src/AFC.c

/*
 * AFC.c 
 * Contains functions for the built-in AFC client.
 * 
 * Copyright (c) 2008 Zach C. All Rights Reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA 
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "AFC.h"
#include "iphone.h"
#include "utils.h"

// This is the maximum size an AFC data packet can be
const int MAXIMUM_PACKET_SIZE = (2 << 15);

/** Locks an AFC client, done for thread safety stuff
 * 
 * @param client The AFC client connection to lock
 */
static void afc_lock(afc_client_t client)
{
	log_debug_msg("%s: Locked\n", __func__);
	g_mutex_lock(client->mutex);
}

/** Unlocks an AFC client, done for thread safety stuff.
 * 
 * @param client The AFC 
 */
static void afc_unlock(afc_client_t client)
{
	log_debug_msg("%s: Unlocked\n", __func__);
	g_mutex_unlock(client->mutex);
}

/** Makes a connection to the AFC service on the phone. 
 * 
 * @param phone The iPhone to connect on.
 * @param s_port The source port. 
 * @param d_port The destination port. 
 * 
 * @return A handle to the newly-connected client or NULL upon error.
 */
afc_error_t afc_client_new(iphone_device_t device, int dst_port, afc_client_t * client)
{
	/* makes sure thread environment is available */
	if (!g_thread_supported())
		g_thread_init(NULL);

	if (!device)
		return AFC_E_INVALID_ARGUMENT;

	/* attempt connection */
	int sfd = usbmuxd_connect(device->handle, dst_port);
	if (sfd < 0) {
		return AFC_E_MUX_ERROR;
	}

	afc_client_t client_loc = (afc_client_t) malloc(sizeof(struct afc_client_int));
	client_loc->sfd = sfd;

	/* allocate a packet */
	client_loc->afc_packet = (AFCPacket *) malloc(sizeof(AFCPacket));
	if (!client_loc->afc_packet) {
		usbmuxd_disconnect(client_loc->sfd);
		free(client_loc);
		return AFC_E_NO_MEM;
	}

	client_loc->afc_packet->packet_num = 0;
	client_loc->afc_packet->entire_length = 0;
	client_loc->afc_packet->this_length = 0;
	memcpy(client_loc->afc_packet->magic, AFC_MAGIC, AFC_MAGIC_LEN);
	client_loc->file_handle = 0;
	client_loc->lock = 0;
	client_loc->mutex = g_mutex_new();

	*client = client_loc;
	return AFC_E_SUCCESS;
}

/** Disconnects an AFC client from the phone.
 * 
 * @param client The client to disconnect.
 */
afc_error_t afc_client_free(afc_client_t client)
{
	if (!client || client->sfd < 0 || !client->afc_packet)
		return AFC_E_INVALID_ARGUMENT;

	usbmuxd_disconnect(client->sfd);
	free(client->afc_packet);
	if (client->mutex) {
		g_mutex_free(client->mutex);
	}
	free(client);
	return AFC_E_SUCCESS;
}

/** Dispatches an AFC packet over a client.
 * 
 * @param client The client to send data through.
 * @param data The data to send.
 * @param length The length to send.
 * 
 * @return The number of bytes actually sent, or -1 on error. 
 * 
 * @warning set client->afc_packet->this_length and
 *          client->afc_packet->entire_length to 0 before calling this.  The
 *          reason is that if you set them to different values, it indicates
 *          you want to send the data as two packets.
 */
static int afc_dispatch_packet(afc_client_t client, const char *data, uint64_t length)
{
	int bytes = 0, offset = 0;
	char *buffer;

	if (!client || client->sfd < 0 || !client->afc_packet)
		return 0;

	if (!data || !length)
		length = 0;

	client->afc_packet->packet_num++;
	if (!client->afc_packet->entire_length) {
		client->afc_packet->entire_length = (length) ? sizeof(AFCPacket) + length : sizeof(AFCPacket);
		client->afc_packet->this_length = client->afc_packet->entire_length;
	}
	if (!client->afc_packet->this_length) {
		client->afc_packet->this_length = sizeof(AFCPacket);
	}
	// We want to send two segments; buffer+sizeof(AFCPacket) to
	// this_length is the parameters
	// And everything beyond that is the next packet. (for writing)
	if (client->afc_packet->this_length != client->afc_packet->entire_length) {
		buffer = (char *) malloc(client->afc_packet->this_length);
		memcpy(buffer, (char *) client->afc_packet, sizeof(AFCPacket));
		offset = client->afc_packet->this_length - sizeof(AFCPacket);

		log_debug_msg("%s: Offset: %i\n", __func__, offset);
		if ((length) < (client->afc_packet->entire_length - client->afc_packet->this_length)) {
			log_debug_msg("%s: Length did not resemble what it was supposed", __func__);
			log_debug_msg("to based on the packet.\n");
			log_debug_msg("%s: length minus offset: %i\n", __func__, length - offset);
			log_debug_msg("%s: rest of packet: %i\n", __func__, client->afc_packet->entire_length - client->afc_packet->this_length);
			free(buffer);
			return -1;
		}
		memcpy(buffer + sizeof(AFCPacket), data, offset);
		usbmuxd_send(client->sfd, buffer, client->afc_packet->this_length, (uint32_t*)&bytes);
		free(buffer);
		if (bytes <= 0) {
			return bytes;
		}

