Improve windows shell mode; fix edit() function for windows

[quinnj]

Prepend 'cmd /c' to edit function start command to allow files to be opened properly on windows. Also prepend it to repl_cmd commands to better emulate shell mode for windows. Fixes #7107.

[Keno]

Do we need some kind of quoting here. What happens when you do e.g. cmd /C ls /?

[Keno]

Seems to work. LGTM then.

[vtjnash]

start can't handle paths with spaces in the name, such as "C:\Program Files" (it handling of escape sequences is very bady flawed), we should probably just replace this will a call to the windows API function which does the same thing

cmd also has awful handling of spaces and quotes (it may expand escape sequences multiple times), so I would rather not invoke it

If /C or /K is specified, then the remainder of the command line after
the switch is processed as a command line, where the following logic is
used to process quote (") characters:

    1.  If all of the following conditions are met, then quote characters
        on the command line are preserved:

        - no /S switch
        - exactly two quote characters
        - no special characters between the two quote characters,
          where special is one of: &<>()@^|
        - there are one or more whitespace characters between the
          two quote characters
        - the string between the two quote characters is the name
          of an executable file.

    2.  Otherwise, old behavior is to see if the first character is
        a quote character and if so, strip the leading character and
        remove the last quote character on the command line, preserving
        any text after the last quote character.

Note that multiple commands separated by the command separator '&&'
are accepted for string if surrounded by quotes.

[quinnj]

Thanks for taking a look @vtjnash. Should we change the default JULIA_EDITOR for windows then? Since it's set to start? I think the edit function should be ok using cmd /c, since it's well-structured, but for shelling out, do you have other suggestions? It seems to work fairly well for most simple commands/opening files and such.

[vtjnash]

for very limiting shelling out, it might be OK to call cmd, but be aware that anything complicated (like paths with spaces in them) will probably be parsed wrong sometimes. the rules cmd uses for text transformations aren't particularly sane (and are quite different from the rules used by the windows function for parsing arguments -- which are also the rules used by libuv to quote the args). to make this change, you would first need to write a function to correctly quote args for cmd, then set the flag VERBATIM flag when calling libuv's uv_spawn function.

[quinnj]

Hmmm....I think we'll be best off to use cmd for the shell mode, at least for now. Take the case with spaces in folder names, I would try to open a file:

shell> C:/Users/karbarcca/Google Drive/Dropbox/Dropbox/keys.docx
'C:/Users/karbarcca/Google' is not recognized as an internal or external command
,
operable program or batch file.

Then I'd realize there are spaces, so I can just run:

shell> 'C:/Users/karbarcca/Google Drive/Dropbox/Dropbox/keys.docx'

Which works, and which is what I have run in the terminal anyway to open files, so I'm familiar with it.

[vtjnash]

No, using cmd will start to break down quickly, since libuv does quote the args so that programs that use the windows API for parsing command lines get what they expect. Cmd uses different rules, and the combination of the two is just a mess

[quinnj]

What would you suggest then?

[vtjnash]

As I mentioned in my post yesterday, you need to implement rules for quoting calls to cmd and set the flag to disable quoting by libuv

[quinnj]

Ok, I'll play around with it some more today.

[ncnc]

I played around a bit with this. It seems like CMD /S /C "..." leaves any quoting within the quotes (the ... part) intact, which would make it easy e.g. to use a command with spaces in combination with an argument with spaces. Any other requirements for a sane handling of shell commands?

Also, how would one go about passing the VERBATIM flag to libuv? Is it necessary to add another input argument to jl_spawn?

[vtjnash]

yes, you would need to add another argument to spawn, and the corresponding flags in the Cmd object.

Note that rather than using cmd to invoke the shell (start, aka explorer.exe), you can also just invoke the shell API directly:
http://msdn.microsoft.com/en-us/library/windows/desktop/bb762154(v=vs.85).aspx

[tkelman]

Mostly superseded by #8725, yeah?

[dhoegh]

I think this one could be closed due to #8725 and #8838. #8838 fixes the issue with shell>C:/Users/karbarcca/Google Drive/Dropbox/Dropbox/keys.docx which today will look like C:\\Users\\karbarcca\\Google\ Drive\\Dropbox\\Dropbox\\keys.docx which will call the correct file.