Proper negotiation with server at startup time.

gui_ocamlmsgAppDelegate.m

@@ -7,6 +7,9 @@
 //
 
 #import "gui_ocamlmsgAppDelegate.h"
+#include <sys/stat.h>
+
+#define HOP_STARTUP_DEADLINE_SECONDS 30
 
 @implementation gui_ocamlmsgAppDelegate
 
@@ -22,11 +25,48 @@
 	 name: NSTaskDidTerminateNotification
 	 object: nil];
 	
-	[task setCurrentDirectoryPath: @"/Users/tonyg/src/ocamlmsg"];
-	[task setLaunchPath: @"/Users/tonyg/src/ocamlmsg/ocamlmsg.native"];
-	[task setArguments: [NSArray new]];
-	[task launch];
-	sleep(1);
+	NSString *serverBinaryPath = [[NSBundle mainBundle] resourcePath];
+	[task setCurrentDirectoryPath: serverBinaryPath];
+	NSString *serverBinary = [serverBinaryPath stringByAppendingPathComponent: @"ocamlmsg.native"];
+	[task setLaunchPath: serverBinary];
+	
+	NSString *readyFile = [NSTemporaryDirectory() stringByAppendingPathComponent: @"hop.ready."];
+	readyFile = [readyFile stringByAppendingFormat: @"%d", getpid()];
+	char const *readyFileUtf8 = [readyFile UTF8String];
+	unlink(readyFileUtf8);
+	
+	[task setArguments: [NSArray arrayWithObjects: @"--ready-file", readyFile, nil]];
+	
+	@try {
+		[task launch];
+	}
+	@catch (NSException *e) {
+		NSLog(@"Could not launch server %@: %@", serverBinary, [e reason]);
+		[NSApp terminate: self];
+		@throw;
+	}
+	
+	int foundReadyFile = 0;
+	time_t startTime = time(NULL);
+	while ([task isRunning] && time(NULL) - startTime < HOP_STARTUP_DEADLINE_SECONDS) {
+		struct stat s;
+		if (lstat(readyFileUtf8, &s) != -1) {
+			foundReadyFile = 1;
+			break;
+		}
+		if (errno != ENOENT) {
+			perror("lstat of readyFileUtf8");
+			exit(EXIT_FAILURE);
+		}
+		usleep(100000);
+	}
+	unlink(readyFileUtf8);
+
+	if (!foundReadyFile) {
+		NSLog(@"Server did not start up within %d seconds.", HOP_STARTUP_DEADLINE_SECONDS);
+		[NSApp terminate: self];
+		return;
+	}
 	
 	[[webview mainFrame] loadRequest:
 	 [NSURLRequest requestWithURL:
@@ -34,7 +74,9 @@
 }
 
 - (void) applicationWillTerminate: (NSNotification *) notification {
-	[task terminate];
+	if ([task isRunning]) {
+		[task terminate];
+	}
 }
 
 - (void) taskStatusChanged: (NSNotification *) aNotification {