Lua

Pre-Allocate Server Space Before an FTP Upload (ALLO)

Demonstrates the AllocateSize property, which sends the FTP ALLO command to pre-allocate disk space on the server before an upload. Set it to the size in bytes of the file about to be uploaded.

Background: ALLO asks the server to reserve storage in advance, a requirement of certain legacy systems — older mainframes in particular — that need the exact file size up front to allocate a dataset. Modern servers allocate space dynamically and typically ignore or accept ALLO without needing it, so most applications never set this. Provide it only when targeting a host known to require pre-allocation.

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Lua

local chilkat = require("chilkat")

local ftp = chilkat.Ftp2.new()

ftp.hostname = "ftp.example.com"
ftp.username = "myFtpLogin"

-- Normally you would not hard-code the password in source.  You should instead obtain it
-- from an interactive prompt, environment variable, or a secrets vault.
ftp.password = "myPassword"

local success = ftp:connect()
if not success then
    print(ftp.last_error_text)
    return
end

-- AllocateSize sends the FTP ALLO command to pre-allocate disk space on the server before an
-- upload.  It is rarely needed -- mainly for certain legacy systems that require the exact size
-- in advance -- since most servers allocate space dynamically.  Set it to the size in bytes of
-- the file about to be uploaded.
ERROR: Assignment type mismatch.  ExpressionType=int, atgType=uint

success = ftp:put_file("qa_data/bigfile.zip", "uploads/bigfile.zip")
if not success then
    print(ftp.last_error_text)
    return
end

print("Uploaded with pre-allocation.")

success = ftp:disconnect()
if not success then
    print(ftp.last_error_text)
    return
end