Reorganise the tree into vendor/ and custom/

1 file changed, 0 insertions, 592 deletions

diff --git a/extensions/about-render.lua b/extensions/about-render.luadeleted file mode 100644index 073b531..0000000--- a/extensions/about-render.lua+++ /dev/null@@ -1,592 +0,0 @@--- Server-side about-page rendering for cgit, used with the about-filter setting--- in cgitrc and the lua: prefix so it runs in cgit's embedded interpreter with--- no per-request process.------     about-filter=lua:/usr/lib/cgit/filters/about-render.lua------ One filter renders the three baseline about formats, chosen by the readme's--- file extension.------     markdown   .md .markdown .mkd .mdown---     man page   .1 through .9 and .man---     plain text everything else, and the fallback for anything that fails------ Add a format by giving it a render function and a row in the handler table--- near the foot of this file. Nothing else needs to change.------ SUPPORTED LUA------ Lua 5.1 through 5.4 and LuaJIT.------ REQUIREMENTS------ lpeg, the parsing module, for the Lua cgit is linked against. Markdown and--- man pages are parsed with lpeg grammars, so without lpeg both fall back to--- escaped plain text. It ships with cgit's syntax highlighter too, so a cgit--- that colours source already has it.------     # Debian and Ubuntu---     sudo apt install lua-lpeg---     # Fedora---     sudo dnf install lua-lpeg---     # Alpine---     sudo apk add lua5.1-lpeg---     # or with LuaRocks, matched to your Lua version---     sudo luarocks --lua-version 5.1 install lpeg------ Plain text needs only Lua itself.------ SECURITY------ The about page renders untrusted repository content, so the safety rule is--- that every run of text reaches the page through cgit's own html_txt, every--- attribute value through html_attr, and every link or image target through--- the safe_url scheme allowlist below before html_attr. Only http, https,--- mailto and relative targets survive, so a hostile readme cannot inject markup--- or a javascript: url. Because all output is routed through those sinks by--- construction, a bug in the parser can only mis-render, never inject.------ LIMITATIONS------ Markdown is a deliberate subset, not CommonMark. Headings, thematic breaks,--- fenced and inline code, blockquotes, pipe tables, single-level lists, links,--- images and emphasis. No reference links, no raw HTML passthrough, no nested--- lists, no setext headings. Emphasis does not span a hard line break inside a--- paragraph. Man rendering covers the common macros (section headings, filled--- and no-fill paragraphs, bold and italic, font escapes) and drops the rest.--- cgit sends filter output through a C string sink that stops at the first NUL--- byte, so content past a NUL is truncated.------ OUTPUT------ Markdown is wrapped in <div class='markdown'>, man pages in--- <div class='markdown manpage'>, plain text in <pre class='plaintext'>, all--- styled by assets/cgit.css.--local ok_lpeg, lpeg = pcall(require, "lpeg")----- ===== configuration ===================================================---- Readmes larger than this are served as escaped plain text rather than parsed.-local max_bytes = 512 * 1024---- Ceiling on blockquote and emphasis nesting, so a hostile readme of stacked--- markers cannot drive the recursive parser into a stack overflow.-local max_depth = 24--local filename, chunks = "", {}----- ===== helpers =========================================================--local function trim(s)-	return (s:gsub("^%s+", ""):gsub("%s+$", ""))-end---- Split on newlines after normalising CRLF and CR, returning the lines without--- their terminators. A trailing newline yields a final empty line, which every--- caller treats as blank.-local function split_lines(s)-	s = s:gsub("\r\n?", "\n")-	local lines, start = {}, 1-	while true do-		local nl = s:find("\n", start, true)-		if not nl then-			lines[#lines + 1] = s:sub(start)-			return lines-		end-		lines[#lines + 1] = s:sub(start, nl - 1)-		start = nl + 1-	end-end---- Split a table row into trimmed cells, dropping one optional leading and--- trailing pipe.-local function split_cells(row)-	row = trim(row):gsub("^|", ""):gsub("|$", "")-	local cells = {}-	for c in (row .. "|"):gmatch("(.-)|") do-		cells[#cells + 1] = trim(c)-	end-	return cells-end---- Return the url if its scheme is safe, else nil. Control and whitespace bytes--- are stripped anywhere first because a browser ignores them when resolving the--- scheme, so "java\nscript:" must still be caught as javascript. The class is--- %c%s rather than a literal 0x00 range so it is safe on Lua 5.1, where an--- embedded zero byte ends a pattern.-local function safe_url(url)-	url = url:gsub("[%c%s]", "")-	-- A leading "//" or "/\" is scheme-relative, which a browser resolves to-	-- another origin, so it is not the local target the parser meant to allow.-	if url:sub(1, 2) == "//" or url:sub(1, 2) == "/\\" then-		return nil-	end-	local scheme = url:match("^(%a[%w%+%.%-]*):")-	if scheme then-		scheme = scheme:lower()-		if scheme ~= "http" and scheme ~= "https" and scheme ~= "mailto" then-			return nil-		end-	end-	return url-end----- ===== emit ============================================================--- html, html_txt and html_attr are injected by cgit's lua filter host. Tag--- scaffolding is a literal argument to html; every value that came from the--- repository goes through html_txt, html_attr or safe_url.