		log_debug_msg("%s: sent the first now go with the second\n", __func__);
		log_debug_msg("%s: Length: %i\n", __func__, length - offset);
		log_debug_msg("%s: Buffer: \n", __func__);
		log_debug_buffer(data + offset, length - offset);

		usbmuxd_send(client->sfd, data + offset, length - offset, (uint32_t*)&bytes);
		return bytes;
	} else {
		log_debug_msg("%s: doin things the old way\n", __func__);
		buffer = (char *) malloc(sizeof(char) * client->afc_packet->this_length);
		log_debug_msg("%s: packet length = %i\n", __func__, client->afc_packet->this_length);
		memcpy(buffer, (char *) client->afc_packet, sizeof(AFCPacket));
		log_debug_msg("%s: packet data follows\n", __func__);
		if (length > 0) {
			memcpy(buffer + sizeof(AFCPacket), data, length);
		}
		log_debug_buffer(buffer, client->afc_packet->this_length);
		log_debug_msg("\n");
		usbmuxd_send(client->sfd, buffer, client->afc_packet->this_length, (uint32_t*)&bytes);

		if (buffer) {
			free(buffer);
			buffer = NULL;
		}
		return bytes;
	}
	return -1;
}

/** Receives data through an AFC client and sets a variable to the received data.
 * 
 * @param client The client to receive data on.
 * @param dump_here The char* to point to the newly-received data.
 * 
 * @return How much data was received, 0 on successful receive with no errors,
 *         -1 if there was an error involved with receiving or if the packet
 *         received raised a non-trivial error condition (i.e. non-zero with
 *         AFC_ERROR operation)
 */
static afc_error_t afc_receive_data(afc_client_t client, char **dump_here, int *bytes)
{
	AFCPacket header;
	uint32_t entire_len = 0;
	uint32_t this_len = 0;
	uint32_t current_count = 0;
	uint64_t param1 = -1;

	*bytes = 0;

	/* first, read the AFC header */
	usbmuxd_recv(client->sfd, (char*)&header, sizeof(AFCPacket), (uint32_t*)bytes);
	if (*bytes <= 0) {
		log_debug_msg("%s: Just didn't get enough.\n", __func__);
		*dump_here = NULL;
		return AFC_E_MUX_ERROR;
	} else if ((uint32_t)*bytes < sizeof(AFCPacket)) {
		log_debug_msg("%s: Did not even get the AFCPacket header\n", __func__);
		*dump_here = NULL;
		return AFC_E_MUX_ERROR;
	}

	/* check if it's a valid AFC header */
	if (strncmp(header.magic, AFC_MAGIC, AFC_MAGIC_LEN)) {
		log_debug_msg("%s: Invalid AFC packet received (magic != " AFC_MAGIC ")!\n", __func__);
	}

	/* check if it has the correct packet number */
	if (header.packet_num != client->afc_packet->packet_num) {
		/* otherwise print a warning but do not abort */
		log_debug_msg("%s: ERROR: Unexpected packet number (%lld != %lld) aborting.\n", __func__, header.packet_num, client->afc_packet->packet_num);
		*dump_here = NULL;
		return AFC_E_OP_HEADER_INVALID;
	}

	/* then, read the attached packet */
	if (header.this_length < sizeof(AFCPacket)) {
		log_debug_msg("%s: Invalid AFCPacket header received!\n", __func__);
		*dump_here = NULL;
		return AFC_E_OP_HEADER_INVALID;
	} else if ((header.this_length == header.entire_length)
			&& header.entire_length == sizeof(AFCPacket)) {
		log_debug_msg("%s: Empty AFCPacket received!\n", __func__);
		*dump_here = NULL;
		*bytes = 0;
		if (header.operation == AFC_OP_DATA) {
			return AFC_E_SUCCESS;
		} else {
			return AFC_E_IO_ERROR;
		}
	}

	log_debug_msg("%s: received AFC packet, full len=%lld, this len=%lld, operation=0x%llx\n", __func__, header.entire_length, header.this_length, header.operation);

	entire_len = (uint32_t)header.entire_length - sizeof(AFCPacket);
	this_len = (uint32_t)header.this_length - sizeof(AFCPacket);

	/* this is here as a check (perhaps a different upper limit is good?) */
	if (entire_len > (uint32_t)MAXIMUM_PACKET_SIZE) {
		fprintf(stderr, "%s: entire_len is larger than MAXIMUM_PACKET_SIZE, (%d > %d)!\n", __func__, entire_len, MAXIMUM_PACKET_SIZE);
	}

