src/sftp.c

/* Copyright (c) 2004-2005, Sara Golemon <sarag@libssh2.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms,
 * with or without modification, are permitted provided
 * that the following conditions are met:
 *
 *   Redistributions of source code must retain the above
 *   copyright notice, this list of conditions and the
 *   following disclaimer.
 *
 *   Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials
 *   provided with the distribution.
 *
 *   Neither the name of the copyright holder nor the names
 *   of any other contributors may be used to endorse or
 *   promote products derived from this software without
 *   specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 */

#include "libssh2_priv.h"
#include "libssh2_sftp.h"

/* Note: Version 6 was documented at the time of writing
 * However it was marked as "DO NOT IMPLEMENT" due to pending changes
 *
 * This release of libssh2 implements Version 5 with automatic downgrade
 * based on server's declaration
 */

/* SFTP packet types */
#define SSH_FXP_INIT				1
#define SSH_FXP_VERSION				2
#define SSH_FXP_OPEN				3
#define SSH_FXP_CLOSE				4
#define SSH_FXP_READ				5
#define SSH_FXP_WRITE				6
#define SSH_FXP_LSTAT				7
#define SSH_FXP_FSTAT				8
#define SSH_FXP_SETSTAT				9
#define SSH_FXP_FSETSTAT			10
#define SSH_FXP_OPENDIR				11
#define SSH_FXP_READDIR				12
#define SSH_FXP_REMOVE				13
#define SSH_FXP_MKDIR				14
#define SSH_FXP_RMDIR				15
#define SSH_FXP_REALPATH			16
#define SSH_FXP_STAT				17
#define SSH_FXP_RENAME				18
#define SSH_FXP_READLINK			19
#define SSH_FXP_SYMLINK				20
#define SSH_FXP_STATUS				101
#define SSH_FXP_HANDLE				102
#define SSH_FXP_DATA				103
#define SSH_FXP_NAME				104
#define SSH_FXP_ATTRS				105
#define SSH_FXP_EXTENDED			200
#define SSH_FXP_EXTENDED_REPLY		201

struct _LIBSSH2_SFTP {
	LIBSSH2_CHANNEL *channel;

	unsigned long request_id, version;

	LIBSSH2_PACKET_BRIGADE packets;

	LIBSSH2_SFTP_HANDLE *handles;

	unsigned long last_errno;
};

#define LIBSSH2_SFTP_HANDLE_FILE	0
#define LIBSSH2_SFTP_HANDLE_DIR		1

/* S_IFREG */
#define LIBSSH2_SFTP_ATTR_PFILETYPE_FILE	0100000
/* S_IFDIR */
#define LIBSSH2_SFTP_ATTR_PFILETYPE_DIR		0040000

struct _LIBSSH2_SFTP_HANDLE {
	LIBSSH2_SFTP *sftp;
	LIBSSH2_SFTP_HANDLE *prev, *next;

	char *handle;
	int handle_len;

	char handle_type;

	union _libssh2_sftp_handle_data {
		struct _libssh2_sftp_handle_file_data {
			libssh2_uint64_t offset;
		} file;
		struct _libssh2_sftp_handle_dir_data {
			unsigned long names_left;
			void *names_packet;
			char *next_name;
		} dir;
	} u;
};

/* {{{ libssh2_sftp_packet_add
 * Add a packet to the SFTP packet brigade
 */
static int libssh2_sftp_packet_add(LIBSSH2_SFTP *sftp, unsigned char *data, unsigned long data_len)
{
	LIBSSH2_SESSION *session = sftp->channel->session;
	LIBSSH2_PACKET *packet;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Received packet %d", (int)data[0]);
#endif
	packet = LIBSSH2_ALLOC(session, sizeof(LIBSSH2_PACKET));
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate datablock for SFTP packet", 0);
		return -1;
	}
	memset(packet, 0, sizeof(LIBSSH2_PACKET));

	packet->data = data;
	packet->data_len = data_len;
	packet->data_head = 5;
	packet->brigade = &sftp->packets;
	packet->next = NULL;
	packet->prev = sftp->packets.tail;
	if (packet->prev) {
		packet->prev->next = packet;
	} else {
		sftp->packets.head = packet;
	}
	sftp->packets.tail = packet;

	return 0;
}
/* }}} */

/* {{{ libssh2_sftp_packet_read
 * Frame an SFTP packet off the channel
 */
static int libssh2_sftp_packet_read(LIBSSH2_SFTP *sftp, int should_block)
{
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
	unsigned char buffer[4]; /* To store the packet length */
	unsigned char *packet;
	unsigned long packet_len, packet_received;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Waiting for packet: %s block", should_block ? "will" : "willnot");
#endif
	if (should_block) {
		libssh2_channel_set_blocking(channel, 1);
		if (4 != libssh2_channel_read(channel, buffer, 4)) {
			libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for FXP packet", 0);
			return -1;
		}
	} else {
		libssh2_channel_set_blocking(channel, 0);
		if (1 != libssh2_channel_read(channel, buffer, 1)) {
			libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for FXP packet", 0);
			return 0;
		}
		libssh2_channel_set_blocking(channel, 1);
		if (3 != libssh2_channel_read(channel, buffer + 1, 3)) {
			libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for FXP packet", 0);
			return -1;
		}
	}
	packet_len = libssh2_ntohu32(buffer);
#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Data begin - Packet Length: %lu", packet_len);
#endif
	if (packet_len > LIBSSH2_SFTP_PACKET_MAXLEN) {
		libssh2_error(session, LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, "SFTP packet too large", 0);
		return -1;
	}

	packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate SFTP packet", 0);
		return -1;
	}

	packet_received = 0;
	while (packet_len > packet_received) {
		long bytes_received = libssh2_channel_read(channel, packet + packet_received, packet_len - packet_received);

		if (bytes_received < 0) {
			libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Receive error waiting for SFTP packet", 0);
			LIBSSH2_FREE(session, packet);
			return -1;
		}
		packet_received += bytes_received;
	}

	if (libssh2_sftp_packet_add(sftp, packet, packet_len)) {
		LIBSSH2_FREE(session, packet);
		return -1;
	}