--local emit_inline--emit_inline = function(list)-	for _, nd in ipairs(list) do-		local t = nd.t-		if t == "text" then-			html_txt(nd.v)-		elseif t == "code" then-			html("<code>"); html_txt(nd.v); html("</code>")-		elseif t == "strong" then-			html("<strong>"); emit_inline(nd.kids); html("</strong>")-		elseif t == "em" then-			html("<em>"); emit_inline(nd.kids); html("</em>")-		elseif t == "link" then-			local u = safe_url(nd.url)-			if u then-				html("<a href='"); html_attr(u); html("'>")-				emit_inline(nd.kids)-				html("</a>")-			else-				emit_inline(nd.kids)-			end-		elseif t == "image" then-			local u = safe_url(nd.url)-			if u then-				html("<img src='"); html_attr(u)-				html("' alt='"); html_attr(nd.alt); html("'/>")-			else-				html_txt("![" .. nd.alt .. "]")-			end-		end-	end-end--local emit_blocks--emit_blocks = function(blocks)-	for _, b in ipairs(blocks) do-		local t = b.t-		if t == "heading" then-			html("<h" .. b.level .. ">")-			emit_inline(b.kids)-			html("</h" .. b.level .. ">")-		elseif t == "hr" then-			html("<hr/>")-		elseif t == "code" then-			html("<pre><code")-			if b.lang and b.lang ~= "" then-				html(" data-lang='"); html_attr(b.lang); html("'")-			end-			html(">"); html_txt(b.text); html("</code></pre>")-		elseif t == "blockquote" then-			html("<blockquote>"); emit_blocks(b.blocks); html("</blockquote>")-		elseif t == "table" then-			html("<table><thead><tr>")-			for _, c in ipairs(b.head) do-				html("<th>"); emit_inline(c); html("</th>")-			end-			html("</tr></thead><tbody>")-			for _, row in ipairs(b.rows) do-				html("<tr>")-				for _, c in ipairs(row) do-					html("<td>"); emit_inline(c); html("</td>")-				end-				html("</tr>")-			end-			html("</tbody></table>")-		elseif t == "list" then-			local tag = b.ordered and "ol" or "ul"-			html("<" .. tag .. ">")-			for _, item in ipairs(b.items) do-				html("<li>"); emit_inline(item); html("</li>")-			end-			html("</" .. tag .. ">")-		elseif t == "para" then-			html("<p>")-			for k, line in ipairs(b.lines) do-				if k > 1 then html("<br/>") end-				emit_inline(line)-			end-			html("</p>")-		end-	end-end----- ===== plain text ======================================================--local function render_plaintext(text)-	html("<pre class='plaintext'>")-	html_txt(text)-	html("</pre>")-end----- ===== markdown and man ================================================--- Both are parsed with lpeg into the block/inline node trees emit_blocks and--- emit_inline above consume. Parsing is pure and builds a tree; emit is the--- only step that writes output, so a parse failure falls back to plain text--- without leaving half a page behind.--local render_markdown, render_man--if ok_lpeg then-	local P, R, S, C, Ct = lpeg.P, lpeg.R, lpeg.S, lpeg.C, lpeg.Ct--	local sp = S(" \t")-	local ws = S(" \t\r\n\f\v")-	local eol = P(-1)--	-- ----- markdown inline ------	local marker = S("`![*_")-	local urlchar = 1 - S(")") - ws-	-- Bound the link and image inner scans. Without a cap a readme of unclosed-	-- brackets ("[[[[...") makes each position scan to end of line for a "]"-	-- that never comes, which is quadratic. Real link text and urls sit far-	-- under this, and anything longer simply renders as plain text.-	local CAP = 512--	local parse_inline-	local inline_depth = 0--	local function node_text(s) return { t = "text", v = s } end-	local function node_code(s) return { t = "code", v = s } end-	local function node_strong(s) return { t = "strong", kids = parse_inline(s) } end-	local function node_em(s) return { t = "em", kids = parse_inline(s) } end-	local function node_link(text, url) return { t = "link", kids = parse_inline(text), url = url } end-	local function node_image(alt, url) return { t = "image", alt = alt, url = url } end--	local inline_grammar = Ct((-		  (P("`") * C((1 - P("`")) ^ 1) * P("`")) / node_code-		+ (P("![") * C((1 - P("]")) ^ (-CAP)) * P("]") * P("(") * sp ^ 0-			* C(urlchar * urlchar ^ (-CAP)) * (1 - P(")")) ^ (-CAP) * P(")")) / node_image-		+ (P("[") * C((1 - P("]")) ^ (-CAP)) * P("]") * P("(") * sp ^ 0-			* C(urlchar * urlchar ^ (-CAP)) * (1 - P(")")) ^ (-CAP) * P(")")) / node_link-		+ (P("**") * C((1 - P("**")) ^ 1) * P("**")) / node_strong-		+ (P("__") * C((1 - P("__")) ^ 1) * P("__")) / node_strong-		+ (P("*") * C((1 - ws) * (1 - P("*")) ^ 0) * P("*")) / node_em-		+ (P("_") * C((1 - ws) * (1 - P("_")) ^ 0) * P("_")) / node_em-		+ C((1 - marker) ^ 1) / node_text-		+ C(P(1)) / node_text-	) ^ 0)--	parse_inline = function(s)-		if inline_depth >= max_depth then-			return { node_text(s) }-		end-		inline_depth = inline_depth + 1-		local nodes = inline_grammar:match(s) or { node_text(s) }-		inline_depth = inline_depth - 1-		return nodes-	end--	-- ----- markdown blocks ------	-- Line matchers. Each is anchored at the start of a single line and returns-	-- its captures, or nil when the line is not of that kind.-	local langchar = R("az", "AZ", "09") + S("_.