20 Apr
2005
20 Apr
'05
4:05 p.m.
Thomas Weidenmueller wrote:
This is not correct. If the mutex already exist, CreateMutex returns a
handle to the existing mutex.
Some lines later in the PSDK: "If the function succeeds, the return
value is a handle to the mutex object. If the named mutex object existed
before the function call, the function returns a handle to the existing
object and GetLastError() returns ERROR_ALREADY_EXISTS. Otherwise, the
caller created the mutex."
- Hartmut
Joseph Galbraith wrote:
This is not correct. CreateMutex fails only if the named object already
exists and if the object is not a mutex.
Regardless of whether the mutex is newly created
or
pre-existing, CreateMutex() will return a handle to
it.
CreateMutex fails if a named object is supposed to be created but
already exists. GetLastError() then will - as you mentioned below -
return ERROR_ALREADY_EXISTS or another failure code. In the case of
a pre-existing mutex, the handle to
the existing object is returned.
Not by CreateMutex. If
CreateMutex() returns NULL, it failed for some
other reason (than that the mutex already existed,
since CreateMutex doesn't fail in this case.)
Quote from the PSDK: "If lpName matches the name of an existing event,
semaphore, waitable timer, job, or file-mapping object, the function
fails and the GetLastError function returns ERROR_INVALID_HANDLE. This
occurs because these objects share the same name space."