ςοδιτεμψσλικ πςογεσσ, shmp_mm.c :

  1 #include        "registration.h"
  2 #include        <string.h>
  3 #include        <unistd.h>
  4 #include        <stdlib.h>
  5 #include        <sys/types.h>
  6 #include        <sys/ipc.h>
  7 #include        <sys/sem.h>
  8 #include        <fcntl.h>
  9 #include        <stdio.h>
 10 #include        <wait.h>
 11 #include        <errno.h>
 12
 13 #define FILENAME        "./class"
 14
 15 static struct CLASS class = {
 16    "1001",
 17    "120191",
 18    "C Language for Programmers",
 19    15 };
 20 #define NCHILD 3
 21 static pid_t child[NCHILD];
 22
 23 static int      semid, fd;
 24 static char     ascsemid[10];
 25
 26 static char pname[14];
 27 static void rpterror(char *),Σlass_init(void),
 28         sem_init(void), wait_and_wrap_up(void);
 29
 30 main(int argc, char *argv[])
 31 {
 32    int i;
 33
 34    strcpy(pname,argv[0]);
 35    class_init();
 36    sem_init();
 37    for(i=0; i<NCHILD; i++){
 38      child[i] = fork();
 39      switch(child[i]){
 40      case -1:
 41        rpterror("fork-failure");


 42        exit(1);
 43      case 0:
 44        sprintf(pname,"shmc%d",i+1);
 45        execl("shmc_mm", pname, FILENAME,
 46                ascsemid, (char*)0);
 47        rpterror("execl failed");
 48        exit(2);
 49        }
 50
 51    }
 52    wait_and_wrap_up();
 53 }
 54
 55 static void class_init(void)
 56 {
 57    fd = open(FILENAME, O_WRONLY | O_CREAT | O_EXCL, 0666);
 58      if(fd == -1)
 59         if( errno == EEXIST ){
 60         printf(FILENAME  "  exists,  starting with presentcount\n");
 61            return;
 62         }
 63         else {
 64            rpterror("open failed");
 65            exit(3);
 66         }
 67
 68    if( write( fd, &class, sizeof(class)) < sizeof(class)) {
 69       rpterror("write of structure failed");
 70       exit(4);
 71    }
 72 }
 73
 74 static void sem_init(void)
 75 {
 76    if((semid=semget(IPC_PRIVATE,1,0600 | IPC_CREAT))== -1){
 77       rpterror("semget failed");
 78       exit(5);
 79    }
 80    if((semctl(semid,0,SETVAL,1)) == -1){
 81       rpterror("parent: semctl, SETVAL failed");


 82       exit(6);
 83    }
 84    sprintf(ascsemid, "%d", semid);
 85 }
 86
 87 static void wait_and_wrap_up(void)
 88 {
 89    pid_t wait_rtn; int w, ch_active = NCHILD;
 90    while( ch_active > 0 ){
 91      wait_rtn = wait( (int *)0 );
 92      for(w=0; w<NCHILD; w++)
 93        if(child[w]==wait_rtn){
 94           ch_active--;
 95           break;
 96      }
 97    }
 98    printf("Parent removing data file and sem\n");
 99    unlink(FILENAME);
100    semctl(semid, 0, IPC_RMID, 0);
101    exit(0);
102 }
103
104 static void rpterror(char *string)
105 {
106    char errline[50];
107    sprintf(errline,"%s %s", string, pname);
108    perror(errline);
109 }

ποδπςογεσσ - πςοδαχεγ νεστ χ λμασσε, shmc_mm.c :

  1     #include    "registration.h"
  2     #include    <stdlib.h>
  3     #include    <unistd.h>
  4     #include    <sys/types.h>
  5     #include    <sys/ipc.h>
  6     #include    <sys/sem.h>
  7     #include    <sys/mman.h>
  8     #include    <fcntl.h>
  9     #include    <stdio.h>
 10     static struct CLASS     *class_ptr;
 11     static char    *pname;
 12     static int      fd, semid, ret;
 13     static struct sembuf lock =   { 0, -1, 0};
 14     static struct sembuf unlock = { 0,  1, 0};
 15     static void sell_seats(void), rpterror(char *);


 16
 17 main(int argc, char *argv[])
 18 {
 19   if(argc < 3){
 20      fprintf(stderr,"Usage: %s shmid semid\n", argv[0]);
 21      exit(1);
 22   }
 23   pname = argv[0];
 24   if((fd =  open(argv[1], O_RDWR)) == -1) {
 25       rpterror("open failed");
 26       exit(2);
 27   }
 28
 29   class_ptr = (struct CLASS *) mmap(0,sizeof (struct CLASS),
 30        PROT_READ|PROT_WRITE,MAP_SHARED, fd,0);
 31   if(class_ptr == (struct CLASS *)-1){
 32       rpterror("mmap failed");
 33       exit(4);
 34   }
 35
 36   sscanf(argv[2], "%d", &semid);
 37
 38   sell_seats();
 39
 40   munmap(class_ptr);
 41   exit(0);
 42 }
 43
 44 static void sell_seats(void){
 45    int all_out = 0;
 46    srand( (unsigned)getpid());
 47    while ( !all_out ){ /* loop to sell all seats */
 48       if(semop(semid,&lock,1) == -1){
 49          rpterror("semop lock failed");
 50          exit(4);
 51       }
 52       if (class_ptr->seats_left > 0){
 53          class_ptr->seats_left--;
 54          printf("%s SOLD SEAT -- %2d left\n",
 55                 pname,class_ptr->seats_left);
 56       }
 57       else{

 58              all_out++;
 59              printf("%s  sees  no  seats left\n", pname);
 60       }
 61       ret = semop(semid,&unlock,1);
 62       if (ret == -1) {
 63           rpterror("semop unlock failed");
 64           exit(5);
 65       }
 66       sleep( (unsigned)rand()%10 + 1);
 67    }
 68 }
 69
 70 static void rpterror(char *string)
 71 {
 72     char errline[50];
 73     sprintf(errline,"%s %s", string, pname);
 74     perror(errline);
 75 }