+#-")-	local m_heading = C(P("#") * P("#") ^ -5) * sp ^ 1 * C(P(1) ^ 0)-	local function rule(c) return sp ^ 0 * P(c) * (sp ^ 0 * P(c)) ^ 2 * sp ^ 0 * eol end-	local m_hr = rule("-") + rule("*") + rule("_")-	local m_fence = sp ^ 0 * (C(P("`") ^ 3) + C(P("~") ^ 3)) * sp ^ 0 * C(langchar ^ 0)-	local m_close_bt = sp ^ 0 * P("`") ^ 3 * sp ^ 0 * eol-	local m_close_ti = sp ^ 0 * P("~") ^ 3 * sp ^ 0 * eol-	local m_bq = sp ^ 0 * P(">")-	local bullet = S("-*+")-	local number = R("09") ^ 1 * S(".)")-	local m_item = sp ^ 0 * C(bullet + number) * sp ^ 1 * C(P(1) ^ 0)-	local dcell = sp ^ 0 * P(":") ^ -1 * P("-") ^ 1 * P(":") ^ -1 * sp ^ 0-	-- A delimiter row is dash-cells joined by pipes. Require at least one pipe,-	-- a leading one or one between cells, so a bare rule of dashes stays a-	-- thematic break and an ordinary paragraph line is never taken for a table.-	local pipe = P("|")-	local m_tdelim = sp ^ 0 * (-		  pipe * dcell * (pipe * dcell) ^ 0 * pipe ^ -1-		+ dcell * (pipe * dcell) ^ 1 * pipe ^ -1-	) * sp ^ 0 * eol-	local m_blockstart = sp ^ 0 * ((P("#") * P("#") ^ -5 * sp) + P(">")-		+ P("`") ^ 3 + P("~") ^ 3 + ((bullet + number) * sp))--	local function ordered(mark) return mark:match("%d") ~= nil end--	local parse_blocks--	parse_blocks = function(lines, depth)-		local blocks, i, n = {}, 1, #lines-		while i <= n do-			local line = lines[i]-			local fence, lang = m_fence:match(line)-			local hashes, htext = m_heading:match(line)-			local mark = m_item:match(line)-			if line:match("^%s*$") then-				i = i + 1-			elseif fence then-				local close = (fence:sub(1, 1) == "`") and m_close_bt or m_close_ti-				local code = {}-				i = i + 1-				while i <= n and not close:match(lines[i]) do-					code[#code + 1] = lines[i]; i = i + 1-				end-				i = i + 1-				local body = table.concat(code, "\n")-				if #code > 0 then body = body .. "\n" end-				blocks[#blocks + 1] = { t = "code", lang = lang, text = body }-			elseif hashes then-				blocks[#blocks + 1] = {-					t = "heading",-					level = #hashes,-					kids = parse_inline((htext:gsub("%s*#*%s*$", ""))),-				}-				i = i + 1-			elseif m_hr:match(line) then-				blocks[#blocks + 1] = { t = "hr" }-				i = i + 1-			elseif m_bq:match(line) then-				local inner = {}-				while i <= n and m_bq:match(lines[i]) do-					inner[#inner + 1] = (lines[i]:gsub("^%s*>%s?", ""))-					i = i + 1-				end-				if depth < max_depth then-					blocks[#blocks + 1] = { t = "blockquote", blocks = parse_blocks(inner, depth + 1) }-				else-					local para = {}-					for _, l in ipairs(inner) do para[#para + 1] = parse_inline(l) end-					blocks[#blocks + 1] = { t = "para", lines = para }-				end-			elseif i + 1 <= n and line:find("|", 1, true) and m_tdelim:match(lines[i + 1]) then-				local head = {}-				for _, c in ipairs(split_cells(line)) do head[#head + 1] = parse_inline(c) end-				local rows = {}-				i = i + 2-				while i <= n and lines[i]:find("|", 1, true) and not lines[i]:match("^%s*$") do-					local row = {}-					for _, c in ipairs(split_cells(lines[i])) do row[#row + 1] = parse_inline(c) end-					rows[#rows + 1] = row-					i = i + 1-				end-				blocks[#blocks + 1] = { t = "table", head = head, rows = rows }-			elseif mark then-				local is_ol = ordered(mark)-				local items = {}-				while i <= n do-					local mk, ct = m_item:match(lines[i])-					if not mk or ordered(mk) ~= is_ol then break end-					items[#items + 1] = parse_inline(ct)-					i = i + 1-				end-				blocks[#blocks + 1] = { t = "list", ordered = is_ol, items = items }-			else-				local para = { parse_inline(line) }-				i = i + 1-				while i <= n and not lines[i]:match("^%s*$") and not m_blockstart:match(lines[i]) do-					para[#para + 1] = parse_inline(lines[i]); i = i + 1-				end-				blocks[#blocks + 1] = { t = "para", lines = para }-			end-		end-		return blocks-	end--	render_markdown = function(text)-		if #text > max_bytes then-			return render_plaintext(text)-		end-		local ok, blocks = pcall(parse_blocks, split_lines(text), 0)-		if not ok then-			return render_plaintext(text)-		end-		html("<div class='markdown'>")-		-- Emit is wrapped so a parser bug can at worst truncate the page, never-		-- error out and let the outer fallback duplicate what was already sent.-		pcall(emit_blocks, blocks)-		html("</div>")-	end--	-- ----- man pages ------	-- Macro lines are matched with lpeg, and the roff inline font and character-	-- escapes are an lpeg grammar producing a flat token list that a fold turns-	-- into the same inline nodes markdown emits. Bold and italic are the current-	-- font, which carries across a run, so the inline pass tokenises and folds-	-- rather than nesting the way markdown does.