> The above does makes errno writable, since the function returns a
> pointer to it, not the value. The question is, is this safe in other
> cases, and do POSIX or other standards allow errno to be a macro?

See ANSI 7.1.4

"... which expands to a modifiable lvalue that has type int ... It is
unspecified whether errno is a macro or an identifier with external linkage."


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John Birrell                                CIMlogic Pty Ltd
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