com.trilead.ssh2

Class SFTPv3Client


public class SFTPv3Client
extends java.lang.Object

A SFTPv3Client represents a SFTP (protocol version 3) client connection tunnelled over a SSH-2 connection. This is a very simple (synchronous) implementation.

Basically, most methods in this class map directly to one of the packet types described in draft-ietf-secsh-filexfer-02.txt.

Note: this is experimental code.

Error handling: the methods of this class throw IOExceptions. However, unless there is catastrophic failure, exceptions of the type SFTPv3Client will be thrown (a subclass of IOException). Therefore, you can implement more verbose behavior by checking if a thrown exception if of this type. If yes, then you can cast the exception and access detailed information about the failure.

Notes about file names, directory names and paths, copy-pasted from the specs:

If you are still not tired then please go on and read the comment for setCharset(String).

Constructor Summary

SFTPv3Client(Connection conn)
Create a SFTP v3 client.
SFTPv3Client(Connection conn, PrintStream debug)
Deprecated. this constructor (debug version) will disappear in the future, use SFTPv3Client(Connection) instead.

Method Summary

String
canonicalPath(String path)
Have the server canonicalize any given path name to an absolute path.
void
close()
Close this SFTP session.
void
closeFile(SFTPv3FileHandle handle)
Close a file.
SFTPv3FileHandle
createFile(String fileName)
Create a file and open it for reading and writing.
SFTPv3FileHandle
createFile(String fileName, SFTPv3FileAttributes attr)
Create a file and open it for reading and writing.
SFTPv3FileHandle
createFileTruncate(String fileName)
Create a file (truncate it if it already exists) and open it for reading and writing.
SFTPv3FileHandle
createFileTruncate(String fileName, SFTPv3FileAttributes attr)
reate a file (truncate it if it already exists) and open it for reading and writing.
void
createSymlink(String src, String target)
Create a symbolic link on the server.
void
fsetstat(SFTPv3FileHandle handle, SFTPv3FileAttributes attr)
Modify the attributes of a file.
SFTPv3FileAttributes
fstat(SFTPv3FileHandle handle)
Retrieve the file attributes of an open file.
String
getCharset()
The currently used charset for filename encoding/decoding.
int
getProtocolVersion()
Returns the negotiated SFTP protocol version between the client and the server.
Vector
ls(String dirName)
List the contents of a directory.
SFTPv3FileAttributes
lstat(String path)
Retrieve the file attributes of a file.
void
mkdir(String dirName, int posixPermissions)
Create a new directory.
void
mv(String oldPath, String newPath)
Move a file or directory.
SFTPv3FileHandle
openFileRO(String fileName)
Open a file for reading.
SFTPv3FileHandle
openFileRW(String fileName)
Open a file for reading and writing.
int
read(SFTPv3FileHandle handle, long fileOffset, byte[] dst, int dstoff, int len)
Read bytes from a file.
String
readLink(String path)
Read the target of a symbolic link.
void
rm(String fileName)
Remove a file.
void
rmdir(String dirName)
Remove an empty directory.
void
setCharset(String charset)
Set the charset used to convert between Java Unicode Strings and byte encodings used by the server for paths and file names.
void
setstat(String path, SFTPv3FileAttributes attr)
Modify the attributes of a file.
SFTPv3FileAttributes
stat(String path)
Retrieve the file attributes of a file.
void
write(SFTPv3FileHandle handle, long fileOffset, byte[] src, int srcoff, int len)
Write bytes to a file.

Constructor Details

SFTPv3Client

public SFTPv3Client(Connection conn)
            throws IOException
Create a SFTP v3 client.
Parameters:
conn - The underlying SSH-2 connection to be used.

SFTPv3Client

public SFTPv3Client(Connection conn,
                    PrintStream debug)
            throws IOException

Deprecated. this constructor (debug version) will disappear in the future, use SFTPv3Client(Connection) instead.

