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From: "Laurent Bercot" <ska-dietlibc@skarnet.org>
To: musl@lists.openwall.com, "Skyler Ferrante (RIT Student)" <sjf5462@rit.edu>
Cc: "Andreas Schwab" <schwab@suse.de>, "Alejandro Colomar" <alx@kernel.org>,
 "Thorsten Glaser" <tg@mirbsd.de>, musl@lists.openwall.com, NRK
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 libc-alpha@sourceware.org, libbsd@lists.freedesktop.org, "Serge E. Hallyn"
 <serge@hallyn.com>, "Iker Pedrosa" <ipedrosa@redhat.com>, "Christian Brauner"
 <christian@brauner.io>
Date: Mon, 11 Mar 2024 21:21:00 +0000
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Subject: Re: [musl] Re: Tweaking the program name for <err.h> functions

>(Aside: making _FORTIFY_SOURCE>1 trap close(n) with n<3 would be an
>interesting idea... :)

  Please don't. close(0); if (open("something", O_RDONLY)) fail();
(only when single-threaded, obviously) is a valid pattern, and uses
one fewer descriptor than fd=3Dopen("something", O_RDONLY); dup2(fd, 0);

  Also, running with stdin or stdout closed (or even stderr but what kind
of monster would do that) is fine for a process that is internal to a
project, that isn't user-facing; it's on the project to know the fd
states of its various components. Private APIs should not have the same
constraints as public ones.

  (And yes, for user-facing programs, i.e. 99% of them, it is a good
idea to always sanitize around 0, 1 and 2.)

--
  Laurent