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.
Functions
apread(ChannelPid, Handle, Position, Len) -> {async, N} | {error, Error}
ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
N = term()
Reason = term()
The apread
function reads from a specified position,
combining the position
and aread
functions.
apwrite(ChannelPid, Handle, Position, Data) -> ok | {error, Reason}
ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
Data = binary()
Timeout = timeout()
Reason = term()
apwrite
writes on a specified position, combining
the position
and awrite
operations.
aread(ChannelPid, Handle, Len) -> {async, N} | {error, Error}
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 {async, N}
, where N
is a term guaranteed to be unique between calls of aread
.
The actual data is sent as a message to the calling process. This
message has the form {async_reply, N, Result}
, where
Result
is the result from the read, either {ok, Data}
,
eof
, or {error, Error}
.
awrite(ChannelPid, Handle, Data) -> ok | {error, Reason}
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 {async, N}
, where N
is a term guaranteed to be unique between calls of
awrite
. The result of the write
operation is sent
as a message to the calling process. This message has the form
{async_reply, N, Result}
, where Result
is the result
from the write, either ok
, or {error, Error}
.
close(ChannelPid, Handle) ->
close(ChannelPid, Handle, Timeout) -> ok | {error, Reason}
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}
ChannelPid = pid()
Name = string()
Timeout = timeout()
Reason = term()
Deletes the file specified by Name
, like
file:delete/1
del_dir(ChannelPid, Name) ->
del_dir(ChannelPid, Name, Timeout) -> ok | {error, Reason}
ChannelPid = pid()
Name = string()
Timeout = timeout()
Reason = term()
Deletes a directory specified by Name
.
The directory must be empty before it can be successfully deleted.
list_dir(ChannelPid, Path) ->
list_dir(ChannelPid, Path, Timeout) -> {ok, Filenames} | {error, Reason}
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}
ChannelPid = pid()
Name = string()
Timeout = timeout()
Reason = term()
Creates a directory specified by Name
. Name
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}
ChannelPid = pid()
Name = string()
Target = string()
Reason = term()
Creates a symbolic link pointing to Target
with the
name Name
, like
file:make_symlink/2
open(ChannelPid, File, Mode) ->
open(ChannelPid, File, Mode, Timeout) -> {ok, Handle} | {error, Reason}
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}
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}
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 PlainBin
s that EncodeFun
is applied
to. If the ChunkSize
is undefined
, the size of the PlainBin
s varies,
because this is intended for stream crypto, whereas a fixed ChunkSize
is intended for block crypto.
ChunkSize
s 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, Error}
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 Handle
.
Returns {ok, NewPosition}
(as an absolute offset) if
successful, otherwise {error, Reason}
. Location
is
one of the following:
Offset
The same as {bof, Offset}
.
{bof, Offset}
Absolute offset.
{cur, Offset}
Offset from the current position.
{eof, Offset}
Offset from the end of file.
bof | cur | eof
The same as eariler with Offset
0,
that is, {bof, 0} | {cur, 0} | {eof, 0}
.
pread(ChannelPid, Handle, Position, Len) ->
pread(ChannelPid, Handle, Position, Len, Timeout) -> {ok, Data} | eof | {error, Error}
ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
Timeout = timeout()
Data = string() | binary()
Reason = term()
The pread
function reads from a specified position,
combining the position
and read
functions.
pwrite(ChannelPid, Handle, Position, Data) -> ok
pwrite(ChannelPid, Handle, Position, Data, Timeout) -> ok | {error, Error}
ChannelPid = pid()
Handle = term()
Position = integer()
Data = iolist()
Timeout = timeout()
Reason = term()
The pread
function writes to a specified position,
combining the position
and write
functions.
read(ChannelPid, Handle, Len) ->
read(ChannelPid, Handle, Len, Timeout) -> {ok, Data} | eof | {error, Error}
ChannelPid = pid()
Handle = term()
Position = integer()
Len = integer()
Timeout = timeout()
Data = string() | binary()
Reason = term()
Reads Len
bytes from the file referenced by
Handle
. Returns {ok, Data}
, eof
, or
{error, Reason}
. If the file is opened with binary
,
Data
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, eof
is returned.
read_file(ChannelPid, File) ->
read_file(ChannelPid, File, Timeout) -> {ok, Data} | {error, Reason}
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}
ChannelPid = pid()
Name = string()
Handle = term()
Timeout = timeout()
FileInfo = record()
Reason = term()
Returns a file_info
record from the file specified by
Name
or Handle
,
like file:read_file_info/2
read_link(ChannelPid, Name) ->
read_link(ChannelPid, Name, Timeout) -> {ok, Target} | {error, Reason}
ChannelPid = pid()
Name = string()
Target = string()
Reason = term()
Reads the link target from the symbolic link specified
by name
, like
file:read_link/1
read_link_info(ChannelPid, Name) -> {ok, FileInfo} | {error, Reason}
read_link_info(ChannelPid, Name, Timeout) -> {ok, FileInfo} | {error, Reason}
ChannelPid = pid()
Name = string()
Handle = term()
Timeout = timeout()
FileInfo = record()
Reason = term()
Returns a file_info
record from the symbolic
link specified by Name
or Handle
, like
file:read_link_info/2
rename(ChannelPid, OldName, NewName) ->
rename(ChannelPid, OldName, NewName, Timeout) -> ok | {error, Reason}
ChannelPid = pid()
OldName = string()
NewName = string()
Timeout = timeout()
Reason = term()
Renames a file named OldName
and gives it the name
NewName
, 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}
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:
{timeout, timeout()}
The time-out is passed to the ssh_channel
start function,
and defaults to infinity
.
{sftp_vsn, integer()}
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
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, Error}
ChannelPid = pid()
Handle = term()
Position = integer()
Data = iolist()
Timeout = timeout()
Reason = term()
Writes data
to the file referenced by Handle
.
The file is to be opened with write
or append
flag. Returns ok
if successful or {error, Reason}
otherwise.
Typical error reasons:
ebadf
File is not opened for writing.
enospc
No space is left on the device.
write_file(ChannelPid, File, Iolist) ->
write_file(ChannelPid, File, Iolist, Timeout) -> ok | {error, Reason}
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}
ChannelPid = pid()
Name = string()
Info = record()
Timeout = timeout()
Reason = term()
Writes file information from a file_info
record to the
file specified by Name
, like
file:write_file_info/[2,3]