c++ - MapViewOfFile returns different adresses with same handle -


im trying implement ipc school assignment sharing memory. made class called sharedmemorybuffer deal creating file mappings , views.

my init() function looks this:

byte * sharedmemorybuffer::init(const wchar_t * name, size_t buffersize) {      filemaphandle = openfilemapping(         file_map_all_access,   // read/write access         false,                 // not inherit name         name);               // name of mapping object      if (filemaphandle == null)     {         filemaphandle =             createfilemapping(invalid_handle_value,                 null,                 page_readwrite,                 0,                 buffersize,                 name);          pbuf = (byte*)mapviewoffile(filemaphandle, // handle map object             file_map_all_access,  // read/write permission             0,             0,             buffersize);     }     else     {         pbuf = (byte*)mapviewoffile(             filemaphandle,             file_map_all_access,             0,             0,             buffersize         );     }     return this->getbuffer(); }

essentially, pass name , size , tries open mapping name. if fails, creates instead.

i call this->ringbuffer.init(widestr.c_str(), buffsize);

after done (i call init 4 times 2 buffers, same process) print out adresses of buffers (pbuf init()) theyre different addresses.

i cant love of life figure out why adresses different! have made sure second time call init() same name indeed open file mapping successfully.

any appreciated!

source: https://github.com/raviolifinoli/sharedmemory

you mapping same region twice in process. 2 distinct addresses, backed same physical memory. writing buffer pointed first address modifies buffer pointed second address, since same memory.


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