[test] Implement unit test for pselect

src/libos/src/interrupt/mod.rs

@@ -38,11 +38,15 @@ pub fn do_handle_interrupt(
 /// Broadcast interrupts to threads by sending POSIX signals.
 pub fn broadcast_interrupts() -> Result<usize> {
     let should_interrupt_thread = |thread: &&ThreadRef| -> bool {
-        // TODO: check Thread::sig_mask to reduce false positives
-        thread.process().is_forced_to_exit()
+        let should_interrupt = thread.process().is_forced_to_exit()
             || thread.is_forced_to_stop()
-            || !thread.sig_queues().read().unwrap().empty()
-            || !thread.process().sig_queues().read().unwrap().empty()
+            || !thread.process().sig_queues().read().unwrap().empty();
+
+        // Check Thread::sig_mask to avoid wrong interrupts
+        let sig_queues = thread.sig_queues().read().unwrap();
+        let sig_mask = thread.sig_mask().read().unwrap();
+
+        should_interrupt || sig_queues.has_valid_signal(&sig_mask)
     };
 
     let num_signaled_threads = crate::process::table::get_all_threads()

src/libos/src/signal/sig_queues.rs

@@ -14,6 +14,13 @@ pub struct SigQueues {
 }
 
 impl SigQueues {
+    const ORDERED_STD_SIGS: [SigNum; COUNT_STD_SIGS] = [
+        SIGKILL, SIGTERM, SIGSTOP, SIGCONT, SIGSEGV, SIGILL, SIGHUP, SIGINT, SIGQUIT, SIGTRAP,
+        SIGABRT, SIGBUS, SIGFPE, SIGUSR1, SIGUSR2, SIGPIPE, SIGALRM, SIGSTKFLT, SIGCHLD, SIGTSTP,
+        SIGTTIN, SIGTTOU, SIGURG, SIGXCPU, SIGXFSZ, SIGVTALRM, SIGPROF, SIGWINCH, SIGIO, SIGPWR,
+        SIGSYS,
+    ];
+
     pub fn new() -> Self {
         let count = 0;
         let std_queues = (0..COUNT_STD_SIGS).map(|_| None).collect();
@@ -31,6 +38,41 @@ impl SigQueues {
         self.count == 0
     }
 
+    pub fn has_valid_signal(&self, blocked: &SigSet) -> bool {
+        // Fast path for the common case of no pending signals
+        if self.empty() {
+            return false;
+        }
+
+        // Check standard signals.
+        for &signum in &Self::ORDERED_STD_SIGS {
+            if blocked.contains(signum) {
+                continue;
+            }
+
+            let queue = self.get_std_queue(signum);
+            if queue.is_some() {
+                return true;
+            }
+        }
+
+        // If no standard signals, then check real-time signals.
+        for signum in MIN_RT_SIG_NUM..=MAX_RT_SIG_NUM {
+            let signum = unsafe { SigNum::from_u8_unchecked(signum) };
+            if blocked.contains(signum) {
+                continue;
+            }
+
+            let queue = self.get_rt_queue(signum);
+            if !queue.is_empty() {
+                return true;
+            }
+        }
+
+        // There must be pending but blocked signals
+        false
+    }
+
     pub fn enqueue(&mut self, signal: Box<dyn Signal>) {
         let signum = signal.num();
         if signum.is_std() {
@@ -81,13 +123,7 @@ impl SigQueues {
         // POSIX leaves unspecified which to deliver first if there are multiple
         // pending standard signals. So we are free to define our own. The
         // principle is to give more urgent signals higher priority (like SIGKILL).
-        const ORDERED_STD_SIGS: [SigNum; COUNT_STD_SIGS] = [
-            SIGKILL, SIGTERM, SIGSTOP, SIGCONT, SIGSEGV, SIGILL, SIGHUP, SIGINT, SIGQUIT, SIGTRAP,
-            SIGABRT, SIGBUS, SIGFPE, SIGUSR1, SIGUSR2, SIGPIPE, SIGALRM, SIGSTKFLT, SIGCHLD,
-            SIGTSTP, SIGTTIN, SIGTTOU, SIGURG, SIGXCPU, SIGXFSZ, SIGVTALRM, SIGPROF, SIGWINCH,
-            SIGIO, SIGPWR, SIGSYS,
-        ];
-        for &signum in &ORDERED_STD_SIGS {
+        for &signum in &Self::ORDERED_STD_SIGS {
             if blocked.contains(signum) {
                 continue;
             }