	*dump_here = (char*)malloc(entire_len);
	if (this_len > 0) {
		usbmuxd_recv(client->sfd, *dump_here, this_len, (uint32_t*)bytes);
		if (*bytes <= 0) {
			free(*dump_here);
			*dump_here = NULL;
			log_debug_msg("%s: Did not get packet contents!\n", __func__);
			return AFC_E_NOT_ENOUGH_DATA;
		} else if ((uint32_t)*bytes < this_len) {
			free(*dump_here);
			*dump_here = NULL;
			log_debug_msg("%s: Could not receive this_len=%d bytes\n", __func__, this_len);
			return AFC_E_NOT_ENOUGH_DATA;
		}
	}

	current_count = this_len;

	if (entire_len > this_len) {
		while (current_count < entire_len) {
			usbmuxd_recv(client->sfd, (*dump_here)+current_count, entire_len - current_count, (uint32_t*)bytes);
			if (*bytes <= 0) {
				log_debug_msg("%s: Error receiving data (recv returned %d)\n", __func__, *bytes);
				break;
			}
			current_count += *bytes;
		}
		if (current_count < entire_len) {
			log_debug_msg("%s: WARNING: could not receive full packet (read %s, size %d)\n", __func__, current_count, entire_len);
		}
	}

	if (current_count >= sizeof(uint64_t)) {
		param1 = *(uint64_t*)(*dump_here);
	}

	log_debug_msg("%s: packet data size = %i\n", __func__, current_count);
	log_debug_msg("%s: packet data follows\n", __func__);
	log_debug_buffer(*dump_here, current_count);

	/* check operation types */
	if (header.operation == AFC_OP_STATUS) {
		/* status response */
		log_debug_msg("%s: got a status response, code=%lld\n", __func__, param1);

		if (param1 != AFC_E_SUCCESS) {
			/* error status */
			/* free buffer */
			free(*dump_here);
			*dump_here = NULL;
			return (afc_error_t)param1;
		}
	} else if (header.operation == AFC_OP_DATA) {
		/* data response */
		log_debug_msg("%s: got a data response\n", __func__);
	} else if (header.operation == AFC_OP_FILE_OPEN_RES) {
		/* file handle response */
		log_debug_msg("%s: got a file handle response, handle=%lld\n", __func__, param1);
	} else if (header.operation == AFC_OP_FILE_TELL_RES) {
		/* tell response */
		log_debug_msg("%s: got a tell response, position=%lld\n", __func__, param1);
	} else {
		/* unknown operation code received */
		free(*dump_here);
		*dump_here = NULL;
		*bytes = 0;

		log_debug_msg("%s: WARNING: Unknown operation code received 0x%llx param1=%lld\n", __func__, header.operation, param1);
		fprintf(stderr, "%s: WARNING: Unknown operation code received 0x%llx param1=%lld\n", __func__, (long long)header.operation, (long long)param1);

		return AFC_E_OP_NOT_SUPPORTED;
	}

	*bytes = current_count;
	return AFC_E_SUCCESS;
}

static int count_nullspaces(char *string, int number)
{
	int i = 0, nulls = 0;

	for (i = 0; i < number; i++) {
		if (string[i] == '\0')
			nulls++;
	}

	return nulls;
}

static char **make_strings_list(char *tokens, int true_length)
{
	int nulls = 0, i = 0, j = 0;
	char **list = NULL;

	if (!tokens || !true_length)
		return NULL;

	nulls = count_nullspaces(tokens, true_length);
	list = (char **) malloc(sizeof(char *) * (nulls + 1));
	for (i = 0; i < nulls; i++) {
		list[i] = strdup(tokens + j);
		j += strlen(list[i]) + 1;
	}
	list[i] = NULL;

	return list;
}

/** Gets a directory listing of the directory requested.
 * 
 * @param client The client to get a directory listing from.
 * @param dir The directory to list. (must be a fully-qualified path)
 * 
 * @return A char ** list of files in that directory, terminated by an empty
 *         string for now or NULL if there was an error.
 */
afc_error_t afc_read_directory(afc_client_t client, const char *dir, char ***list)
{
	int bytes = 0;
	char *data = NULL, **list_loc = NULL;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client || !dir || !list || (list && *list))
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	// Send the command
	client->afc_packet->operation = AFC_OP_READ_DIR;
	client->afc_packet->entire_length = 0;
	client->afc_packet->this_length = 0;
	bytes = afc_dispatch_packet(client, dir, strlen(dir)+1);
	if (bytes <= 0) {
		afc_unlock(client);
		return AFC_E_NOT_ENOUGH_DATA;
	}
	// Receive the data
	ret = afc_receive_data(client, &data, &bytes);
	if (ret != AFC_E_SUCCESS) {
		afc_unlock(client);
		return ret;
	}
	// Parse the data
	list_loc = make_strings_list(data, bytes);
	if (data)
		free(data);

	afc_unlock(client);
	*list = list_loc;

	return ret;
}

/** Get device info for a client connection to phone. (free space on disk, etc.)
 * 
 * @param client The client to get device info for.
 * 
 * @return A char ** list of parameters as given by AFC or NULL if there was an
 *         error.
 */
afc_error_t afc_get_device_info(afc_client_t client, char ***infos)
{
	int bytes = 0;
	char *data = NULL, **list = NULL;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client || !infos)
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	// Send the command
	client->afc_packet->operation = AFC_OP_GET_DEVINFO;
	client->afc_packet->entire_length = client->afc_packet->this_length = 0;
	bytes = afc_dispatch_packet(client, NULL, 0);
	if (bytes < 0) {
		afc_unlock(client);
		return AFC_E_NOT_ENOUGH_DATA;
	}
	// Receive the data
	ret = afc_receive_data(client, &data, &bytes);
	if (ret != AFC_E_SUCCESS) {
		afc_unlock(client);
		return ret;
	}
	// Parse the data
	list = make_strings_list(data, bytes);
	if (data)
		free(data);

	afc_unlock(client);

