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From: Gil Pedersen <kanongil@gmail.com>
To: musl@lists.openwall.com
Subject: [musl] bug: isatty() can return wrong value
Date: Tue, 20 Aug 2024 11:50:02 +0200	[thread overview]
Message-ID: <A914634C-F598-4187-A85A-03BBA280A884@gmail.com> (raw)

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Hi,

I found a musl related issue in systemd, where it relies on glibc specific behaviour for isatty(), which happens to work out. When using musl, it will fail in another way, causing some essential retry logic to not run.

The error occurs when the isatty() implementation calls an ioctl() that sets the EIO error. glibc will directly forward any errors, while musl remaps it to an ENOTTY error.

Neither behaviour are POSIX compliant. glibc sets an undocumented errno, while musl sets ENOTTY for something that is definitely a TTY.

It seems that the correct fix is to remap the EIO to a success (1).

See https://github.com/systemd/systemd/pull/34039 and https://sourceware.org/bugzilla/show_bug.cgi?id=32103.

I'm not on the mailing list, so please CC any replies.

Regards,
Gil

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             reply	other threads:[~2024-08-20 10:16 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-08-20  9:50 Gil Pedersen [this message]
2024-08-20 11:11 ` Rich Felker
2024-08-20 15:18   ` Thorsten Glaser

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