[PATCH 1 of 3] hgweb: add a hook for processing LFS Batch API requests

[Yuya Nishihara]

On Thu, 22 Feb 2018 01:02:41 -0500, Matt Harbison wrote:
> # HG changeset patch
> # User Matt Harbison <matt_harbison at yahoo.com>
> # Date 1519274700 18000
> #      Wed Feb 21 23:45:00 2018 -0500
> # Node ID d38f7cc80f9dc453e7968fdb594e0a1119003d14
> # Parent  c8891cc3fa9ec855a3bdefd3dd759d19927c6b85
> hgweb: add a hook for processing LFS Batch API requests
> 
> There really isn't a clean way to give LFS a crack at intercepting the requests
> without hardcoding some LFS knowledge in the core.  The rationale for this URI
> is that the spec for the Batch API[1] defines the URL as the LFS server url +
> '/objects/batch'.  The default git URLs are:
> 
>     Git remote: https://git-server.com/foo/bar
>     LFS server: https://git-server.com/foo/bar.git/info/lfs
>     Batch API: https://git-server.com/foo/bar.git/info/lfs/objects/batch
> 
> '.git/' seems like it's not something a user would normally track.  If we adhere
> to how git defines the URLs, then the hg-git extension should be able to talk to
> a git based server without any additional work.
> 
> [1] https://github.com/git-lfs/git-lfs/blob/master/docs/api/batch.md
> 
> diff --git a/mercurial/hgweb/hgweb_mod.py b/mercurial/hgweb/hgweb_mod.py
> --- a/mercurial/hgweb/hgweb_mod.py
> +++ b/mercurial/hgweb/hgweb_mod.py
> @@ -95,6 +95,12 @@
>          urlel = os.path.dirname(urlel)
>      return reversed(breadcrumb)
>  
> +def _processlfsbatchreq(repo, req):
> +    """A hook for the LFS extension to wrap that handles requests to the Batch
> +    API, and returns the appropriate JSON response.
> +    """
> +    raise ErrorResponse(HTTP_NOT_FOUND)
> +
>  class requestcontext(object):
>      """Holds state/context for an individual request.
>  
> @@ -371,6 +377,11 @@
>  
>              return protohandler['dispatch']()
>  
> +        # Route LFS Batch API requests to the appropriate handler
> +
> +        if req.env[r'PATH_INFO'] == '/.git/info/lfs/objects/batch':
> +            return _processlfsbatchreq(rctx.repo, req)

(CC: indygreg as web expert)

I'm not pretty sure, but given we do "'PATH_INFO' in req.env" before,
req.env['PATH_INFO'] could be missing. And maybe we'll need some check_perm().