exec()之后的共享内存 [英] shared memory after exec()

问题描述

如果孩子已经运行 exec()来加载另一个程序，如何在父母和孩子之间共享内存?

How can I share memory between the parent and the child if the child has run exec() to load another program?

是否可以使用 mmap ?

现在，父母和孩子可以使用mmap正确共享内存，但是在完成 exec 之后不能这样做

By now parent and child share memory properly using mmap, but not after exec is done

推荐答案

您可以使用shm_open打开由文件系统上的文件标识的命名"共享内存块.例子: 在父项中:

You can use shm_open to open a "named" shared memory block which is identified by a file on the filesystem. Example: In the parent:

int memFd = shm_open("example_memory", O_CREAT | O_RDWR, S_IRWXU);
if (memFd == -1)
{
    perror("Can't open file");
    return 1;
}

int res = ftruncate(memFd, /*size of the memory block you want*/);
if (res == -1)
{
    perror("Can't truncate file");
    return res;
}
void *buffer = mmap(NULL, /*size of the memory block you want*/, PROT_READ | PROT_WRITE, MAP_SHARED, memFd, 0);
if (buffer == NULL)
{
    perror("Can't mmap");
    return -1;
}

在另一个文件中:

int memFd = shm_open("example_memory", O_RDONLY, 0);
if (memFd == -1)
{
    perror("Can't open file");
    return 1;
}

void *buffer = mmap(NULL, /*size of the memory block you want*/, PROT_READ, MAP_SHARED, memFd, 0);
if (buffer == NULL)
{
    perror("Can't mmap");
    return -1;
}

这些代码段之后，您可以使用buffer访问共享内存. (注意:它不必为void*，您可以使其成为指向要存储在共享内存中的任何内容的指针)

After these segments of code you can use buffer to access the shared memory. (Note: it doesn't need to be void*, you can make it a pointer to whatever you intend to store in the shared mem)

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