patchgit-remote-mediawiki: escape double quotes and LF in file names

> A mediawiki page can contain, and even start with a " character, we have
> to escape it when generating the fast-export stream. While we're there,
> also escape newlines, but I don't think we can get them from MediaWiki
> pages.
>
> Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
> ---
>  contrib/mw-to-git/git-remote-mediawiki | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/contrib/mw-to-git/git-remote-mediawiki b/contrib/mw-to-git/git-remote-mediawiki
> index 68555d4..e7a0e7b 100755
> --- a/contrib/mw-to-git/git-remote-mediawiki
> +++ b/contrib/mw-to-git/git-remote-mediawiki
> @@ -711,6 +711,13 @@ sub fetch_mw_revisions {
>  	return ($n, @revisions);
>  }
>  
> +sub fe_escape_path {
> +    my $path = shift;
> +    $path =~ s/"/\\"/g;
> +    $path =~ s/\n/\\n/g;
> +    return $path;
> +}

>  sub import_file_revision {
>  	my $commit = shift;
>  	my %commit = %{$commit};
> @@ -738,15 +745,17 @@ sub import_file_revision {
>  		print STDOUT "from refs/mediawiki/$remotename/master^0\n";
>  	}
>  	if ($content ne DELETED_CONTENT) {
> -		print STDOUT "M 644 inline $title.mw\n";
> +		print STDOUT "M 644 inline " .
> +		    fe_escape_path($title . ".mw") . "\n";
>  		literal_data($content);
>  		if (%mediafile) {
> -			print STDOUT "M 644 inline $mediafile{title}\n";
> +			print STDOUT "M 644 inline "
> +			    . fe_escape_path($mediafile{title}) . "\n";
>  			literal_data_raw($mediafile{content});
>  		}
>  		print STDOUT "\n\n";
>  	} else {
> -		print STDOUT "D $title.mw\n";
> +		print STDOUT "D " . fe_escape_path($title . ".mw") . "\n";
>  	}
>  
>  	# mediawiki revision number in the git note

>> +sub fe_escape_path {
>> +    my $path = shift;
>> +    $path =~ s/"/\\"/g;
>> +    $path =~ s/\n/\\n/g;
>> +    return $path;
>> +}
>
> Is this sufficient?
>
> My reading of the big comment at the beginning of fast-import.c is
> that you would also want to quote each backslash;

> diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
> index 6603a7a..35b909c 100644
> --- a/Documentation/git-fast-import.txt
> +++ b/Documentation/git-fast-import.txt
> @@ -558,8 +558,9 @@ A `<path>` string must use UNIX-style directory separators (forward
>  slash `/`), may contain any byte other than `LF`, and must not
>  start with double quote (`"`).
>  
> -If an `LF` or double quote must be encoded into `<path>` shell-style
> -quoting should be used, e.g. `"path/with\n and \" in it"`.
> +If an `LF`, backslash or double quote must be encoded into `<path>`
> +shell-style quoting should be used, and the complete name should be
> +surrounded with double quotes e.g. `"path/with\n, \\ and \" in it"`.

> Jeff King <peff@peff.net> writes:
> 
> > So technically, your modification to the beginning of the sentence is
> > not correct.
> 
> I'd say the resulting sentence is somehow incorrect, but not more than
> the previous one (both say "if ..." without really telling what the
> condition was).

> >> If an `LF`, backslash or double quote must be encoded
> >                        ^
> >                        missing comma as list delimiter
> 
> Google tells me that my version was UK-correct but not US-correct. As
> french, I have no opinion on the subject, I take yours ;-).

> How about this:
> 
> A path can use the C-style string quoting (this is accepted in all
> cases and mandatory if the filename starts with double quote or
> contains `LF`). In C-style quoting, `LF`, backslash, and double quote
> characters must be escaped by preceding them with a backslash. Also,
> the complete name should be surrounded with double quotes (e.g.
> `"path/with\n, \\ and \" in it"`).
> 
> This should be technically correct, and "this is accepted in all cases"
> should encourrage people to use it.

