如何解决分段错误(核心已转储)

我正在尝试使用循环队列实现生产者和消费者问题,但出现错误:  文件未找到  分段故障(核心已转储)

第一次使用Ubuntu和C语言时,对ubuntu以及此错误一无所知

请帮我解决这个错误 我正在使用C语言 我的代码:

#define _XOPEN_SOURCE
#include <stdlib.h> 
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include <sys/wait.h>

#define NUM_ELEM 15 /* Number of elements in shared memory buffer */
#define SEM_MUTEX 0
#define SEM_EMPTY 1
#define SEM_FULL 2

FILE* fp;
int rc, semID, shmID, status, i, x;
char elem;
union semun
{
    int val;
    struct semid_ds *buf;
    short *array;
} seminfo;

struct sembuf WaitMutex={SEM_MUTEX, -1, 0};
struct sembuf SignalMutex={SEM_MUTEX, 1, 0};
struct sembuf WaitEmpty={SEM_EMPTY, -1, 0};
struct sembuf SignalEmpty={SEM_EMPTY, 1, 0};
struct sembuf WaitFull={SEM_FULL, -1, 0};
struct sembuf SignalFull={SEM_FULL, 1, 0};
struct shmid_ds shminfo;
char *shmPtr;

void initialize();
void producer();
void consumer();

int main()
{

  /* Initialize shared memory and semaphores */
  initialize();

  /* Start a child process and proceed accordingly*/
  if (fork()==0)
  {
    /* Child becomes the consumer */
    consumer();
    exit(0);
  }
  else
  {
    /* Parent becomes the producer */
    producer();

    /* Wait for child to finish */
    wait(&status);

    /* Remove shared memory */
    shmctl(shmID, IPC_RMID, &shminfo);

    /* Remove semaphores */
    semctl(semID, SEM_MUTEX, IPC_RMID, seminfo);

    /* Close file */
    fclose(fp);

    /* Parent is done cleaning up, so now quits */
    return 0;
  }
}

void initialize()
{

  /* Init semaphores */
  /* Three semaphores (Empty, Full, Mutex) are created in one set */
  semID=semget(IPC_PRIVATE, 3, 0666 | IPC_CREAT);

  /* Init Mutex to one, allowing access to critical section */
  seminfo.val=1;
  semctl(semID, SEM_MUTEX, SETVAL, seminfo);

  /* Init Empty to number of elements in shared memory (circular buffer) */
  seminfo.val=NUM_ELEM;
  semctl(semID, SEM_EMPTY, SETVAL, seminfo);

  /* Init Full to zero, no elements are produced yet */
  seminfo.val=0;
  semctl(semID, SEM_FULL, SETVAL, seminfo);

  /* Init Shared memory */
  shmID=shmget(IPC_PRIVATE, NUM_ELEM, 0666 | IPC_CREAT);

  if (shmID == -1)
  {
    perror("shmget failed");
    exit(1);
  }
}

void producer()
{

    /* Open file */
     fp= fopen("mytest.dat", "r");
     if (fp == NULL)
    {
        printf("File not found!\n");
    }

    /* attach shared memory to process */
    shmPtr=(char*)shmat(shmID, 0, SHM_W);

    /* Check for error in shmptr assignment */
    if (shmPtr == (void *)(-1))
    {
       perror("shmat failed in producer");
       exit(1);
    }

    while((x = fgetc(fp)) != EOF)
    {

    /* Wait(Empty) - pause if no empty spots in circular buffer (i.e. all filled) */
        semop(semID, &WaitEmpty, 1);

        elem = x;
        printf("Produced elem '%c'\n", elem);

        /* Wait(Mutex) - don't touch shared memory while consumer is using it */
        semop(semID, &WaitMutex, 1);

        /* Put element into shared memory buffer (circular buffer) */
        *(shmPtr + (i%NUM_ELEM))=elem;

        /* Signal(Mutex) - allow consumer to access shared memory now */
        semop(semID, &SignalMutex, 1);

        /* Signal(Full) - record one more filled spot in circular buffer */
        semop(semID, &SignalFull, 1);
    }
}

void consumer()
{
    /* attach shared memory to process */
    shmPtr=(char*)shmat(shmID, 0, SHM_R) = 0;

    while((x = fgetc(fp)) != EOF)
    {
        /* Wait(Full) - pause if no filled spots in circular buffer (i.e. all empty) */
        semop(semID, &WaitFull, 1);

        /* Wait(Mutex) - don't touch shared memory while producer is using it */
     semop(semID, &WaitMutex, 1);

        /* Get element from the shared memory buffer (circular buffer) */
        elem=*(shmPtr + (i%NUM_ELEM));

        /* Signal(Mutex) - allow producer to access shared memory now */
        semop(semID, &SignalMutex, 1);

        /* Display character */
        printf("%c", (char)elem);

        /* Signal(Empty) - record one more empty spot in circular buffer */
        semop(semID, &SignalEmpty, 1);
    }
}

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