/*

     File: Zipper.m

 Abstract: 

  Version: 1.0

 Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple

 Inc. ("Apple") in consideration of your agreement to the following

 terms, and your use, installation, modification or redistribution of

 this Apple software constitutes acceptance of these terms.  If you do

 not agree with these terms, please do not use, install, modify or

 redistribute this Apple software.

 In consideration of your agreement to abide by the following terms, and

 subject to these terms, Apple grants you a personal, non-exclusive

 license, under Apple's copyrights in this original Apple software (the

 "Apple Software"), to use, reproduce, modify and redistribute the Apple

 Software, with or without modifications, in source and/or binary forms;

 provided that if you redistribute the Apple Software in its entirety and

 without modifications, you must retain this notice and the following

 text and disclaimers in all such redistributions of the Apple Software.

 Neither the name, trademarks, service marks or logos of Apple Inc. may

 be used to endorse or promote products derived from the Apple Software

 without specific prior written permission from Apple.  Except as

 expressly stated in this notice, no other rights or licenses, express or

 implied, are granted by Apple herein, including but not limited to any

 patent rights that may be infringed by your derivative works or by other

 works in which the Apple Software may be incorporated.

 The Apple Software is provided by Apple on an "AS IS" basis.  APPLE

 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

 THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS

 FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND

 OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

 IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL

 OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,

 MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED

 AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),

 STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE

 POSSIBILITY OF SUCH DAMAGE.

 Copyright (C) 2012 Apple Inc. All Rights Reserved.

 */

#import "Zipper.h"

#include <zlib.h>

@implementation Zipper

#define ZIP_BUF_SIZE    16384

// Given an input and output file, compress the input into the output using

// the gzip algorithm (using given compression level and strategy).

//

// Return Z_OK on success.  Otherwise return a zlib error.

static int

zip_compress_file(int infd, int outfd, int level, int strategy, 

                  const char **errmsg)

{

    int err = Z_OK;

    int len;

    uint8_t *buf = NULL;

    gzFile gzoutfp = NULL;

    char mode[5] = "wb  ";

    // Build mode argument for gzdopen().

    if (level < 1 || level > 9)

        level = 6;

    mode[2] = '0' + level;

    switch (strategy) {

        case Z_FILTERED:

            mode[3] = 'f';

            break;

        case Z_HUFFMAN_ONLY:

            mode[3] = 'h';

            break;

        case Z_RLE:

            mode[3] = 'R';

            break;

        case Z_FIXED:

            mode[3] = 'F';

            break;

        default:

            mode[3] = '\0';

            break;

    }

    if ((buf = (uint8_t *)malloc(ZIP_BUF_SIZE)) == NULL) {

        err = Z_MEM_ERROR;

        if (errmsg)

            *errmsg = "Out of memory";

        goto errout;

    }

    // Use zlib gzip wrapper functions to do the compression.

    if ((gzoutfp = gzdopen(outfd, mode)) == NULL) {

        err = Z_ERRNO;

        if (errmsg)

            *errmsg = "Can't not gzdopen() output file";

        goto errout;

    }

    while(1) {

        if ((len = (int)read(infd, buf, ZIP_BUF_SIZE)) < 0) {

            err = Z_ERRNO;

            if (errmsg)

                *errmsg = "Can't read input";

            goto errout;

        }

        if (0 == len)

            break;

        if (gzwrite(gzoutfp, buf, len) != len) {

            if (errmsg)

                *errmsg = gzerror(gzoutfp, &err);

            goto errout;

        }

    }

errout:

    if (buf)

        free(buf);

    if (gzoutfp)

        gzclose(gzoutfp);

    return (err);

}

+ (Zipper *)sharedZipper {

    static dispatch_once_t onceToken;

    static Zipper *shared;

    dispatch_once(&onceToken, ^{

        shared = [Zipper new];

    });

    return shared;

}

// This method will handle compressing a file. Note that NSFileHandle works together with NSXPCConnection, to allow an open file to be automatically passed from one application to another. The zip service itself does not have permissions to access arbitary files. It will be allowed to talk only to the file that it is given from the main GUI application.

- (void)compressFile:(NSFileHandle *)inFile toFile:(NSFileHandle *)outFile withReply:(void (^)(NSError *error))reply {

    int64_t errcode = 0;

    const char *errmsg = NULL;

    int infd = [inFile fileDescriptor];

    int outfd = [outFile fileDescriptor];

    if (infd == -1 || outfd == -1) {

        errcode = Z_ERRNO;

        errmsg = "Invalid file descriptor(s)";

    } else {

        errcode = zip_compress_file(infd, outfd, 6, 0, &errmsg);

    }

    // Create an error object to pass back, if appropriate.

    NSError *error = nil;

    if (errcode) {

        error = [NSError errorWithDomain:NSPOSIXErrorDomain code:errcode userInfo:nil];

    }

    // Invoke the reply block, which will send a response back to the main application to let it know that we are finished.

    reply(error);

}

// Implement the one method in the NSXPCListenerDelegate protocol.

- (BOOL)listener:(NSXPCListener *)listener shouldAcceptNewConnection:(NSXPCConnection *)newConnection {

    // Configure the new connection and resume it. Because this is a singleton object, we set 'self' as the exported object and configure the connection to export the 'Zip' protocol that we implement on this object.

    newConnection.exportedInterface = [NSXPCInterface interfaceWithProtocol:@protocol(Zip)];

    newConnection.exportedObject = self;

    [newConnection resume];

    return YES;

}

@end