> The documentation mentionned only newlines and double quotes as
> characters needing escaping, but the backslash also needs it. Also, the
> documentation was not clearly saying that double quotes around the file
> name were required (double quotes in the examples could be interpreted as
> part of the sentence, not part of the actual string).
>
> Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
> ---
> cut-and-paste of Peff's version, adapted from mine.
>
>  Documentation/git-fast-import.txt | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
> index 959e4d3..d1844ea 100644
> --- a/Documentation/git-fast-import.txt
> +++ b/Documentation/git-fast-import.txt
> @@ -562,8 +562,12 @@ A `<path>` string must use UNIX-style directory separators (forward
>  slash `/`), may contain any byte other than `LF`, and must not
>  start with double quote (`"`).
>  
> -If an `LF` or double quote must be encoded into `<path>` shell-style
> -quoting should be used, e.g. `"path/with\n and \" in it"`.
> +A path can use C-style string quoting; this is accepted in all cases
> +and mandatory if the filename starts with double quote or contains
> +`LF`.

> +In C-style quoting, the complete name should be surrounded with
> +double quotes, and any `LF`, backslash, or double quote characters
> +must be escaped by preceding them with a backslash (e.g.,
> +`"path/with\n, \\ and \" in it"`).
>  
>  The value of `<path>` must be in canonical form. That is it must not:

> > diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
> > index 959e4d3..d1844ea 100644
> > --- a/Documentation/git-fast-import.txt
> > +++ b/Documentation/git-fast-import.txt
> > @@ -562,8 +562,12 @@ A `<path>` string must use UNIX-style directory separators (forward
> >  slash `/`), may contain any byte other than `LF`, and must not
> >  start with double quote (`"`).
> >  
> > -If an `LF` or double quote must be encoded into `<path>` shell-style
> > -quoting should be used, e.g. `"path/with\n and \" in it"`.
> > +A path can use C-style string quoting; this is accepted in all cases
> > +and mandatory if the filename starts with double quote or contains
> > +`LF`.
> 
> ... or backslash?

> On Thu, Nov 29, 2012 at 06:00:54PM +0100, Matthieu Moy wrote:
>
>> The documentation mentionned only newlines and double quotes as
>
> s/nn/n/
>
>> diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
>> index 6603a7a..35b909c 100644
>> --- a/Documentation/git-fast-import.txt
>> +++ b/Documentation/git-fast-import.txt
>> @@ -558,8 +558,9 @@ A `<path>` string must use UNIX-style directory separators (forward
>>  slash `/`), may contain any byte other than `LF`, and must not
>>  start with double quote (`"`).
>>  
>> -If an `LF` or double quote must be encoded into `<path>` shell-style
>> -quoting should be used, e.g. `"path/with\n and \" in it"`.
>> +If an `LF`, backslash or double quote must be encoded into `<path>`
>> +shell-style quoting should be used, and the complete name should be
>> +surrounded with double quotes e.g. `"path/with\n, \\ and \" in it"`.

> >> -If an `LF` or double quote must be encoded into `<path>` shell-style
> >> -quoting should be used, e.g. `"path/with\n and \" in it"`.
> >> +If an `LF`, backslash or double quote must be encoded into `<path>`
> >> +shell-style quoting should be used, and the complete name should be
> >> +surrounded with double quotes e.g. `"path/with\n, \\ and \" in it"`.
> 
> That "shell-style" contradicts with what fast-import.c says, though.
> It claims to grok \octal and described as C-style.

> Junio C Hamano <gitster@pobox.com> writes:
>
>> That "shell-style" contradicts with what fast-import.c says, though.
>> It claims to grok \octal and described as C-style.
>
> As Peff mentionned, my last version is better, although still a bit
> incomplete. My new version documents things that _must_ be escaped, but
> not what _can_.