彻底销毁System V共享内存段 [英] Cleanly destroy a System V shared memory segment

问题描述

我正在使用 shmget ， shmat 和 shmctl 分别获取和创建共享内存段，将其附加在进程地址空间中并删除它.

I am using shmget, shmat and shmctl to respectively get and create a shared memory segment, attach it in processes address space and remove it.

我想知道即使已分离共享内存段并要求使用删除共享内存段，进程是否仍可以使用共享内存段

I am wondering if processes can still use the shared memory segment even if it has been detached and asked for removal using

shmctl(id, IPC_RMID, ...)

在一个过程中.

我无法从手册页中获取信息:

I am not able to get the information from the man page:

IPC_RMID 标记要销毁的网段.实际上，只有在最后一个进程将其分离后，该段才会被销毁(即，当关联结构 shmid_ds 的 shm_nattch 成员为零时).呼叫者必须是所有者或创建者，或具有特权.如果某个段已标记为要销毁，则 shm_perm.mode 的(非标准) SHM_DEST 标志将设置由 IPC_STAT 检索的关联数据结构中的字段.

IPC_RMID Mark the segment to be destroyed. The segment will only actually be destroyed after the last process detaches it (i.e., when the shm_nattch member of the associated structure shmid_ds is zero). The caller must be the owner or creator, or be privileged. If a segment has been marked for destruction, then the (nonstandard) SHM_DEST flag of the shm_perm.mode field in the associated data structure retrieved by IPC_STAT will be set.

推荐答案

在 Linux 上，即使共享内存段已经被标记为删除，也可以附加它.但是，POSIX.1-2001没有指定此行为，并且许多其他实现也不支持此行为.

On Linux, it is possible to attach a shared memory segment even if it is already marked to be deleted. However, POSIX.1-2001 does not specify this behavior and many other implementations do not support it.

这篇关于彻底销毁System V共享内存段的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！