Date: Thu, 6 Dec 2018 02:43:40 +0000 From: Orivej Desh <orivej@....fr> To: musl@...ts.openwall.com Subject: Re: sem_wait and EINTR * Rich Felker <dalias@...c.org> [2018-12-05] > On Wed, Dec 05, 2018 at 10:27:16PM +0100, Ondřej Jirman wrote: > > On Wed, Dec 05, 2018 at 08:47:59PM +0100, Markus Wichmann wrote: > > > > It's specified by POSIX: > > > > https://pubs.opengroup.org/onlinepubs/9699919799/functions/sem_wait.html > > > > Sates: "The sem_wait() function is interruptible by the delivery of a signal." > > This seems contradictory with EINTR being a "may fail" error, and, if > interpreted the way you want to interpret it, seems to be > contradictory with SA_RESTART semantics, since it doesn't say anything > about whether that signal is an interrupting one. I think we should > attempt to obtain a clarification on what the intent is here. Does "is > interruptible" mean that it needs to fail on signals (only without > SA_RESTART?) or simply that signal handlers must be permitted to run > (i.e. the wait can't happen with signals blocked)? There is a definition of interruptible functions on the sigaction page: SA_RESTART This flag affects the behavior of interruptible functions; that is, those specified to fail with errno set to [EINTR]. If set, and a function specified as interruptible is interrupted by this signal, the function shall restart and shall not fail with [EINTR] unless otherwise specified. If the flag is not set, interruptible functions interrupted by this signal shall fail with errno set to [EINTR]. https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigaction.html
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