	*infos = list;

	return ret;
}

/** Get a specific field of the device info for a client connection to phone.
 * Known values are: Model, FSTotalBytes, FSFreeBytes and FSBlockSize. This is
 * a helper function for afc_get_device_info().
 *
 * @param client The client to get device info for.
 * @param field The field to get the information for
 *
 * @return A char * or NULL if there was an error.
 */
char * afc_get_device_info_field(afc_client_t client, const char *field)
{
	char *ret = NULL;
	char **kvps, **ptr;

	if (field == NULL || afc_get_device_info(client, &kvps) != AFC_E_SUCCESS)
		return NULL;

	for (ptr = kvps; *ptr; ptr++) {
		if (!strcmp(*ptr, field)) {
			ret = strdup(*(ptr+1));
			break;
		}
	}

	g_strfreev(kvps);

	return ret;
}

/** Deletes a file or directory.
 * 
 * @param client The client to use.
 * @param path The path to delete. (must be a fully-qualified path)
 * 
 * @return AFC_E_SUCCESS if everythong went well, AFC_E_INVALID_ARGUMENT
 *         if arguments are NULL or invalid, AFC_E_NOT_ENOUGH_DATA otherwise.
 */
afc_error_t afc_remove_path(afc_client_t client, const char *path)
{
	char *response = NULL;
	int bytes;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client || !path || !client->afc_packet || client->sfd < 0)
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	// Send command
	client->afc_packet->this_length = client->afc_packet->entire_length = 0;
	client->afc_packet->operation = AFC_OP_REMOVE_PATH;
	bytes = afc_dispatch_packet(client, path, strlen(path)+1);
	if (bytes <= 0) {
		afc_unlock(client);
		return AFC_E_NOT_ENOUGH_DATA;
	}
	// Receive response
	ret = afc_receive_data(client, &response, &bytes);
	if (response)
		free(response);

	/* special case; unknown error actually means directory not empty */
	if (ret == AFC_E_UNKNOWN_ERROR)
		ret = AFC_E_DIR_NOT_EMPTY;

	afc_unlock(client);

	return ret;
}

/** Renames a file or directory on the phone.
 * 
 * @param client The client to have rename.
 * @param from The name to rename from. (must be a fully-qualified path)
 * @param to The new name. (must also be a fully-qualified path)
 * 
 * @return AFC_E_SUCCESS if everythong went well, AFC_E_INVALID_ARGUMENT
 *         if arguments are NULL or invalid, AFC_E_NOT_ENOUGH_DATA otherwise.
 */
afc_error_t afc_rename_path(afc_client_t client, const char *from, const char *to)
{
	char *response = NULL;
	char *send = (char *) malloc(sizeof(char) * (strlen(from) + strlen(to) + 1 + sizeof(uint32_t)));
	int bytes = 0;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client || !from || !to || !client->afc_packet || client->sfd < 0)
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	// Send command
	memcpy(send, from, strlen(from) + 1);
	memcpy(send + strlen(from) + 1, to, strlen(to) + 1);
	client->afc_packet->entire_length = client->afc_packet->this_length = 0;
	client->afc_packet->operation = AFC_OP_RENAME_PATH;
	bytes = afc_dispatch_packet(client, send, strlen(to)+1 + strlen(from)+1);
	free(send);
	if (bytes <= 0) {
		afc_unlock(client);
		return AFC_E_NOT_ENOUGH_DATA;
	}
	// Receive response
	ret = afc_receive_data(client, &response, &bytes);
	if (response)
		free(response);

	afc_unlock(client);

	return ret;
}

/** Creates a directory on the phone.
 * 
 * @param client The client to use to make a directory.
 * @param dir The directory's path. (must be a fully-qualified path, I assume
 *        all other mkdir restrictions apply as well)
 *
 * @return AFC_E_SUCCESS if everythong went well, AFC_E_INVALID_ARGUMENT
 *         if arguments are NULL or invalid, AFC_E_NOT_ENOUGH_DATA otherwise.
 */
afc_error_t afc_make_directory(afc_client_t client, const char *dir)
{
	int bytes = 0;
	char *response = NULL;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client)
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	// Send command
	client->afc_packet->operation = AFC_OP_MAKE_DIR;
	client->afc_packet->this_length = client->afc_packet->entire_length = 0;
	bytes = afc_dispatch_packet(client, dir, strlen(dir)+1);
	if (bytes <= 0) {
		afc_unlock(client);
		return AFC_E_NOT_ENOUGH_DATA;
	}
	// Receive response
	ret = afc_receive_data(client, &response, &bytes);
	if (response)
		free(response);

