Is memcpy process-safe?

Question

Ive looked online and have not been able to satisfy myself with an answer.

Is memcpy threadsafe? (in Windows)

What I mean is if I write to an area of memory shared between processes (using boost::shared_memory_object) using a single memcpy and then try read that area from another process using a single memcpy then will one process be blocked automatically while that write is happening? Where can I read about this?

Answer 1

memcpy is typically coded for raw speed. It will not be thread safe. If you require this, you need to perform the memcpy call inside of a critical section or use some other semaphor mechanism.

take_mutex(&mutex);
memcpy(dst, src, count);
yield_mutex(&mutex);

Answer 2

memcpy is not thread/process safe

Answer 3

Routines like memcpy() (or memmove()) are part of standard C library, are included through standard <string.h> header and know nothing about any locking mechanics. Locking should be provided by some external way like inter-process mutexes, semaphores or things like this.