(CkPython) SFTP Upload Large File in Parts

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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.

Chilkat Python Downloads install with pip pip3 install chilkat or download... Python Module for Windows, MacOS, Linux, Alpine Linux, Solaris

import sys
import chilkat

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

sftp = chilkat.CkSFtp()

# Set some timeouts, in milliseconds:
sftp.put_ConnectTimeoutMs(5000)
sftp.put_IdleTimeoutMs(10000)

# Connect to the SSH server.  
# The standard SSH port = 22
# The hostname may be a hostname or IP address.
hostname = "sftp.example.com"
port = 22
success = sftp.Connect(hostname,port)
if (success != True):
    print(sftp.lastErrorText())
    sys.exit()

# Authenticate with the SSH server.  Chilkat SFTP supports
# both password-based authenication as well as public-key
# authentication.  This example uses password authenication.
success = sftp.AuthenticatePw("myLogin","myPassword")
if (success != True):
    print(sftp.lastErrorText())
    sys.exit()

# After authenticating, the SFTP subsystem must be initialized:
success = sftp.InitializeSftp()
if (success != True):
    print(sftp.lastErrorText())
    sys.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.)
handle = sftp.openFile("big.zip","writeOnly","createTruncate")
if (sftp.get_LastMethodSuccess() != True):
    print(sftp.lastErrorText())
    sys.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.
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.
fac = chilkat.CkFileAccess()

success = fac.OpenForRead(localFilePath)
if (success == False):
    sftp.CloseHandle(handle)
    print(fac.lastErrorText())
    sys.exit()

# If we were to split the local file into 128K chunks, how many chunks (blocks) would
# we have, including the last partial block?
blockSize = 131072
numBlocks = fac.GetNumBlocks(blockSize)
print("Number of blocks = " + str(numBlocks))

bd = chilkat.CkBinData()
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)
    success = fac.ReadBlockBd(i,blockSize,bd)
    if (success == False):
        sftp.CloseHandle(handle)
        print(fac.lastErrorText())
        sys.exit()

    # Upload this block to the open remote file.
    success = sftp.WriteFileBd(handle,bd)
    if (success == False):
        print(sftp.lastErrorText())
        sys.exit()

    # Clear the contents for the next iteration.
    bd.Clear()

    i = i + 1

# Close the local file.
fac.FileClose()

# -----------------------------------------------------------------------------
# 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.
success = sftp.CloseHandle(handle)
if (success != True):
    print(sftp.lastErrorText())
    sys.exit()

print("Success.")