	afc_unlock(client);

	return ret;
}

/** Gets information about a specific file.
 * 
 * @param client The client to use to get the information of the file.
 * @param path The fully-qualified path to the file. 
 * @param infolist Pointer to a buffer that will be filled with a NULL-terminated
 *                 list of strings with the file information.
 *                 Set to NULL before calling this function.
 * 
 * @return AFC_E_SUCCESS on success or an AFC_E_* error value
 *         when something went wrong.
 */
afc_error_t afc_get_file_info(afc_client_t client, const char *path, char ***infolist)
{
	char *received = NULL;
	int bytes;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client || !path || !infolist)
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	// Send command
	client->afc_packet->operation = AFC_OP_GET_FILE_INFO;
	client->afc_packet->entire_length = client->afc_packet->this_length = 0;
	afc_dispatch_packet(client, path, strlen(path)+1);

	// Receive data
	ret = afc_receive_data(client, &received, &bytes);
	if (received) {
		*infolist = make_strings_list(received, bytes);
		free(received);
	}

	afc_unlock(client);

	return ret;
}

/** Opens a file on the phone.
 * 
 * @param client The client to use to open the file. 
 * @param filename The file to open. (must be a fully-qualified path)
 * @param file_mode The mode to use to open the file. Can be AFC_FILE_READ or
 * 		    AFC_FILE_WRITE; the former lets you read and write,
 * 		    however, and the second one will *create* the file,
 * 		    destroying anything previously there.
 * @param handle Pointer to a uint64_t that will hold the handle of the file
 * 
 * @return AFC_E_SUCCESS on success or an AFC_E_* error on failure.
 */
iphone_error_t
afc_file_open(afc_client_t client, const char *filename,
					 afc_file_mode_t file_mode, uint64_t *handle)
{
	uint32_t ag = 0;
	int bytes = 0;
	char *data = (char *) malloc(sizeof(char) * (8 + strlen(filename) + 1));
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	// set handle to 0 so in case an error occurs, the handle is invalid
	*handle = 0;

	if (!client || client->sfd < 0|| !client->afc_packet)
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	// Send command
	memcpy(data, &file_mode, 4);
	memcpy(data + 4, &ag, 4);
	memcpy(data + 8, filename, strlen(filename));
	data[8 + strlen(filename)] = '\0';
	client->afc_packet->operation = AFC_OP_FILE_OPEN;
	client->afc_packet->entire_length = client->afc_packet->this_length = 0;
	bytes = afc_dispatch_packet(client, data, 8 + strlen(filename) + 1);
	free(data);

	if (bytes <= 0) {
		log_debug_msg("%s: Didn't receive a response to the command\n", __func__);
		afc_unlock(client);
		return AFC_E_NOT_ENOUGH_DATA;
	}
	// Receive the data
	ret = afc_receive_data(client, &data, &bytes);
	if ((ret == AFC_E_SUCCESS) && (bytes > 0) && data) {
		afc_unlock(client);

		// Get the file handle
		memcpy(handle, data, sizeof(uint64_t));
		free(data);
		return ret;
	}

	log_debug_msg("%s: Didn't get any further data\n", __func__);

	afc_unlock(client);

	return ret;
}

/** Attempts to the read the given number of bytes from the given file.
 * 
 * @param client The relevant AFC client
 * @param handle File handle of a previously opened file
 * @param data The pointer to the memory region to store the read data
 * @param length The number of bytes to read
 *
 * @return The number of bytes read if successful. If there was an error -1.
 */
iphone_error_t
afc_file_read(afc_client_t client, uint64_t handle, char *data, int length, uint32_t * bytes)
{
	char *input = NULL;
	int current_count = 0, bytes_loc = 0;
	const int MAXIMUM_READ_SIZE = 1 << 16;
	afc_error_t ret = AFC_E_SUCCESS;

	if (!client || !client->afc_packet || client->sfd < 0 || handle == 0)
		return AFC_E_INVALID_ARGUMENT;
	log_debug_msg("%s: called for length %i\n", __func__, length);

	afc_lock(client);

	// Looping here to get around the maximum amount of data that
	// afc_receive_data can handle
	while (current_count < length) {
		log_debug_msg("%s: current count is %i but length is %i\n", __func__, current_count, length);

