 break;             case 'z':                 attr.mq_msgsize=atol(optarg);                 break;         }     }       if(optind != argc-1) {         fprintf(stderr, "mqcreate [-e] [ -m maxmsg -z msgsize ] <name>\n");         exit(-1);     }       if((attr.mq_maxmsg!=0&&attr.mq_msgsize==0) || (attr.mq_maxmsg==0&&attr.mq_msgsize!=0)) {         fprintf(stderr, "must specify both -m maxmsg -z msgsize\n");         exit(-1);     }       if((mqd=mq_open(argv[optind], flags, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH, (attr.mq_maxmsg!=0) ? &attr:NULL))<0) {         strerror_r(errno, errbuff, maxline);         fprintf(stderr, "mq_open error: %s\n", errbuff);         exit(-1);     }       mq_close(mqd);           exit(0); }

指定创建队列的最大消息数和每个消息的最大大小