Create a SFTP v3 client.
Parameters:
conn - The underlying SSH-2 connection to be used.
debug -

Method Details

canonicalPath

public String canonicalPath(String path)
            throws IOException
Have the server canonicalize any given path name to an absolute path. This is useful for converting path names containing ".." components or relative pathnames without a leading slash into absolute paths.
Parameters:
path - See the comment for the class for more details.
Returns:
An absolute path.

close

public void close()
Close this SFTP session. NEVER forget to call this method to free up resources - even if you got an exception from one of the other methods. Sometimes these other methods may throw an exception, saying that the underlying channel is closed (this can happen, e.g., if the other server sent a close message.) However, as long as you have not called the close() method, you are likely wasting resources.

closeFile

public void closeFile(SFTPv3FileHandle handle)
            throws IOException
Close a file.
Parameters:
handle - a SFTPv3FileHandle handle

createFile

public SFTPv3FileHandle createFile(String fileName)
            throws IOException
Create a file and open it for reading and writing. Same as createFile(fileName, null).
Parameters:
fileName - See the comment for the class for more details.
Returns:
a SFTPv3FileHandle handle

createFile

public SFTPv3FileHandle createFile(String fileName,
                                   SFTPv3FileAttributes attr)
            throws IOException
Create a file and open it for reading and writing. You can specify the default attributes of the file (the server may or may not respect your wishes).
Parameters:
fileName - See the comment for the class for more details.
attr - may be null to use server defaults. Probably only the uid, gid and permissions (remember the server may apply a umask) entries of the SFTPv3FileHandle structure make sense. You need only to set those fields where you want to override the server's defaults.
Returns:
a SFTPv3FileHandle handle

createFileTruncate

public SFTPv3FileHandle createFileTruncate(String fileName)
            throws IOException
Create a file (truncate it if it already exists) and open it for reading and writing. Same as createFileTruncate(fileName, null).
Parameters:
fileName - See the comment for the class for more details.
Returns:
a SFTPv3FileHandle handle

createFileTruncate

public SFTPv3FileHandle createFileTruncate(String fileName,
                                           SFTPv3FileAttributes attr)
            throws IOException
reate a file (truncate it if it already exists) and open it for reading and writing. You can specify the default attributes of the file (the server may or may not respect your wishes).
Parameters:
fileName - See the comment for the class for more details.
attr - may be null to use server defaults. Probably only the uid, gid and permissions (remember the server may apply a umask) entries of the SFTPv3FileHandle structure make sense. You need only to set those fields where you want to override the server's defaults.
Returns:
a SFTPv3FileHandle handle

createSymlink

public void createSymlink(String src,
                          String target)
            throws IOException
Create a symbolic link on the server. Creates a link "src" that points to "target".
Parameters:
src - See the comment for the class for more details.
target - See the comment for the class for more details.

fsetstat

public void fsetstat(SFTPv3FileHandle handle,
                     SFTPv3FileAttributes attr)
            throws IOException
Modify the attributes of a file. Used for operations such as changing the ownership, permissions or access times, as well as for truncating a file.
Parameters:
handle - a SFTPv3FileHandle handle
attr - A SFTPv3FileAttributes object. Specifies the modifications to be made to the attributes of the file. Empty fields will be ignored.

fstat

public SFTPv3FileAttributes fstat(SFTPv3FileHandle handle)
            throws IOException
Retrieve the file attributes of an open file.
Parameters:
handle - a SFTPv3FileHandle handle.
Returns:
a SFTPv3FileAttributes object.

getCharset

public String getCharset()
The currently used charset for filename encoding/decoding.
Returns:
The name of the charset (null if the platform's default charset is being used)

getProtocolVersion

public int getProtocolVersion()
Returns the negotiated SFTP protocol version between the client and the server.
Returns:
SFTP protocol version, i.e., "3".

ls

public Vector ls(String dirName)
            throws IOException
List the contents of a directory.
Parameters:
dirName - See the comment for the class for more details.
Returns:
A Vector containing SFTPv3DirectoryEntry objects.

lstat

public SFTPv3FileAttributes lstat(String path)
            throws IOException
Retrieve the file attributes of a file. This method does NOT follow symbolic links on the server.
Parameters:
path - See the comment for the class for more details.
Returns:
a SFTPv3FileAttributes object.
See Also:
stat(String)

mkdir

public void mkdir(String dirName,
                  int posixPermissions)
            throws IOException
Create a new directory.
Parameters:
dirName - See the comment for the class for more details.
posixPermissions - the permissions for this directory, e.g., "0700" (remember that this is octal noation). The server will likely apply a umask.

