从另一个进程访问mmap内存 [英] Access mmap memory from another process
问题描述
我已经开始玩mmap.我正在尝试创建一个示例工作空间，然后将其扩展到实际情况.
I've started playing with mmap. I'm trying to create an example workspace that will be then extended to the real case.
这是我想要实现的:
过程1:
- 映射文件(实际上是设备，但是可以生成带有文本文件的示例)
过程2 :(不属于过程1；只是一个独立的过程)
PROCESS 2: (not foked from process 1; just an independent process)
- 读取进程1映射的内存
- 更改一些位
- 将其写入新文件
我已经阅读了一些示例和文档，但是我仍然没有找到实现该目标的方法.我所缺少的是:
I've read several examples and documentations, but I still didn't find how to achieve this. What I'm missing is:
- 进程2如何在不了解打开文件的情况下访问进程1映射的内存?
- 如何将mmap内容放入新文件中?我想我必须ftruncate一个新文件，mmap此文件并memcpy进程1内存映射的内容到进程2内存映射(然后是msync)
侧面信息，我在两个进程之间打开了一个消息队列，因此它们可以在需要时共享一些消息(例如，内存地址/大小，...).
Side info, I have a message queue opened between the two processes, so they can share some messages if needed (ex. the memory address/size, ...).
有任何提示吗?
提前谢谢！
MIX
推荐答案
此答案认为您正在尝试在linux/unix上执行此操作.
This answer considers you are trying to do this stuff on linux/unix.
进程2如何在不了解有关打开的文件的情况下访问进程1映射的内存?
how can process 2 access the memory mapped by process 1, without knowing anything about the opened file?
进程1将标志MAP_SHARED传递给mmap [1].
Process 1 passes to mmap[1] the flag MAP_SHARED.
您可以:
- A)使用unix域套接字共享文件描述符[2].
- B)发送 使用您在末尾提到的队列的文件名 您的留言.
- A) Share the file descriptor using unix domain sockets[2].
- B) Send the name of the file using the queues you mentioned at the end of your message.
进程2使用标志MAP_SHARED打开mmap.对于进程2，将看到对进程1中的mmaped内存的修改.如果需要精细控制何时显示从进程1到进程2的更改，则应使用msync [3]
Process 2 opens mmap with the flag MAP_SHARED. Modifications to the mmaped memory in Process 1 will be visible for Process 2. If you need fine control of when the changes from process 1 are shown to process 2 you should control it with msync[3]
如何将mmap内容放入新文件中?我想我必须 ftruncate一个新文件，mmap这个文件并memcpy进程的内容 1个内存映射来处理2个内存映射(然后是msync)
how can I put the mmap content in a new file? I suppose I have to ftruncate a new file, mmap this file and memcpy the content of process 1 memory map to process 2 memory map (then msync)
为什么不通过写操作将mmaped内存写为常规内存?
Why just don't write the mmaped memory as regular memory with write?
[1] http://man7.org/linux/man-pages/man2/mmap.2.html
[3] http://man7.org/linux/man-pages/man2/msync.2.html
这篇关于从另一个进程访问mmap内存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！
