On Tuesday, 7 February 2017 at 11:41:44 UTC, Walter Bright wrote:
I haven't examined that particular issue, but @trusted applies
to things with a SAFE INTERFACE. Just sticking it on any old
system function does not work. For example, declaring strlen()
to be @trusted is a giant mistake, because it's interface is
not safe.
On 2/5/2017 1:44 PM, Jakub Łabaj via phobos wrote:
There is an idea to make stdio.readf @trusted/@safe (reported
here:
https://issues.dlang.org/show_bug.cgi?id=8471). What currently
makes it unsafe
is LockingTextReader using functions FLOCK, FUNLOCK, FGETC
(aliased from extern
functions, dependent on the OS) and using a cast from
'shared(_IO_FILE)*' to
'_IO_FILE*'.
I found out that stdio.write* functions are made @safe by
declaring all methods
of LockingTextWriter (similar to LockingTextReader) @trusted
and using helper
function:
/**
* Property used by writeln/etc. so it can infer @safe since
stdout is __gshared
*/
private @property File trustedStdout() @trusted
{
return stdout;
}
So the obvious solution is to copy the approach of
stdio.write. The other one
would be to mark underlying functions FLOCK/FUNLOCK/FGETC
@trusted (which in the
process would allow to get rid off @trusted from
LockingTextWriter, except
casting from shared), but I'm not sure if it's legit as there
may be some quirks
and they should not be @trusted at all.
So my question are: are both solutions presented acceptable?
If yes, which one
is preferred? Or maybe there is a better one?
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Ok, so I have doubts whether these functions can be @trusted. On
the one hand they get just FILE* as an argument which (as I see
it) makes it safe interface. On the other hand FGETC is unlocked
version of fgetc and requires explicit lock to be used safely;
FLOCK and FUNLOCK invocations should match, therefore there is
also possibility to use it incorrectly. Personally I would not
mark them @trusted then, is it correct?
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