feat(c/sys): restore native select and time functions

c/sys/generated_native_llgo_test.go

@@ -0,0 +1,25 @@
+//go:build llgo && ((darwin && arm64 && !ios) || (linux && (amd64 || arm64) && !android))
+
+package sys
+
+import (
+	"testing"
+	"unsafe"
+)
+
+func TestGeneratedGettimeofday(t *testing.T) {
+	var timeout Timeval
+	if result := Select(0, nil, nil, nil, &timeout); result != 0 {
+		t.Fatalf("select with zero timeout = %d", result)
+	}
+	var value Timeval
+	if unsafe.Sizeof(value) != 16 || unsafe.Alignof(value) != 8 {
+		t.Fatalf("timeval layout = %d/%d", unsafe.Sizeof(value), unsafe.Alignof(value))
+	}
+	if result := Gettimeofday(&value, nil); result != 0 {
+		t.Fatalf("gettimeofday = %d", result)
+	}
+	if value.Sec <= 0 || value.Usec < 0 || value.Usec >= 1000000 {
+		t.Fatalf("invalid timeval %v", value)
+	}
+}

c/sys/llcppg.cfg

@@ -0,0 +1,3 @@
+{
+  "Dir": ".sysroot/include"
+}

c/sys/llcppg.pub

@@ -0,0 +1,8 @@
+D github.com/goplus/lib/c/signal
+D github.com/goplus/lib/c/time
+T __itimer_which X__ItimerWhich
+T __timezone_ptr_t X__TimezonePtrT
+T fd_set FdSet
+T itimerval Itimerval
+T timeval Timeval
+T timezone Timezone

c/sys/select.go

@@ -30,7 +30,16 @@ func FD_SET(fd c.Int, fds *FdSet)
 //go:linkname FD_ISSET C.llgo_FD_ISSET
 func FD_ISSET(fd c.Int, fds *FdSet) c.Int
 
-//go:linkname Select C.select
-func Select(n c.Int, fdsRead, fdsWrite, fdsError *FdSet, timeout *Timeval) c.Int
-
 // -----------------------------------------------------------------------------
+
+// Check the first NFDS descriptors each in READFDS (if not NULL) for read
+// readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
+// (if not NULL) for exceptional conditions.  If TIMEOUT is not NULL, time out
+// after waiting the interval specified therein.  Returns the number of ready
+// descriptors, or -1 for errors.
+//
+// This function is a cancellation point and therefore not marked with
+// __THROW.
+//
+//go:linkname Select C.select
+func Select(__nfds c.Int, __readfds *FdSet, __writefds *FdSet, __exceptfds *FdSet, __timeout *Timeval) c.Int