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From Sam Robb <sr...@wisewire.com>
Subject RE: MSDOS File System Curiosities
Date Wed, 06 May 1998 16:45:09 GMT
I think I mentioned this when the subject came up a few
months back... NT uses UNC-like names to specify devices,
for example:

  \\.\DISPLAY1
  \\.\PHYSICALDRIVE0

  Under normal working conditions (logged in as admin
for development/debugging), I can open \\.\PHYSICALDRIVE0
and dump my entire C:\ drive to the console, if I want...
can't write to it, though.

  CONIN$ and CONOUT$ are also valid names under NT; I'm
not sure about Win95, but the docs I've got don't make
any special note about them being NT-only.

- Samrobb (srobb@wisewire.com)
- WiseWire Corporation - The Content Agent Company (SM)
- http://www.wisewire.com
- http://www.lycos.com/webguides/webguides.html

The box said 'Requires Windows 95, or better.' So I bought a Macintosh.


> -----Original Message-----
> From:	Ben Hyde [SMTP:bhyde@gensym.com]
> Sent:	Wednesday, May 06, 1998 12:04 PM
> To:	'new-httpd@apache.org'
> Subject:	MSDOS File System Curiosities
> 
> There is a great many pages in the "developer's network" CD about these
> filenames.
> 
> Approximately one for every application MS has ever made that attempts
> to explain
> why something seems broken as a result of this.  The following is
> typical:
> ---
> If you search for a file in the Microsoft Windows File Manager program,
> using some MS-DOS reserved words with the File Search command, File
> Manager finds those reserved word in all directories because MS-DOS
> character devices are defined as files in all directories. This is
> standard MS-DOS behavior. 
> 
> Examples of MS-DOS reserved words are: 
>    CON   COM1 - COM4
>    PRN   AUX    LPT1
> ---
> It's particularly obnoxious that they say "examples"   I believe this is
> the complete
> list, but I'm not sure.  The note this a longer list.
>    CON     Keyboard and display
>    PRN     System list device, usually a parallel port
>    AUX     Auxiliary device, usually a serial port
>    CLOCK$  System real-time clock
>    NUL     Bit-bucket device
>    A:-Z:   Drive letters
>    COM1    First serial communications port
>    LPT1    First parallel printer port
>    LPT2    Second parallel printer port
>    LPT3    Third parallel printer port
>    COM2    Second serial communications port
>    COM3    Third serial communications port
>    COM4    Fourth serial communications port
> 
> It maybe this is the whole list, or that it is in fact all devices that
> are character based, or WHO KNOWS!
> 
> One note suggests looking at memory around 0070 to find this list.
>   > debug
>   -  d 0070:0000
>   0070:0000  E9 6D 03 A7 00 EA FD 02-70 00 00 00 00 FF AF 00
> .m......p.......
>   0070:0010  DC 02 87 DB 00 32 20 00-94 03 A7 00 00 00 00 00   .....2
> .........
>   0070:0020  00 00 E8 00 36 00 70 00-13 80 EC 01 F7 01 43 4F
> ....6.p.......CO
>   0070:0030  4E 20 20 20 20 20 48 00-70 00 00 80 EC 01 18 02   N
> H.p.......
>   0070:0040  41 55 58 20 20 20 20 20-5A 00 70 00 C0 A8 EC 01   AUX
> Z.p.....
>   0070:0050  FC 01 50 52 4E 20 20 20-20 20 6C 00 70 00 08 80   ..PRN
> l.p...
> 
> To add to my confusion there is a note about how to delete such files
> under NT,
> so it must be possible for them to exist.  It recomends (I love this) rm
> from the
> posix tools.  Which opens the possiblity that this is all a mute point
> within the
> "posix" subsystem.
> 
> In summary I suspect that taking the list above and declining to handle
> any
> of those, i.e. not LPT3 or LPT3.* we are pretty safe.   I'm not
> preparing a 
> patch, I'm just reading the "doc."
> 
>   - ben
> 
> 
> 
> 

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