-	local m_macro = S(".'") * sp ^ 0 * C((1 - sp) ^ 1) * sp ^ 0 * C(P(1) ^ 0)--	local one_font = { B = "B", I = "I" }-	local two_font = { CB = "B", BI = "B", CI = "I" }-	local man_chars = {-		aq = "'", cq = "'", oq = "'", dq = '"', lq = '"', rq = '"',-		hy = "-", en = "-", em = "-",-	}-	local esc = P("\\")-	local function font_tok(f) return { k = "font", f = f } end-	local function text_tok(v) return { k = "text", v = v } end-	local skip_tok = { k = "skip" }--	local man_inline_grammar = Ct((-		  (esc * P("f") * P("(") * C(P(1) * P(1))) / function(nm) return font_tok(two_font[nm] or "R") end-		+ (esc * P("f") * P("[") * C((1 - P("]")) ^ 0) * P("]")) / function(nm) return font_tok(one_font[nm] or "R") end-		+ (esc * P("f") * C(P(1))) / function(f) return font_tok(one_font[f] or "R") end-		+ (esc * P("-")) / function() return text_tok("-") end-		+ (esc * P("e")) / function() return text_tok("\\") end-		+ (esc * P(" ")) / function() return text_tok(" ") end-		+ (esc * S("&|^")) / function() return skip_tok end-		+ (esc * P("(") * C(P(1) * P(1))) / function(nm) return text_tok(man_chars[nm] or "") end-		+ (esc * P("*") * (P("(") * P(1) * P(1) + P(1))) / function() return skip_tok end-		+ (esc * C(P(1))) / text_tok-		+ esc / function() return skip_tok end-		+ C((1 - esc) ^ 1) / text_tok-	) ^ 0)--	local function man_inline(s)-		local toks = man_inline_grammar:match(s) or {}-		local nodes, buf, font = {}, {}, "R"-		local function flush()-			if #buf == 0 then return end-			local txt = table.concat(buf); buf = {}-			if txt == "" then return end-			if font == "B" then-				nodes[#nodes + 1] = { t = "strong", kids = { { t = "text", v = txt } } }-			elseif font == "I" then-				nodes[#nodes + 1] = { t = "em", kids = { { t = "text", v = txt } } }-			else-				nodes[#nodes + 1] = { t = "text", v = txt }-			end-		end-		for _, tk in ipairs(toks) do-			if tk.k == "text" then-				buf[#buf + 1] = tk.v-			elseif tk.k == "font" then-				flush(); font = tk.f-			end-		end-		flush()-		return nodes-	end--	local function parse_man(text)-		local lines = split_lines(text)-		local blocks = {}-		local para, pre, nofill = nil, nil, false-		local function flush_para()-			if para and #para > 0 then-				blocks[#blocks + 1] = { t = "para", lines = para }-			end-			para = nil-		end-		local function flush_pre()-			if pre then-				local body = table.concat(pre, "\n")-				if #pre > 0 then body = body .. "\n" end-				blocks[#blocks + 1] = { t = "code", text = body }-				pre = nil-			end-		end-		local function add_line(nodes)-			para = para or {}-			para[#para + 1] = nodes-		end-		for _, line in ipairs(lines) do-			local macro, rest = m_macro:match(line)-			if rest then rest = (rest:gsub('^"(.*)"$', "%1")) end-			if nofill then-				if macro == "fi" then-					nofill = false; flush_pre()-				else-					pre[#pre + 1] = line-				end-			elseif line:match("^%s*$") then-				flush_para()-			elseif macro and macro:sub(1, 1) == "\\" then-				-- roff comment, dropped-			elseif macro == "SH" or macro == "SS" then-				flush_para()-				blocks[#blocks + 1] = {-					t = "heading",-					level = (macro == "SH") and 2 or 3,-					kids = man_inline(rest),-				}-			elseif macro == "nf" then-				flush_para(); nofill = true; pre = {}-			elseif macro == "fi" then-				flush_pre()-			elseif macro == "B" or macro == "BR" or macro == "RB"-			    or macro == "BI" or macro == "IB" then-				add_line({ { t = "strong", kids = man_inline(rest) } })-			elseif macro == "I" or macro == "IR" or macro == "RI" then-				add_line({ { t = "em", kids = man_inline(rest) } })-			elseif macro == "TH" or macro == "PP" or macro == "LP"-			    or macro == "P" or macro == "TP" or macro == "IP"-			    or macro == "HP" or macro == "RS" or macro == "RE"-			    or macro == "sp" or macro == "br" then-				flush_para()-			elseif macro then-				if rest ~= "" then add_line(man_inline(rest)) end-			else-				add_line(man_inline(line))-			end-		end-		flush_para(); flush_pre()-		return blocks-	end--	render_man = function(text)-		if #text > max_bytes then-			return render_plaintext(text)-		end-		local ok, blocks = pcall(parse_man, text)-		if not ok then-			return render_plaintext(text)-		end-		html("<div class='markdown manpage'>")-		pcall(emit_blocks, blocks)-		html("</div>")-	end-else-	-- No lpeg, so markdown and man readmes read as escaped source, not nothing.-	render_markdown = render_plaintext-	render_man = render_plaintext-end----- ===== dispatch ========================================================--local handlers = {}-for _, ext in ipairs({ "md", "markdown", "mkd", "mdown" }) do-	handlers[ext] = render_markdown-end-for _, ext in ipairs({ "1", "2", "3", "4", "5", "6", "7", "8", "9", "man" }) do-	handlers[ext] = render_man-end--function filter_open(name)-	filename = name or ""-	chunks = {}-end--function filter_write(str)-	chunks[#chunks + 1] = str-end--function filter_close()-	local text = table.concat(chunks)-	chunks = {}-	local ext = (filename:match("%.([^.]+)$") or ""):lower()-	local render = handlers[ext] or render_plaintext-	local ok = pcall(render, text)-	if not ok then-		render_plaintext(text)-	end-	return 0-end
diff --git a/extensions/about-render.lua b/extensions/about-render.lua
deleted file mode 100644
index 073b531..0000000
--- a/extensions/about-render.lua
+++ /dev/null
@@ -1,592 +0,0 @@
--- Server-side about-page rendering for cgit, used with the about-filter setting
--- in cgitrc and the lua: prefix so it runs in cgit's embedded interpreter with
--- no per-request process.
---
---     about-filter=lua:/usr/lib/cgit/filters/about-render.lua
---
--- One filter renders the three baseline about formats, chosen by the readme's
--- file extension.
---
---     markdown   .md .markdown .mkd .mdown
---     man page   .1 through .9 and .man
---     plain text everything else, and the fallback for anything that fails
---
--- Add a format by giving it a render function and a row in the handler table
--- near the foot of this file. Nothing else needs to change.