	return packet[0];
}
/* }}} */

/* {{{ libssh2_sftp_packet_ask
 * A la libssh2_packet_ask()
 */
static int libssh2_sftp_packet_ask(LIBSSH2_SFTP *sftp, unsigned char packet_type, unsigned long request_id, unsigned char **data, unsigned long *data_len, int poll_channel)
{
	LIBSSH2_SESSION *session = sftp->channel->session;
	LIBSSH2_PACKET *packet = sftp->packets.head;
	unsigned char match_buf[5];
	int match_len = 5;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Asking for %d packet", (int)packet_type);
#endif
	if (poll_channel) {
		if (libssh2_sftp_packet_read(sftp, 0) < 0) {
			return -1;
		}
	}

	match_buf[0] = packet_type;
	if (packet_type == SSH_FXP_VERSION) {
		/* Special consideration when matching VERSION packet */
		match_len = 1;
	} else {
		libssh2_htonu32(match_buf + 1, request_id);
	}

	while (packet) {
		if (strncmp(packet->data, match_buf, match_len) == 0) {
			*data = packet->data;
			*data_len = packet->data_len;

			if (packet->prev) {
				packet->prev->next = packet->next;
			} else {
				sftp->packets.head = packet->next;
			}

			if (packet->next) {
				packet->next->prev = packet->prev;
			} else {
				sftp->packets.tail = packet->prev;
			}

			LIBSSH2_FREE(session, packet);

			return 0;
		}
		packet = packet->next;
	}
	return -1;
}
/* }}} */

/* {{{ libssh2_sftp_packet_require
 * A la libssh2_packet_require
 */
static int libssh2_sftp_packet_require(LIBSSH2_SFTP *sftp, unsigned char packet_type, unsigned long request_id, unsigned char **data, unsigned long *data_len)
{
	LIBSSH2_SESSION *session = sftp->channel->session;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Requiring %d packet", (int)packet_type);
#endif
	if (libssh2_sftp_packet_ask(sftp, packet_type, request_id, data, data_len, 0) == 0) {
		/* A packet was available in the packet brigade */
		return 0;
	}

	while (session->socket_state == LIBSSH2_SOCKET_CONNECTED) {
		int ret = libssh2_sftp_packet_read(sftp, 1);
		if (ret < 0) {
			return -1;
		}
		if (ret == 0) continue;

		if (packet_type == ret) {
			/* Be lazy, let packet_ask pull it out of the brigade */
			return libssh2_sftp_packet_ask(sftp, packet_type, request_id, data, data_len, 0);
		}
	}

	/* Only reached if the socket died */
	return -1;
}
/* }}} */

/* {{{ libssh2_sftp_packet_requirev
 * Requie one of N possible reponses
 */
static int libssh2_sftp_packet_requirev(LIBSSH2_SFTP *sftp, int num_valid_responses, unsigned char *valid_responses, unsigned long request_id, unsigned char **data, unsigned long *data_len)
{
	int i;

	/* Flush */
	while (libssh2_sftp_packet_read(sftp, 0) > 0);

	while (sftp->channel->session->socket_state == LIBSSH2_SOCKET_CONNECTED) {
		int ret;
		for(i = 0; i < num_valid_responses; i++) {
			if (libssh2_sftp_packet_ask(sftp, valid_responses[i], request_id, data, data_len, 0) == 0) {
				return 0;
			}
		}
		ret = libssh2_sftp_packet_read(sftp, 1);
		if (ret < 0) {
			return -1;
		}
		if (ret == 0) continue;
	}

	return -1;
}
/* }}} */

/* {{{ libssh2_sftp_attrsize
 * Size that attr will occupy when turned into a bin struct
 */
static int libssh2_sftp_attrsize(LIBSSH2_SFTP_ATTRIBUTES *attrs)
{
	int attrsize = 4; /* flags(4) */

	if (!attrs) {
		return attrsize;
	}

	if (attrs->flags & LIBSSH2_SFTP_ATTR_SIZE)				attrsize += 8;
	if (attrs->flags & LIBSSH2_SFTP_ATTR_UIDGID)			attrsize += 8;
	if (attrs->flags & LIBSSH2_SFTP_ATTR_PERMISSIONS)		attrsize += 4;
	if (attrs->flags & LIBSSH2_SFTP_ATTR_ACMODTIME)			attrsize += 8;			/* atime + mtime as u32 */

	return attrsize;
}
/* }}} */

/* {{{ libssh2_sftp_attr2bin
 * Populate attributes into an SFTP block
 */
static int libssh2_sftp_attr2bin(unsigned char *p, LIBSSH2_SFTP_ATTRIBUTES *attrs)
{
	unsigned char *s = p;
	unsigned long flag_mask = LIBSSH2_SFTP_ATTR_SIZE | LIBSSH2_SFTP_ATTR_UIDGID | LIBSSH2_SFTP_ATTR_PERMISSIONS | LIBSSH2_SFTP_ATTR_ACMODTIME;

	/* TODO: When we add SFTP4+ functionality flag_mask can get additional bits */

	if (!attrs) {
		libssh2_htonu32(s, 0);
		return 4;
	}

	libssh2_htonu32(s, attrs->flags & flag_mask);				s += 4;

	if (attrs->flags & LIBSSH2_SFTP_ATTR_SIZE) {
		libssh2_htonu64(s, attrs->filesize);					s += 8;
	}

	if (attrs->flags & LIBSSH2_SFTP_ATTR_UIDGID) {
		libssh2_htonu32(s, attrs->uid);							s += 4;
		libssh2_htonu32(s, attrs->gid);							s += 4;
	}

	if (attrs->flags & LIBSSH2_SFTP_ATTR_PERMISSIONS) {
		libssh2_htonu32(s, attrs->permissions);					s += 4;
	}

	if (attrs->flags & LIBSSH2_SFTP_ATTR_ACMODTIME) {
		libssh2_htonu32(s, attrs->atime);						s += 4;
		libssh2_htonu32(s, attrs->mtime);						s += 4;
	}

	return (s - p);
}
/* }}} */

/* {{{ libssh2_sftp_bin2attr
 */
static int libssh2_sftp_bin2attr(LIBSSH2_SFTP_ATTRIBUTES *attrs, unsigned char *p)
{
	unsigned char *s = p;

	memset(attrs, 0, sizeof(LIBSSH2_SFTP_ATTRIBUTES));
	attrs->flags = libssh2_ntohu32(s);				s += 4;

	if (attrs->flags & LIBSSH2_SFTP_ATTR_SIZE) {
		attrs->filesize = libssh2_ntohu64(s);		s += 8;
	}

	if (attrs->flags & LIBSSH2_SFTP_ATTR_UIDGID) {
		attrs->uid = libssh2_ntohu32(s);			s += 4;
		attrs->gid = libssh2_ntohu32(s);			s += 4;
	}

	if (attrs->flags & LIBSSH2_SFTP_ATTR_PERMISSIONS) {
		attrs->permissions = libssh2_ntohu32(s);	s += 4;
	}

	if (attrs->flags & LIBSSH2_SFTP_ATTR_ACMODTIME) {
		attrs->atime = libssh2_ntohu32(s);			s += 4;
		attrs->mtime = libssh2_ntohu32(s);			s += 4;
	}

	return (s - p);
}
/* }}} */

/* ************
   * SFTP API *
   ************ */

/* {{{ libssh2_sftp_dtor
 * Shutdown an SFTP stream when the channel closes
 */
LIBSSH2_CHANNEL_CLOSE_FUNC(libssh2_sftp_dtor) {
	LIBSSH2_SFTP *sftp = (LIBSSH2_SFTP*)(*channel_abstract);

	/* Loop through handles closing them */
	while (sftp->handles) {
		libssh2_sftp_close_handle(sftp->handles);
	}

	LIBSSH2_FREE(session, sftp);
}
/* }}} */

/* {{{ libssh2_sftp_init
 * Startup an SFTP session
 */
LIBSSH2_API LIBSSH2_SFTP *libssh2_sftp_init(LIBSSH2_SESSION *session)
{
	LIBSSH2_SFTP *sftp;
	LIBSSH2_CHANNEL *channel;
	unsigned char *data, *s, buffer[9]; /* sftp_header(5){excludes request_id} + version_id(4) */
	unsigned long data_len;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Initializing SFTP subsystem");
#endif
	channel = libssh2_channel_open_session(session);
	if (!channel) {
		libssh2_error(session, LIBSSH2_ERROR_CHANNEL_FAILURE, "Unable to startup channel", 0);
		return NULL;
	}
	if (libssh2_channel_subsystem(channel, "sftp")) {
		libssh2_error(session, LIBSSH2_ERROR_CHANNEL_FAILURE, "Unable to request SFTP subsystem", 0);
		libssh2_channel_free(channel);
		return NULL;
	}

	libssh2_channel_set_blocking(channel, 1);

	libssh2_channel_handle_extended_data(channel, LIBSSH2_CHANNEL_EXTENDED_DATA_IGNORE);

	sftp = LIBSSH2_ALLOC(session, sizeof(LIBSSH2_SFTP));
	if (!sftp) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate a new SFTP structure", 0);
		libssh2_channel_free(channel);
		return NULL;
	}
	memset(sftp, 0, sizeof(LIBSSH2_SFTP));
	sftp->channel = channel;
	sftp->request_id = 0;

	libssh2_htonu32(buffer, 5);
	buffer[4] = SSH_FXP_INIT;
	libssh2_htonu32(buffer + 5, LIBSSH2_SFTP_VERSION);

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Sending FXP_INIT packet advertising version %d support", (int)LIBSSH2_SFTP_VERSION);
#endif
	if (9 != libssh2_channel_write(channel, buffer, 9)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send SSH_FXP_INIT", 0);
		libssh2_channel_free(channel);
		LIBSSH2_FREE(session, sftp);
		return NULL;
	}

	if (libssh2_sftp_packet_require(sftp, SSH_FXP_VERSION, 0, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for response from SFTP subsystem", 0);
		libssh2_channel_free(channel);
		LIBSSH2_FREE(session, sftp);
		return NULL;
	}
	if (data_len < 5) {
		libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "Invalid SSH_FXP_VERSION response", 0);
		libssh2_channel_free(channel);
		LIBSSH2_FREE(session, sftp);
		return NULL;
	}

	s = data + 1;
	sftp->version = libssh2_ntohu32(s);					s += 4;
	if (sftp->version > LIBSSH2_SFTP_VERSION) {
#ifdef LIBSSH2_DEBUG_SFTP
		_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Truncating remote SFTP version from %lu", sftp->version);
#endif
		sftp->version = LIBSSH2_SFTP_VERSION;
	}
#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Enabling SFTP version %lu compatability", sftp->version);
#endif
	while (s < (data + data_len)) {
		char *extension_name, *extension_data;
		unsigned long extname_len, extdata_len;

		extname_len = libssh2_ntohu32(s);				s += 4;
		extension_name = s;								s += extname_len;

		extdata_len = libssh2_ntohu32(s);				s += 4;
		extension_data = s;								s += extdata_len;

		/* TODO: Actually process extensions */
	}
	LIBSSH2_FREE(session, data);

	/* Make sure that when the channel gets closed, the SFTP service is shut down too */
	sftp->channel->abstract = sftp;
	sftp->channel->close_cb = libssh2_sftp_dtor;

	return sftp;
}
/* }}} */

/* {{{ libssh2_sftp_shutdown
 * Shutsdown the SFTP subsystem
 */
LIBSSH2_API int libssh2_sftp_shutdown(LIBSSH2_SFTP *sftp) {
	return libssh2_channel_free(sftp->channel);
}
/* }}} */

/* *******************************
   * SFTP File and Directory Ops *
   ******************************* */

/* {{{ libssh2_sftp_open_ex
 *
 */
LIBSSH2_API LIBSSH2_SFTP_HANDLE *libssh2_sftp_open_ex(LIBSSH2_SFTP *sftp, char *filename, int filename_len, unsigned long flags, long mode, int open_type)
{
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
	LIBSSH2_SFTP_HANDLE *fp;
	LIBSSH2_SFTP_ATTRIBUTES attrs = { LIBSSH2_SFTP_ATTR_PERMISSIONS };
	unsigned long data_len, packet_len = filename_len + 13 + ((open_type == LIBSSH2_SFTP_OPENFILE) ? (4 + libssh2_sftp_attrsize(&attrs)) : 0);
							/* packet_len(4) + packet_type(1) + request_id(4) + filename_len(4) + flags(4) */
	unsigned char *packet, *data, *s;
	unsigned char fopen_responses[2] = { SSH_FXP_HANDLE,	SSH_FXP_STATUS	};
	unsigned long request_id;

	s = packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for FXP_REMOVE packet", 0);
		return NULL;
	}
	/* Filetype in SFTP 3 and earlier */
	attrs.permissions = mode | ((open_type == LIBSSH2_SFTP_OPENFILE) ? LIBSSH2_SFTP_ATTR_PFILETYPE_FILE : LIBSSH2_SFTP_ATTR_PFILETYPE_DIR);

	libssh2_htonu32(s, packet_len - 4);					s += 4;
	*(s++) = (open_type == LIBSSH2_SFTP_OPENFILE) ? SSH_FXP_OPEN : SSH_FXP_OPENDIR;
	request_id = sftp->request_id++;
	libssh2_htonu32(s, request_id);						s += 4;
	libssh2_htonu32(s, filename_len);					s += 4;
	memcpy(s, filename, filename_len);					s += filename_len;
	if (open_type == LIBSSH2_SFTP_OPENFILE) {
		libssh2_htonu32(s, flags);						s += 4;
		s += libssh2_sftp_attr2bin(s, &attrs);
	}

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Sending %s open request", (open_type == LIBSSH2_SFTP_OPENFILE) ? "file" : "directory");
#endif
	if (packet_len != libssh2_channel_write(channel, packet, packet_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send FXP_REMOVE command", 0);
		LIBSSH2_FREE(session, packet);
		return NULL;
	}
	LIBSSH2_FREE(session, packet);

	if (libssh2_sftp_packet_requirev(sftp, 2, fopen_responses, request_id, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for status message", 0);
		return NULL;
	}

	if (data[0] == SSH_FXP_STATUS) {
		libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "Failed opening remote file", 0);
		sftp->last_errno = libssh2_ntohu32(data + 5);
		LIBSSH2_FREE(session, data);
		return NULL;
	}

	fp = LIBSSH2_ALLOC(session, sizeof(LIBSSH2_SFTP_HANDLE));
	if (!fp) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate new SFTP handle structure", 0);
		LIBSSH2_FREE(session, data);
		return NULL;
	}
	memset(fp, 0, sizeof(LIBSSH2_SFTP_HANDLE));
	fp->handle_type = (open_type == LIBSSH2_SFTP_OPENFILE) ? LIBSSH2_SFTP_HANDLE_FILE : LIBSSH2_SFTP_HANDLE_DIR;

	fp->handle_len = libssh2_ntohu32(data + 5);
	if (fp->handle_len > 256) {
		/* SFTP doesn't allow handles longer than 256 characters */
		fp->handle_len = 256;
	}
	fp->handle = LIBSSH2_ALLOC(session, fp->handle_len);
	if (!fp->handle) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate space for SFTP file/dir handle", 0);
		LIBSSH2_FREE(session, data);
		LIBSSH2_FREE(session, fp);
		return NULL;
	}
	memcpy(fp->handle, data + 9, fp->handle_len);
	LIBSSH2_FREE(session, data);

	/* Link the file and the sftp session together */
	fp->next = sftp->handles;
	if (fp->next) {
		fp->next->prev = fp;
	}
	fp->sftp = sftp;

	fp->u.file.offset = 0;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Open command successful");
#endif
	return fp;
}
/* }}} */

/* {{{ libssh2_sftp_read
 * Read from an SFTP file handle
 */
LIBSSH2_API size_t libssh2_sftp_read(LIBSSH2_SFTP_HANDLE *handle, char *buffer, size_t buffer_maxlen) 
{
	LIBSSH2_SFTP	*sftp	 = handle->sftp;
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
	unsigned long data_len, request_id;
	unsigned long packet_len = handle->handle_len + 25; /* packet_len(4) + packet_type(1) + request_id(4) + handle_len(4) + offset(8) + length(4) */
	unsigned char *packet, *s, *data;
	unsigned char read_responses[2] = { SSH_FXP_DATA,		SSH_FXP_STATUS };
	size_t bytes_read = 0;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Reading %lu bytes from SFTP handle", (unsigned long)buffer_maxlen);
#endif
	s = packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for FXP_CLOSE packet", 0);
		return -1;
	}

	libssh2_htonu32(s, packet_len - 4);					s += 4;
	*(s++) = SSH_FXP_READ;
	request_id = sftp->request_id++;
	libssh2_htonu32(s, request_id);						s += 4;
	libssh2_htonu32(s, handle->handle_len);				s += 4;
	memcpy(s, handle->handle, handle->handle_len);		s += handle->handle_len;
	libssh2_htonu64(s, handle->u.file.offset);			s += 8;
	libssh2_htonu32(s, buffer_maxlen);					s += 4;

	if (packet_len != libssh2_channel_write(channel, packet, packet_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send FXP_READ command", 0);
		LIBSSH2_FREE(session, packet);
		return -1;
	}
	LIBSSH2_FREE(session, packet);

	if (libssh2_sftp_packet_requirev(sftp, 2, read_responses, request_id, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for status message", 0);
		return -1;
	}

	switch (data[0]) {
		case SSH_FXP_STATUS:
			sftp->last_errno = libssh2_ntohu32(data + 5);
			libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "SFTP Protocol Error", 0);
			LIBSSH2_FREE(session, data);
			return -1;
		case SSH_FXP_DATA:
			bytes_read = libssh2_ntohu32(data + 5);
			if (bytes_read > (data_len - 9)) {
				return -1;
			}
#ifdef LIBSSH2_DEBUG_SFTP
			_libssh2_debug(session, LIBSSH2_DBG_SFTP, "%lu bytes returned", (unsigned long)bytes_read);
#endif
			memcpy(buffer, data + 9, bytes_read);
			handle->u.file.offset += bytes_read;
			LIBSSH2_FREE(session, data);
			return bytes_read;
	}

	return -1;
}
/* }}} */

/* {{{ libssh2_sftp_readdir
 * Read from an SFTP directory handle
 */
LIBSSH2_API int libssh2_sftp_readdir(LIBSSH2_SFTP_HANDLE *handle, char *buffer, size_t buffer_maxlen, LIBSSH2_SFTP_ATTRIBUTES *attrs) 
{
	LIBSSH2_SFTP	*sftp	 = handle->sftp;
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
	LIBSSH2_SFTP_ATTRIBUTES attrs_dummy;
	unsigned long data_len, request_id, filename_len, num_names;
	unsigned long packet_len = handle->handle_len + 13; /* packet_len(4) + packet_type(1) + request_id(4) + handle_len(4) */
	unsigned char *packet, *s, *data;
	unsigned char read_responses[2] = { SSH_FXP_NAME,		SSH_FXP_STATUS };

	if (handle->u.dir.names_left) {
		/* A prior request returned more than one directory entry, feed it back from the buffer */
		unsigned char *s = handle->u.dir.next_name;
		unsigned long real_filename_len = libssh2_ntohu32(s);

		filename_len = real_filename_len;			s += 4;
		if (filename_len > buffer_maxlen) {
			filename_len = buffer_maxlen;
		}
		memcpy(buffer, s, filename_len);			s += real_filename_len;

		/* Skip longname */
		s += 4 + libssh2_ntohu32(s);

		if (attrs) {
			memset(attrs, 0, sizeof(LIBSSH2_SFTP_ATTRIBUTES));
		}
		s += libssh2_sftp_bin2attr(attrs ? attrs : &attrs_dummy, s);

		handle->u.dir.next_name = s;
		if ((--handle->u.dir.names_left) == 0) {
			LIBSSH2_FREE(session, handle->u.dir.names_packet);
		}

		return filename_len;
	}

	/* Request another entry(entries?) */

	s = packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for FXP_READDIR packet", 0);
		return -1;
	}

	libssh2_htonu32(s, packet_len - 4);					s += 4;
	*(s++) = SSH_FXP_READDIR;
	request_id = sftp->request_id++;
	libssh2_htonu32(s, request_id);						s += 4;
	libssh2_htonu32(s, handle->handle_len);				s += 4;
	memcpy(s, handle->handle, handle->handle_len);		s += handle->handle_len;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Reading entries from directory handle");
#endif
	if (packet_len != libssh2_channel_write(channel, packet, packet_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send FXP_READ command", 0);
		LIBSSH2_FREE(session, packet);
		return -1;
	}
	LIBSSH2_FREE(session, packet);

	if (libssh2_sftp_packet_requirev(sftp, 2, read_responses, request_id, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for status message", 0);
		return -1;
	}

	if (data[0] == SSH_FXP_STATUS) {
		int retcode;

		retcode = libssh2_ntohu32(data + 5);
		LIBSSH2_FREE(session, data);
		if (retcode == LIBSSH2_FX_EOF) {
			return 0;
		} else {
			sftp->last_errno = retcode;
			libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "SFTP Protocol Error", 0);
			return -1;
		}
	}

	num_names = libssh2_ntohu32(data + 5);
#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "%lu entries returned", num_names);
#endif
	if (num_names <= 0) {
		LIBSSH2_FREE(session, data);
		return (num_names == 0) ? 0 : -1;
	}

	if (num_names == 1) {
		unsigned long real_filename_len = libssh2_ntohu32(data + 9);

		filename_len = real_filename_len;
		if (filename_len > buffer_maxlen) {
			filename_len = buffer_maxlen;
		}
		memcpy(buffer, data + 13, filename_len);

		if (attrs) {
			memset(attrs, 0, sizeof(LIBSSH2_SFTP_ATTRIBUTES));
			libssh2_sftp_bin2attr(attrs, data + 13 + real_filename_len + (4 + libssh2_ntohu32(data + 13 + real_filename_len)));
		}
		LIBSSH2_FREE(session, data);

		return filename_len; 
	}

	handle->u.dir.names_left = num_names;
	handle->u.dir.names_packet = data;
	handle->u.dir.next_name = data + 9;

	/* Be lazy, just use the name popping mechanism from the start of the function */
	return libssh2_sftp_readdir(handle, buffer, buffer_maxlen, attrs);
}
/* }}} */

/* {{{ libssh2_sftp_write
 * Write data to a file handle
 */
LIBSSH2_API size_t libssh2_sftp_write(LIBSSH2_SFTP_HANDLE *handle, const char *buffer, size_t count)
{
	LIBSSH2_SFTP	*sftp	 = handle->sftp;
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
	unsigned long data_len, request_id, retcode;
	unsigned long packet_len = handle->handle_len + count + 25; /* packet_len(4) + packet_type(1) + request_id(4) + handle_len(4) + offset(8) + count(4) */
	unsigned char *packet, *s, *data;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Writing %lu bytes", (unsigned long)count);
#endif
	s = packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for FXP_WRITE packet", 0);
		return -1;
	}

	libssh2_htonu32(s, packet_len - 4);					s += 4;
	*(s++) = SSH_FXP_WRITE;
	request_id = sftp->request_id++;
	libssh2_htonu32(s, request_id);						s += 4;
	libssh2_htonu32(s, handle->handle_len);				s += 4;
	memcpy(s, handle->handle, handle->handle_len);		s += handle->handle_len;
	libssh2_htonu64(s, handle->u.file.offset);			s += 8;
	libssh2_htonu32(s, count);							s += 4;
	memcpy(s, buffer, count);							s += count;

	if (packet_len != libssh2_channel_write(channel, packet, packet_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send FXP_WRITE command", 0);
		LIBSSH2_FREE(session, packet);
		return -1;
	}
	LIBSSH2_FREE(session, packet);

	if (libssh2_sftp_packet_require(sftp, SSH_FXP_STATUS, request_id, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for status message", 0);
		return -1;
	}

	retcode = libssh2_ntohu32(data + 5);
	LIBSSH2_FREE(session, data);

	if (retcode == LIBSSH2_FX_OK) {
		handle->u.file.offset += count;
		return count;
	}
	libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "SFTP Protocol Error", 0);
	sftp->last_errno = retcode;

	return -1;
}
/* }}} */

/* {{{ libssh2_sftp_fstat_ex
 * Get or Set stat on a file
 */
LIBSSH2_API int libssh2_sftp_fstat_ex(LIBSSH2_SFTP_HANDLE *handle, LIBSSH2_SFTP_ATTRIBUTES *attrs, int setstat)
{
	LIBSSH2_SFTP	*sftp	 = handle->sftp;
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
	unsigned long data_len, request_id;
	unsigned long packet_len = handle->handle_len + 13 + (setstat ? libssh2_sftp_attrsize(attrs) : 0); 
											/* packet_len(4) + packet_type(1) + request_id(4) + handle_len(4) */
	unsigned char *packet, *s, *data;
	unsigned char fstat_responses[2] = { SSH_FXP_ATTRS,		SSH_FXP_STATUS };

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Issuing %s command", setstat ? "set-stat" : "stat");
#endif
	s = packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for FSTAT/FSETSTAT packet", 0);
		return -1;
	}

	libssh2_htonu32(s, packet_len - 4);					s += 4;
	*(s++) = setstat ? SSH_FXP_FSETSTAT : SSH_FXP_FSTAT;
	request_id = sftp->request_id++;
	libssh2_htonu32(s, request_id);						s += 4;
	libssh2_htonu32(s, handle->handle_len);				s += 4;
	memcpy(s, handle->handle, handle->handle_len);		s += handle->handle_len;
	if (setstat) {
		s += libssh2_sftp_attr2bin(s, attrs);
	}

	if (packet_len != libssh2_channel_write(channel, packet, packet_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, setstat ? "Unable to send FXP_FSETSTAT" : "Unable to send FXP_FSTAT command", 0);
		LIBSSH2_FREE(session, packet);
		return -1;
	}
	LIBSSH2_FREE(session, packet);

	if (libssh2_sftp_packet_requirev(sftp, 2, fstat_responses, request_id, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for status message", 0);
		return -1;
	}

	if (data[0] == SSH_FXP_STATUS) {
		int retcode;

		retcode = libssh2_ntohu32(data + 5);
		LIBSSH2_FREE(session, data);
		if (retcode == LIBSSH2_FX_OK) {
			return 0;
		} else {
			sftp->last_errno = retcode;
			libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "SFTP Protocol Error", 0);
			return -1;
		}
	}

	libssh2_sftp_bin2attr(attrs, data + 5);

	return 0;
}
/* }}} */

/* {{{ libssh2_sftp_seek
 * Set the read/write pointer to an arbitrary position within the file
 */
LIBSSH2_API void libssh2_sftp_seek(LIBSSH2_SFTP_HANDLE *handle, size_t offset)
{
	handle->u.file.offset = offset;
}
/* }}} */

/* {{{ libssh2_sftp_tell
 * Return the current read/write pointer's offset
 */
LIBSSH2_API size_t libssh2_sftp_tell(LIBSSH2_SFTP_HANDLE *handle)
{
	return handle->u.file.offset;
}
/* }}} */


/* {{{ libssh2_sftp_close_handle
 * Close a file or directory handle
 * Also frees handle resource and unlinks it from the SFTP structure
 */
LIBSSH2_API int libssh2_sftp_close_handle(LIBSSH2_SFTP_HANDLE *handle)
{
	LIBSSH2_SFTP	*sftp	 = handle->sftp;
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
	unsigned long data_len, retcode, request_id;
	unsigned long packet_len = handle->handle_len + 13; /* packet_len(4) + packet_type(1) + request_id(4) + handle_len(4) */
	unsigned char *packet, *s, *data;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Closing handle");
#endif
	s = packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for FXP_CLOSE packet", 0);
		return -1;
	}

	libssh2_htonu32(s, packet_len - 4);					s += 4;
	*(s++) = SSH_FXP_CLOSE;
	request_id = sftp->request_id++;
	libssh2_htonu32(s, request_id);						s += 4;
	libssh2_htonu32(s, handle->handle_len);				s += 4;
	memcpy(s, handle->handle, handle->handle_len);		s += handle->handle_len;

	if (packet_len != libssh2_channel_write(channel, packet, packet_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send FXP_CLOSE command", 0);
		LIBSSH2_FREE(session, packet);
		return -1;
	}
	LIBSSH2_FREE(session, packet);

	if (libssh2_sftp_packet_require(sftp, SSH_FXP_STATUS, request_id, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for status message", 0);
		return -1;
	}

	retcode = libssh2_ntohu32(data + 5);
	LIBSSH2_FREE(session, data);

	if (retcode != LIBSSH2_FX_OK) {
		sftp->last_errno = retcode;
		libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "SFTP Protocol Error", 0);
		return -1;
	}

	if (handle == sftp->handles) {
		sftp->handles = handle->next;
	}
	if (handle->next) {
		handle->next->prev = NULL;
	}

	if ((handle->handle_type == LIBSSH2_SFTP_HANDLE_DIR) &&
		handle->u.dir.names_left) {
		LIBSSH2_FREE(session, handle->u.dir.names_packet);
	}

	LIBSSH2_FREE(session, handle->handle);
	LIBSSH2_FREE(session, handle);

	return 0;
}
/* }}} */

/* **********************
   * SFTP Miscellaneous *
   ********************** */

/* {{{ libssh2_sftp_unlink_ex
 * Delete a file from the remote server
 */
LIBSSH2_API int libssh2_sftp_unlink_ex(LIBSSH2_SFTP *sftp, char *filename, int filename_len)
{
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
	unsigned long data_len, retcode, request_id;
	unsigned long packet_len = filename_len + 13; /* packet_len(4) + packet_type(1) + request_id(4) + filename_len(4) */
	unsigned char *packet, *s, *data;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Unlinking %s", filename);
#endif
	s = packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for FXP_REMOVE packet", 0);
		return -1;
	}

	libssh2_htonu32(s, packet_len - 4);					s += 4;
	*(s++) = SSH_FXP_REMOVE;
	request_id = sftp->request_id++;
	libssh2_htonu32(s, request_id);						s += 4;
	libssh2_htonu32(s, filename_len);					s += 4;
	memcpy(s, filename, filename_len);					s += filename_len;

	if (packet_len != libssh2_channel_write(channel, packet, packet_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send FXP_REMOVE command", 0);
		LIBSSH2_FREE(session, packet);
		return -1;
	}
	LIBSSH2_FREE(session, packet);

	if (libssh2_sftp_packet_require(sftp, SSH_FXP_STATUS, request_id, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for status message", 0);
		return -1;
	}

	retcode = libssh2_ntohu32(data + 5);
	LIBSSH2_FREE(session, data);

	if (retcode == LIBSSH2_FX_OK) {
		return 0;
	} else {
		sftp->last_errno = retcode;
		libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "SFTP Protocol Error", 0);
		return -1;
	}
}
/* }}} */

/* {{{ libssh2_sftp_rename_ex
 * Rename a file on the remote server
 */
LIBSSH2_API int libssh2_sftp_rename_ex(LIBSSH2_SFTP *sftp,  char *source_filename,	int source_filename_len,
															char *dest_filename,	int dest_filename_len,
															long flags)
{
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
	unsigned long data_len, retcode = -1, request_id;
	unsigned long packet_len = source_filename_len + dest_filename_len + 21; /* packet_len(4) + packet_type(1) + request_id(4) + 
																				source_filename_len(4) + dest_filename_len(4) + flags(4) */
	unsigned char *packet, *s, *data;

	if (sftp->version < 2) {
		libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "Server does not support RENAME", 0);
		return -1;
	}

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Renaming %s to %s", source_filename, dest_filename);
#endif
	s = packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for FXP_RENAME packet", 0);
		return -1;
	}

	libssh2_htonu32(s, packet_len - 4);					s += 4;
	*(s++) = SSH_FXP_RENAME;
	request_id = sftp->request_id++;
	libssh2_htonu32(s, request_id);						s += 4;
	libssh2_htonu32(s, source_filename_len);			s += 4;
	memcpy(s, source_filename, source_filename_len);	s += source_filename_len;
	libssh2_htonu32(s, dest_filename_len);				s += 4;
	memcpy(s, dest_filename, dest_filename_len);		s += dest_filename_len;
	libssh2_htonu32(s, flags);							s += 4;

	if (packet_len != libssh2_channel_write(channel, packet, packet_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send FXP_REMOVE command", 0);
		LIBSSH2_FREE(session, packet);
		return -1;
	}
	LIBSSH2_FREE(session, packet);

	if (libssh2_sftp_packet_require(sftp, SSH_FXP_STATUS, request_id, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for status message", 0);
		return -1;
	}

	retcode = libssh2_ntohu32(data + 5);
	LIBSSH2_FREE(session, data);

	switch (retcode) {
		case LIBSSH2_FX_OK:
			retcode = 0;
			break;
		case LIBSSH2_FX_FILE_ALREADY_EXISTS:
			libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "File already exists and SSH_FXP_RENAME_OVERWRITE not specified", 0);
			sftp->last_errno = retcode;
			retcode = -1;
			break;
		case LIBSSH2_FX_OP_UNSUPPORTED:
			libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "Operation Not Supported", 0);
			sftp->last_errno = retcode;
			retcode = -1;
			break;
		default:
			libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "SFTP Protocol Error", 0);
			sftp->last_errno = retcode;
			retcode = -1;
	}

	return retcode;
}
/* }}} */

/* {{{ libssh2_sftp_mkdir_ex
 * Create a directory
 */
LIBSSH2_API int libssh2_sftp_mkdir_ex(LIBSSH2_SFTP *sftp, char *path, int path_len, long mode)
{
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
    LIBSSH2_SFTP_ATTRIBUTES attrs = { LIBSSH2_SFTP_ATTR_PERMISSIONS };
	unsigned long data_len, retcode, request_id;
	unsigned long packet_len = path_len + 13 + libssh2_sftp_attrsize(&attrs);
			/* packet_len(4) + packet_type(1) + request_id(4) + path_len(4) */
	unsigned char *packet, *s, *data;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Creating directory %s with mode 0%lo", path, mode);
#endif
	s = packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for FXP_MKDIR packet", 0);
		return -1;
	}
	/* Filetype in SFTP 3 and earlier */
	attrs.permissions = mode | LIBSSH2_SFTP_ATTR_PFILETYPE_DIR;

	libssh2_htonu32(s, packet_len - 4);					s += 4;
	*(s++) = SSH_FXP_MKDIR;
	request_id = sftp->request_id++;
	libssh2_htonu32(s, request_id);						s += 4;
	libssh2_htonu32(s, path_len);						s += 4;
	memcpy(s, path, path_len);							s += path_len;
	s += libssh2_sftp_attr2bin(s, &attrs);

	if (packet_len != libssh2_channel_write(channel, packet, packet_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send FXP_REMOVE command", 0);
		LIBSSH2_FREE(session, packet);
		return -1;
	}
	LIBSSH2_FREE(session, packet);

	if (libssh2_sftp_packet_require(sftp, SSH_FXP_STATUS, request_id, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for status message", 0);
		return -1;
	}

	retcode = libssh2_ntohu32(data + 5);
	LIBSSH2_FREE(session, data);

	if (retcode == LIBSSH2_FX_OK) {
		return 0;
	} else {
		libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "SFTP Protocol Error", 0);
		sftp->last_errno = retcode;
		return -1;
	}
}
/* }}} */

/* {{{ libssh2_sftp_rmdir_ex
 * Remove a directory
 */
LIBSSH2_API int libssh2_sftp_rmdir_ex(LIBSSH2_SFTP *sftp, char *path, int path_len)
{
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
	unsigned long data_len, retcode, request_id;
	unsigned long packet_len = path_len + 13; /* packet_len(4) + packet_type(1) + request_id(4) + path_len(4) */
	unsigned char *packet, *s, *data;

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "Removing directory: %s", path);
#endif
	s = packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for FXP_MKDIR packet", 0);
		return -1;
	}

	libssh2_htonu32(s, packet_len - 4);					s += 4;
	*(s++) = SSH_FXP_RMDIR;
	request_id = sftp->request_id++;
	libssh2_htonu32(s, request_id);						s += 4;
	libssh2_htonu32(s, path_len);						s += 4;
	memcpy(s, path, path_len);							s += path_len;

	if (packet_len != libssh2_channel_write(channel, packet, packet_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send FXP_REMOVE command", 0);
		LIBSSH2_FREE(session, packet);
		return -1;
	}
	LIBSSH2_FREE(session, packet);

	if (libssh2_sftp_packet_require(sftp, SSH_FXP_STATUS, request_id, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for status message", 0);
		return -1;
	}

	retcode = libssh2_ntohu32(data + 5);
	LIBSSH2_FREE(session, data);

	if (retcode == LIBSSH2_FX_OK) {
		return 0;
	} else {
		sftp->last_errno = retcode;
		libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "SFTP Protocol Error", 0);
		return -1;
	}
}
/* }}} */

/* {{{ libssh2_sftp_stat_ex
 * Stat a file or symbolic link
 */
LIBSSH2_API int libssh2_sftp_stat_ex(LIBSSH2_SFTP *sftp, char *path, int path_len, int stat_type, LIBSSH2_SFTP_ATTRIBUTES *attrs)
{
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
	unsigned long data_len, request_id;
	unsigned long packet_len = path_len + 13 + ((stat_type == LIBSSH2_SFTP_SETSTAT) ? libssh2_sftp_attrsize(attrs) : 0); 
									/* packet_len(4) + packet_type(1) + request_id(4) + path_len(4) */
	unsigned char *packet, *s, *data;
	unsigned char stat_responses[2] = { SSH_FXP_ATTRS,		SSH_FXP_STATUS	};

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "%s %s", (stat_type == LIBSSH2_SFTP_SETSTAT) ? "Set-statting" : (stat_type == LIBSSH2_SFTP_LSTAT ? "LStatting" : "Statting"), path);
#endif
	s = packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for FXP_MKDIR packet", 0);
		return -1;
	}

	libssh2_htonu32(s, packet_len - 4);					s += 4;
	switch (stat_type) {
		case LIBSSH2_SFTP_SETSTAT:
			*(s++) = SSH_FXP_SETSTAT;
			break;
		case LIBSSH2_SFTP_LSTAT:
			*(s++) = SSH_FXP_LSTAT;
			break;
		case LIBSSH2_SFTP_STAT:
		default:
			*(s++) = SSH_FXP_STAT;
	}
	request_id = sftp->request_id++;
	libssh2_htonu32(s, request_id);						s += 4;
	libssh2_htonu32(s, path_len);						s += 4;
	memcpy(s, path, path_len);							s += path_len;
	if (stat_type == LIBSSH2_SFTP_SETSTAT) {
		s += libssh2_sftp_attr2bin(s, attrs);
	}

	if (packet_len != libssh2_channel_write(channel, packet, packet_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send STAT/LSTAT/SETSTAT command", 0);
		LIBSSH2_FREE(session, packet);
		return -1;
	}
	LIBSSH2_FREE(session, packet);

	if (libssh2_sftp_packet_requirev(sftp, 2, stat_responses, request_id, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for status message", 0);
		return -1;
	}

	if (data[0] == SSH_FXP_STATUS) {
		int retcode;

		retcode = libssh2_ntohu32(data + 5);
		LIBSSH2_FREE(session, data);
		if (retcode == LIBSSH2_FX_OK) {
			return 0;
		} else {
			sftp->last_errno = retcode;
			libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "SFTP Protocol Error", 0);
			return -1;
		}
	}

	memset(attrs, 0, sizeof(LIBSSH2_SFTP_ATTRIBUTES));
	libssh2_sftp_bin2attr(attrs, data + 5);
	LIBSSH2_FREE(session, data);

	return 0;
}
/* }}} */

/* {{{ libssh2_sftp_symlink_ex
 * Read or set a symlink
 */
LIBSSH2_API int libssh2_sftp_symlink_ex(LIBSSH2_SFTP *sftp, const char *path, int path_len, char *target, int target_len, int link_type)
{
	LIBSSH2_CHANNEL *channel = sftp->channel;
	LIBSSH2_SESSION *session = channel->session;
	unsigned long data_len, request_id, link_len;
	unsigned long packet_len = path_len + 13 + ((link_type == LIBSSH2_SFTP_SYMLINK) ? (4 + target_len) : 0); 
									/* packet_len(4) + packet_type(1) + request_id(4) + path_len(4) */
	unsigned char *packet, *s, *data;
	unsigned char link_responses[2] = { SSH_FXP_NAME,		SSH_FXP_STATUS	};

	if ((sftp->version < 3) &&
		(link_type != LIBSSH2_SFTP_REALPATH)) {
		libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "Server does not support SYMLINK or READLINK", 0);
		return -1;
	}

	s = packet = LIBSSH2_ALLOC(session, packet_len);
	if (!packet) {
		libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate memory for SYMLINK/READLINK/REALPATH packet", 0);
		return -1;
	}

#ifdef LIBSSH2_DEBUG_SFTP
	_libssh2_debug(session, LIBSSH2_DBG_SFTP, "%s %s on %s", (link_type == LIBSSH2_SFTP_SYMLINK) ? "Creating" : "Reading",
															 (link_type == LIBSSH2_SFTP_REALPATH) ? "realpath" : "symlink", path);
#endif
	libssh2_htonu32(s, packet_len - 4);					s += 4;
	switch (link_type) {
		case LIBSSH2_SFTP_REALPATH:
			*(s++) = SSH_FXP_REALPATH;
			break;
		case LIBSSH2_SFTP_SYMLINK:
			*(s++) = SSH_FXP_SYMLINK;
			break;
		case LIBSSH2_SFTP_READLINK:
		default:
			*(s++) = SSH_FXP_READLINK;
	}
	request_id = sftp->request_id++;
	libssh2_htonu32(s, request_id);						s += 4;
	libssh2_htonu32(s, path_len);						s += 4;
	memcpy(s, path, path_len);							s += path_len;
	if (link_type == LIBSSH2_SFTP_SYMLINK) {
		libssh2_htonu32(s, target_len);					s += 4;
		memcpy(s, target, target_len);					s += target_len;
	}

	if (packet_len != libssh2_channel_write(channel, packet, packet_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send SYMLINK/READLINK command", 0);
		LIBSSH2_FREE(session, packet);
		return -1;
	}
	LIBSSH2_FREE(session, packet);

	if (libssh2_sftp_packet_requirev(sftp, 2, link_responses, request_id, &data, &data_len)) {
		libssh2_error(session, LIBSSH2_ERROR_SOCKET_TIMEOUT, "Timeout waiting for status message", 0);
		return -1;
	}

	if (data[0] == SSH_FXP_STATUS) {
		int retcode;

		retcode = libssh2_ntohu32(data + 5);
		LIBSSH2_FREE(session, data);
		if (retcode == LIBSSH2_FX_OK) {
			return 0;
		} else {
			sftp->last_errno = retcode;
			libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "SFTP Protocol Error", 0);
			return -1;
		}
	}

	if (libssh2_ntohu32(data + 5) < 1) {
		libssh2_error(session, LIBSSH2_ERROR_SFTP_PROTOCOL, "Invalid READLINK/REALPATH response, no name entries", 0);
		LIBSSH2_FREE(session, data);
		return -1;
	}

	link_len = libssh2_ntohu32(data + 9);
	if (link_len > target_len) {
		link_len = target_len;
	}
	memcpy(target, data + 13, link_len);
	LIBSSH2_FREE(session, data);

	return link_len;
}
/* }}} */

/* {{{ libssh2_sftp_last_error
 * Returns the last error code reported by SFTP
 */
LIBSSH2_API unsigned long libssh2_sftp_last_error(LIBSSH2_SFTP *sftp)
{
	return sftp->last_errno;
}
/* }}} */