From b5988111398bf3b5a1cc58c374c1ef1cb58fe0ea Mon Sep 17 00:00:00 2001 From: Bryce Kwon Date: Sat, 25 Jul 2026 22:36:52 -1000 Subject: Reorganize the tree into vendor/ and custom/ --- custom/extensions/syntax-highlight.lua | 278 +++++++++++++++++++++++++++++++++ 1 file changed, 278 insertions(+) create mode 100644 custom/extensions/syntax-highlight.lua (limited to 'custom/extensions/syntax-highlight.lua') 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) +-- /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 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 = { ["&"] = "&", ["<"] = "<", [">"] = ">" } + +-- 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 = "" .. part .. "" + 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 -- cgit v2.8.0