實驗五進程間通信（DOC）

1、實驗五 進程間通信unix/linux系統(tǒng)的進程間通信機構(gòu)（ipc）允許在任意進程間大批量地交換數(shù)據(jù)。本實驗的目的是了解和熟悉linux支持的信號機制、管道機制、消息隊列通信機制及共享存儲區(qū)機制。5.1信號機制實驗（一）【實驗?zāi)康摹?了解什么是信號。2熟悉linux系統(tǒng)中進程之間軟中斷通信的基本原理?！緦嶒炘怼坷胹ignal來實現(xiàn)發(fā)送信號和接受信號的原理【實驗內(nèi)容】1編寫一段程序，使用系統(tǒng)調(diào)用fork( )創(chuàng)建兩個子進程，再用系統(tǒng)調(diào)用signal( )讓父進程捕捉鍵盤上來的中斷信號（即按ctrl+c鍵），當捕捉到中斷信號后，父進程用系統(tǒng)調(diào)用kill( )向兩個子進程發(fā)出信號，子進程捕捉到父

2、進程發(fā)來的信號后，分別輸出下列信息后終止： child process 1 is killed by parent!child process 2 is killed by parent!父進程等待兩個子進程終止后，輸出以下信息后終止： parent process is killed! # include# include# includeint wait_mark;void waiting(),stop();void main() int p1, p2;signal(sigint,stop);while(p1=fork()=-1);if(p10)/*在父進程中*/ while(p2=for

3、k()= =-1); if(p20)/*在父進程中*/ wait_mark=1; waiting(0); kill(p1,10); kill(p2,12); wait( ); wait( ); printf(“parent process is killed!n”); exit(0); else/*在子進程2中*/ wait_mark=1;signal(12,stop);waiting();lockf(1,1,0);printf(“child process 2 is killed by parent!n”);lockf(1,0,0);exit(0); else/*在子進程1中*/ wait_

4、mark=1; signal(10,stop); waiting(); lockf(1,1,0); printf(“child process 1 is killed by parent!n”); lockf(1,0,0); exit(0);void waiting() while(wait_mark!=0);void stop() wait_mark=0;實驗要求： 運行程序并分析結(jié)果。 如果把signal(sigint,stop)放在號和號位置，結(jié)果會怎樣并分析原因。 該程序段前面部分用了兩個wait(0),為什么？ 該程序段中每個進程退出時都用了語句exit(0),為什么？5.2信號機制

5、實驗（二）【實驗?zāi)康摹繉W習signal的函數(shù)的使用【實驗原理】利用signal的函數(shù)的機制來實習我們發(fā)送截獲信號的功能【實驗內(nèi)容】修改上面的程序，增加語句signal(sigint,sig_ign)和語句signal(sigquit,sig_ign)，再觀察程序執(zhí)行時屏幕上出現(xiàn)的現(xiàn)象，并分析其原因。# include# include# includeint pid1, pid2;int endflag=0;pf1=0;pf2=0;void intdelete() kill(pid1,10); kill(pid2,12);endflag=1;void int1() printf(“child

6、process 1 is killed by parent !n”); exit(0);void int2() printf(“child process 2 is killed by parent !n”); exit(0);main() int exitcode; signal(sigint,sig_ign); signal(sigquit,sig_ign);while(pid1=fork()=-1); if(pid1=0) signal(sigusr1,int1);signal(sigint,sig_ign);pause();exit(0); else while(pid2=fork()

7、= =-1); if(pid2=0) signal(sigusr2,int2);signal(sigint,sig_ign);pause();exit(0); else signal(sigint,intdelete); waitpid(-1,&exitcode,0);/*等待任何子進程中斷或結(jié)束*/ printf(“parent process is killed n”); exit(0); 實驗要求：運行程序并分析結(jié)果。司機售票員問題（選做題）編程用fork()創(chuàng)建一個子進程代表售票員，司機在父進程中，再用系統(tǒng)調(diào)用signal()讓父進程（司機）捕捉來自子進程（售票員）發(fā)出的中斷信號，讓子

8、進程（售票員）捕捉來自（司機）發(fā)出的中斷信號，以實現(xiàn)進程間的同步運行。5.3管道通信實驗（一）【實驗?zāi)康摹?、了解什么是管道2、熟悉unix/linux支持的管道通信方式【實驗內(nèi)容】編寫程序?qū)崿F(xiàn)進程的管道通信。用系統(tǒng)調(diào)用pipe( )建立一管道，二個子進程p1和p2分別向管道各寫一句話： child 1 is sending a message! child 2 is sending a message!父進程從管道中讀出二個來自子進程的信息并顯示（要求先接收p1，后p2）。參考程序#include #include #include int pid1,pid2;main( ) int fd2

