patchremote-hg: unquote C-style paths when exporting

> git-fast-import documentation says that paths can be C-style quoted.
> Unfortunately, the current remote-hg helper doesn't unquote quoted
> path and pass them as-is to Mercurial when the commit is created.
>
> This result in the following situation:
>
> - clone a mercurial repository with git
> - Add a file with space: `mkdir dir/foo\ bar`
> - Commit that new file, and push the change to mercurial
> - The mercurial repository as now a new directory named '"dir', which
> contains a file named 'foo bar"'
>
> Use python ast.literal_eval to unquote the string if it starts with ".
> It has been tested with quotes, spaces, and utf-8 encoded file-names.
>
> Signed-off-by: Antoine Pelisse <apelisse@gmail.com>
> ---

>  contrib/remote-helpers/git-remote-hg | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/contrib/remote-helpers/git-remote-hg b/contrib/remote-helpers/git-remote-hg
> index 92d994e..0141949 100755
> --- a/contrib/remote-helpers/git-remote-hg
> +++ b/contrib/remote-helpers/git-remote-hg
> @@ -14,6 +14,7 @@
>  
>  from mercurial import hg, ui, bookmarks, context, encoding, node, error, extensions, discovery, util
>  
> +import ast
>  import re
>  import sys
>  import os
> @@ -742,6 +743,8 @@ def parse_commit(parser):
>              f = { 'deleted' : True }
>          else:
>              die('Unknown file command: %s' % line)
> +        if path.startswith('"'):
> +            path = ast.literal_eval(path)
>          files[path] = f
>  
>      # only export the commits if we are on an internal proxy repo

> Antoine Pelisse <apelisse@gmail.com> writes:
>
>> git-fast-import documentation says that paths can be C-style quoted.
>> Unfortunately, the current remote-hg helper doesn't unquote quoted
>> path and pass them as-is to Mercurial when the commit is created.
>>
>> This result in the following situation:
>>
>> - clone a mercurial repository with git
>> - Add a file with space: `mkdir dir/foo\ bar`

>> - Commit that new file, and push the change to mercurial
>> - The mercurial repository as now a new directory named '"dir', which
>> contains a file named 'foo bar"'
>>
>> Use python ast.literal_eval to unquote the string if it starts with ".
>> It has been tested with quotes, spaces, and utf-8 encoded file-names.
>>
>> Signed-off-by: Antoine Pelisse <apelisse@gmail.com>
>> ---
>
> A path you read in fast-import input indeed needs to be unquoted
> when it begins with a dq, and I _think_ by using ast.literal_eval(),
> you probably can correctly unquote any valid C-quoted string.
>
> But it bothers me somewhat that what the patch does seems to be
> overly broad.  Doesn't ast.literal_eval() take a lot more than just
> strings?

>     ast.literal_eval(node_or_string)
>
>         Safely evaluate an expression node or a Unicode or Latin-1
>         encoded string containing a Python expression. The string or
>         node provided may only consist of the following Python literal
>         structures: strings, numbers, tuples, lists, dicts, booleans,
>         and None.

> Also doesn't Python's double-quoted string have a lot more magic
> than C-quoted string, e.g.
>
>         $ python -i
>         >>> import ast
>         >>> not_cq_path = '"abc" "def"'
>         >>> ast.literal_eval(not_cq_path)
>         'abcdef'

> On Tue, Oct 22, 2013 at 3:49 PM, Antoine Pelisse <apelisse@gmail.com> wrote:
>
>> It is true that I have expected "valid output" from git-fast-export.
>> And I don't have in mind any easy solution to detect that the output
>> is broken, yet still accepted as a valid string by python. We could
>> obviously write a unquote_c_style() equivalent in python if needed.
>
> Something like this?
>
> def c_style_unescape(string):
>     if string[0] == string[-1] == '"':
>         return string.decode('string-escape')[1:-1]
>     return string
>
> It's in git-remote-bzr.py.

>> def c_style_unescape(string):
>>     if string[0] == string[-1] == '"':
>>         return string.decode('string-escape')[1:-1]
>>     return string
>>
>> It's in git-remote-bzr.py.
>
> Yeah, that's certainly better,
>
> Thanks,

> Antoine Pelisse <apelisse@gmail.com> writes:
>
>>> def c_style_unescape(string):
>>>     if string[0] == string[-1] == '"':
>>>         return string.decode('string-escape')[1:-1]
>>>     return string
>>>
>>> It's in git-remote-bzr.py.
>>
>> Yeah, that's certainly better,
>>
>> Thanks,
>
> OK, so an amended one will look like this?

> -- >8 --
> From: Antoine Pelisse <apelisse@gmail.com>
> Subject: remote-hg: unquote C-style paths when exporting
>
> git-fast-import documentation says that paths can be C-style quoted.
> Unfortunately, the current remote-hg helper doesn't unquote quoted
> path and pass them as-is to Mercurial when the commit is created.
>
> This result in the following situation:

> It has been tested with quotes, spaces, and utf-8 encoded file-names.
>
> Signed-off-by: Antoine Pelisse <apelisse@gmail.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  contrib/remote-helpers/git-remote-hg | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/contrib/remote-helpers/git-remote-hg b/contrib/remote-helpers/git-remote-hg
> index 0194c67..85abbed 100755
> --- a/contrib/remote-helpers/git-remote-hg
> +++ b/contrib/remote-helpers/git-remote-hg
> @@ -678,6 +678,11 @@ def get_merge_files(repo, p1, p2, files):
>              f = { 'ctx' : repo[p1][e] }
>              files[e] = f
>
> +def c_style_unescape(string):
> +    if string[0] == string[-1] == '"':
> +        return string.decode('string-escape')[1:-1]
> +    return string
> +
>  def parse_commit(parser):
>      global marks, blob_marks, parsed_refs
>      global mode
> @@ -720,6 +725,7 @@ def parse_commit(parser):
>              f = { 'deleted' : True }
>          else:
>              die('Unknown file command: %s' % line)
> +        path = c_style_unescape(path).decode('utf-8')
>          files[path] = f
>
>      # only export the commits if we are on an internal proxy repo