/*

     File: FileSendOperation.m

 Abstract: An NSOperation that sends a file over a TCP connection.

  Version: 2.2

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#import "FileSendOperation.h"

#include <zlib.h>

enum {

    kFileSendOperationStateStart,

    kFileSendOperationStateHeader, 

    kFileSendOperationStateBody, 

    kFileSendOperationStateTrailer

};

enum {

    kFileSendOperationBufferSize = 32768

};

@interface FileSendOperation () <NSStreamDelegate>

// internal properties

@property (atomic, assign, readwrite) NSInteger         sendState;

@property (atomic, strong, readwrite) NSInputStream *   fileStream;

@property (atomic, strong, readwrite) NSMutableData *   buffer;

@property (atomic, assign, readwrite) NSUInteger        bufferOffset;

@property (atomic, assign, readwrite) off_t             fileLength;

@property (atomic, assign, readwrite) off_t             fileOffset;

@property (atomic, assign, readwrite) uLong             crc;

@end

@implementation FileSendOperation

- (id)initWithFilePath:(NSString *)filePath outputStream:(NSOutputStream *)outputStream

{

    assert(filePath != nil);

    assert(outputStream != nil);

    self = [super init];

    if (self != nil) {

        self->_filePath     = [filePath copy];

        self->_outputStream = outputStream;

    }

    return self;

}

- (void)dealloc

{

    assert(self->_buffer == nil);

    assert(self->_fileStream == nil);

}

#pragma mark * Start and stop

- (void)operationDidStart

    // Our superclass calls this on the actual run loop thread to give us an opportunity 

    // to install our run loop sources (and do various other bits of initialisation).

{

    NSDictionary *  fileAttributes;

    NSError *       error;

    assert(self.isActualRunLoopThread);

    assert(self.state == kQRunLoopOperationStateExecuting);

    assert(self.fileStream == nil);

    // First get the file attributes, to allows us to send the header which contains the file size.

    // This has the added benefit of flush out errors early.

    fileAttributes = [[NSFileManager defaultManager] attributesOfItemAtPath:self.filePath error:&error];

    if (fileAttributes == nil) {

        [self finishWithError:error];

    } else {

        // Now open the file stream.

        self.fileStream = [NSInputStream inputStreamWithFileAtPath:self.filePath];

        if (self.fileStream == nil) {

            [self finishWithError:[NSError errorWithDomain:NSCocoaErrorDomain code:NSFileNoSuchFileError userInfo:nil]];

        } else {

            // Determine the file length.

            assert( [fileAttributes[NSFileSize] isKindOfClass:[NSNumber class]] );

            self.fileLength = [fileAttributes[NSFileSize] longLongValue];

            assert(self.fileLength >= 0);

            // Allocate a transfer buffer.

            self.buffer = [NSMutableData dataWithCapacity:kFileSendOperationBufferSize];

            assert(self.buffer != nil);

            assert(self.sendState == kFileSendOperationStateStart);

            assert(self.bufferOffset == 0);

            assert(self.fileOffset == 0);

            assert(self.crc == 0);

            // Open up our streams.

            [self.fileStream open];

            [self.outputStream setDelegate:self];

            for (NSString * mode in self.actualRunLoopModes) {

                [self.outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:mode];

            }

            [self.outputStream open];

        }

    }

}

- (void)operationWillFinish

    // Our superclass calls this on the actual run loop thread to give us an opportunity 

    // to remove our run loop sources (and do various other bits of clean up).

{

    assert(self.isActualRunLoopThread);

    if (self.fileStream != nil) {

        [self.fileStream close];

        self.fileStream = nil;

    }

    if (self.outputStream != nil) {

        // We want to hold on to our reference to outputStream until -dealloc, but 

        // we don't want to do this teardown twice, so we conditionalise it based on 

        // whether the delegate is still set.

        if ([self.outputStream delegate] != nil) {

            [self.outputStream setDelegate:nil];

            for (NSString * mode in self.actualRunLoopModes) {

                [self.outputStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:mode];

            }

            [self.outputStream close];

        }

    }

    self.buffer = nil;      // might as well free up the memory now

}

#pragma mark * Stream delegate callbacks

- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode

    // An NSStream delegate callback that's called when events happen on our TCP stream.

