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[104.10.248.87]) by smtp.gmail.com with ESMTPSA id u27sm7236292pfa.0.2015.12.16.16.57.17 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 16 Dec 2015 16:57:17 -0800 (PST) From: "Nicolas S. Dade" To: uclibc@uclibc.org Subject: [PATCH] pselect: Use linux pselect syscall when available Date: Wed, 16 Dec 2015 16:57:08 -0800 Message-Id: <1450313828-6669-1-git-send-email-nic.dade@gmail.com> X-Mailer: git-send-email 1.9.1 Cc: "Nicolas S. Dade" X-BeenThere: uclibc@uclibc.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: "Discussion and development of uClibc \(the embedded C library\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: uclibc-bounces@uclibc.org Sender: "uClibc" Linux has a pselect syscall since 2.6.something. Using it rather than emulating it with sigprocmask+select+sigprocmask is smaller code, and works properly. (The emulation has race conditions when unblocked signals arrive before or after the select) The tv.nsec >= 1E9 handling comes from uclibc's linux select() implementation, which itself uses pselect() internally if the pselect syscall exists. I though it would be good to do the same here. Signed-off-by: Nicolas S. Dade --- libc/sysdeps/linux/common/pselect.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/libc/sysdeps/linux/common/pselect.c b/libc/sysdeps/linux/common/pselect.c index bf19ce3..928577e 100644 --- a/libc/sysdeps/linux/common/pselect.c +++ b/libc/sysdeps/linux/common/pselect.c @@ -30,6 +30,32 @@ static int __NC(pselect)(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, const struct timespec *timeout, const sigset_t *sigmask) { +#ifdef __NR_pselect6 +#define NSEC_PER_SEC 1000000000L + struct timespec _ts, *ts = 0; + if (timeout) { + /* The Linux kernel can in some situations update the timeout value. + * We do not want that so use a local variable. + */ + _ts.tv_sec = timeout->tv_sec; + _ts.tv_nsec = timeout->tv_nsec; + + /* GNU extension: allow for timespec values where the sub-sec + * field is equal to or more than 1 second. The kernel will + * reject this on us, so take care of the time shift ourself. + * Some applications (like readline and linphone) do this. + * See 'clarification on select() type calls and invalid timeouts' + * on the POSIX general list for more information. + */ + if (_ts.tv_nsec >= NSEC_PER_SEC) { + _ts.tv_sec += _ts.tv_nsec / NSEC_PER_SEC; + _ts.tv_nsec %= NSEC_PER_SEC; + } + + ts = &_ts; + } + return INLINE_SYSCALL(pselect6, 6, nfds, readfds, writefds, exceptfds, ts, sigmask); +#else struct timeval tval; int retval; sigset_t savemask; @@ -57,6 +83,7 @@ static int __NC(pselect)(int nfds, fd_set *readfds, fd_set *writefds, sigprocmask (SIG_SETMASK, &savemask, NULL); return retval; +#endif } CANCELLABLE_SYSCALL(int, pselect, (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, const struct timespec *timeout, const sigset_t *sigmask),