管道的三种使用方案中，唯一正确而安全的使用方法

系统自带的管道方法：

全局变量：

NSPipe * pipe = [NSPipe pipe] ;

NSFileHandle *pipeReadHandle = [pipe fileHandleForReading] ；

int pipeReadFd = [[pipe fileHandleForReading] fileDescriptor], fd];

int pipeWriteFd = [[pipe fileHandleForWriting] fileDescriptor], fd];

写管道处，注意这个函数是无返回的函数，无法判断管道异常：

[self.pipeWriteFd writeData: [@”send” dataUsingEncoding: NSASCIIStringEncoding]]; 见我的文章管道，信号量，共享内存，socket的实际使用场景和NSPipe管道的使用 （http://blog.csdn.net/jia12216/article/details/47360637）

它的缺点也很显然，线程被杀，管道资源被回收时，你访问该管道，会出现管道破裂的系统级崩溃。详细见我的文章。

Signal 13 was raised（SIGPIPE管道破裂）

http://blog.csdn.net/jia12216/article/details/50844013

所以还时用系统级别的管道最安全，可以通过写管道是否可以写来判断管道是否可用。

这样使用申请管道也是错误的，因为你的线程申请的管道，在外部要可以用，肯定要能用，你申请个局部变量，等你离开线程时，你再使用管道，你就访问了空指针，造成管道破裂崩溃。下面是例子

int pipeSNO[2];

pipeSNO[0] = -1;

pipeSNO[1] = -1;

pipe(pipeSNO);

self.fdGuardModifyWaitTimeReadPipe = pipeSNO[0];

self.fdGuardModifyWaitTimeWritePipe = pipeSNO[1];

int set = 1;

setsockopt(self.fdGuardModifyWaitTimeReadPipe, SOL_SOCKET, SO_NOSIGPIPE, (void *)&set, sizeof(int));

int write = 1;

setsockopt(self.fdGuardModifyWaitTimeWritePipe, SOL_SOCKET, SO_NOSIGPIPE, (void *)&write, sizeof(int));

看来你向获得强大的功能，那么你就要从操作系统层做起，并且自己负责管道的申请和释放，不受系统ARC自动管理内存控制。下面是正确而强大的使用管道的部分例子，

申请管道部分：

if(self.fdGuardPipeHead != nil)

{

close(self.fdGuardModifyWaitTimeReadPipe);

close(self.fdGuardModifyWaitTimeWritePipe);

free(self.fdGuardPipeHead);

}
self.fdGuardPipeHead = malloc(2 * sizeof(int));

_fdGuardPipeHead[0] = -1;

_fdGuardPipeHead[1] = -1;

pipe(_fdGuardPipeHead);

self.fdGuardModifyWaitTimeReadPipe = _fdGuardPipeHead[0];

self.fdGuardModifyWaitTimeWritePipe = _fdGuardPipeHead[1];

int set = 1;

setsockopt(self.fdGuardModifyWaitTimeReadPipe, SOL_SOCKET, SO_NOSIGPIPE, (void *)&set, sizeof(int));

int write = 1;

setsockopt(self.fdGuardModifyWaitTimeWritePipe, SOL_SOCKET, SO_NOSIGPIPE, (void *)&write, sizeof(int));

[self creatSocketConnection];

发送于异常判断

//通过长连接的监控管道发送char *格式的消息

-(BOOL)sendMessageBySocketMonitorPipeWithCharArr : (const char *)message

{

NSUInteger len = 0;

len = strlen(message);

if(0 == len)

{

return YES;

}
unsigned char input_msg[BUFFER_SIZE] = {0};

memcpy(input_msg, message, len);;

@try {

long ret = write(self.fdWritePipe, input_msg, len);

if(ret != len)

{

[self processSocketPipeClosed];

return NO;

}
else

{

return YES;

}
}
@catch (NSException *exception) {

FLDDLogInfo(@”exception:%@”, exception);

[self processSocketPipeClosed];

return NO;

}
@finally {

}

}
关闭管道的操作

-(void)processSocketPipeClosed

{

FLDDLogDebug(@”函数”);

if(self.socketThreadPipeHead != nil)

{

close(self.fdReadPipe);

close(self.fdWritePipe);

free(self.socketThreadPipeHead);

}

self.socketThreadPipeHead = malloc(2 * sizeof(int));
_socketThreadPipeHead[0] = -1;
_socketThreadPipeHead[1] = -1;
pipe(_socketThreadPipeHead);
self.fdReadPipe = _socketThreadPipeHead[0];
self.fdWritePipe = _socketThreadPipeHead[1];
int setPipe = 1;
setsockopt(self.fdReadPipe, SOL_SOCKET, SO_NOSIGPIPE, (void *)&setPipe, sizeof(int));
int writePipe = 1;
setsockopt(self.fdWritePipe, SOL_SOCKET, SO_NOSIGPIPE, (void *)&writePipe, sizeof(int));
if(![self sendMessageByPipeWithCharArr : g_guardThreadCheckIfNormal])
{
//守护线程的监控管道被系统关闭，需要建立守护线程时立刻重新建立长连接，防止无法通过监控管道控制守护线程
_connectTime = (long long)[[NSDate date] timeIntervalSince1970] - SOCKET_CONNECT_ABORT_WAIT_TIME - 1;
_currentSocketThreadDic = nil;
_socketThreadDic = nil;
if(self.fd > 0)
{
close(self.fd);
}self.socketConnectStat = SOCKECT_CONNECT_ABNORMAL;
}else
{
[self creatSocketConnection];
}

}