Tcl

SFTP Upload Large File in Parts

See more SFTP Examples

Demonstrates how to split a large file into N parts and then upload each part separately. This technique can be used to potentially avoid limits a SFTP server might impose on upload file size. Tcl

load ./chilkat.dll

set success 0

# This example assumes the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

set sftp [new_CkSFtp]

# Set some timeouts, in milliseconds:
CkSFtp_put_ConnectTimeoutMs $sftp 5000
CkSFtp_put_IdleTimeoutMs $sftp 10000

# Connect to the SSH server.  
# The standard SSH port = 22
# The hostname may be a hostname or IP address.
set hostname "sftp.example.com"
set port 22
set success [CkSFtp_Connect $sftp $hostname $port]
if {$success != 1} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    exit
}

# Authenticate with the SSH server.  Chilkat SFTP supports
# both password-based authenication as well as public-key
# authentication.  This example uses password authenication.
set success [CkSFtp_AuthenticatePw $sftp "myLogin" "myPassword"]
if {$success != 1} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    exit
}

# After authenticating, the SFTP subsystem must be initialized:
set success [CkSFtp_InitializeSftp $sftp]
if {$success != 1} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    exit
}

# Open a remote file for writing on the SSH server.
# If the file already exists, it is overwritten.
# (Specify "createNew" instead of "createTruncate" to
# prevent overwriting existing files.)
set handle [CkSFtp_openFile $sftp "big.zip" "writeOnly" "createTruncate"]
if {[CkSFtp_get_LastMethodSuccess $sftp] != 1} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    exit
}

# We're going to upload the local file "qa_data/zips/big.zip" (a relative local path from our current working directory)
# to the SFTP server.
set localFilePath "qa_data/zips/big.zip"

# Rather than uploading in one shot, we'll read the local file in chunks
# and upload a chunk at a time.
set fac [new_CkFileAccess]

set success [CkFileAccess_OpenForRead $fac $localFilePath]
if {$success == 0} then {
    CkSFtp_CloseHandle $sftp $handle
    puts [CkFileAccess_lastErrorText $fac]
    delete_CkSFtp $sftp
    delete_CkFileAccess $fac
    exit
}

# If we were to split the local file into 128K chunks, how many chunks (blocks) would
# we have, including the last partial block?
set blockSize 131072
set numBlocks [CkFileAccess_GetNumBlocks $fac $blockSize]
puts "Number of blocks = $numBlocks"

set bd [new_CkBinData]

set i 0
while {$i < $numBlocks} {
    # Read the Nth block, which gets appended to the bd.  (which means
    # we must clear the contents of bd before the next iteration)
    set success [CkFileAccess_ReadBlockBd $fac $i $blockSize $bd]
    if {$success == 0} then {
        CkSFtp_CloseHandle $sftp $handle
        puts [CkFileAccess_lastErrorText $fac]
        delete_CkSFtp $sftp
        delete_CkFileAccess $fac
        delete_CkBinData $bd
        exit
    }

    # Upload this block to the open remote file.
    set success [CkSFtp_WriteFileBd $sftp $handle $bd]
    if {$success == 0} then {
        puts [CkSFtp_lastErrorText $sftp]
        delete_CkSFtp $sftp
        delete_CkFileAccess $fac
        delete_CkBinData $bd
        exit
    }

    # Clear the contents for the next iteration.
    CkBinData_Clear $bd

    set i [expr $i + 1]
}

# Close the local file.
CkFileAccess_FileClose $fac

# -----------------------------------------------------------------------------
# This is important.  You must close the handle on the server.
# Otherwise open handles will accumulate on the server until eventually a limit
# is reached and the server will fail on a call to OpenFile.
# -----------------------------------------------------------------------------

# Close the remote file handle on the server.
set success [CkSFtp_CloseHandle $sftp $handle]
if {$success != 1} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    delete_CkFileAccess $fac
    delete_CkBinData $bd
    exit
}

puts "Success."

delete_CkSFtp $sftp
delete_CkFileAccess $fac
delete_CkBinData $bd