为什么在共享内存中给memcpy一个分段错误

时间:2018-05-03 13:39:54

标签: c struct shared-memory mmap memcpy

我的当前项目有问题。

这是我的标题:

#define SHARED_MEMORY_NAME "/osmpmemory"
#define OSMP_MAX_MESSAGES_PROC 16
#define OSMP_MAX_SLOTS 256
#define OSMP_MAX_PAYLOAD_LENGTH 128

typedef struct {
        char msg[OSMP_MAX_PAYLOAD_LENGTH];
    } osmp_msg;

typedef struct {
        size_t memory_size;
        int process_count;
        osmp_msg slots[OSMP_MAX_SLOTS];
    } shm_conf;

这是我的代码:

shm_conf* memory_conf;
size_t shm_size =  sizeof(shm_conf) + sizeof(int[count][2]) + sizeof(osmp_msg[count][OSMP_MAX_MESSAGES_PROC]);
int fd;

if((fd = shm_open(SHARED_MEMORY_NAME, O_CREAT | O_RDWR, 0640)) == -1) {
        return -1;
    }

if(ftruncate(fd, shm_size) == -1) {
        printf("%s\n", strerror(errno));
        return -1;
    }


if((memory_conf = (shm_conf*)mmap(NULL, shm_size , PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)) == MAP_FAILED) {
        printf("%s\n", strerror(errno));
        return 0;
    }

memory_conf->process_count = count;
memory_conf->memory_size = shm_size;

int process_numbers[memory_conf->process_count][2];

for(int i = 0; i < memory_conf->process_count; i++) {
        process_numbers[i][0] = 0;
        process_numbers[i][1] = i;
    }

memcpy(memory_conf + sizeof(shm_conf), process_numbers, sizeof(process_numbers));

我想在shm_conf结构之后存储一个二维数组。但memcpy给了我一个分段错误,我不知道为什么,你能帮助我吗?

在这个数组之后,我想存储另一个数组,这就是为什么shm_size比我当前需要的更大。

1 个答案:

答案 0 :(得分:3)

错误可能是$File1 = "C:\Scripts\Txt1.txt" $File2 = "C:\Scripts\Txt2.txt" $Location = "C:\Scripts\Txt3.txt" compare-object (get-content $File1) (get-content $File2) | format-list | Out-File $Location 调用中的指针算术。

memcpy

memcpy(memory_conf + sizeof(shm_conf), process_numbers, sizeof(process_numbers)); 已经是memory_conf指针,因此递增shm_conf。该行应更改为:

sizeof(shm_conf)

避免复制到尚未分配的内存

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