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From: Khem Raj <raj.khem@gmail.com>
To: musl@lists.openwall.com
Cc: Dominic Chen <d.c.ddcc@gmail.com>
Subject: Re: [musl] fdopen() doesn't check for valid fd
Date: Sat, 27 Feb 2021 09:13:17 -0800	[thread overview]
Message-ID: <CAMKF1sr59Lke2TK4zy42N88kcz_qCKC5kBRqMFCRpMfWA4A29w@mail.gmail.com> (raw)
In-Reply-To: <20210226180040.GC32655@brightrain.aerifal.cx>

On Fri, Feb 26, 2021 at 10:01 AM Rich Felker <dalias@libc.org> wrote:
>
> On Fri, Feb 26, 2021 at 12:36:19PM -0500, Dominic Chen wrote:
> > I've been verifying the behavior of an application between glibc and
> > musl, and have noticed that the musl implementation of fdopen()
> > assumes that the input fd is valid, whereas glibc does not. Per
> > https://pubs.opengroup.org/onlinepubs/9699919799/, it seems that
> > fdopen() is allowed to fail with EBADF, so inside __fdopen(), the
> > syscalls to SYS_fcntl and SYS_ioctl should probably check for an
> > error, deallocate the FILE *, and return nullptr.
>
> This is specified as a "may fail" error not a "shall fail". It was
> discussed before (I can look up the old thread if you're interested)
> and there are some paths in which checking for it would be free, but
> others where it would not, and it would require reorganizing the
> function's flow in a way that's less desirable in one way or another,
> so it doesn't seem like a good idea for the sake of something a caller
> can't actually use.
>

perhaps we should add it to differences with glibc document [1]

> Rich

[1] https://wiki.musl-libc.org/functional-differences-from-glibc.html

  reply	other threads:[~2021-02-27 17:14 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-26 17:36 Dominic Chen
2021-02-26 18:00 ` Rich Felker
2021-02-27 17:13   ` Khem Raj [this message]
2021-02-27 17:35     ` Rich Felker
2021-02-27 17:42       ` Khem Raj

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