9、;char outpipe100,inpipe100;pipe(fd); /*創(chuàng)建一個管道*/while (pid1=fork( )= =-1);if(pid1= =0)lockf(fd1,1,0); sprintf(outpipe,child 1 process is sending message!); /*把串放入數(shù)組outpipe中*/ write(fd1,outpipe,50); /*向管道寫長為50字節(jié)的串*/ sleep(5); /*自我阻塞5秒*/ lockf(fd1,0,0); exit(0);elsewhile(pid2=fork( )= =-1); if(pid2= =0

10、) lockf(fd1,1,0); /*互斥*/ sprintf(outpipe,child 2 process is sending message!); write(fd1,outpipe,50); sleep(5);lockf(fd1,0,0); exit(0); else wait(0); /*同步*/ read(fd0,inpipe,50); /*從管道中讀長為50字節(jié)的串*/ printf(%s/n,inpipe); wait(0); read(fd0,inpipe,50); printf(%s/n,inpipe); exit(0); 五、運行結(jié)果 延遲5秒后顯示child 1 p

11、rocess is sending message! 再延遲5秒child 2 process is sending message!5.4管道通信實驗（二）【實驗?zāi)康摹?、掌握有名管道的創(chuàng)建和讀寫方式2、熟悉unix/linux支持的有名管道通信方式【實驗內(nèi)容】1. 創(chuàng)建有名管道2. 本進程執(zhí)行循環(huán)等待數(shù)據(jù)被寫入到管道中并讀有名管道3. 打開有名管道并寫數(shù)據(jù)到名管道參考代碼：/read_fifo.c#include #include #include #include #include #include #include #define buffer_size1024int main(int

12、 argc, char *argv) int fd; if (argc 2) fprintf(stdout, usage: %s n, argv0); exit(1); /int open(const char *path, int oflag, .); if (fd = open(argv1, o_rdonly) 0) fprintf(stderr, open fifo %s for reading failed: %sn, argv1, strerror(errno); exit(1); fprintf(stdout, open fifo %s for reading successed.

13、n, argv0); char bufferbuffer_size; ssize_t n; while (1) again: /ssize_t read(int fd, void *buf, size_t count); if (n = read(fd, buffer, buffer_size) 0) if (errno = eintr) goto again; else fprintf(stderr, read failed on %s: %sn, argv1, strerror(errno);exit(1); else if (n = 0) fprintf(stderr, peer clo

14、sed fifo.n); break; else buffern = 0; fprintf(stdout, read %d bytes from fifo: %sn, n, buffer); return 0;/ write_fifo.c#include #include #include #include #include #include #include #include #define buffer_size1024void signal_handler(int s);int main(int argc, char *argv) int fd; if (argc 2) fprintf(

15、stdout, usage: %s n, argv0); exit(1); signal(sigpipe, signal_handler); /int open(const char *path, int oflag, .); if (fd = open(argv1, o_wronly) 0) fprintf(stderr, open fifo %s for writting failed: %sn, argv1, strerror(errno); exit(1); fprintf(stdout, open fifo %s for writting successed.n, argv0); c

16、har bufferbuffer_size; ssize_t n; /char *fgets(char *s, int size, file * stream); while (fgets(buffer, buffer_size, stdin) again: /ssize_t write(int fd, const void *buf, size_t count); if (n = write(fd, buffer, strlen(buffer) 0) if (errno = eintr) goto again; else fprintf(stderr, write() failed on f

17、ifo: %sn, strerror(errno);/ fixme:break; return 0;void signal_handler(int s) fprintf(stdout, caught signal %dn, s);/ create_fifo.c#include #include #include #include #include int main(int argc, char *argv) if (argc 2) fprintf(stdout, usage: %s n, argv0); exit(1); /int mkfifo(const char *path, mode_t