---
--- SUPPORTED LUA
---
--- Lua 5.1 through 5.4 and LuaJIT.
---
--- REQUIREMENTS
---
--- lpeg, the parsing module, for the Lua cgit is linked against. Markdown and
--- man pages are parsed with lpeg grammars, so without lpeg both fall back to
--- escaped plain text. It ships with cgit's syntax highlighter too, so a cgit
--- that colours source already has it.
---
---     # Debian and Ubuntu
---     sudo apt install lua-lpeg
---     # Fedora
---     sudo dnf install lua-lpeg
---     # Alpine
---     sudo apk add lua5.1-lpeg
---     # or with LuaRocks, matched to your Lua version
---     sudo luarocks --lua-version 5.1 install lpeg
---
--- Plain text needs only Lua itself.
---
--- SECURITY
---
--- The about page renders untrusted repository content, so the safety rule is
--- that every run of text reaches the page through cgit's own html_txt, every
--- attribute value through html_attr, and every link or image target through
--- the safe_url scheme allowlist below before html_attr. Only http, https,
--- mailto and relative targets survive, so a hostile readme cannot inject markup
--- or a javascript: url. Because all output is routed through those sinks by
--- construction, a bug in the parser can only mis-render, never inject.
---
--- LIMITATIONS
---
--- Markdown is a deliberate subset, not CommonMark. Headings, thematic breaks,
--- fenced and inline code, blockquotes, pipe tables, single-level lists, links,
--- images and emphasis. No reference links, no raw HTML passthrough, no nested
--- lists, no setext headings. Emphasis does not span a hard line break inside a
--- paragraph. Man rendering covers the common macros (section headings, filled
--- and no-fill paragraphs, bold and italic, font escapes) and drops the rest.
--- cgit sends filter output through a C string sink that stops at the first NUL
--- byte, so content past a NUL is truncated.
---
--- OUTPUT
---
--- Markdown is wrapped in <div class='markdown'>, man pages in
--- <div class='markdown manpage'>, plain text in <pre class='plaintext'>, all
--- styled by assets/cgit.css.
-
-local ok_lpeg, lpeg = pcall(require, "lpeg")
-
-
--- ===== configuration ===================================================
-
--- Readmes larger than this are served as escaped plain text rather than parsed.
-local max_bytes = 512 * 1024
-
--- Ceiling on blockquote and emphasis nesting, so a hostile readme of stacked
--- markers cannot drive the recursive parser into a stack overflow.
-local max_depth = 24
-
-local filename, chunks = "", {}
-
-
--- ===== helpers =========================================================
-
-local function trim(s)
-	return (s:gsub("^%s+", ""):gsub("%s+$", ""))
-end
-
--- Split on newlines after normalising CRLF and CR, returning the lines without
--- their terminators. A trailing newline yields a final empty line, which every
--- caller treats as blank.
-local function split_lines(s)
-	s = s:gsub("\r\n?", "\n")
-	local lines, start = {}, 1
-	while true do
-		local nl = s:find("\n", start, true)
-		if not nl then
-			lines[#lines + 1] = s:sub(start)
-			return lines
-		end
-		lines[#lines + 1] = s:sub(start, nl - 1)
-		start = nl + 1
-	end
-end
-
--- Split a table row into trimmed cells, dropping one optional leading and
--- trailing pipe.
-local function split_cells(row)
-	row = trim(row):gsub("^|", ""):gsub("|$", "")
-	local cells = {}
-	for c in (row .. "|"):gmatch("(.-)|") do
-		cells[#cells + 1] = trim(c)
-	end
-	return cells
-end
-
--- Return the url if its scheme is safe, else nil. Control and whitespace bytes
--- are stripped anywhere first because a browser ignores them when resolving the
--- scheme, so "java\nscript:" must still be caught as javascript. The class is
--- %c%s rather than a literal 0x00 range so it is safe on Lua 5.1, where an
--- embedded zero byte ends a pattern.
-local function safe_url(url)
-	url = url:gsub("[%c%s]", "")
-	-- A leading "//" or "/\" is scheme-relative, which a browser resolves to
-	-- another origin, so it is not the local target the parser meant to allow.
-	if url:sub(1, 2) == "//" or url:sub(1, 2) == "/\\" then
-		return nil
-	end
-	local scheme = url:match("^(%a[%w%+%.%-]*):")
-	if scheme then
-		scheme = scheme:lower()
-		if scheme ~= "http" and scheme ~= "https" and scheme ~= "mailto" then
-			return nil
-		end
-	end
-	return url
-end
-
-
--- ===== emit ============================================================
--- html, html_txt and html_attr are injected by cgit's lua filter host. Tag
--- scaffolding is a literal argument to html; every value that came from the
--- repository goes through html_txt, html_attr or safe_url.
