linux共享內(nèi)存專題講座

by1IPCIPC對象2SystemVstructshmid_dsstructipc_permshm_perm;/*Ownershipandpermissions*/ shm_segsz;/*Sizeofsegment(bytes)*/ shm_atime;/*Lastattachtime*/ shm_dtime;/*Lastdetachtime*/ shm_ctime;/*Lastchangetime /*PIDofcreator /*PIDoflastshmat(2)/shmdt(2)*/ /*No.ofcurrentattaches*/#include#includevoid*shmat(intshmid,constvoid*shmaddr,intshmintshmdt(constvoidintshmctl(intshmid,intcmd,structshmid_dsshmgetintshmget(key_tkey,size_tsize,intshmshmatvoid*shmat(intshmid,constvoid*shmaddr,intshmshmid:shmat函數(shù)（續(xù)shmaddrshmaddr不為NULL且shm無SHM_RND標(biāo)記，則以shmaddr為連接地址shmaddr不為NULL且shm設(shè)置了SHM_RND標(biāo)記則連接的地址會自下調(diào)整為SHMLBA的整數(shù)倍。：shmaddr-(shmaddr%SHMLBA)shm，表示連接操作用來只讀共享內(nèi)shmdtintshmdt(constvoidshmaddr:shmatshmctlintshmctl(intshmid,intcmd,structshmid_dsshmctl函數(shù)（續(xù)3API intmain(intargc,char{intret=intshmid=shmget(0x2234,sizeof(Teacher),IPC_CREAT|0666);if(shmid==-1){perror("shmgeterr");returnerrno;}printf("shmid:%d\n",shmid);Teacher*p=NULL;p=shmat(shmid,NULL,0);if(p==(void*)-1){perror("shmgeterr");returnerrno;}strcpy(p->name,"aaaa");p->age=33;printf("1刪除共享內(nèi)存，其他不刪除\n");intnum;scanf("%d",&num);if(num==1){ret=shmctl(shmid,IPC_RMID,NULL);if(ret<0){}}return}intmain(intargc,char{intret=int//shmid=shmget(0x2234,sizeof(Teacher),IPC_CREAT|IPC_EXCL|0666);shmid=shmget(0x2234,0,0);if(shmid==-{perror("shmgeterr");returnerrno;}printf("shmid:%d\n",shmid);Teacher*p=NULL;p=shmat(shmid,NULL,0);if(p==(void*)-1){perror("shmgeterr");returnerrno;}printf("age:%d\n",p->age);