嵌入式專題linux進(jìn)程間通信課件

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程序程序動(dòng)態(tài)性"執(zhí)行"本身就是動(dòng)態(tài)的，由開(kāi)始到終止，中途可以暫停。因此進(jìn)程由“創(chuàng)建” 獨(dú)立性進(jìn)程是系統(tǒng)中獨(dú)立存在的實(shí)體。只 structtask_structvolatilelongstate; /*-1unrunnable,0runnable,>0stopped*/structthread_info*thread_info;atomic_tunsignedlongunsignedlong

/*perprocessflags,definedbelowint /*BKLlockdepth}操作系統(tǒng)利用PCB實(shí)現(xiàn)進(jìn)程的動(dòng)態(tài)和 #define #define #define #define #define #define #define pid_tif((child=fork())</*elseif(child==/*

/*pid_tpid_tintnice(int全雙工管道(STREAMS管道)PosixSystemV最初UnixIPC管 信SystemVIPCSystemVPosixIPC #includeintpipe(int1：errnoEMFILEEFAULT(fd 數(shù)據(jù)，那么它應(yīng)該關(guān)閉fd數(shù)據(jù)，那么它應(yīng)該關(guān)閉fd1，同時(shí)子進(jìn)程關(guān)閉fd0。數(shù)據(jù)，那么它應(yīng)該關(guān)閉fd0，同時(shí)子進(jìn)程關(guān)閉fd1{intpid_tif((childpid=fork())==-{}} {intfd[2];pid_tchildpid;if((childpid=fork())==-{perror("fork");}if(childpid=={close(fd[0]); /*Childprocessclosesupinputsideofpipe*/ {close(fd[1]);/*Parentprocessclosesupoutputsideofpipe } L_CHILD時(shí)經(jīng)由上一個(gè)管道寫一個(gè)字符“P”，子進(jìn)程在調(diào)用 時(shí)，經(jīng)由下一個(gè)管道寫一個(gè)字符“C”。相應(yīng)的回-1。 int{intFILEchar*strings[MAXSTRS]={"echo","bravo","alpha"," /*Createonewaypipelinewithcalltopopen()if((pipe_fp=popen("sort","w"))=={}/*Processingloopfputc('\n',pipe_fp);}pclose(pipe_fp);/*Closethepipe} 原型：intsemget(key_tkey,intnsems,int 如果失敗，則返回-1errno=EEXIST信號(hào)量集已經(jīng)存在，無(wú)法創(chuàng)建)EIDRM(信號(hào)量集已經(jīng)刪除)ENOENT信號(hào)量集不存在，沒(méi)有使用IPC_CREAT)ENOMEM(沒(méi)有足夠的內(nèi)存創(chuàng)建新的信號(hào)量集)ENOSPC(超出限制)intopen_semaphore_set(key_tkeyval,intnumsems{intif(!numsems)if((sid=semget(mykey,numsems,IPC_CREAT|0660==-{}}intsemopintsemidstructsembuf*sopsunsignedE2BIG(nsops大于最大的ops數(shù)目)(EFAULTsops指向的地址無(wú)效intsemctlintsemidintsemnumintcmdunionsemunargEPERMEUID沒(méi)有cmd的權(quán)利 /*semctlCommandDefinitions.#defineGETPID#defineGETVAL#defineGETALL T T#defineSETVAL#defineSETALL/*ipcsctlcmds#defineSEM_STAT#defineSEM_INFO

/*getsempid/*getsemval/*getallsemval's/* t/* t/*setsemval/*setallsemval's原型：intshmget(key_tkeyintsizeint如果失敗，則返回-1：errno=EINVAL無(wú)效的內(nèi)存段大小) 原型：intshmat(intshmid,char*shmaddr,int 址。如果失敗，則返回1：errno系統(tǒng)調(diào)用：shmctl原型：intshmctlintshmqid,intcmdstructshmid_ds*buf如果失敗返回-1：errno調(diào)用原型：intshmdtchar*shmaddr返回值：如果失敗，則返回