		// Send the read command
		AFCFilePacket *packet = (AFCFilePacket *) malloc(sizeof(AFCFilePacket));
		packet->filehandle = handle;
		packet->size = ((length - current_count) < MAXIMUM_READ_SIZE) ? (length - current_count) : MAXIMUM_READ_SIZE;
		client->afc_packet->operation = AFC_OP_READ;
		client->afc_packet->entire_length = client->afc_packet->this_length = 0;
		bytes_loc = afc_dispatch_packet(client, (char *) packet, sizeof(AFCFilePacket));
		free(packet);

		if (bytes_loc <= 0) {
			afc_unlock(client);
			return AFC_E_NOT_ENOUGH_DATA;
		}
		// Receive the data
		ret = afc_receive_data(client, &input, &bytes_loc);
		log_debug_msg("%s: afc_receive_data returned error: %d\n", __func__, ret);
		log_debug_msg("%s: bytes returned: %i\n", __func__, bytes_loc);
		if (ret != AFC_E_SUCCESS) {
			afc_unlock(client);
			return ret;
		} else if (bytes_loc == 0) {
			if (input)
				free(input);
			afc_unlock(client);
			*bytes = current_count;
			/* FIXME: check that's actually a success */
			return ret;
		} else {
			if (input) {
				log_debug_msg("%s: %d\n", __func__, bytes_loc);
				memcpy(data + current_count, input, (bytes_loc > length) ? length : bytes_loc);
				free(input);
				input = NULL;
				current_count += (bytes_loc > length) ? length : bytes_loc;
			}
		}
	}
	log_debug_msg("%s: returning current_count as %i\n", __func__, current_count);

	afc_unlock(client);
	*bytes = current_count;
	return ret;
}

/** Writes a given number of bytes to a file.
 * 
 * @param client The client to use to write to the file.
 * @param handle File handle of previously opened file. 
 * @param data The data to write to the file.
 * @param length How much data to write.
 * 
 * @return The number of bytes written to the file, or a value less than 0 if
 *         none were written...
 */
iphone_error_t
afc_file_write(afc_client_t client, uint64_t handle,
					  const char *data, int length, uint32_t * bytes)
{
	char *acknowledgement = NULL;
	const int MAXIMUM_WRITE_SIZE = 1 << 15;
	uint32_t zero = 0, current_count = 0, i = 0;
	uint32_t segments = (length / MAXIMUM_WRITE_SIZE);
	int bytes_loc = 0;
	char *out_buffer = NULL;
	afc_error_t ret = AFC_E_SUCCESS;

	if (!client || !client->afc_packet || client->sfd < 0 || !bytes || (handle == 0))
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	log_debug_msg("%s: Write length: %i\n", __func__, length);

	// Divide the file into segments.
	for (i = 0; i < segments; i++) {
		// Send the segment
		client->afc_packet->this_length = sizeof(AFCPacket) + 8;
		client->afc_packet->entire_length = client->afc_packet->this_length + MAXIMUM_WRITE_SIZE;
		client->afc_packet->operation = AFC_OP_WRITE;
		out_buffer = (char *) malloc(sizeof(char) * client->afc_packet->entire_length - sizeof(AFCPacket));
		memcpy(out_buffer, (char *)&handle, sizeof(uint64_t));
		memcpy(out_buffer + 8, data + current_count, MAXIMUM_WRITE_SIZE);
		bytes_loc = afc_dispatch_packet(client, out_buffer, MAXIMUM_WRITE_SIZE + 8);
		if (bytes_loc < 0) {
			afc_unlock(client);
			return AFC_E_NOT_ENOUGH_DATA;
		}
		free(out_buffer);
		out_buffer = NULL;

		current_count += bytes_loc;
		ret = afc_receive_data(client, &acknowledgement, &bytes_loc);
		if (ret != AFC_E_SUCCESS) {
			afc_unlock(client);
			return ret;
		} else {
			free(acknowledgement);
		}
	}

	// By this point, we should be at the end. i.e. the last segment that
	// didn't get sent in the for loop
	// this length is fine because it's always sizeof(AFCPacket) + 8, but
	// to be sure we do it again
	if (current_count == (uint32_t)length) {
		afc_unlock(client);
		*bytes = current_count;
		return ret;
	}

	client->afc_packet->this_length = sizeof(AFCPacket) + 8;
	client->afc_packet->entire_length = client->afc_packet->this_length + (length - current_count);
	client->afc_packet->operation = AFC_OP_WRITE;
	out_buffer = (char *) malloc(sizeof(char) * client->afc_packet->entire_length - sizeof(AFCPacket));
	memcpy(out_buffer, (char *) &handle, sizeof(uint64_t));
	memcpy(out_buffer + 8, data + current_count, (length - current_count));
	bytes_loc = afc_dispatch_packet(client, out_buffer, (length - current_count) + 8);
	free(out_buffer);
	out_buffer = NULL;

	current_count += bytes_loc;

	if (bytes_loc <= 0) {
		afc_unlock(client);
		*bytes = current_count;
		return AFC_E_SUCCESS;
	}

	zero = bytes_loc;
	ret = afc_receive_data(client, &acknowledgement, &bytes_loc);
	afc_unlock(client);
	if (ret != AFC_E_SUCCESS) {
		log_debug_msg("%s: uh oh?\n", __func__);
	} else {
		free(acknowledgement);
	}
	*bytes = current_count;
	return ret;
}

/** Closes a file on the phone. 
 * 
 * @param client The client to close the file with.
 * @param handle File handle of a previously opened file.
 */
afc_error_t afc_file_close(afc_client_t client, uint64_t handle)
{
	char *buffer = malloc(sizeof(char) * 8);
	int bytes = 0;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client || (handle == 0))
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	log_debug_msg("%s: File handle %i\n", __func__, handle);

