From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/12431 Path: news.gmane.org!.POSTED!not-for-mail From: Alexander Monakov Newsgroups: gmane.linux.lib.musl.general Subject: Re: [PATCH] faccessat: fix error code on setreXid failure Date: Wed, 31 Jan 2018 00:51:58 +0300 (MSK) Message-ID: References: <20180130203237.4580-1-amonakov@ispras.ru> <20180130213353.GM1627@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Trace: blaine.gmane.org 1517349025 25838 195.159.176.226 (30 Jan 2018 21:50:25 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 30 Jan 2018 21:50:25 +0000 (UTC) User-Agent: Alpine 2.20.13 (LNX 116 2015-12-14) To: musl@lists.openwall.com Original-X-From: musl-return-12447-gllmg-musl=m.gmane.org@lists.openwall.com Tue Jan 30 22:50:21 2018 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by blaine.gmane.org with smtp (Exim 4.84_2) (envelope-from ) id 1egdn5-0005ax-Tw for gllmg-musl@m.gmane.org; Tue, 30 Jan 2018 22:50:07 +0100 Original-Received: (qmail 23574 invoked by uid 550); 30 Jan 2018 21:52:10 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 23555 invoked from network); 30 Jan 2018 21:52:09 -0000 In-Reply-To: <20180130213353.GM1627@brightrain.aerifal.cx> Xref: news.gmane.org gmane.linux.lib.musl.general:12431 Archived-At: 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