Anonymous semaphore in Win API

Asked Apr 03 '19 at 04:09

Active Apr 03 '19 at 18:21

Viewed 185 times

I have 2 processes which are running on the same Windows machine. Both of them are using semaphores that are provided from CreateSemaphore(), and these 2 semaphores are created with the lpName parameter set to NULL (0).

Do these 2 processes share the same semaphore object? Or are anonymous semaphores unique in the OS?

edited Apr 03 '19 at 18:21

Remy Lebeau

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asked Apr 03 '19 at 04:09

Rick

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Each call to `CreateSemaphore` with no name creates a new, separate semaphore. – Igor Tandetnik Apr 03 '19 at 04:19
Synchronization primitives that have no name are always local-only. – Michael Chourdakis Apr 03 '19 at 04:20
every no-name object is unique - you create new object every time when create it without name – RbMm Apr 03 '19 at 08:20
@MichaelChourdakis - what you mean under *local-only* ? – RbMm Apr 03 '19 at 08:27
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Sometimes unnamed semaphore can be shared by using inheritable handle. [How to pass handle to child process](https://stackoverflow.com/questions/7420508/how-to-pass-handle-to-child-process) – Daniel Sęk Apr 03 '19 at 09:14
@DanielSęk - or by duplicate handle too – RbMm Apr 03 '19 at 09:35
They are not automatically shared. Named priminitives are automatically shared between whoever application knows the name and has the permissions. – Michael Chourdakis Apr 03 '19 at 10:53

Anonymous semaphore in Win API

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