/*

     File: zip_service.c 

 Abstract: XPC service that compress a file using zlib.

  Version: 1.0

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 */

#include <asl.h>

#include <assert.h>

#include <errno.h>

#include <stdio.h>

#include <zlib.h>

#include <xpc/xpc.h>

#include <fcntl.h>

#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);

}

// Process the XPC request, create a temporary file to hold downloaded,

// data, and build/return XPC reply.

static void

zip_process_request(xpc_object_t request, xpc_object_t reply)

{

    // Get the input and output file descriptors from the XPC request

    int infd = xpc_dictionary_dup_fd(request, "infd");

    int outfd = xpc_dictionary_dup_fd(request, "outfd");

    int64_t errcode = 0;

    const char *errmsg = NULL;

    // Check arguments.

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

        errcode = Z_ERRNO;

        errmsg = "Invalid file descriptor(s)";

        goto errout;

    }

    // "gzip" file using level 6 compress and default strategy

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

errout:

    // Clean up and add errcode/errmsg to reply.

    if (infd != -1)

        close(infd);

    if (outfd != -1)

        close(outfd);

    xpc_dictionary_set_int64(reply, "errcode", errcode);

    if (errmsg)

        xpc_dictionary_set_string(reply, "errmsg", errmsg);

}

static void

zip_peer_event_handler(xpc_connection_t peer, xpc_object_t event)

{

    // Get the object type.

    xpc_type_t type = xpc_get_type(event);

    if (XPC_TYPE_ERROR == type) {

        // Handle an error.

        if (XPC_ERROR_CONNECTION_INVALID == event) {

            // The client process on the other end of the connection

            // has either crashed or cancelled the connection.

            asl_log(NULL, NULL, ASL_LEVEL_NOTICE, "peer(%d) received "

                "XPC_ERROR_CONNECTION_INVALID",

                xpc_connection_get_pid(peer));

            xpc_connection_cancel(peer);

        } else if (XPC_ERROR_TERMINATION_IMMINENT == event) {

            // Handle per-connection termination cleanup. This

            // service is about to exit.

            asl_log(NULL, NULL, ASL_LEVEL_NOTICE, "peer(%d) received "

                "XPC_ERROR_TERMINATION_IMMINENT",

                xpc_connection_get_pid(peer));

        }

    } else if (XPC_TYPE_DICTIONARY == type) {

        xpc_object_t requestMessage = event;

        char *messageDescription = xpc_copy_description(requestMessage);

        asl_log(NULL, NULL, ASL_LEVEL_NOTICE, "received message from peer(%d)\n:%s",

            xpc_connection_get_pid(peer), messageDescription);

        free(messageDescription);

        xpc_object_t replyMessage = xpc_dictionary_create_reply(requestMessage);

        assert(replyMessage != NULL);

        // Process request and build a reply message.

        zip_process_request(requestMessage, replyMessage);

    messageDescription = xpc_copy_description(replyMessage);

    asl_log(NULL, NULL, ASL_LEVEL_NOTICE, "reply message to peer(%d)\n: %s",

        xpc_connection_get_pid(peer), messageDescription);

    free(messageDescription);

        xpc_connection_send_message(peer, replyMessage);

        xpc_release(replyMessage);

    }

}

static void

zip_event_handler(xpc_connection_t peer)

{

    // Generate an unique name for the queue to handle messages from

    // this peer and create a new dispatch queue for it.

    char *queue_name = NULL;

    asprintf(&queue_name, "%s-peer-%d", "com.apple.SandboxedFetch.zip",

             xpc_connection_get_pid(peer));

    dispatch_queue_t peer_event_queue =

    dispatch_queue_create(queue_name, DISPATCH_QUEUE_SERIAL);

    assert(peer_event_queue != NULL);

    free(queue_name);

    // Set the target queue for connection.

    xpc_connection_set_target_queue(peer, peer_event_queue);

    // Set the handler block for connection.

    xpc_connection_set_event_handler(peer, ^(xpc_object_t event) {

        zip_peer_event_handler(peer, event);

    });

    // Enable the peer connection to receive messages.

    xpc_connection_resume(peer);

}

int

main(int argc, const char *argv[])

{

    xpc_main(zip_event_handler);

    exit(EXIT_FAILURE);

}