18、 mode); if (mkfifo(argv1, 0644) 0) fprintf(stderr, mkfifo() failed: %sn, strerror(errno); exit(1); return 0;5.5共享內(nèi)存通信實驗【實驗?zāi)康摹?、掌握共享內(nèi)存的創(chuàng)建和讀寫方式2、熟悉unix/linux支持的共享內(nèi)存通信方式【實驗內(nèi)容】1. 創(chuàng)建共享內(nèi)存2. 寫入到共享內(nèi)存3. 讀數(shù)據(jù)從共享內(nèi)存代碼參考：/write.c#include #include #include #include #include #include #include #include #include #def

19、ine mapped_filename/tmp/test.mmap.1int main(int argc, char *argv) int fd; if (argc 2) fprintf(stdout, usage: %s n, argv0); exit(1); / xxx: step 1, open file, get a fd /int open(const char *pathname, int flags, mode_t mode); if (fd = open(argv1, o_rdwr | o_creat | o_excl, 0644) 0) if (errno = eexist)

20、 fprintf(stderr, fatal error: the target mapped file existed, exit.n); else fprintf(stderr, error: open file failed: (errno = %d)%sn, errno, strerror(errno); exit(1); off_t offset; offset = 1024; / xxx: step 2, create a hole file /off_t lseek(int fildes, off_t offset, int whence); if (lseek(fd, offs

21、et, seek_set) = (off_t) - 1) fprintf(stderr, lseek() failed: %sn, strerror(errno); /fixme: unlink the file close(fd); exit(1); ssize_t n; /ssize_t write(int fd, const void *buf, size_t count); if (n = write(fd, , 1) 0) fprintf(stderr, write() failed: %sn, strerror(errno); exit(1); /* * on success, m

22、map returns a pointer to the mapped area. on error, the value map_failed (that is, (void*) -1) is returned, and errno is set appropriately. on success, munmap returns 0, on failure -1, and errno is set (probably to einval). */* prot_exec pages may be executed. prot_read pages may be read. prot_write

23、 pages may be written. prot_none pages may not be accessed.*/ void *p; / xxx: step 3, mmap(), get a pointer /void * mmap(void *start, size_t length, int prot , int flags, int fd, off_t offset); if (p = mmap(null, 1024, prot_write, map_shared, fd, 0) = map_failed) fprintf(stderr, mmap() failed: %sn,

24、strerror(errno); close(fd); exit(1); close(fd); fprintf(stdout, mapped file to memory, size = %dn, 1024); / xxx: step 4, read/write on shared memory char *banner = hello world.; /void *memcpy(void *dest, const void *src, size_t n); memcpy(p + 256, banner, strlen(banner); / xxx: step 5, munmap(); /in

25、t munmap(void *start, size_t length); pause(); /close(fd); return 0;/ read.c#include #include #include #include #include #include #include #include #include #define mapped_filename/tmp/test.mmap.1#define buffer_size1024int main(int argc, char *argv) int fd; if (argc 2) fprintf(stdout, usage: %s n, a

26、rgv0); exit(1); / xxx: step 1, open file, get a fd /int open(const char *pathname, int flags, mode_t mode); if (fd = open(argv1, o_rdwr) 0) fprintf(stderr, error: open file failed: (errno = %d)%sn, errno, strerror(errno); exit(1); #if 0 off_t offset; offset = 1024; / xxx: step 2, create a hole file

27、/off_t lseek(int fildes, off_t offset, int whence); if (lseek(fd, offset, seek_set) = (off_t) - 1) fprintf(stderr, lseek() failed: %sn, strerror(errno); /fixme: unlink the file close(fd); exit(1); ssize_t n; /ssize_t write(int fd, const void *buf, size_t count); if (n = write(fd, , 1) 0) fprintf(std

28、err, write() failed: %sn, strerror(errno); exit(1); #endif /* * on success, mmap returns a pointer to the mapped area. on error, the value map_failed (that is, (void*) -1) is returned, and errno is set appropriately. on success, munmap returns 0, on failure -1, and errno is set (probably to einval).

29、 */* prot_exec pages may be executed. prot_read pages may be read. prot_write pages may be written. prot_none pages may not be accessed.*/ void *p; / xxx: step 3, mmap(), get a pointer /void * mmap(void *start, size_t length, int prot , int flags, int fd, off_t offset); if (p = mmap(null, 1024, prot

30、_write, map_shared, fd, 0) = map_failed) fprintf(stderr, mmap() failed: %sn, strerror(errno); close(fd); exit(1); close(fd); fprintf(stdout, mapped file to memory, size = %dn, 1024); char bufferbuffer_size; / xxx: step 4, read/write on shared memory /void *memcpy(void *dest, const void *src, size_t

