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 <nic.d...@gmail.com>
---
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),
--
1.9.1
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