[ale] Question about ftp clients

[jknapka at earthlink.net (Joseph A Knapka)]

Mike Panetta wrote:
> 
> I do not think it even can transfer the remainder of the block, as FTP
> programs do not access the disk in blocks, they access it in files.
> Unless the filesystem is broken, when you ask for a file you should only
> get that file and nothing else.  I guess someone could write the FTP
> client so that it could get the inode(s) the file uses and then find
> that partially used inode and transfer the remainder of what was there,
> but why?

That is exactly right. The thing being transferred by FTP is
the *file abstraction as defined by the OS*, not any particular
disk blocks (consider FTP of files across different filesystems
or media, for example - it's clear that a "file" is the same
kind of thing whether it lives on a hard drive, a tape, or a
RAM disk, and the physical details of file storage don't
have anything to do with the semantics of an FTP operation).
If you transfer a file in binary mode, the byte stream seen
by a program that opens that file on the client should be
identical to the byte stream seen by a program that opens
the corresponding file on the server. (But should you be so
unfortunate as to have to exchange files with a VMS system
via FTP, YMMV - mine certainly has.)

Cheers,

-- Joe
   "Thanks to Microsoft, I am now blind in both eyes. They have
    rolled back in my head so many times this week that they
    are apparently stuck there now."
      - Jonathan Rickman, regarding M$ anti-open-source PR.

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