demo: select

c/sys/_demo/selectdemo/select.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"unsafe"
+
+	"github.com/goplus/llgo/c"
+	"github.com/goplus/llgo/c/os"
+	"github.com/goplus/llgo/c/sys"
+)
+
+func main() {
+	var readFds sys.FdSet
+	sys.FD_ZERO(&readFds)
+	sys.FD_SET(0, &readFds)
+
+	var tv sys.Timeval
+	tv.Sec = 5
+	tv.Usec = 0
+
+	c.Printf(c.Str("Waiting for input on stdin...\n"))
+	ret := sys.Select(1, &readFds, nil, nil, &tv)
+	if ret == -1 {
+		c.Perror(c.Str("select error"))
+		c.Exit(1)
+	} else if ret == 0 {
+		c.Printf(c.Str("Timeout occurred! No data after 5 seconds.\n"))
+	} else {
+		if sys.FD_ISSET(0, &readFds) != 0 {
+			var buffer [100]c.Char
+			n := os.Read(0, c.Pointer(&buffer[:][0]), unsafe.Sizeof(buffer)-1)
+			if n == -1 {
+				c.Perror(c.Str("read error"))
+				c.Exit(1)
+			} else if n == 0 {
+				c.Printf(c.Str("End of file\n"))
+			} else {
+				buffer[n] = c.Char(0)
+				c.Printf(c.Str("Read %ld bytes: %s\n"), n, &buffer[0])
+			}
+		}
+	}
+}