	// Send command
	memcpy(buffer, &handle, sizeof(uint64_t));
	client->afc_packet->operation = AFC_OP_FILE_CLOSE;
	client->afc_packet->entire_length = client->afc_packet->this_length = 0;
	bytes = afc_dispatch_packet(client, buffer, 8);
	free(buffer);
	buffer = NULL;

	if (bytes <= 0) {
		afc_unlock(client);
		return AFC_E_UNKNOWN_ERROR;
	}

	// Receive the response
	ret = afc_receive_data(client, &buffer, &bytes);
	if (buffer)
		free(buffer);

	afc_unlock(client);

	return ret;
}

/** Locks or unlocks a file on the phone. 
 *
 * makes use of flock on the device, see
 * http://developer.apple.com/documentation/Darwin/Reference/ManPages/man2/flock.2.html
 *
 * @param client The client to lock the file with.
 * @param handle File handle of a previously opened file.
 * @param operation the lock or unlock operation to perform, this is one of
 *        AFC_LOCK_SH (shared lock), AFC_LOCK_EX (exclusive lock),
 *        or AFC_LOCK_UN (unlock).
 */
afc_error_t afc_file_lock(afc_client_t client, uint64_t handle, afc_lock_op_t operation)
{
	char *buffer = malloc(16);
	int bytes = 0;
	uint64_t op = operation;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client || (handle == 0))
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	log_debug_msg("%s: file handle %i\n", __func__, handle);

	// Send command
	memcpy(buffer, &handle, sizeof(uint64_t));
	memcpy(buffer + 8, &op, 8);

	client->afc_packet->operation = AFC_OP_FILE_LOCK;
	client->afc_packet->entire_length = client->afc_packet->this_length = 0;
	bytes = afc_dispatch_packet(client, buffer, 16);
	free(buffer);
	buffer = NULL;

	if (bytes <= 0) {
		afc_unlock(client);
		log_debug_msg("%s: could not send lock command\n", __func__);
		return AFC_E_UNKNOWN_ERROR;
	}
	// Receive the response
	ret = afc_receive_data(client, &buffer, &bytes);
	if (buffer) {
		log_debug_buffer(buffer, bytes);
		free(buffer);
	}
	afc_unlock(client);

	return ret;
}

/** Seeks to a given position of a pre-opened file on the phone. 
 * 
 * @param client The client to use to seek to the position.
 * @param handle File handle of a previously opened.
 * @param offset Seek offset.
 * @param whence Seeking direction, one of SEEK_SET, SEEK_CUR, or SEEK_END.
 * 
 * @return AFC_E_SUCCESS on success, AFC_E_NOT_ENOUGH_DATA on failure.
 */
afc_error_t afc_file_seek(afc_client_t client, uint64_t handle, int64_t offset, int whence)
{
	char *buffer = (char *) malloc(sizeof(char) * 24);
	uint32_t zero = 0;
	int bytes = 0;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client || (handle == 0))
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	// Send the command
	memcpy(buffer, &handle, sizeof(uint64_t));	// handle
	memcpy(buffer + 8, &whence, sizeof(int32_t));	// fromwhere
	memcpy(buffer + 12, &zero, sizeof(uint32_t));	// pad
	memcpy(buffer + 16, &offset, sizeof(uint64_t));	// offset
	client->afc_packet->operation = AFC_OP_FILE_SEEK;
	client->afc_packet->this_length = client->afc_packet->entire_length = 0;
	bytes = afc_dispatch_packet(client, buffer, 24);
	free(buffer);
	buffer = NULL;

	if (bytes <= 0) {
		afc_unlock(client);
		return AFC_E_NOT_ENOUGH_DATA;
	}
	// Receive response
	ret = afc_receive_data(client, &buffer, &bytes);
	if (buffer)
		free(buffer);

	afc_unlock(client);

	return ret;
}

/** Returns current position in a pre-opened file on the phone.
 * 
 * @param client The client to use.
 * @param handle File handle of a previously opened file.
 * @param position Position in bytes of indicator
 * 
 * @return AFC_E_SUCCESS on success, AFC_E_NOT_ENOUGH_DATA on failure.
 */
afc_error_t afc_file_tell(afc_client_t client, uint64_t handle, uint64_t *position)
{
	char *buffer = (char *) malloc(sizeof(char) * 8);
	int bytes = 0;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client || (handle == 0))
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	// Send the command
	memcpy(buffer, &handle, sizeof(uint64_t));	// handle
	client->afc_packet->operation = AFC_OP_FILE_TELL;
	client->afc_packet->this_length = client->afc_packet->entire_length = 0;
	bytes = afc_dispatch_packet(client, buffer, 8);
	free(buffer);
	buffer = NULL;