31、n); memcpy(buffer, p+256, 32); fprintf(stdout, %sn, buffer); / xxx: step 5, munmap(); /int munmap(void *start, size_t length); /close(fd); return 0;5.6用消息隊列編寫一個客戶端服務(wù)器通信的程序【實驗?zāi)康摹客ㄟ^此實驗，學員可以熟悉消息隊列的概念，并能夠用消息隊列編寫一個客戶端服務(wù)器通信的程序?！緦嶒炘怼勘緦嶒炐枰孟㈥犃性O(shè)計一個簡易的雙人聊天程序（一個服務(wù)器，兩個客戶端）。消息隊列重點在于消息類型的匹配，客戶端和服務(wù)端的“通信協(xié)議”的設(shè)計。設(shè)計

32、思想如下：服務(wù)器端：接受客戶端發(fā)來的任何信息，并根據(jù)其消息類型，轉(zhuǎn)發(fā)給對應(yīng)的客戶端。同時，檢測是否有退出標志，有則給所有的客戶端發(fā)送退出標志，等待10s后，確定客戶端都退出后，刪除消息隊列，釋放空間，并退出?？蛻舳耍篴和b，a給b發(fā)送信息，先發(fā)給服務(wù)器，由服務(wù)器根據(jù)自定義協(xié)議轉(zhuǎn)發(fā)該消息給b。同時b接受到消息后，經(jīng)由服務(wù)器給a一個回執(zhí)信息，以此形成簡易的聊天模式?！緦嶒灧椒ā烤帉懛?wù)器端程序：#define key_msg 0x101 /使用共有的ipc key#define msgsize 128#include #include #include #include #include main

33、() int msgid; struct msgbuf /定義消息結(jié)構(gòu)體：消息類型和消息數(shù)據(jù) long mtype; char mtext128; buf1, buf2; msgid = msgget( key_msg, ipc_creat|0666 ); while( 1 ) /無限循環(huán)，退出標志則會break msgrcv( msgid, &buf1, msgsize, 1l, 0 ); /接受客戶端1的消息printf( receive client1 message: %sn, buf1.mtext ); /打印收到的消息if( buf1.mtext0 = x | buf1.mtext

34、0 = x ) /若是退出標志，則給2個客戶端都發(fā)退出信息 strcpy( buf1.mtext, x ); buf1.mtype = 3l; msgsnd( msgid, &buf1, msgsize, 0 ); buf1.mtype = 4l; msgsnd( msgid, &buf1, msgsize, 0 ); break; buf1.mtype = 4l;msgsnd( msgid, &buf1, msgsize, 0 ); /將客戶端1的消息轉(zhuǎn)發(fā)給客戶端2 msgrcv( msgid, &buf2, msgsize, 2l, 0 ); /接受客戶端2的消息printf( recei

35、ve client2 message: %sn, buf2.mtext ); /打印收到的消息if( buf2.mtext0 = x | buf2.mtext0 = x )/若是退出標志，則給2個客戶端發(fā)退出信息 strcpy( buf2.mtext, x ); buf2.mtype = 3l; msgsnd( msgid, &buf2, msgsize, 0 ); buf2.mtype = 4l; msgsnd( msgid, &buf2, msgsize, 0 ); break; buf2.mtype = 3l;msgsnd( msgid, &buf2, msgsize, 0 ); /將客

36、戶端2的消息轉(zhuǎn)發(fā)給客戶端1 sleep(5); /若退出，則先等待，以確?？蛻舳顺绦蛲顺?msgctl( msgid, ipc_rmid, null ); /刪除消息隊列，釋放空間 exit(0);客戶端1：#define key_msg 0x101#define msgsize 128#include #include #include #include #include main() int msgid; struct msgbuf long mtype; char mtext128; buf1, buf2; msgid = msgget( key_msg, 0666 ); while( 1 ) printf( input the msg to client2: ); gets( buf1.mtext ); buf1.mtype = 1l; msgsnd( msgid, &buf1, msgsize, 0 ); /客戶端1獲取消息并發(fā)往服務(wù)器sleep(1); /等待一秒，以確?？蛻舳?已經(jīng)收到并發(fā)了回執(zhí) msgrcv( msgid, &buf2, msgsize, 3l, 0 ); /準備從客戶端2獲取回執(zhí)消息 if( buf2.mtext0 = x | buf2.mtext0 = x ) printf( client1 will quit!n ); break; p