Reorganize the tree into vendor/ and custom/

1 file changed, 278 insertions, 0 deletions

diff --git a/custom/extensions/syntax-highlight.lua b/custom/extensions/syntax-highlight.lua
new file mode 100644
index 0000000..8310504
--- /dev/null
+++ b/custom/extensions/syntax-highlight.lua
@@ -0,0 +1,278 @@
+-- Server-side syntax highlighting for the tree and blob views, used with the
+-- source-filter setting in cgitrc and the lua: prefix so it runs in cgit's
+-- embedded interpreter with no per-request process.
+--
+--     source-filter=lua:/usr/lib/cgit/extensions/syntax-highlight.lua
+--
+-- Highlighting is deliberately not built into cgit itself. Without this filter
+-- cgit serves plain escaped text, and any other program can take its place.
+--
+-- SUPPORTED LUA
+--
+-- Lua 5.1 through 5.4 and LuaJIT. The Scintillua version matters too. Recent
+-- Scintillua (6.x) needs Lua 5.3 or newer to load its lexers, older Scintillua
+-- releases still load under 5.1 and 5.2. Pick a Scintillua release that matches
+-- the Lua cgit is built against.
+--
+-- REQUIREMENTS
+--
+-- Two pieces, and BOTH must be installed. When either is missing the filter
+-- serves plain escaped text by design, so uncolored code means a missing
+-- dependency, not an error.
+--
+-- 1. lpeg, the parsing module, for the Lua cgit is linked against. Scintillua
+--    does NOT bundle it, it must come from the system, and forgetting it is the
+--    usual reason nothing happens.
+--
+--        # 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
+--
+-- 2. Scintillua, the lexer collection from the Textadept editor. Roughly 120
+--    languages as plain .lua files, nothing to compile. Download a release and
+--    unpack it anywhere.
+--
+--        https://orbitalquark.github.io/scintillua/
+--
+-- The lexers are found by probing, in order
+--
+--     $CGIT_SCINTILLUA_PATH        (used alone when set, no fallback)
+--     <dir of $CGIT_CONFIG>/scintillua/lexers
+--     the scintillua_dirs list in the CONFIGURATION block below
+--
+-- so either set the variable in the web server environment, or place (or
+-- symlink) the scintillua directory next to your cgitrc.
+--
+-- SECURITY
+--
+-- Every probed directory is placed on package.path and its Lua is executed in
+-- cgit's process. Make sure none of them is writable by other users, or someone
+-- who can write there gains code execution as the web server. On macOS in
+-- particular, /opt/homebrew/share is group-writable by default.
+--
+-- LIMITATIONS
+--
+-- cgit sends the filter output through a C string sink that stops at the first
+-- NUL byte, so a blob containing a NUL is truncated there. This affects binary
+-- files that slip past cgit's text detection, not ordinary source.
+--
+-- OUTPUT
+--
+-- Tokens are wrapped in <span> elements carrying the hl- classes that
+-- assets/cgit.css styles. Every input byte up to the first NUL is preserved, so
+-- the line number gutter stays aligned.
+
+--
+-- ===== CONFIGURATION =====
+--
+
+-- Files larger than this many bytes are served escaped but unhighlighted, so a
+-- huge blob does not cost a lexing pass. Kept well below cgit's max-blob-size.
+local max_bytes = 512 * 1024
+
+-- Environment variable that, when set, points straight at the Scintillua
+-- lexers directory and is used alone.
+local scintillua_env = "CGIT_SCINTILLUA_PATH"
+
+-- Directories probed for the lexers when that variable is not set. The
+-- directory of $CGIT_CONFIG, when set, is tried ahead of these. Keep every one
+-- of these unwritable by others, see the SECURITY note above.
+local scintillua_dirs = {
+	"/usr/local/share/scintillua/lexers",
+	"/usr/share/scintillua/lexers",
+	"/opt/homebrew/share/scintillua/lexers",
+}
+
+-- Scintillua tag name (its first dotted component) to a cgit css class. Only
+-- the six classes below exist in assets/cgit.css. Add a class there and a row
+-- here to style more token kinds. Tokens with no row render as plain text,
+-- which is what most themes want for operators and identifiers.
+local css = {
+	comment      = "hl-comment",
+	string       = "hl-string",
+	regex        = "hl-string",
+	number       = "hl-number",
+	constant     = "hl-number",
+	keyword      = "hl-keyword",
+	preprocessor = "hl-keyword",
+	tag          = "hl-keyword",
+	label        = "hl-keyword",
+	annotation   = "hl-keyword",
+	type         = "hl-type",
+	class        = "hl-type",
+	attribute    = "hl-type",
+	["function"] = "hl-func",
+}
+
+-- Extension to lexer-name fixes for the fallback path, used only when this
+-- Scintillua has no detect(). Most extensions already equal their lexer name,
+-- these are the frequent exceptions. A wrong guess just falls back to plain
+-- text, so there is no harm in listing best-effort entries.
