Class SFTPv3Client
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:
- SFTP v3 represents file names as strings. File names are assumed to use the slash ('/') character as a directory separator.
- File names starting with a slash are "absolute", and are relative to the root of the file system. Names starting with any other character are relative to the user's default directory (home directory).
- Servers SHOULD interpret a path name component ".." as referring to the parent directory, and "." as referring to the current directory. If the server implementation limits access to certain parts of the file system, it must be extra careful in parsing file names when enforcing such restrictions. There have been numerous reported security bugs where a ".." in a path name has allowed access outside the intended area.
- An empty path name is valid, and it refers to the user's default directory (usually the user's home directory).
If you are still not tired then please go on and read the comment for
setCharset(String)
.
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Constructor Summary
ConstructorsConstructorDescriptionSFTPv3Client
(Connection conn) Create a SFTP v3 client.SFTPv3Client
(Connection conn, PrintStream debug) Deprecated. -
Method Summary
Modifier and TypeMethodDescriptioncanonicalPath
(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.createFile
(String fileName) Create a file and open it for reading and writing.createFile
(String fileName, SFTPv3FileAttributes attr) Create a file and open it for reading and writing.createFileTruncate
(String fileName) Create a file (truncate it if it already exists) and open it for reading and writing.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.fstat
(SFTPv3FileHandle handle) Retrieve the file attributes of an open file.The currently used charset for filename encoding/decoding.int
Returns the negotiated SFTP protocol version between the client and the server.List the contents of a directory.Retrieve the file attributes of a file.void
Create a new directory.void
Move a file or directory.openFileRO
(String fileName) Open a file for reading.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.Read the target of a symbolic link.void
Remove a file.void
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.Retrieve the file attributes of a file.void
write
(SFTPv3FileHandle handle, long fileOffset, byte[] src, int srcoff, int len) Write bytes to a file.
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Constructor Details
-
SFTPv3Client
Deprecated.this constructor (debug version) will disappear in the future, useSFTPv3Client(Connection)
instead.Create a SFTP v3 client.- Parameters:
conn
- The underlying SSH-2 connection to be used.debug
-- Throws:
IOException
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SFTPv3Client
Create a SFTP v3 client.- Parameters:
conn
- The underlying SSH-2 connection to be used.- Throws:
IOException
-
-
Method Details
-
setCharset
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 ornull
to use the platform's default encoding.- Throws:
IOException
- See Also:
-
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) - See Also:
-
fstat
Retrieve the file attributes of an open file.- Parameters:
handle
- a SFTPv3FileHandle handle.- Returns:
- a SFTPv3FileAttributes object.
- Throws:
IOException
-
stat
Retrieve the file attributes of a file. This method follows symbolic links on the server.- Parameters:
path
- See thecomment
for the class for more details.- Returns:
- a SFTPv3FileAttributes object.
- Throws:
IOException
- See Also:
-
lstat
Retrieve the file attributes of a file. This method does NOT follow symbolic links on the server.- Parameters:
path
- See thecomment
for the class for more details.- Returns:
- a SFTPv3FileAttributes object.
- Throws:
IOException
- See Also:
-
readLink
Read the target of a symbolic link.- Parameters:
path
- See thecomment
for the class for more details.- Returns:
- The target of the link.
- Throws:
IOException
-
setstat
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 thecomment
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.- Throws:
IOException
-
fsetstat
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 handleattr
- A SFTPv3FileAttributes object. Specifies the modifications to be made to the attributes of the file. Empty fields will be ignored.- Throws:
IOException
-
createSymlink
Create a symbolic link on the server. Creates a link "src" that points to "target".- Parameters:
src
- See thecomment
for the class for more details.target
- See thecomment
for the class for more details.- Throws:
IOException
-
canonicalPath
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 thecomment
for the class for more details.- Returns:
- An absolute path.
- Throws:
IOException
-
getProtocolVersion
public int getProtocolVersion()Returns the negotiated SFTP protocol version between the client and the server.- Returns:
- SFTP protocol version, i.e., "3".
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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 theclose()
method, you are likely wasting resources. -
ls
List the contents of a directory.- Parameters:
dirName
- See thecomment
for the class for more details.- Returns:
- A Vector containing
SFTPv3DirectoryEntry
objects. - Throws:
IOException
-
mkdir
Create a new directory.- Parameters:
dirName
- See thecomment
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.- Throws:
IOException
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rm
Remove a file.- Parameters:
fileName
- See thecomment
for the class for more details.- Throws:
IOException
-
rmdir
Remove an empty directory.- Parameters:
dirName
- See thecomment
for the class for more details.- Throws:
IOException
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mv
Move a file or directory.- Parameters:
oldPath
- See thecomment
for the class for more details.newPath
- See thecomment
for the class for more details.- Throws:
IOException
-
openFileRO
Open a file for reading.- Parameters:
fileName
- See thecomment
for the class for more details.- Returns:
- a SFTPv3FileHandle handle
- Throws:
IOException
-
openFileRW
Open a file for reading and writing.- Parameters:
fileName
- See thecomment
for the class for more details.- Returns:
- a SFTPv3FileHandle handle
- Throws:
IOException
-
createFile
Create a file and open it for reading and writing. Same ascreateFile(fileName, null)
.- Parameters:
fileName
- See thecomment
for the class for more details.- Returns:
- a SFTPv3FileHandle handle
- Throws:
IOException
-
createFile
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 thecomment
for the class for more details.attr
- may benull
to use server defaults. Probably only theuid
,gid
andpermissions
(remember the server may apply a umask) entries of theSFTPv3FileHandle
structure make sense. You need only to set those fields where you want to override the server's defaults.- Returns:
- a SFTPv3FileHandle handle
- Throws:
IOException
-
createFileTruncate
Create a file (truncate it if it already exists) and open it for reading and writing. Same ascreateFileTruncate(fileName, null)
.- Parameters:
fileName
- See thecomment
for the class for more details.- Returns:
- a SFTPv3FileHandle handle
- Throws:
IOException
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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 thecomment
for the class for more details.attr
- may benull
to use server defaults. Probably only theuid
,gid
andpermissions
(remember the server may apply a umask) entries of theSFTPv3FileHandle
structure make sense. You need only to set those fields where you want to override the server's defaults.- Returns:
- a SFTPv3FileHandle handle
- Throws:
IOException
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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 handlefileOffset
- offset (in bytes) in the filedst
- the destination byte arraydstoff
- offset in the destination byte arraylen
- 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
- Throws:
IOException
- The server will read as many bytes as it can from the file (up to
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write
public void write(SFTPv3FileHandle handle, long fileOffset, byte[] src, int srcoff, int len) throws IOException Write bytes to a file. Iflen
> 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.- Throws:
IOException
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closeFile
Close a file.- Parameters:
handle
- a SFTPv3FileHandle handle- Throws:
IOException
-
SFTPv3Client(Connection)
instead.