-
-local emit_inline
-
-emit_inline = function(list)
-	for _, nd in ipairs(list) do
-		local t = nd.t
-		if t == "text" then
-			html_txt(nd.v)
-		elseif t == "code" then
-			html("<code>"); html_txt(nd.v); html("</code>")
-		elseif t == "strong" then
-			html("<strong>"); emit_inline(nd.kids); html("</strong>")
-		elseif t == "em" then
-			html("<em>"); emit_inline(nd.kids); html("</em>")
-		elseif t == "link" then
-			local u = safe_url(nd.url)
-			if u then
-				html("<a href='"); html_attr(u); html("'>")
-				emit_inline(nd.kids)
-				html("</a>")
-			else
-				emit_inline(nd.kids)
-			end
-		elseif t == "image" then
-			local u = safe_url(nd.url)
-			if u then
-				html("<img src='"); html_attr(u)
-				html("' alt='"); html_attr(nd.alt); html("'/>")
-			else
-				html_txt("![" .. nd.alt .. "]")
-			end
-		end
-	end
-end
-
-local emit_blocks
-
-emit_blocks = function(blocks)
-	for _, b in ipairs(blocks) do
-		local t = b.t
-		if t == "heading" then
-			html("<h" .. b.level .. ">")
-			emit_inline(b.kids)
-			html("</h" .. b.level .. ">")
-		elseif t == "hr" then
-			html("<hr/>")
-		elseif t == "code" then
-			html("<pre><code")
-			if b.lang and b.lang ~= "" then
-				html(" data-lang='"); html_attr(b.lang); html("'")
-			end
-			html(">"); html_txt(b.text); html("</code></pre>")
-		elseif t == "blockquote" then
-			html("<blockquote>"); emit_blocks(b.blocks); html("</blockquote>")
-		elseif t == "table" then
-			html("<table><thead><tr>")
-			for _, c in ipairs(b.head) do
-				html("<th>"); emit_inline(c); html("</th>")
-			end
-			html("</tr></thead><tbody>")
-			for _, row in ipairs(b.rows) do
-				html("<tr>")
-				for _, c in ipairs(row) do
-					html("<td>"); emit_inline(c); html("</td>")
-				end
-				html("</tr>")
-			end
-			html("</tbody></table>")
-		elseif t == "list" then
-			local tag = b.ordered and "ol" or "ul"
-			html("<" .. tag .. ">")
-			for _, item in ipairs(b.items) do
-				html("<li>"); emit_inline(item); html("</li>")
-			end
-			html("</" .. tag .. ">")
-		elseif t == "para" then
-			html("<p>")
-			for k, line in ipairs(b.lines) do
-				if k > 1 then html("<br/>") end
-				emit_inline(line)
-			end
-			html("</p>")
-		end
-	end
-end
-
-
--- ===== plain text ======================================================
-
-local function render_plaintext(text)
-	html("<pre class='plaintext'>")
-	html_txt(text)
-	html("</pre>")
-end
-
-
--- ===== markdown and man ================================================
--- Both are parsed with lpeg into the block/inline node trees emit_blocks and
--- emit_inline above consume. Parsing is pure and builds a tree; emit is the
--- only step that writes output, so a parse failure falls back to plain text
--- without leaving half a page behind.
-
-local render_markdown, render_man
-
-if ok_lpeg then
-	local P, R, S, C, Ct = lpeg.P, lpeg.R, lpeg.S, lpeg.C, lpeg.Ct
-
-	local sp = S(" \t")
-	local ws = S(" \t\r\n\f\v")
-	local eol = P(-1)
-
-	-- ----- markdown inline -----
-	local marker = S("`![*_")
-	local urlchar = 1 - S(")") - ws
-	-- Bound the link and image inner scans. Without a cap a readme of unclosed
-	-- brackets ("[[[[...") makes each position scan to end of line for a "]"
-	-- that never comes, which is quadratic. Real link text and urls sit far
-	-- under this, and anything longer simply renders as plain text.
-	local CAP = 512
-
-	local parse_inline
-	local inline_depth = 0
-
-	local function node_text(s) return { t = "text", v = s } end
-	local function node_code(s) return { t = "code", v = s } end
-	local function node_strong(s) return { t = "strong", kids = parse_inline(s) } end
-	local function node_em(s) return { t = "em", kids = parse_inline(s) } end
-	local function node_link(text, url) return { t = "link", kids = parse_inline(text), url = url } end
-	local function node_image(alt, url) return { t = "image", alt = alt, url = url } end
-
-	local inline_grammar = Ct((
-		  (P("`") * C((1 - P("`")) ^ 1) * P("`")) / node_code
-		+ (P("![") * C((1 - P("]")) ^ (-CAP)) * P("]") * P("(") * sp ^ 0
-			* C(urlchar * urlchar ^ (-CAP)) * (1 - P(")")) ^ (-CAP) * P(")")) / node_image
-		+ (P("[") * C((1 - P("]")) ^ (-CAP)) * P("]") * P("(") * sp ^ 0
-			* C(urlchar * urlchar ^ (-CAP)) * (1 - P(")")) ^ (-CAP) * P(")")) / node_link
-		+ (P("**") * C((1 - P("**")) ^ 1) * P("**")) / node_strong
-		+ (P("__") * C((1 - P("__")) ^ 1) * P("__")) / node_strong
-		+ (P("*") * C((1 - ws) * (1 - P("*")) ^ 0) * P("*")) / node_em
-		+ (P("_") * C((1 - ws) * (1 - P("_")) ^ 0) * P("_")) / node_em
-		+ C((1 - marker) ^ 1) / node_text
-		+ C(P(1)) / node_text
-	) ^ 0)
-
-	parse_inline = function(s)
-		if inline_depth >= max_depth then
-			return { node_text(s) }
-		end
-		inline_depth = inline_depth + 1
-		local nodes = inline_grammar:match(s) or { node_text(s) }
-		inline_depth = inline_depth - 1
-		return nodes
-	end
-
-	-- ----- markdown blocks -----
-	-- Line matchers. Each is anchored at the start of a single line and returns
-	-- its captures, or nil when the line is not of that kind.
-	local langchar = R("az", "AZ", "09") + S("_.+#-")
-	local m_heading = C(P("#") * P("#") ^ -5) * sp ^ 1 * C(P(1) ^ 0)
-	local function rule(c) return sp ^ 0 * P(c) * (sp ^ 0 * P(c)) ^ 2 * sp ^ 0 * eol end
-	local m_hr = rule("-") + rule("*") + rule("_")
-	local m_fence = sp ^ 0 * (C(P("`") ^ 3) + C(P("~") ^ 3)) * sp ^ 0 * C(langchar ^ 0)
-	local m_close_bt = sp ^ 0 * P("`") ^ 3 * sp ^ 0 * eol
-	local m_close_ti = sp ^ 0 * P("~") ^ 3 * sp ^ 0 * eol
-	local m_bq = sp ^ 0 * P(">")
-	local bullet = S("-*+")
-	local number = R("09") ^ 1 * S(".)")
