C文件数据到共享内存

Question

我喜欢打开一个二进制文件，然后喜欢检查一些标头，并且在读取之后，我喜欢通过ftell（）获取FilePosition，并将结构分配到共享内存中。我喜欢将文件数据循环放入该Struct中。但我收到此错误-

MWriter.c:71:43: error: invalid conversion from ‘char’ to ‘void*’ [-fpermissive]
             fread(M->Data[i*BufferSize], sizeof(char), BufferSize, FP+FilePosition);

我喜欢打开一个二进制文件，然后喜欢检查一些标头，并且在读取之后，我喜欢通过ftell（）获取FilePosition，并将结构分配到共享内存中。我喜欢将文件数据循环放入该Struct中。但我收到此错误-

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/mman.h>

int main(void){
    struct MemData{
        char FileName[128];//POINTER PUTS DATA INTO NON-SHARED MEMORY
        int LastByteLength;
        int ReadPointer;
        int WritePointer;
        char Data[512000];//MEMORY BLOCK SIZE: 500 KB
    };
    int SD;
    struct MemData *M;
    int NumberOfBuffers=10;
    int BufferSize=51200;//FILE BUFFER SIZE 50 KB

    SD= shm_open("/program.shared", O_RDWR|O_CREAT, S_IREAD|S_IWRITE);
    if(SD< 0){
        printf("\nshm_open() error \n");
        return EXIT_FAILURE;
    }
    fchmod(SD, S_IRWXU|S_IRWXG|S_IRWXO);
    if(ftruncate(SD, sizeof(MemData))< 0){
        printf ("ftruncate() error \n");
        return EXIT_FAILURE;
    }
    //THE FOLLOWING TYPECASTING AVOIDS THE NEED TO ATTACH THROUGH shmat() in shm.h HEADER I GUESS.
    M=(struct MemData*)mmap(NULL, sizeof(MemData), PROT_READ|PROT_WRITE, MAP_SHARED, SD, 0);
    if(M== MAP_FAILED){
        printf("mmap() error");
        return EXIT_FAILURE;
    }else{
        strcpy(M->FileName, "xaa");
        M->LastByteLength=0;
        M->ReadPointer=-1;
        M->WritePointer=-1;
        memset(M->Data, '\0', strlen(M->Data));
    }
    char FileName[128]="xaa";
    FILE *FP= fopen(FileName, "rb");
    if(FP!= NULL){
        struct stat StatBuf;
        if(stat(FileName, &StatBuf)==-1){
            printf("failed to fstat %s\n", FileName);
            exit(EXIT_FAILURE);
        }
        long long FileSize=StatBuf.st_size;
        printf("\n File Size: %lld", FileSize);
        long long FilePosition=ftell(FP);
        FilePosition=ftell(FP);
        long long CopyableMemorySize=FileSize-FilePosition;
        printf("\n Copyable File Size: %lld", CopyableMemorySize);
        int NumberOfFileBuffers=CopyableMemorySize/BufferSize;
        printf("\n Number Of File Buffers: %d", NumberOfFileBuffers);
        for(int i=0; i<NumberOfFileBuffers; i++){
            if(abs(M->WritePointer-M->ReadPointer)==NumberOfBuffers){
                //WAIT
            }else{
                fread(M->Data[i*BufferSize], sizeof(char), BufferSize, FP+FilePosition);
            }
        }
        fclose(FP);
    }
    close(SD);
    return 0;
}