How to open a document using an application launched via NSTask?

Question

Hello world,

I've grown tired of the built-in open Mac OS X command, mostly because it runs programs with your actual user ID instead of the effective user ID; this results in the fact sudo open Foo opens Foo with its associated application with your account instead of the root account, and it annoys me. So I decided to make some kind of replacement.

So far I've been successful: I can open any program under the open -a or open -b fashion, and support optionally waiting. I'm using NSTask for that purpose.

However, I'd like to be able to open documents too. As far as I can see, you need to use NSWorkspace for that, but using NSWorkspace to launch programs results in them being launched with your account's credentials instead of your command line program's credentials. Which is precisely what the default open tool does, and precisely what I don't want.

So, how can I have a program request that another program opens a document without using NSWorkspace? From the NSTask object, I can have the process ID, but that's about it.

Answer 1

Hopefully this will do the trick:

- (void)openFile:(NSString *)filePath withTask:(NSTask *)task {
    int pid = [task processIdentifier];
    NSAppleEventDescriptor *target = [NSAppleEventDescriptor descriptorWithDescriptorType:typeKernelProcessID bytes:&pid length:sizeof(pid)];

    const char *urlUTF8 = [[[NSURL fileURLWithPath:filePath] absoluteString] UTF8String];
    NSAppleEventDescriptor *urlDescriptor = [NSAppleEventDescriptor descriptorWithDescriptorType:typeFileURL bytes:urlUTF8 length:strlen(urlUTF8)];

    NSAppleEventDescriptor *event = [NSAppleEventDescriptor appleEventWithEventClass:kEventParamAppleEvent eventID:kAEOpen targetDescriptor:target returnID:kAutoGenerateReturnID transactionID:kAnyTransactionID];
    [event setParamDescriptor:urlDescriptor forKeyword:keyDirectObject];

    OSStatus err = AESendMessage([event aeDesc], NULL, kAENoReply | kAENeverInteract, kAEDefaultTimeout);

    if (err != noErr) {
        // Error handling goes here
    }

    // Activate the application

    event = [NSAppleEventDescriptor appleEventWithEventClass:kAEMiscStandards eventID:kAEActivate targetDescriptor:target returnID:kAutoGenerateReturnID transactionID:kAnyTransactionID];
    err = AESendMessage([event aeDesc], NULL, kAENoReply | kAENeverInteract, kAEDefaultTimeout); 
}

You may have to launch the application using an NSTask and then send it the appropriate open Apple Event.

Actually, can you launch using an NSTask and then open the file via NSWorkspace once you know it's running? Or does that launch a new instance of the application under your user?

Original reply:

Does

open -a SomeApplication SomeFile

work?