change order of resolutions, fix tests

src/zsession.js

@@ -737,10 +737,12 @@ Zmodem.Session.Receive = class ZmodemReceiveSession extends Zmodem.Session {
                     this._next_header_handler = {
                         ZEOF: function on_ZEOF(hdr) {
                             this._next_subpacket_handler = null;
-                            this._consume_ZEOF(hdr);
 
-                            var next_promise = this._make_promise_for_between_files();
-                            resolve_accept(next_promise);
+                            this._make_promise_for_between_files();
+
+                            resolve_accept();
+
+                            this._consume_ZEOF(hdr)
                         },
                     };
                 },
@@ -756,6 +758,16 @@ Zmodem.Session.Receive = class ZmodemReceiveSession extends Zmodem.Session {
         var ret = this._make_promise_for_between_files();
 
         if (this._accepted_offer) {
+            // There’s a race condition where we might attempt to
+            // skip() an in-progress transfer near its end but actually
+            // the skip() will fire after the transfer is complete.
+            // While there might be ways to prevent this, they likely
+            // would require extra work on the part of implementations.
+            //
+            // It seems far simpler just to make this function a no-op
+            // in these cases.
+            if (!this._current_transfer) return;
+
             //For cancel of an in-progress transfer from lsz,
             //it’s necessary to avoid this buffer overflow bug:
             //
@@ -818,10 +830,10 @@ Zmodem.Session.Receive = class ZmodemReceiveSession extends Zmodem.Session {
             throw( "ZEOF offset mismatch; unimplemented (local: " + this._file_offset + "; ZEOF: " + header.get_offset() + ")" );
         }
 
-        this._send_ZRINIT();
-
         this._on_file_end();
 
+        this._send_ZRINIT();
+
         //Preserve these two so that file_end callbacks
         //will have the right information.
         this._file_info = null;

tests/zsession_rz.js

@@ -25,8 +25,6 @@ var helper = require('./lib/testhelp');
 var dir_before = process.cwd();
 tape.onFinish( () => process.chdir( dir_before ) );
 
-process.chdir( helper.make_temp_dir() );
-
 let TEST_STRINGS = [
     "",
     "0",

tests/zsession_sz.js

@@ -158,17 +158,22 @@ tape('skip() - immediately - at end of download', { timeout: 30000 }, (t) => {
     ] );
 });
 
+// Verify a skip() that happens after a transfer is complete.
+// There are no assertions here.
 tape('skip() - after a parse - at end of download', { timeout: 30000 }, (t) => {
     var filenames = [helper.make_temp_file(123)];
 
-    var the_offer, started, skipped;
+    var the_offer, started, skipped, completed;
 
     return _test_steps( t, filenames, [
         (zsession) => {
             if (!started) {
                 function offer_taker(offer) {
                     the_offer = offer;
-                    the_offer.accept();
+                    var promise = the_offer.accept();
+                    promise.then( () => {
+                        completed = 1;
+                    } );
                 }
                 zsession.on("offer", offer_taker);
                 zsession.start();
@@ -178,7 +183,7 @@ tape('skip() - after a parse - at end of download', { timeout: 30000 }, (t) => {
             return the_offer;
         },
         () => {
-            if (!skipped) {
+            if (!skipped && !completed) {
                 the_offer.skip();
                 skipped = true;
             }