+local ext_lexer = {
+	py = "python", js = "javascript", ts = "typescript",
+	rb = "ruby", pl = "perl", pm = "perl", sh = "bash",
+	md = "markdown", htm = "html", yml = "yaml",
+	rs = "rust", c = "ansi_c", h = "ansi_c",
+}
+
+--
+-- =========================
+--
+
+local lexer_mod = nil
+local filename = ""
+local chunks = {}
+
+local escape_map = { ["&"] = "&amp;", ["<"] = "&lt;", [">"] = "&gt;" }
+
+-- Escape the three HTML metacharacters in a single pass.
+local function escape(s)
+	return (string.gsub(s, "[&<>]", escape_map))
+end
+
+local function scintillua_path()
+	local env = os.getenv(scintillua_env)
+	if env then
+		return env
+	end
+	local candidates = {}
+	local config = os.getenv("CGIT_CONFIG")
+	if config then
+		local dir = string.match(config, "^(.*)/[^/]+$")
+		if dir then
+			candidates[#candidates + 1] = dir .. "/scintillua/lexers"
+		end
+	end
+	for _, d in ipairs(scintillua_dirs) do
+		candidates[#candidates + 1] = d
+	end
+	for _, dir in ipairs(candidates) do
+		local f = io.open(dir .. "/lexer.lua", "r")
+		if f then
+			f:close()
+			return dir
+		end
+	end
+	return nil
+end
+
+local function load_scintillua()
+	local dir = scintillua_path()
+	if not dir then
+		return nil
+	end
+	if not string.find(package.path, dir, 1, true) then
+		package.path = dir .. "/?.lua;" .. package.path
+	end
+	local ok, mod = pcall(require, "lexer")
+	-- A real Scintillua exposes load(). Anything else on the path that happens
+	-- to be called lexer is not usable.
+	if ok and type(mod) == "table" and type(mod.load) == "function" then
+		return mod
+	end
+	return nil
+end
+
+local function load_lexer_name(name)
+	if name == nil then
+		return nil
+	end
+	local ok, lex = pcall(lexer_mod.load, name)
+	if ok and lex then
+		return lex
+	end
+	return nil
+end
+
+-- Resolve a lexer for the file, preferring Scintillua's own filename detection
+-- when this version provides it, then an extension map, then the raw extension.
+local function lexer_for(name)
+	if type(lexer_mod.detect) == "function" then
+		local ok, lang = pcall(lexer_mod.detect, name)
+		if ok and lang then
+			local lex = load_lexer_name(lang)
+			if lex then
+				return lex
+			end
+		end
+	end
+	local ext = string.match(name, "%.([^.]+)$")
+	if not ext then
+		return nil
+	end
+	ext = string.lower(ext)
+	return load_lexer_name(ext_lexer[ext]) or load_lexer_name(ext)
+end
+
+local function highlight(text)
+	local lex = lexer_for(filename)
+	if not lex then
+		return nil
+	end
+	local ok, tokens = pcall(lex.lex, lex, text)
+	if not ok or type(tokens) ~= "table" then
+		return nil
+	end
+	local out = {}
+	local pos = 1
+	for i = 1, #tokens, 2 do
+		local tag = tokens[i]
+		local fin = tokens[i + 1]
+		local part = escape(string.sub(text, pos, fin - 1))
+		local class = css[string.match(tag, "^[%w_]+")]
+		if class and part ~= "" then
+			part = "<span class='" .. class .. "'>" .. part .. "</span>"
+		end
+		out[#out + 1] = part
+		pos = fin
+	end
+	-- Anything the lexer left unconsumed is kept, escaped.
+	if pos <= #text then
+		out[#out + 1] = escape(string.sub(text, pos))
+	end
+	return table.concat(out)
+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 = {}
+	if #text <= max_bytes then
+		if lexer_mod == nil then
+			lexer_mod = load_scintillua() or false
+		end
+		if lexer_mod then
+			local ok, marked = pcall(highlight, text)
+			if ok and marked then
+				html(marked)
+				return 0
+			end
+		end
+	end
+	-- Fallback, escaped plain text emitted in slices so a large blob does not
+	-- cost a full-size second copy all at once.
+	local n = #text
+	if n == 0 then
+		html("")
+		return 0
+	end
+	local pos = 1
+	while pos <= n do
+		html(escape(string.sub(text, pos, pos + 65535)))
+		pos = pos + 65536
+	end
+	return 0
+end