NSTask / NSPipe从Unix命令读取 [英] NSTask/NSPipe read from Unix command

问题描述

我正在编写一个Cocoa应用程序，它需要执行一个UNIX程序，并在生成时逐行读取其输出。我设置一个NSTask和NSPipe如下：

  task = [[NSTask alloc] init]; 
 pipe = [NSPipe pipe]; 
 [task setStandardOutput：pipe]; 
 // ... later ... 
 [task setArguments：...]; 
 [task setLaunchPath：@...]; 
 [任务启动]; 
 handle = [[task fileHandleForReading] retain]; 
  

命令不会终止，直到程序通过任务终止] 。我已经尝试了从句柄读取的几种方法，如 -readInBackgroundAndNotify ， while（[（data = [handle availableData]）length]> 0）和 -waitForDataInBackgroundAndNotify ，但管道从未似乎产生任何数据。是否有一些方法，我可以戳 NSTask 或 NSPipe 以清除数据？

EDIT ： -readInBackgroundAndNotify ：

  [handle readInBackgroundAndNotify]; 
 notification_block_t handlerBlock = 
 ^（NSNotification * notification）{
 NSData * data = [[notification userInfo] 
 objectForKey：NSFileHandleNotificationDataItem]; 
 / * ... do stuff ... * / 
 [self addNotification：handle block：handlerBlock]; 
}; 
 [self addNotification：handler block：handlerBlock]; 
 // ... 
  - （void）addNotification：（id）handle block：（notification_block_t）block {
 [[NSNotificationCenter defaultCenter] 
 addObserverForName：NSFileHandleReadCompletionNotification 
 object：handle 
 queue：[NSOperationQueue mainQueue] 
 usingBlock：block]; 
} 
  

与 -waitForDataInBackgroundAndNotify ：

  [handle waitForDataInBackgroundAndNotify]; 
 notification_block_t handlerBlock = 
 ^（NSNotification * notification）{
 NSData * data = [handle availableData]; 
 / * ... do stuff ... * / 
}; 
 [self addNotification：handler block：handlerBlock]; 
   
 
 
 
 
 
 
  [self startProcessingThread：handle]; 
 // ... 
  - （void）startProcessingThread：（NSFileHandle *）handle {
 [[NSOperationQueue mainQueue] 
 addOperation：[[[NSInvocationOperation alloc] 
 initWithTarget：self 
 selector：@selector（dataLoop :) 
 object：handle] autorelease]]; 
} 
  - （void）dataLoop：（NSFileHandle *）handle {
 NSData * data; 
 while（[（data = [handle availableData]）length]> 0）{
 / * ... do stuff ... * / 
} 
} 
 
  EDIT 2 ：参数设置如下（命令为 tshark ）：
  NSArray * cmd = [NSArray arrayWithObjects：@ ，@http.request，
 @ -  Tfields，@ -  Eseparator ='|'，
 @ -  ehttp.host，@ -  ehttp.request.method 
 @ -  ehttp.request.uri，nil]; 
 cmd = [[cmd arrayByAddingObjectsFromArray：[self.ports map：^（id arg1，NSUInteger idx）{
 return [NSString stringWithFormat：@ -  d tcp.port ==％d，http [arg1 intValue]]; 
}]] 
 arrayByAddingObject：[@dststringByAppendingString：
 [self.hosts componentsJoinedByString：@or dst]]]; 
 [self.tsharktask setArguments：cmd]; 
  
 
 
解决方案
这是一个工作示例， ：
  task = [[NSTask alloc] init]; 
 [task setLaunchPath：...] 
 NSArray * arguments; 
 arguments = ...; 
 [task setArguments：arguments]; 
 
 NSPipe * outPipe; 
 outPipe = [NSPipe pipe]; 
 [task setStandardOutput：outPipe]; 
 
 outFile = [outPipe fileHandleForReading]; 
 [outFile waitForDataInBackgroundAndNotify]; 
 [[NSNotificationCenter defaultCenter] addObserver：self 
 selector：@selector（commandNotification :) 
 name：NSFileHandleDataAvailableNotification 
 object：nil]; 
 
