From d1b1ccb72f4dee5728f0878054709721b1163f62 Mon Sep 17 00:00:00 2001 From: Leonid Lisovskiy Date: Sun, 27 Dec 2015 20:46:49 +0300 Subject: Fix "pselect: Use linux pselect6 syscall when available" Commit e3c3bf2b58 introduce use of pselect6, but has following disadvantages: * Use of userspace types in args67 structure - it breaks, for example, configs when 32-bit uClibc-ng compiled against 64-bit kernel. Syscall will always return EINVAL. We must use __kernel_* types and __SYSCALL_SIGSET_T_SIZE. * It have excess checks for NSEC_PER_SEC. Original code from select() implementation has struct timeval => struct timespec conversion, kernel select() syscall implementation do the same. But none of libc versions (glibc, eglibc, musl) I know, perform similar checks for pselect() - there is no structure fields conversions, just struct timespec through all the calls. To have such checks in uClibc-ng we need one example, at least. * It is possible to avoid extra userspace reads from kernel code if sigmask == NULL. I suggest to do it, for a few bytes cost. * Commit didn't add test case to testsuite. Signed-off-by: Leonid Lisovskiy --- test/unistd/tst-pselect.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 test/unistd/tst-pselect.c (limited to 'test') diff --git a/test/unistd/tst-pselect.c b/test/unistd/tst-pselect.c new file mode 100644 index 000000000..cab945119 --- /dev/null +++ b/test/unistd/tst-pselect.c @@ -0,0 +1,51 @@ +#include +#include +#include +#include +#include +#include +#include +#include + +// our SIGALRM handler +void handler(int signum) { + (void)signum; + puts("got signal\n"); +} + +static int +do_test (void) +{ + int rc; + sigset_t wait_mask, mask_sigchld; + struct sigaction act; + + // block SIGALRM. We want to handle it only when we're ready + sigemptyset(&mask_sigchld); + sigaddset(&mask_sigchld, SIGALRM); + sigprocmask(SIG_BLOCK, &mask_sigchld, &wait_mask); + sigdelset(&wait_mask, SIGALRM); + + // register a signal handler so we can see when the signal arrives + memset(&act, 0, sizeof(act)); + sigemptyset(&act.sa_mask); // just in case an empty set isn't all 0's (total paranoia) + act.sa_handler = handler; + sigaction(SIGALRM, &act, NULL); + + // send ourselves a SIGARLM. It will pend until we unblock that signal in pselect() + printf("sending ourselves a signal\n"); + kill(getpid(), SIGALRM); + + printf("signal is pending; calling pselect()\n"); + rc = pselect(0, NULL, NULL, NULL, NULL, &wait_mask); + if (rc != -1 || errno != EINTR) { + int e = errno; + printf("pselect() returned %d, errno %d (%s)\n", rc, e, strerror(e)); + exit(1); + } + + return 0; +} + +#define TEST_FUNCTION do_test () +#include -- cgit v1.2.3