	if (bytes <= 0) {
		afc_unlock(client);
		return AFC_E_NOT_ENOUGH_DATA;
	}

	// Receive the data
	ret = afc_receive_data(client, &buffer, &bytes);
	if (bytes > 0 && buffer) {
		/* Get the position */
		memcpy(position, buffer, sizeof(uint64_t));
	}
	if (buffer)
		free(buffer);

	afc_unlock(client);

	return ret;
}

/** Sets the size of a file on the phone.
 * 
 * @param client The client to use to set the file size.
 * @param handle File handle of a previously opened file.
 * @param newsize The size to set the file to. 
 * 
 * @return 0 on success, -1 on failure. 
 * 
 * @note This function is more akin to ftruncate than truncate, and truncate
 *       calls would have to open the file before calling this, sadly.
 */
afc_error_t afc_file_truncate(afc_client_t client, uint64_t handle, uint64_t newsize)
{
	char *buffer = (char *) malloc(sizeof(char) * 16);
	int bytes = 0;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client || (handle == 0))
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	// Send command
	memcpy(buffer, &handle, sizeof(uint64_t));	// handle
	memcpy(buffer + 8, &newsize, sizeof(uint64_t));	// newsize
	client->afc_packet->operation = AFC_OP_FILE_SET_SIZE;
	client->afc_packet->this_length = client->afc_packet->entire_length = 0;
	bytes = afc_dispatch_packet(client, buffer, 16);
	free(buffer);
	buffer = NULL;

	if (bytes <= 0) {
		afc_unlock(client);
		return AFC_E_NOT_ENOUGH_DATA;
	}
	// Receive response
	ret = afc_receive_data(client, &buffer, &bytes);
	if (buffer)
		free(buffer);

	afc_unlock(client);

	return ret;
}

/** Sets the size of a file on the phone without prior opening it.
 * 
 * @param client The client to use to set the file size.
 * @param path The path of the file to be truncated.
 * @param newsize The size to set the file to. 
 * 
 * @return AFC_E_SUCCESS if everything went well, AFC_E_INVALID_ARGUMENT
 *         if arguments are NULL or invalid, AFC_E_NOT_ENOUGH_DATA otherwise.
 */
afc_error_t afc_truncate(afc_client_t client, const char *path, off_t newsize)
{
	char *response = NULL;
	char *send = (char *) malloc(sizeof(char) * (strlen(path) + 1 + 8));
	int bytes = 0;
	uint64_t size_requested = newsize;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client || !path || !client->afc_packet || client->sfd < 0)
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	// Send command
	memcpy(send, &size_requested, 8);
	memcpy(send + 8, path, strlen(path) + 1);
	client->afc_packet->entire_length = client->afc_packet->this_length = 0;
	client->afc_packet->operation = AFC_OP_TRUNCATE;
	bytes = afc_dispatch_packet(client, send, 8 + strlen(path) + 1);
	free(send);
	if (bytes <= 0) {
		afc_unlock(client);
		return AFC_E_NOT_ENOUGH_DATA;
	}
	// Receive response
	ret = afc_receive_data(client, &response, &bytes);
	if (response)
		free(response);

	afc_unlock(client);

	return ret;
}

/** Creates a hard link or symbolic link on the device. 
 * 
 * @param client The client to use for making a link
 * @param type 1 = hard link, 2 = symlink
 * @param target The file to be linked.
 * @param linkname The name of link.
 * 
 * @return AFC_E_SUCCESS if everything went well, AFC_E_INVALID_ARGUMENT
 *         if arguments are NULL or invalid, AFC_E_NOT_ENOUGH_DATA otherwise.
 */
afc_error_t afc_make_link(afc_client_t client, afc_link_type_t linktype, const char *target, const char *linkname)
{
	char *response = NULL;
	char *send = (char *) malloc(sizeof(char) * (strlen(target)+1 + strlen(linkname)+1 + 8));
	int bytes = 0;
	uint64_t type = linktype;
	afc_error_t ret = AFC_E_UNKNOWN_ERROR;

	if (!client || !target || !linkname || !client->afc_packet || client->sfd < 0)
		return AFC_E_INVALID_ARGUMENT;

	afc_lock(client);

	log_debug_msg("%s: link type: %lld\n", __func__, type);
	log_debug_msg("%s: target: %s, length:%d\n", __func__, target, strlen(target));
	log_debug_msg("%s: linkname: %s, length:%d\n", __func__, linkname, strlen(linkname));

	// Send command
	memcpy(send, &type, 8);
	memcpy(send + 8, target, strlen(target) + 1);
	memcpy(send + 8 + strlen(target) + 1, linkname, strlen(linkname) + 1);
	client->afc_packet->entire_length = client->afc_packet->this_length = 0;
	client->afc_packet->operation = AFC_OP_MAKE_LINK;
	bytes = afc_dispatch_packet(client, send, 8 + strlen(linkname) + 1 + strlen(target) + 1);
	free(send);
	if (bytes <= 0) {
		afc_unlock(client);
		return AFC_E_NOT_ENOUGH_DATA;
	}
	// Receive response
	ret = afc_receive_data(client, &response, &bytes);
	if (response)
		free(response);

	afc_unlock(client);

	return ret;
}