-	local m_item = sp ^ 0 * C(bullet + number) * sp ^ 1 * C(P(1) ^ 0)
-	local dcell = sp ^ 0 * P(":") ^ -1 * P("-") ^ 1 * P(":") ^ -1 * sp ^ 0
-	-- A delimiter row is dash-cells joined by pipes. Require at least one pipe,
-	-- a leading one or one between cells, so a bare rule of dashes stays a
-	-- thematic break and an ordinary paragraph line is never taken for a table.
-	local pipe = P("|")
-	local m_tdelim = sp ^ 0 * (
-		  pipe * dcell * (pipe * dcell) ^ 0 * pipe ^ -1
-		+ dcell * (pipe * dcell) ^ 1 * pipe ^ -1
-	) * sp ^ 0 * eol
-	local m_blockstart = sp ^ 0 * ((P("#") * P("#") ^ -5 * sp) + P(">")
-		+ P("`") ^ 3 + P("~") ^ 3 + ((bullet + number) * sp))
-
-	local function ordered(mark) return mark:match("%d") ~= nil end
-
-	local parse_blocks
-
-	parse_blocks = function(lines, depth)
-		local blocks, i, n = {}, 1, #lines
-		while i <= n do
-			local line = lines[i]
-			local fence, lang = m_fence:match(line)
-			local hashes, htext = m_heading:match(line)
-			local mark = m_item:match(line)
-			if line:match("^%s*$") then
-				i = i + 1
-			elseif fence then
-				local close = (fence:sub(1, 1) == "`") and m_close_bt or m_close_ti
-				local code = {}
-				i = i + 1
-				while i <= n and not close:match(lines[i]) do
-					code[#code + 1] = lines[i]; i = i + 1
-				end
-				i = i + 1
-				local body = table.concat(code, "\n")
-				if #code > 0 then body = body .. "\n" end
-				blocks[#blocks + 1] = { t = "code", lang = lang, text = body }
-			elseif hashes then
-				blocks[#blocks + 1] = {
-					t = "heading",
-					level = #hashes,
-					kids = parse_inline((htext:gsub("%s*#*%s*$", ""))),
-				}
-				i = i + 1
-			elseif m_hr:match(line) then
-				blocks[#blocks + 1] = { t = "hr" }
-				i = i + 1
-			elseif m_bq:match(line) then
-				local inner = {}
-				while i <= n and m_bq:match(lines[i]) do
-					inner[#inner + 1] = (lines[i]:gsub("^%s*>%s?", ""))
-					i = i + 1
-				end
-				if depth < max_depth then
-					blocks[#blocks + 1] = { t = "blockquote", blocks = parse_blocks(inner, depth + 1) }
-				else
-					local para = {}
-					for _, l in ipairs(inner) do para[#para + 1] = parse_inline(l) end
-					blocks[#blocks + 1] = { t = "para", lines = para }
-				end
-			elseif i + 1 <= n and line:find("|", 1, true) and m_tdelim:match(lines[i + 1]) then
-				local head = {}
-				for _, c in ipairs(split_cells(line)) do head[#head + 1] = parse_inline(c) end
-				local rows = {}
-				i = i + 2
-				while i <= n and lines[i]:find("|", 1, true) and not lines[i]:match("^%s*$") do
-					local row = {}
-					for _, c in ipairs(split_cells(lines[i])) do row[#row + 1] = parse_inline(c) end
-					rows[#rows + 1] = row
-					i = i + 1
-				end
-				blocks[#blocks + 1] = { t = "table", head = head, rows = rows }
-			elseif mark then
-				local is_ol = ordered(mark)
-				local items = {}
-				while i <= n do
-					local mk, ct = m_item:match(lines[i])
-					if not mk or ordered(mk) ~= is_ol then break end
-					items[#items + 1] = parse_inline(ct)
-					i = i + 1
-				end
-				blocks[#blocks + 1] = { t = "list", ordered = is_ol, items = items }
-			else
-				local para = { parse_inline(line) }
-				i = i + 1
-				while i <= n and not lines[i]:match("^%s*$") and not m_blockstart:match(lines[i]) do
-					para[#para + 1] = parse_inline(lines[i]); i = i + 1
-				end
-				blocks[#blocks + 1] = { t = "para", lines = para }
-			end
-		end
-		return blocks
-	end
-
-	render_markdown = function(text)
-		if #text > max_bytes then
-			return render_plaintext(text)
-		end
-		local ok, blocks = pcall(parse_blocks, split_lines(text), 0)
-		if not ok then
-			return render_plaintext(text)
-		end
-		html("<div class='markdown'>")
-		-- Emit is wrapped so a parser bug can at worst truncate the page, never
-		-- error out and let the outer fallback duplicate what was already sent.
-		pcall(emit_blocks, blocks)
-		html("</div>")
-	end
-
-	-- ----- man pages -----
-	-- Macro lines are matched with lpeg, and the roff inline font and character
-	-- escapes are an lpeg grammar producing a flat token list that a fold turns
-	-- into the same inline nodes markdown emits. Bold and italic are the current
-	-- font, which carries across a run, so the inline pass tokenises and folds
-	-- rather than nesting the way markdown does.