 [任务启动]; 
 
 
  - （void）commandNotification：（NSNotification *）notification 
 {
 NSData * data = nil; 
 while（（data = [self.outFile availableData]）&& [data length]）{
 ... 
} 
} 
  
 
I am writing a Cocoa application which needs to execute a UNIX program and read its output, line by line, as they are produced. I set up a NSTask and NSPipe as such:
task = [[NSTask alloc] init];
pipe = [NSPipe pipe];
[task setStandardOutput:pipe];
//... later ...
[task setArguments:...];
[task setLaunchPath:@"..."];
[task launch];
handle = [[task fileHandleForReading] retain];
The command does not terminate until the program tells it to do so with [task terminate]. I have tried several methods of reading from the handle, such as -readInBackgroundAndNotify, while([(data = [handle availableData]) length] > 0), and -waitForDataInBackgroundAndNotify, but the pipe never seems to yield any data. Is there some way I can "poke" the NSTask or NSPipe to flush the data through?


EDIT: with -readInBackgroundAndNotify:
[handle readInBackgroundAndNotify];
notification_block_t handlerBlock =
    ^(NSNotification *notification) {
         NSData *data = [[notification userInfo]
                             objectForKey: NSFileHandleNotificationDataItem];
         /*... do stuff ...*/
         [self addNotification: handle block: handlerBlock];
     };
[self addNotification: handler block: handlerBlock];
//...
- (void)addNotification:(id)handle block:(notification_block_t)block {
    [[NSNotificationCenter defaultCenter]
         addObserverForName: NSFileHandleReadCompletionNotification
         object: handle
         queue: [NSOperationQueue mainQueue]
         usingBlock: block];
}
with -waitForDataInBackgroundAndNotify:
[handle waitForDataInBackgroundAndNotify];
notification_block_t handlerBlock =
    ^(NSNotification *notification) {
        NSData *data = [handle availableData];
        /*... do stuff ...*/
    };
[self addNotification: handler block: handlerBlock];
with while loop:
[self startProcessingThread: handle];
//...
- (void)startProcessingThread:(NSFileHandle *)handle {
    [[NSOperationQueue mainQueue]
         addOperation: [[[NSInvocationOperation alloc]
                             initWithTarget: self
                             selector: @selector(dataLoop:)
                             object: handle] autorelease]];
}
- (void)dataLoop:(NSFileHandle *)handle {
    NSData *data;
    while([(data = [handle availableData]) length] > 0) {
        /*... do stuff ...*/
    }
}
EDIT 2: The arguments are set as follows (the command is tshark):
NSArray *cmd = [NSArray arrayWithObjects:@"-R", @"http.request", 
                                         @"-Tfields", @"-Eseparator='|'", 
                                         @"-ehttp.host", @"-ehttp.request.method", 
                                         @"-ehttp.request.uri", nil];
cmd = [[cmd arrayByAddingObjectsFromArray:[self.ports map:^(id arg1, NSUInteger idx) {
           return [NSString stringWithFormat:@"-d tcp.port==%d,http", [arg1 intValue]];
       }]] 
        arrayByAddingObject:[@"dst " stringByAppendingString:
            [self.hosts componentsJoinedByString:@" or dst "]]];
[self.tsharktask setArguments:cmd];

解决方案
Here is a working example of how I usually do it:
    task = [[NSTask alloc] init];
    [task setLaunchPath:...];
    NSArray *arguments;
    arguments = ...;
    [task setArguments:arguments];

    NSPipe *outPipe;
    outPipe = [NSPipe pipe];
    [task setStandardOutput:outPipe];

    outFile = [outPipe fileHandleForReading];
    [outFile waitForDataInBackgroundAndNotify];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(commandNotification:)
                                                 name:NSFileHandleDataAvailableNotification 
                                               object:nil];    

    [task launch];


- (void)commandNotification:(NSNotification *)notification
{
    NSData *data = nil;
    while ((data = [self.outFile availableData]) && [data length]){
        ...
    }   
}


                        
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