test/Makefile

@@ -21,7 +21,7 @@ TEST_DEPS := client data_sink naughty_child
 TESTS ?= env empty hello_world malloc mmap file fs_perms getpid spawn sched pipe time timerfd \
 	truncate readdir mkdir open stat link symlink chmod chown tls pthread system_info rlimit \
 	server server_epoll unix_socket cout hostfs cpuid rdtsc device sleep exit_group posix_flock \
-	ioctl fcntl eventfd emulate_syscall access signal sysinfo prctl rename procfs wait \
+	ioctl fcntl eventfd emulate_syscall access signal sysinfo prctl rename procfs wait pselect \
 	spawn_attribute exec statfs random umask pgrp vfork mount flock utimes shm epoll brk posix_shm
 # Benchmarks: need to be compiled and run by bench-% target
 BENCHES := spawn_and_exit_latency pipe_throughput unix_socket_throughput

test/pselect/Makefile

@@ -0,0 +1,5 @@
+include ../test_common.mk
+
+EXTRA_C_FLAGS :=
+EXTRA_LINK_FLAGS := -lpthread
+BIN_ARGS :=

test/pselect/main.c

@@ -0,0 +1,83 @@
+#include <sys/select.h>
+#include <sys/timerfd.h>
+#include <signal.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <errno.h>
+#include <stdint.h> // for uint64_t
+#include <pthread.h>
+
+// Signal handler for SIGUSR1
+void sigusr1_handler(int sig) {
+    printf("SIGUSR1 received\n");
+}
+
+void *send_signal(void *arg) {
+    pthread_t main_thread_id = *(pthread_t *)arg;
+    sleep(1);
+    pthread_kill(main_thread_id, SIGUSR1);
+    return NULL;
+}
+
+int main() {
+    struct sigaction sa;
+    sa.sa_handler = sigusr1_handler;
+    sigemptyset(&sa.sa_mask);
+    sa.sa_flags = 0;
+    sigaction(SIGUSR1, &sa, NULL);
+
+    sigset_t sigmask;
+    sigemptyset(&sigmask);
+    sigaddset(&sigmask, SIGUSR1);
+
+    // Access pthread id
+    pthread_t main_thread_id = pthread_self();
+
+    // Spawn new thread for sending signal when call pselect syscall
+    pthread_t signal_thread;
+    if (pthread_create(&signal_thread, NULL, send_signal, &main_thread_id) != 0) {
+        perror("pthread_create");
+        return 1;
+    }
+
+    int timer_fd = timerfd_create(CLOCK_REALTIME, 0);
+    if (timer_fd == -1) {
+        perror("timerfd_create");
+        return 1;
+    }
+
+    struct itimerspec timerValue;
+    timerValue.it_value.tv_sec = 2;
+    timerValue.it_value.tv_nsec = 0;
+    timerValue.it_interval.tv_sec = 0;
+    timerValue.it_interval.tv_nsec = 0;
+    if (timerfd_settime(timer_fd, 0, &timerValue, NULL) == -1) {
+        perror("timerfd_settime");
+        close(timer_fd);
+        return 1;
+    }
+
+    fd_set readfds;
+    FD_ZERO(&readfds);
+    FD_SET(timer_fd, &readfds);
+
+    int ready = pselect(timer_fd + 1, &readfds, NULL, NULL, NULL, &sigmask);
+
+    if (ready == -1) {
+        perror("pselect6");
+    } else if (ready == 0) {
+        // Impossible case
+        printf("No input - timeout reached\n");
+    } else {
+        if (FD_ISSET(timer_fd, &readfds)) {
+            printf("Timer expired, pselect blocked SIGUSR1 signal successfully\n");
+            uint64_t expirations;
+            read(timer_fd, &expirations, sizeof(expirations));
+        }
+    }
+
+    pthread_join(signal_thread, NULL);
+    close(timer_fd);
+
+    return 0;
+}