-	local m_macro = S(".'") * sp ^ 0 * C((1 - sp) ^ 1) * sp ^ 0 * C(P(1) ^ 0)
-
-	local one_font = { B = "B", I = "I" }
-	local two_font = { CB = "B", BI = "B", CI = "I" }
-	local man_chars = {
-		aq = "'", cq = "'", oq = "'", dq = '"', lq = '"', rq = '"',
-		hy = "-", en = "-", em = "-",
-	}
-	local esc = P("\\")
-	local function font_tok(f) return { k = "font", f = f } end
-	local function text_tok(v) return { k = "text", v = v } end
-	local skip_tok = { k = "skip" }
-
-	local man_inline_grammar = Ct((
-		  (esc * P("f") * P("(") * C(P(1) * P(1))) / function(nm) return font_tok(two_font[nm] or "R") end
-		+ (esc * P("f") * P("[") * C((1 - P("]")) ^ 0) * P("]")) / function(nm) return font_tok(one_font[nm] or "R") end
-		+ (esc * P("f") * C(P(1))) / function(f) return font_tok(one_font[f] or "R") end
-		+ (esc * P("-")) / function() return text_tok("-") end
-		+ (esc * P("e")) / function() return text_tok("\\") end
-		+ (esc * P(" ")) / function() return text_tok(" ") end
-		+ (esc * S("&|^")) / function() return skip_tok end
-		+ (esc * P("(") * C(P(1) * P(1))) / function(nm) return text_tok(man_chars[nm] or "") end
-		+ (esc * P("*") * (P("(") * P(1) * P(1) + P(1))) / function() return skip_tok end
-		+ (esc * C(P(1))) / text_tok
-		+ esc / function() return skip_tok end
-		+ C((1 - esc) ^ 1) / text_tok
-	) ^ 0)
-
-	local function man_inline(s)
-		local toks = man_inline_grammar:match(s) or {}
-		local nodes, buf, font = {}, {}, "R"
-		local function flush()
-			if #buf == 0 then return end
-			local txt = table.concat(buf); buf = {}
-			if txt == "" then return end
-			if font == "B" then
-				nodes[#nodes + 1] = { t = "strong", kids = { { t = "text", v = txt } } }
-			elseif font == "I" then
-				nodes[#nodes + 1] = { t = "em", kids = { { t = "text", v = txt } } }
-			else
-				nodes[#nodes + 1] = { t = "text", v = txt }
-			end
-		end
-		for _, tk in ipairs(toks) do
-			if tk.k == "text" then
-				buf[#buf + 1] = tk.v
-			elseif tk.k == "font" then
-				flush(); font = tk.f
-			end
-		end
-		flush()
-		return nodes
-	end
-
-	local function parse_man(text)
-		local lines = split_lines(text)
-		local blocks = {}
-		local para, pre, nofill = nil, nil, false
-		local function flush_para()
-			if para and #para > 0 then
-				blocks[#blocks + 1] = { t = "para", lines = para }
-			end
-			para = nil
-		end
-		local function flush_pre()
-			if pre then
-				local body = table.concat(pre, "\n")
-				if #pre > 0 then body = body .. "\n" end
-				blocks[#blocks + 1] = { t = "code", text = body }
-				pre = nil
-			end
-		end
-		local function add_line(nodes)
-			para = para or {}
-			para[#para + 1] = nodes
-		end
-		for _, line in ipairs(lines) do
-			local macro, rest = m_macro:match(line)
-			if rest then rest = (rest:gsub('^"(.*)"$', "%1")) end
-			if nofill then
-				if macro == "fi" then
-					nofill = false; flush_pre()
-				else
-					pre[#pre + 1] = line
-				end
-			elseif line:match("^%s*$") then
-				flush_para()
-			elseif macro and macro:sub(1, 1) == "\\" then
-				-- roff comment, dropped
-			elseif macro == "SH" or macro == "SS" then
-				flush_para()
-				blocks[#blocks + 1] = {
-					t = "heading",
-					level = (macro == "SH") and 2 or 3,
-					kids = man_inline(rest),
-				}
-			elseif macro == "nf" then
-				flush_para(); nofill = true; pre = {}
-			elseif macro == "fi" then
-				flush_pre()
-			elseif macro == "B" or macro == "BR" or macro == "RB"
-			    or macro == "BI" or macro == "IB" then
-				add_line({ { t = "strong", kids = man_inline(rest) } })
-			elseif macro == "I" or macro == "IR" or macro == "RI" then
-				add_line({ { t = "em", kids = man_inline(rest) } })
-			elseif macro == "TH" or macro == "PP" or macro == "LP"
-			    or macro == "P" or macro == "TP" or macro == "IP"
-			    or macro == "HP" or macro == "RS" or macro == "RE"
-			    or macro == "sp" or macro == "br" then
-				flush_para()
-			elseif macro then
-				if rest ~= "" then add_line(man_inline(rest)) end
-			else
-				add_line(man_inline(line))
-			end
-		end
-		flush_para(); flush_pre()
-		return blocks
-	end
-
-	render_man = function(text)
-		if #text > max_bytes then
-			return render_plaintext(text)
-		end
-		local ok, blocks = pcall(parse_man, text)
-		if not ok then
-			return render_plaintext(text)
-		end
-		html("<div class='markdown manpage'>")
-		pcall(emit_blocks, blocks)
-		html("</div>")
-	end
-else
-	-- No lpeg, so markdown and man readmes read as escaped source, not nothing.
-	render_markdown = render_plaintext
-	render_man = render_plaintext
-end
-
-
--- ===== dispatch ========================================================
-
-local handlers = {}
-for _, ext in ipairs({ "md", "markdown", "mkd", "mdown" }) do
-	handlers[ext] = render_markdown
-end
-for _, ext in ipairs({ "1", "2", "3", "4", "5", "6", "7", "8", "9", "man" }) do
-	handlers[ext] = render_man
-end
-
-function filter_open(name)
-	filename = name or ""
-	chunks = {}
-end
-
-function filter_write(str)
-	chunks[#chunks + 1] = str
-end
-
-function filter_close()
-	local text = table.concat(chunks)
-	chunks = {}
-	local ext = (filename:match("%.([^.]+)$") or ""):lower()
-	local render = handlers[ext] or render_plaintext
-	local ok = pcall(render, text)
-	if not ok then
-		render_plaintext(text)
-	end
-	return 0
-end