Date: Thu, 18 Aug 2022 13:40:36 +0300 From: Alexey Izbyshev <izbyshev@...ras.ru> To: musl@...ts.openwall.com Subject: Re: [PATCH] add close_range() syscall wrapper On 2022-08-18 13:11, Érico Nogueira wrote: > On Wed Aug 17, 2022 at 9:35 PM -03, Rich Felker wrote: >> On Wed, Aug 10, 2022 at 01:03:11PM +0000, Guilherme Janczak wrote: >> > close_range() is a syscall present in FreeBSD 8.0 and Linux 5.9. glibc >> > 2.34 added a wrapper. >> > --- >> >> The existence of this operation has been controversial, and it's >> arguable that it should be excluded by policy not to support UB (it's >> UB to close fds you don't own that might be used internally by the >> implementation) though I'm not sure it really helps since folks who >> want to use it will just make the syscall directly. We should probably >> at least consider it for inclusion. > > I remember an idea to implement fallback logic, in case the syscall is > unavailable, had been mentioned. It would then avoid whatever fallback > code the application tried to implement, which might not be as > relevant, > now that opendir() can be called in a forked child. And I don't know if > there's interest in implementing anything more complex at all. > Glibc doesn't implement a fallback and explicitly says it in the manual. Using a different implementation in musl seems undesirable. Note that CPython since 3.10 can use close_range() in fork/vfork child for subprocess.Popen(close_fds=True) (which is the default), so it expects close_range() to be async-signal-safe. Alexey
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