dispatch_io_create() is supposed to be the correct way to read from a stream. However, it doesn't seem to work and I believe it's due to poll() not working with pseudo terminals in OS X.

Leaving the code in just for fun.

Underlying issue - when the pty closes, the block doesn't always get notified so the fd doesn't close until the window closes.

English.lproj/MainMenu.xib

@@ -1,7 +1,8 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="3.0" toolsVersion="11762" systemVersion="16C67" targetRuntime="MacOSX.Cocoa" propertyAccessControl="none">
+<document type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="3.0" toolsVersion="13529" targetRuntime="MacOSX.Cocoa" propertyAccessControl="none">
     <dependencies>
-        <plugIn identifier="com.apple.InterfaceBuilder.CocoaPlugin" version="11762"/>
+        <deployment identifier="macosx"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.CocoaPlugin" version="13529"/>
     </dependencies>
     <objects>
         <customObject id="-2" userLabel="File's Owner" customClass="NSApplication">
@@ -10,13 +11,13 @@
             </connections>
         </customObject>
         <customObject id="-1" userLabel="First Responder" customClass="FirstResponder"/>
-        <customObject id="-3" userLabel="Application"/>
+        <customObject id="-3" userLabel="Application" customClass="NSObject"/>
         <menu title="AMainMenu" systemMenu="main" id="29">
             <items>
-                <menuItem title="2Term" id="56">
-                    <menu key="submenu" title="2Term" systemMenu="apple" id="57">
+                <menuItem title="TwoTerm" id="56" userLabel="TwoTerm">
+                    <menu key="submenu" title="TwoTerm" systemMenu="apple" id="57">
                         <items>
-                            <menuItem title="About 2Term" id="58">
+                            <menuItem title="About TwoTerm" id="58">
                                 <modifierMask key="keyEquivalentModifierMask"/>
                                 <connections>
                                     <action selector="orderFrontStandardAboutPanel:" target="-2" id="142"/>
@@ -35,7 +36,7 @@
                             <menuItem isSeparatorItem="YES" id="144">
                                 <modifierMask key="keyEquivalentModifierMask" command="YES"/>
                             </menuItem>
-                            <menuItem title="Hide 2Term" keyEquivalent="h" id="134">
+                            <menuItem title="Hide TwoTerm" keyEquivalent="h" id="134">
                                 <connections>
                                     <action selector="hide:" target="-1" id="367"/>
                                 </connections>
@@ -54,7 +55,7 @@
                             <menuItem isSeparatorItem="YES" id="149">
                                 <modifierMask key="keyEquivalentModifierMask" command="YES"/>
                             </menuItem>
-                            <menuItem title="Quit 2Term" keyEquivalent="q" id="136">
+                            <menuItem title="Quit TwoTerm" keyEquivalent="q" id="136">
                                 <connections>
                                     <action selector="terminate:" target="-3" id="449"/>
                                 </connections>
@@ -648,7 +649,7 @@
                     <modifierMask key="keyEquivalentModifierMask"/>
                     <menu key="submenu" title="Help" systemMenu="help" id="491">
                         <items>
-                            <menuItem title="2Term Help" keyEquivalent="?" id="492">
+                            <menuItem title="TwoTerm Help" keyEquivalent="?" id="492">
                                 <connections>
                                     <action selector="showHelp:" target="-1" id="493"/>
                                 </connections>

TermWindowController.mm

@@ -107,7 +107,7 @@
         std::string s;
         
             
-        s.append("TERM_PROGRAM=2Term");
+        s.append("TERM_PROGRAM=TwoTerm");
         s.append(1, (char)0);
         
         s.append("LANG=C");
@@ -226,7 +226,33 @@
         dispatch_resume(_wait_source);
     }
 
+#if 0
+    dispatch_io_t io = dispatch_io_create(DISPATCH_IO_STREAM, fd, queue, ^(int error){
+        close(fd);
+        NSLog(@"dispatch_io_create: %d", error);
+    });
     
+    dispatch_io_read(io, 0, SIZE_MAX, queue, ^(bool done, dispatch_data_t data, int error){
+        if (error) {
+            NSLog(@"dispatch_io_read: %d", error);
+            dispatch_io_close(io, DISPATCH_IO_STOP);
+            return;
+        }
+        
+        dispatch_data_apply(data, ^(dispatch_data_t, size_t, const void *buffer, size_t size){
+            [_emulatorView processData: (uint8_t *)buffer size: size];
+            return true;
+        } );
+        
+        if (done) {
+            NSLog(@"closing fd");
+            dispatch_io_close(io, DISPATCH_IO_STOP);
+            return;
+        }
+        
+    });
+    
+#else
     _read_source = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ,
                                                           fd, 0, queue);
     if (_read_source)
@@ -236,7 +262,7 @@
 
             static uint8_t sbuffer[1024];
             size_t estimated = dispatch_source_get_data(_read_source);
-
+            estimated = std::max(estimated, sizeof(sbuffer));
             
             uint8_t *buffer = estimated > sizeof(sbuffer) ? (uint8_t *)malloc(estimated) : sbuffer;
             if (buffer)
@@ -244,7 +270,8 @@
                 ssize_t actual;
                 
                 for (;;) {
-                    actual = read(fd, buffer, (estimated));
+                    actual = read(fd, buffer, estimated);
+                    //fprintf(stderr, "read: %ld\n", actual);
                     if (actual < 0) {
                         if (errno == EINTR) continue;
 
@@ -266,7 +293,6 @@
                 if (buffer != sbuffer) free(buffer);
 
                 if (actual == 0) {
-                    NSLog(@"closing fd");
                     dispatch_source_cancel(_read_source);
                     dispatch_release(_read_source);
                     _read_source = nullptr;
@@ -276,6 +302,7 @@
 
         
         dispatch_source_set_cancel_handler(_read_source, ^{
+            NSLog(@"closing fd");
             _fd = -1;
             [_emulatorView setFd: -1];
             close(fd);
@@ -283,6 +310,7 @@
         
         dispatch_resume(_read_source);
     }
+#endif
 }
 
 #pragma mark -

TwoTerm.xcodeproj/project.pbxproj

@@ -62,6 +62,7 @@
 			isEditable = 1;
 			outputFiles = (
 			);
+			script = "";
 		};
 		B6C173931D32A8840024E360 /* PBXBuildRule */ = {
 			isa = PBXBuildRule;