From: Alexander Monakov <amonakov@ispras.ru>
To: musl@lists.openwall.com
Subject: Re: [PATCH] faccessat: fix error code on setreXid failure
Date: Wed, 31 Jan 2018 00:51:58 +0300 (MSK) [thread overview]
Message-ID: <alpine.LNX.2.20.13.1801310040250.604@monopod.intra.ispras.ru> (raw)
In-Reply-To: <20180130213353.GM1627@brightrain.aerifal.cx>
On Tue, 30 Jan 2018, Rich Felker wrote:
>
> AFAIK wait4 can also return due to Stopped status or trace-related
> reasons, not just exit. That was the motivation I think.
We know we are not tracing this child, and stop notifications are only
delivered if WUNTRACED is given in flags, aren't they?
> > - the code seems to assume that the zombie will not be auto-collected even if
> > SIGCHLD disposition is set to SIG_IGN; this sounds logical, but not explicitly
> > documented as far as I can tell;
>
> Indeed, I'm not sure, but I don't know any good fix.
Bring back the pipe (similar to how posix_spawn receives the status)?
> > --- a/src/unistd/faccessat.c
> > +++ b/src/unistd/faccessat.c
> > @@ -25,7 +25,7 @@ static int checker(void *p)
> > int i;
> > if (__syscall(SYS_setregid, __syscall(SYS_getegid), -1)
> > || __syscall(SYS_setreuid, __syscall(SYS_geteuid), -1))
> > - __syscall(SYS_exit, 1);
> > + return sizeof errors/sizeof *errors - 1;
> > ret = __syscall(SYS_faccessat, c->fd, c->filename, c->amode, 0);
> > for (i=0; i < sizeof errors/sizeof *errors - 1 && ret!=errors[i]; i++);
> > return i;
>
> Looks ok except it encodes an assumption that EBUSY is last. It might
> make more sense to goto the errno-searching loop.
Well, the loop also implicitly encodes that assumption anyway: it stops
at the last entry regardless if it matches, making EBUSY the fallback code
for unrecognized SYS_faccessat return values.
The loop will be gone if the pipe method is re-introduced.
Alexander
next prev parent reply other threads:[~2018-01-30 21:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-30 20:32 Alexander Monakov
2018-01-30 21:33 ` Rich Felker
2018-01-30 21:51 ` Alexander Monakov [this message]
2018-01-30 22:07 ` Rich Felker
2018-01-30 22:20 ` Alexander Monakov
2018-02-01 3:19 ` Rich Felker
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.LNX.2.20.13.1801310040250.604@monopod.intra.ispras.ru \
--to=amonakov@ispras.ru \
--cc=musl@lists.openwall.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/musl/
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).