Add unix stream socket test

regression/apps/network/socketpair.c

@@ -0,0 +1,38 @@
+#include <stdio.h>
+#include <sys/socket.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#define MESG1 "Hello from child"
+#define MESG2 "Hello from parent"
+
+int main() {
+    int sockets[2], child;
+    char buf[1024];
+    if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets) < 0) {
+        perror("create socket pair");
+        exit(1);
+    }
+    if ((child = fork()) == -1)
+        perror("fork");
+    else if (child) {
+        // parent
+        close(sockets[0]);
+        if (read(sockets[1], buf, 1024) < 0)
+            perror("read from child");
+        printf("Receive from child: %s\n", buf);
+        if (write(sockets[1], MESG2, sizeof(MESG2)) < 0) 
+            perror("write to child");
+        close(sockets[1]);
+    } else {     
+        // child
+        close(sockets[1]);
+        if (write(sockets[0], MESG1, sizeof(MESG1)) < 0)
+            perror("write to parent");
+        if (read(sockets[0], buf, 1024) < 0)
+            perror("read from parent");
+        printf("Receive from parent: %s\n", buf);
+        close(sockets[0]);
+    }
+    return 0;
+}