add unix.fork&unix.pipe(do not work on windows platform)

lib.nas

@@ -273,8 +273,8 @@ var math=
 
 var unix=
 {
-    pipe:     func(){die("not supported yet");},
+    pipe:     func(){return __builtin_pipe;},
-    fork:     func(){die("not supported yet");},
+    fork:     func(){return __builtin_fork;},
     dup2:     func(fd0,fd1){die("not supported yet");},
     exec:     func(filename,argv,envp){die("not supported yet");},
     waitpid:  func(pid,nohang=0){die("not supported yet");},

nasal_builtin.h

@@ -79,6 +79,8 @@ nas_native(builtin_sfld);
 nas_native(builtin_setfld);
 nas_native(builtin_buf);
 nas_native(builtin_sleep);
+nas_native(builtin_pipe);
+nas_native(builtin_fork);
 nas_native(builtin_opendir);
 nas_native(builtin_readdir);
 nas_native(builtin_closedir);
@@ -163,6 +165,8 @@ struct
     {"__builtin_setfld",  builtin_setfld  },
     {"__builtin_buf",     builtin_buf     },
     {"__builtin_sleep",   builtin_sleep   },
+    {"__builtin_pipe",    builtin_pipe    },
+    {"__builtin_fork",    builtin_fork    },
     {"__builtin_opendir", builtin_opendir },
     {"__builtin_readdir", builtin_readdir },
     {"__builtin_closedir",builtin_closedir},
@@ -955,6 +959,26 @@ nasal_ref builtin_sleep(nasal_ref* local,nasal_gc& gc)
     usleep((useconds_t)(val.num()*1e6));
     return nil;
 }
+nasal_ref builtin_pipe(nasal_ref* local,nasal_gc& gc)
+{
+    int fd[2];
+    nasal_ref res=gc.alloc(vm_vec);
+#ifndef _WIN32
+    if(pipe(fd)==-1)
+        return builtin_err("pipe","failed to create pipe");
+    res.vec()->elems.push_back({vm_num,(double)fd[0]});
+    res.vec()->elems.push_back({vm_num,(double)fd[1]});
+    return res;
+#endif
+    return builtin_err("pipe","not supported yet");
+}
+nasal_ref builtin_fork(nasal_ref* local,nasal_gc& gc)
+{
+#ifndef _WIN32
+    return {vm_num,(double)fork()};
+#endif
+    return builtin_err("fork","not supported yet");
+}
 nasal_ref builtin_opendir(nasal_ref* local,nasal_gc& gc)
 {
     nasal_ref path=local[1];

stl/lib.nas

@@ -273,8 +273,8 @@ var math=
 
 var unix=
 {
-    pipe:     func(){die("not supported yet");},
+    pipe:     func(){return __builtin_pipe;},
-    fork:     func(){die("not supported yet");},
+    fork:     func(){return __builtin_fork;},
     dup2:     func(fd0,fd1){die("not supported yet");},
     exec:     func(filename,argv,envp){die("not supported yet");},
     waitpid:  func(pid,nohang=0){die("not supported yet");},

test/props_sim.nas

@@ -1,7 +1,28 @@
 import("lib.nas");
 
-var geodinfo=func(lat,lon){}
+var geodinfo=func(lat,lon){
-var maketimer=func(t,f){}
+    return {};
+}
+var maketimer=func(interval,function){
+    return {
+        isRunning:0,
+        start:func(){
+            me.isRunning=1;
+            while(1){
+                unix.sleep(interval);
+                function();
+            }
+        },
+        stop:func(){
+            me.isRunning=0;
+        },
+        restart:func(interval){
+
+        },
+        singleShot:0,
+        simulatedTime:0
+    };
+}
 
 var props=
 {