Ruby

Check Whether the Last SFTP Read Failed

Demonstrates the Chilkat SFtp.LastReadFailed method, which returns whether the most recent read for a handle failed. The only argument is the handle. A normal end-of-file is not a failure.

Background: A chunked read loop needs to tell three outcomes apart: more data, a clean end-of-file, and an actual error such as a dropped connection or a revoked handle. LastReadFailed isolates the error case — it is false on a normal EOF read (which succeeds with zero bytes) and true for an empty, malformed, or already-closed handle — so the loop can stop cleanly on EOF but bail out with an error message on a genuine failure.

Chilkat Ruby Downloads

Download Chilkat for Ruby

Ruby

require 'chilkat'

success = false

#  Demonstrates the SFtp.LastReadFailed method, which returns whether the most recent read for a
#  handle failed.  The only argument is the handle.  A normal end-of-file is NOT a failure.

sftp = Chilkat::CkSFtp.new()

#  Connect, authenticate, and initialize the SFTP subsystem.
port = 22
success = sftp.Connect("sftp.example.com",port)
if (success == false)
    print sftp.lastErrorText() + "\n";
    exit
end

#  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.
password = "mySshPassword"

success = sftp.AuthenticatePw("mySshLogin",password)
if (success == false)
    print sftp.lastErrorText() + "\n";
    exit
end

success = sftp.InitializeSftp()
if (success == false)
    print sftp.lastErrorText() + "\n";
    exit
end

handle = sftp.openFile("subdir/data.txt","readOnly","openExisting")
if (sftp.get_LastMethodSuccess() == false)
    print sftp.lastErrorText() + "\n";
    exit
end

reading = true
chunkSize = 4096
bd = Chilkat::CkBinData.new()
while reading
    success = sftp.ReadFileBd(handle,chunkSize,bd)

    #  Distinguish an actual read failure from a normal EOF.  On EOF the read succeeds, returns
    #  zero bytes, and LastReadFailed is false.
    if (sftp.LastReadFailed(handle))
        print "Read failed: " + sftp.lastErrorText() + "\n";
        exit
    end

    reading = !sftp.Eof(handle)
end

success = sftp.CloseHandle(handle)
if (success == false)
    print sftp.lastErrorText() + "\n";
    exit
end

print "Read " + bd.get_NumBytes().to_s() + " bytes with no read failures." + "\n";

sftp.Disconnect()