Question

我正在使用NSUserUnixTask在我的沙盒应用上运行未经过沙盒的NSTask。但是，我的代码会在调用[NSFileHandle readDataToEndOfFile]时挂起。如果我删除这些调用它完美地工作。如果我将[NSFileHandle readDataToEndOfFile]替换为[NSFileHandle availableData]，它也会挂起。

以下是代码：

NSUserUnixTask* unixTask = [[NSUserUnixTask alloc] initWithURL: [NSURL fileURLWithPath: path] error: nil];

// Create error file handle
NSFileHandle* errorFH = [NSFileHandle fileHandleWithStandardError];
[unixTask setStandardError: errorFH];

// Create output file handle
NSFileHandle* outputFH = [NSFileHandle fileHandleWithStandardOutput];
[unixTask setStandardOutput: outputFH];

// Run task with termination handler
[unixTask executeWithArguments: nil completionHandler: ^(NSError* error2) {

    // Save output
    NSString* output = [[NSString alloc] initWithData: [outputFH readDataToEndOfFile] encoding: NSUTF8StringEncoding];
    if ([output length]) { // <-- Execution never reaches this line when the block is called
        NSLog(@"%@", output);
    }

    // Read error 1
    NSString* error1 = [[NSString alloc] initWithData: [errorFH readDataToEndOfFile] encoding: NSUTF8StringEncoding];
    if ([error1 length]) {
        NSLog(@"%@", error1);
    }

    // Read error 2
    if (error2) {
        NSLog(@"%@", error2);
    }
}];

Xcode的控制台上没有记录任何内容，但如果我打开Console.app，我会看到这一行：

Warning: Exception caught during decoding of received reply to message 'executeScript:interpreter:arguments:standardInput:standardOutput:standardError::', dropping incoming message and calling failure block.

Exception: *** -[NSConcreteFileHandle readDataOfLength:]: Bad file descriptor

嗯，我该怎么解决这个问题？在我的应用程序使用沙盒之前，我将NSPipe与NSTask结合使用，一切正常，但现在NSUserUnixTask需要使用NSFileHandle而我认为我的问题仅仅是因为我没有正确使用它。但我仍然不知道我做错了什么。

Answer 1

在我看来，您必须使用NSPipe从NSUserUnixTask读取stderr和stdout，就像使用NSTask一样。

我用“/ bin / ls”任务测试了它，它产生了预期的输出：

NSPipe *outPipe = [NSPipe pipe];
NSPipe *errPipe = [NSPipe pipe];
NSString *path = @"/bin/ls";
NSUserUnixTask *unixTask = [[NSUserUnixTask alloc] initWithURL: [NSURL fileURLWithPath: path] error: nil];
[unixTask setStandardOutput:[outPipe fileHandleForWriting]];
[unixTask setStandardError:[errPipe fileHandleForWriting]];
[unixTask executeWithArguments:nil completionHandler:^(NSError *error) {
    NSString *output = [[NSString alloc] initWithData: [[outPipe fileHandleForReading] readDataToEndOfFile] encoding: NSUTF8StringEncoding];
    NSLog(@"stdout: %@", output);

    NSString *error1 = [[NSString alloc] initWithData: [[errPipe fileHandleForReading] readDataToEndOfFile] encoding: NSUTF8StringEncoding];
    NSLog(@"stderr: %@", error1);
}];

异常` - [NSConcreteFileHandle readDataOfLength：]：运行NSUserUnixTask时出现错误的文件描述符`

1 个答案: