ssh_sftp

20052015 Ericsson AB. All Rights Reserved. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. ssh_sftp OTP 2005-09-22 ssh_sftp.sgml

ssh_sftp SFTP client.

This module implements an SSH FTP (SFTP) client. SFTP is a secure, encrypted file transfer service available for SSH.

DATA TYPES

Type definitions that are used more than once in this module, or abstractions to indicate the intended use of the data type, or both:

ssh_connection_ref() =

opaque() - as returned by ssh:connect/3

timeout()

= infinity | integer() in milliseconds. Default infinity.

Time-outs

If the request functions for the SFTP channel return {error, timeout}, it does not guarantee that the request never reached the server and was not performed. It only means that no answer was received from the server within the expected time.

apread(ChannelPid, Handle, Position, Len) -> {async, N} | {error, Reason} Reads asynchronously from an open file. ChannelPid = pid() Handle = term() Position = integer() Len = integer() N = term() Reason = term()

The function reads from a specified position, combining the and functions.

ssh_sftp:apread/4

apwrite(ChannelPid, Handle, Position, Data) -> ok | {error, Reason} Writes asynchronously to an open file. ChannelPid = pid() Handle = term() Position = integer() Len = integer() Data = binary() Timeout = timeout() Reason = term()

writes on a specified position, combining the and operations.

ssh_sftp:awrite/3

aread(ChannelPid, Handle, Len) -> {async, N} | {error, Error} Reads asynchronously from an open file. ChannelPid = pid() Handle = term() Position = integer() Len = integer() N = term() Reason = term()

Reads from an open file, without waiting for the result. If the handle is valid, the function returns , where N is a term guaranteed to be unique between calls of . The actual data is sent as a message to the calling process. This message has the form , where is the result from the read, either , , or .

awrite(ChannelPid, Handle, Data) -> ok | {error, Reason} Writes asynchronously to an open file. ChannelPid = pid() Handle = term() Position = integer() Len = integer() Data = binary() Timeout = timeout() Reason = term()

Writes to an open file, without waiting for the result. If the handle is valid, the function returns , where N is a term guaranteed to be unique between calls of . The result of the operation is sent as a message to the calling process. This message has the form , where is the result from the write, either , or .

close(ChannelPid, Handle) -> close(ChannelPid, Handle, Timeout) -> ok | {error, Reason} Closes an open handle. ChannelPid = pid() Handle = term() Timeout = timeout() Reason = term()

Closes a handle to an open file or directory on the server.

delete(ChannelPid, Name) -> delete(ChannelPid, Name, Timeout) -> ok | {error, Reason} Deletes a file. ChannelPid = pid() Name = string() Timeout = timeout() Reason = term()

Deletes the file specified by , like file:delete/1

del_dir(ChannelPid, Name) -> del_dir(ChannelPid, Name, Timeout) -> ok | {error, Reason} Deletes an empty directory. ChannelPid = pid() Name = string() Timeout = timeout() Reason = term()

Deletes a directory specified by . The directory must be empty before it can be successfully deleted.

list_dir(ChannelPid, Path) -> list_dir(ChannelPid, Path, Timeout) -> {ok, Filenames} | {error, Reason} Lists the directory. ChannelPid = pid() Path = string() Filenames = [Filename] Filename = string() Timeout = timeout() Reason = term()

Lists the given directory on the server, returning the filenames as a list of strings.

make_dir(ChannelPid, Name) -> make_dir(ChannelPid, Name, Timeout) -> ok | {error, Reason} Creates a directory. ChannelPid = pid() Name = string() Timeout = timeout() Reason = term()

Creates a directory specified by . must be a full path to a new directory. The directory can only be created in an existing directory.

make_symlink(ChannelPid, Name, Target) -> make_symlink(ChannelPid, Name, Target, Timeout) -> ok | {error, Reason} Creates a symbolic link. ChannelPid = pid() Name = string() Target = string() Reason = term()

Creates a symbolic link pointing to with the name , like file:make_symlink/2

open(ChannelPid, File, Mode) -> open(ChannelPid, File, Mode, Timeout) -> {ok, Handle} | {error, Reason} Opens a file and returns a handle. ChannelPid = pid() File = string() Mode = [Modeflag] Modeflag = read | write | creat | trunc | append | binary Timeout = timeout() Handle = term() Reason = term()

Opens a file on the server and returns a handle, which can be used for reading or writing.

opendir(ChannelPid, Path) -> opendir(ChannelPid, Path, Timeout) -> {ok, Handle} | {error, Reason} Opens a directory and returns a handle. ChannelPid = pid() Path = string() Timeout = timeout() Reason = term()

Opens a handle to a directory on the server. The handle can be used for reading directory contents.

open_tar(ChannelPid, Path, Mode) -> open_tar(ChannelPid, Path, Mode, Timeout) -> {ok, Handle} | {error, Reason} Opens a tar file on the server to which ChannelPid is connected and returns a handle. ChannelPid = pid() Path = string() Mode = [read] | [write] | [read,EncryptOpt] | [write,DecryptOpt] EncryptOpt = {crypto,{InitFun,EncryptFun,CloseFun}} DecryptOpt = {crypto,{InitFun,DecryptFun}} InitFun = (fun() -> {ok,CryptoState}) | (fun() -> {ok,CryptoState,ChunkSize}) CryptoState = any() ChunkSize = undefined | pos_integer() EncryptFun = (fun(PlainBin,CryptoState) -> EncryptResult) EncryptResult = {ok,EncryptedBin,CryptoState} | {ok,EncryptedBin,CryptoState,ChunkSize} PlainBin = binary() EncryptedBin = binary() DecryptFun = (fun(EncryptedBin,CryptoState) -> DecryptResult) DecryptResult = {ok,PlainBin,CryptoState} | {ok,PlainBin,CryptoState,ChunkSize} CloseFun = (fun(PlainBin,CryptoState) -> {ok,EncryptedBin}) Timeout = timeout() Reason = term()

Opens a handle to a tar file on the server, associated with ChannelPid. The handle can be used for remote tar creation and extraction, as defined by the erl_tar:init/3 function.

For code exampel see Section SFTP Client with TAR Compression and Encryption in the ssh Users Guide.

The crypto mode option is applied to the generated stream of bytes prior to sending them to the SFTP server. This is intended for encryption but can be used for other purposes.

The InitFun is applied once prior to any other crypto operation. The returned CryptoState is then folded into repeated applications of the EncryptFun or DecryptFun. The binary returned from those funs are sent further to the remote SFTP server. Finally, if doing encryption, the CloseFun is applied to the last piece of data. The CloseFun is responsible for padding (if needed) and encryption of that last piece.

The ChunkSize defines the size of the PlainBins that EncodeFun is applied to. If the ChunkSize is undefined, the size of the PlainBins varies, because this is intended for stream crypto, whereas a fixed ChunkSize is intended for block crypto. ChunkSizes can be changed in the return from the EncryptFun or DecryptFun. The value can be changed between pos_integer() and undefined.

position(ChannelPid, Handle, Location) -> position(ChannelPid, Handle, Location, Timeout) -> {ok, NewPosition} | {error, Reason} Sets the file position of a file. ChannelPid = pid() Handle = term() Location = Offset | {bof, Offset} | {cur, Offset} | {eof, Offset} | bof | cur | eof Offset = integer() Timeout = timeout() NewPosition = integer() Reason = term()

Sets the file position of the file referenced by . Returns (as an absolute offset) if successful, otherwise . is one of the following:

The same as .

Absolute offset.

Offset from the current position.

Offset from the end of file.

The same as eariler with 0, that is, .

pread(ChannelPid, Handle, Position, Len) -> pread(ChannelPid, Handle, Position, Len, Timeout) -> {ok, Data} | eof | {error, Error} Reads from an open file. ChannelPid = pid() Handle = term() Position = integer() Len = integer() Timeout = timeout() Data = string() | binary() Reason = term()

The function reads from a specified position, combining the and functions.

ssh_sftp:read/4

pwrite(ChannelPid, Handle, Position, Data) -> ok pwrite(ChannelPid, Handle, Position, Data, Timeout) -> ok | {error, Reason} Writes to an open file. ChannelPid = pid() Handle = term() Position = integer() Data = iolist() Timeout = timeout() Reason = term()

The function writes to a specified position, combining the and functions.

ssh_sftp:write/3

read(ChannelPid, Handle, Len) -> read(ChannelPid, Handle, Len, Timeout) -> {ok, Data} | eof | {error, Error} Reads from an open file. ChannelPid = pid() Handle = term() Position = integer() Len = integer() Timeout = timeout() Data = string() | binary() Reason = term()

Reads bytes from the file referenced by . Returns , , or . If the file is opened with , is a binary, otherwise it is a string.

If the file is read past eof, only the remaining bytes are read and returned. If no bytes are read, is returned.

read_file(ChannelPid, File) -> read_file(ChannelPid, File, Timeout) -> {ok, Data} | {error, Reason} Reads a file. ChannelPid = pid() File = string() Data = binary() Timeout = timeout() Reason = term()

Reads a file from the server, and returns the data in a binary, like file:read_file/1

read_file_info(ChannelPid, Name) -> read_file_info(ChannelPid, Name, Timeout) -> {ok, FileInfo} | {error, Reason} Gets information about a file. ChannelPid = pid() Name = string() Handle = term() Timeout = timeout() FileInfo = record() Reason = term()

Returns a record from the file specified by or , like file:read_file_info/2

read_link(ChannelPid, Name) -> read_link(ChannelPid, Name, Timeout) -> {ok, Target} | {error, Reason} Reads symbolic link. ChannelPid = pid() Name = string() Target = string() Reason = term()

Reads the link target from the symbolic link specified by , like file:read_link/1

read_link_info(ChannelPid, Name) -> {ok, FileInfo} | {error, Reason} read_link_info(ChannelPid, Name, Timeout) -> {ok, FileInfo} | {error, Reason} Gets information about a symbolic link. ChannelPid = pid() Name = string() Handle = term() Timeout = timeout() FileInfo = record() Reason = term()

Returns a record from the symbolic link specified by or , like file:read_link_info/2

rename(ChannelPid, OldName, NewName) -> rename(ChannelPid, OldName, NewName, Timeout) -> ok | {error, Reason} Renames a file. ChannelPid = pid() OldName = string() NewName = string() Timeout = timeout() Reason = term()

Renames a file named and gives it the name , like file:rename/2

start_channel(ConnectionRef) -> start_channel(ConnectionRef, Options) -> start_channel(Host, Options) -> start_channel(Host, Port, Options) -> {ok, Pid} | {ok, Pid, ConnectionRef} | {error, Reason} Starts an SFTP client. Host = string() ConnectionRef = ssh_connection_ref() Port = integer() Options = [{Option, Value}] Reason = term()

If no connection reference is provided, a connection is set up, and the new connection is returned. An SSH channel process is started to handle the communication with the SFTP server. The returned pid for this process is to be used as input to all other API functions in this module.

Options:

The time-out is passed to the ssh_channel start function, and defaults to infinity.

Desired SFTP protocol version. The actual version is the minimum of the desired version and the maximum supported versions by the SFTP server.

All other options are directly passed to ssh:connect/3 or ignored if a connection is already provided.

stop_channel(ChannelPid) -> ok Stops the SFTP client channel. ChannelPid = pid()

Stops an SFTP channel. Does not close the SSH connection. Use ssh:close/1 to close it.

write(ChannelPid, Handle, Data) -> write(ChannelPid, Handle, Data, Timeout) -> ok | {error, Reason} Writes to an open file. ChannelPid = pid() Handle = term() Position = integer() Data = iolist() Timeout = timeout() Reason = term()

Writes to the file referenced by . The file is to be opened with or flag. Returns if successful or otherwise.

Typical error reasons:

File is not opened for writing.

No space is left on the device.

write_file(ChannelPid, File, Iolist) -> write_file(ChannelPid, File, Iolist, Timeout) -> ok | {error, Reason} Writes a file. ChannelPid = pid() File = string() Iolist = iolist() Timeout = timeout() Reason = term()

Writes a file to the server, like file:write_file/2 The file is created if it does not exist. The file is overwritten if it exists.

write_file_info(ChannelPid, Name, Info) -> write_file_info(ChannelPid, Name, Info, Timeout) -> ok | {error, Reason} Writes information for a file. ChannelPid = pid() Name = string() Info = record() Timeout = timeout() Reason = term()

Writes file information from a record to the file specified by , like file:write_file_info/[2,3]