examples/cgit-wwwhighlight-filter.lua

   1 -- Copyright (C) 2019-2021 all contributors <meta@public-inbox.org>
   2 -- License: GPL-2.0+ <https://www.gnu.org/licenses/gpl-2.0.txt>
   3 --
   4 -- This filter accesses the PublicInbox::WwwHighlight PSGI endpoint
   5 -- (see examples/highlight.psgi)
   6 --
   7 -- Dependencies: lua-http
   8 --
   9 -- disclaimer: written by someone who does not know Lua.
  10 --
  11 -- This requires cgit linked with Lua
  12 -- Usage (in your cgitrc(5) config file):
  13 --
  14 --   source-filter=lua:/path/to/this/script.lua
  15 --   about-filter=lua:/path/to/this/script.lua
  16 --
  17 local wwwhighlight_url = 'http://127.0.0.1:9090/'
  18 local req_timeout = 10
  19 local too_big = false
  20
  21 -- match $PublicInbox::HTTP::MAX_REQUEST_BUFFER
  22 local max_len = 10 * 1024 * 1024
  23
  24 -- about-filter needs surrounding <pre> tags if all we do is
  25 -- highlight and linkify
  26 local pre = true
  27
  28 function filter_open(...)
  29         req_body = ""
  30
  31         -- detect when we're used in an about-filter
  32         local repo_url = os.getenv('CGIT_REPO_URL')
  33         if repo_url then
  34                 local path_info = os.getenv('PATH_INFO')
  35                 rurl = path_info:match("^/(.+)/about/?$")
  36                 pre = rurl == repo_url
  37         end
  38
  39         -- hand filename off for language detection
  40         local fn = select(1, ...)
  41         if fn then
  42                 local http_util = require 'http.util'
  43                 wwwhighlight_url = wwwhighlight_url .. http_util.encodeURI(fn)
  44         end
  45 end
  46
  47 -- try to buffer the entire source in memory
  48 function filter_write(str)
  49         if too_big then
  50                 html(str)
  51         elseif (req_body:len() + str:len()) > max_len then
  52                 too_big = true
  53                 req_body = ""
  54                 html(req_body)
  55                 html(str)
  56         else
  57                 req_body = req_body .. str
  58         end
  59 end
  60
  61 function fail(err)
  62         io.stderr:write(tostring(err), "\n")
  63         if pre then
  64                 html("<pre>")
  65         end
  66         html_txt(req_body)
  67         if pre then
  68                 html("</pre>")
  69         end
  70         return 1
  71 end
  72
  73 function filter_close()
  74         if too_big then
  75                 return 0
  76         end
  77         local request = require 'http.request'
  78         local req = request.new_from_uri(wwwhighlight_url)
  79         req.headers:upsert(':method', 'PUT')
  80         req:set_body(req_body)
  81
  82         -- don't wait for 100-Continue message from the PSGI app
  83         req.headers:delete('expect')
  84
  85         local headers, stream = req:go(req_timeout)
  86         if headers == nil then
  87                 return fail(stream)
  88         end
  89         local status = headers:get(':status')
  90         if status ~= '200' then
  91                 return fail('status ' .. status)
  92         end
  93         local body, err = stream:get_body_as_string()
  94         if not body and err then
  95                 return fail(err)
  96         end
  97         if pre then
  98                 html("<pre>")
  99         end
 100         html(body)
 101         if pre then
 102                 html("</pre>")
 103         end
 104         return 0
 105 end