mv

public void mv(String oldPath,
               String newPath)
            throws IOException
Move a file or directory.
Parameters:
oldPath - See the comment for the class for more details.
newPath - See the comment for the class for more details.

openFileRO

public SFTPv3FileHandle openFileRO(String fileName)
            throws IOException
Open a file for reading.
Parameters:
fileName - See the comment for the class for more details.
Returns:
a SFTPv3FileHandle handle

openFileRW

public SFTPv3FileHandle openFileRW(String fileName)
            throws IOException
Open a file for reading and writing.
Parameters:
fileName - See the comment for the class for more details.
Returns:
a SFTPv3FileHandle handle

read

public int read(SFTPv3FileHandle handle,
                long fileOffset,
                byte[] dst,
                int dstoff,
                int len)
            throws IOException
Read bytes from a file. No more than 32768 bytes may be read at once. Be aware that the semantics of read() are different than for Java streams.

  • The server will read as many bytes as it can from the file (up to len), and return them.
  • If EOF is encountered before reading any data, -1 is returned.
  • If an error occurs, an exception is thrown
  • For normal disk files, it is guaranteed that the server will return the specified number of bytes, or up to end of file. For, e.g., device files this may return fewer bytes than requested.
Parameters:
handle - a SFTPv3FileHandle handle
fileOffset - offset (in bytes) in the file
dst - the destination byte array
dstoff - offset in the destination byte array
len - how many bytes to read, 0 < len <= 32768 bytes
Returns:
the number of bytes that could be read, may be less than requested if the end of the file is reached, -1 is returned in case of EOF

readLink

public String readLink(String path)
            throws IOException
Read the target of a symbolic link.
Parameters:
path - See the comment for the class for more details.
Returns:
The target of the link.

rm

public void rm(String fileName)
            throws IOException
Remove a file.
Parameters:
fileName - See the comment for the class for more details.

rmdir

public void rmdir(String dirName)
            throws IOException
Remove an empty directory.
Parameters:
dirName - See the comment for the class for more details.

setCharset

public void setCharset(String charset)
            throws IOException
Set the charset used to convert between Java Unicode Strings and byte encodings used by the server for paths and file names. Unfortunately, the SFTP v3 draft says NOTHING about such conversions (well, with the exception of error messages which have to be in UTF-8). Newer drafts specify to use UTF-8 for file names (if I remember correctly). However, a quick test using OpenSSH serving a EXT-3 filesystem has shown that UTF-8 seems to be a bad choice for SFTP v3 (tested with filenames containing german umlauts). "windows-1252" seems to work better for Europe. Luckily, "windows-1252" is the platform default in my case =).

If you don't set anything, then the platform default will be used (this is the default behavior).

Parameters:
charset - the name of the charset to be used or null to use the platform's default encoding.

setstat

public void setstat(String path,
                    SFTPv3FileAttributes attr)
            throws IOException
Modify the attributes of a file. Used for operations such as changing the ownership, permissions or access times, as well as for truncating a file.
Parameters:
path - See the comment for the class for more details.
attr - A SFTPv3FileAttributes object. Specifies the modifications to be made to the attributes of the file. Empty fields will be ignored.

stat

public SFTPv3FileAttributes stat(String path)
            throws IOException
Retrieve the file attributes of a file. This method follows symbolic links on the server.
Parameters:
path - See the comment for the class for more details.
Returns:
a SFTPv3FileAttributes object.
See Also:
lstat(String)

write

public void write(SFTPv3FileHandle handle,
                  long fileOffset,
                  byte[] src,
                  int srcoff,
                  int len)
            throws IOException
Write bytes to a file. If len > 32768, then the write operation will be split into multiple writes.
Parameters:
handle - a SFTPv3FileHandle handle.
fileOffset - offset (in bytes) in the file.
src - the source byte array.
srcoff - offset in the source byte array.
len - how many bytes to write.