{

    // CFSocketStream does not retain its delegate.  It's possible that actions early 

    // in this method can affect the state of the program (typically by setting isFinished 

    // to YES so that all our clients release their references to the operation) such that 

    // all references to this object are released, resulting in code later in the method 

    // accessing a self that's been deallocated <rdar://problem/12682482>.  To avoid this, 

    // we manually retain self across the lifetime of this callback.

    CFRetain( (__bridge CFTypeRef) self );

    assert([NSThread isMainThread]);

    assert(aStream == self.outputStream);

    #pragma unused(aStream)

    switch (eventCode) {

        case NSStreamEventOpenCompleted: {

            // do nothing

        } break;

        case NSStreamEventHasBytesAvailable: {

            assert(NO);

        } break;

        case NSStreamEventHasSpaceAvailable: {

            NSInteger   bytesWritten;

            #if ! defined(NDEBUG)

                if (self.debugStallSend) {

                    return;

                }

            #endif

            // If the buffer has no more data to send, refill it.

            if (self.bufferOffset == [self.buffer length]) {

                self.bufferOffset = 0;

                switch (self.sendState) {

                    case kFileSendOperationStateStart: {

                        uint64_t    header;

                        // Set up the buffer to send the header.

                        header = OSSwapHostToBigInt64(self.fileLength);

                        [self.buffer setLength:0];

                        [self.buffer appendBytes:&header length:sizeof(header)];

                        self.sendState = kFileSendOperationStateHeader;

                    } break;

                    case kFileSendOperationStateHeader:

                        self.sendState = kFileSendOperationStateBody;

                        // fall through

                    case kFileSendOperationStateBody: {

                        if (self.fileOffset < self.fileLength) {

                            NSUInteger  bytesToRead;

                            NSInteger   bytesRead;

                            // Set up the buffer to send the next chunk of body data.

                            if ( (self.fileLength - self.fileOffset) < (off_t) kFileSendOperationBufferSize ) {

                                bytesToRead = (NSUInteger) (self.fileLength - self.fileOffset);

                            } else {

                                bytesToRead = kFileSendOperationBufferSize;

                            }

                            [self.buffer setLength:bytesToRead];

                            bytesRead = [self.fileStream read:[self.buffer mutableBytes] maxLength:bytesToRead];

                            if (bytesRead < 0) {

                                [self finishWithError:[self.fileStream streamError]];

                            } else if (bytesRead == 0) {

                                // The file must have shrunk while we were reading it!

                                [self finishWithError:[NSError errorWithDomain:NSPOSIXErrorDomain code:EPIPE userInfo:nil]];

                            } else {

                                [self.buffer setLength:(NSUInteger) bytesRead];

                                self.crc = crc32(self.crc, [self.buffer bytes], (uInt) [self.buffer length]);

                                self.fileOffset += bytesRead;

                            }

                        } else {

                            uint32_t    trailer;

                            // Set up the buffer to send the trailer.

                            trailer = OSSwapHostToBigInt32( (uint32_t) self.crc );

                            #if ! defined(NDEBUG)

                                if (self.debugSendBadChecksum) {

                                    trailer ^= 1;

                                }

                            #endif

                            [self.buffer setLength:0];

                            [self.buffer appendBytes:&trailer length:sizeof(trailer)];

                            self.sendState = kFileSendOperationStateTrailer;

                        }

                    } break;

                    case kFileSendOperationStateTrailer: {

                        [self finishWithError:nil];

                    } break;

                }

            }

            // Try to send the remaining bytes in the buffer.

            if ( ! [self isFinished] ) {

                assert(self.bufferOffset < [self.buffer length]);

                bytesWritten = [self.outputStream write:((const uint8_t *) [self.buffer bytes]) + self.bufferOffset maxLength:[self.buffer length] - self.bufferOffset];

                if (bytesWritten < 0) {

                    [self finishWithError:[self.outputStream streamError]];

                } else {

                    self.bufferOffset += bytesWritten;

                }

            }

        } break;

        case NSStreamEventErrorOccurred: {

            assert([self.outputStream streamError] != nil);

            [self finishWithError:[self.outputStream streamError]];

        } break;

        case NSStreamEventEndEncountered: {

            assert(NO);

        } break;

        default: {

            assert(NO);

        } break;

    }

    CFRelease( (__bridge CFTypeRef) self );

}

@end