Re: Reading /proc/registry/... returns extra char

[Andrey Repin <anrdaemon at freemail dot ru>]

Greetings, Christopher Faylor!

>>>> >> > $ cat >a.dat
>>>> >> > /proc/registry/HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Control/Syst
>>>> >> > emBootDevice
>>>> 
>>>> > This trailing NUL character was always there, already with Cygwin 1.5.
>>>> > It's part of the file content.  If strings are stored with a trailing
>>>> > NUL in a file, you don't want Cygwin to remove it for you, right?
>>>> 
>>>> Wrong. The training NULL is a string value terminator for REG_SZ variables,
>>>> also a string separator for REG_MULTI_SZ ones. (Which ends with a spare NULL)
>>>> It must not be exposed to the user.
>>
>>> I disagree.  When you're using tools like regtool, you're right.  But
>>> when accessing the registry as *files* via the virtual /proc filesystem,
>>> you want the file content.
>>
>>Yep. And I certainly not expect the NULL in text files. You know, not every
>>console program is binary-safe when working with STDIO? Not even cygwin, as we
>>can see in this thread.
>>
>>> And the file contains the trailing NUL in REG_SZ and REG_EXPAND_SZ values,
>>> and multiple NULs in REG_MULTI_SZ values.
>>
>>That's right and true, when you're working with interface directly, but... all
>>the programs I've used in the past, and all the interfaces, they do not expose
>>trailing NULL to the client application.
>>In this case, /proc/registry is an interface, but cat is the application.

> NAME
>        cat - concatenate files and print on the standard output

> I don't see anything in cat's description which claims it should know
> that some files are special and should be handled differently.

I didn't said about cat, but rather about file it reading from.

>>> What do you suppose Cygwin should do with the NULs in REG_MULTI_SZ values?
>>> Just remove them?
>>
>>Convert them to appropriate EOL sequences. And back to NULL's on write. As per
>>definition of a text as "multiple strings".
>>You don't need to argue over it, just document it properly :)

> Converting a NUL to a EOL would be very strange behavior.

Strange? I don't think so. I expect text data from text file. Not binary
stream.

> I don't think you really know what you're asking for.

I know. Look at windows own regedit and Registry Browser FAR plugin as two
examples.
They do such two-way conversion transparently for user.


--
WBR,
 Andrey Repin (anrdaemon@freemail.ru) 31.05.2010, <3:29>

Sorry for my terrible english...


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