Fix #78883: fgets(STDIN) fails on Windows

[cmb69]

We add the is_seekable member to php_stdio_stream_data, and prefer
that over is_pipe, since the latter is simply a misnomer. We keep
is_pipe for now for Windows only, though, because we need special
support for pipes there. We also fix the misaligned bitfield which
formerly took 33 bit.

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This is the cleaner alternative to PR #4952.

[cmb69]

This is an important bugfix for Windows (PHP 7.4.0 can't run any interactive console app), so the PR should be addressed ASAP (IOW, before 7.4.1RC1 is tagged tomorrow). Thanks!

[weltling]

Thanks, @cmb69, for checking on this direction. The old code path would be preserved this way, and is_seekable would be used just for the given purpose.

One thing yet - if a stream is created not with *_from_fd, it should have this default to true. To check at the stream allocation time.

Thanks.

[cmb69]

Thanks for reviewing @weltling!

if a stream is created not with *_from_fd, it should have this default to true

Sorry, I don't understand. As it's now, _from_file and _from_fd dynamically detect that flags. Do you mean that is_pipe should default to true for these cases?

[weltling]

@cmb69, actually I was talking about is_seekable being true by default. Just for the case, so it's not left uninitialized occasionally. Currently all the code paths seem to initialize it, so looks fine overall.

Thanks.

[cmb69]

Thanks! Applied as 996f217.

[samdark]

@weltling any estimate on 7.4.1 release date?

[cmb69]

PHP 7.4.1 is scheduled for Dec, 19th.