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To: Matthew Rickard <rickard DOT matt AT gmail DOT com>, Csaba Raduly <rcsaba AT gmail DOT com>,
        cygwin list <cygwin AT cygwin DOT com>
Subject: RE: [EXTERNAL] Re: 3.4.6-1 shm_open always returns -1, errno EINVAL
Thread-Topic: [EXTERNAL] Re: 3.4.6-1 shm_open always returns -1, errno EINVAL
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Date: Mon, 13 Mar 2023 15:07:28 +0000
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From: "Lavrentiev, Anton \(NIH/NLM/NCBI\) \[C\] via Cygwin" <cygwin AT cygwin DOT com>
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> > returns 3 and sets errno to zero.

Note that "setting errno to zero" is not guaranteed in case of a successful completion of a library function or a system call.
Generally, "errno" reflects an error that occurred last when such a call failed (so in other words, in case of a successful
completion, "errno" can still carry over an error from a previously failed call).  In this particular use case, it looks like
"errno" was clear from the get go because nothing was called prior to "shm_open()", and so it remained so when the call returned (successfully).

HTH,

Anton Lavrentiev
Contractor NIH/NLM/NCBI


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