Diff options
Diffstat (limited to 'extensions/syntax-highlight.lua')
| -rw-r--r-- | extensions/syntax-highlight.lua | 224 |
1 file changed, 150 insertions, 74 deletions
diff --git a/extensions/syntax-highlight.lua b/extensions/syntax-highlight.lua index c88be87..8310504 100644 --- a/extensions/syntax-highlight.lua +++ b/extensions/syntax-highlight.lua @@ -1,30 +1,41 @@ --- 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. +-- 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 --- this filter's place. +-- 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. Works with Lua 5.1 onward, --- including LuaJIT. +-- 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 that cgit is linked --- against. Scintillua does NOT bundle it, it must come from the --- system, and forgetting it is the usual reason nothing happens. +-- 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 --- macOS luarocks --lua-version 5.1 install lpeg +-- # 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. +-- 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/ -- @@ -32,75 +43,122 @@ -- -- $CGIT_SCINTILLUA_PATH (used alone when set, no fallback) -- <dir of $CGIT_CONFIG>/scintillua/lexers --- /usr/local/share/scintillua/lexers --- /usr/share/scintillua/lexers --- /opt/homebrew/share/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. -- --- so either set the variable in the web server environment, or place --- (or symlink) the scintillua directory next to your cgitrc. When --- Scintillua or lpeg is missing the filter passes text through escaped --- and unhighlighted, so it is safe to enable before the dependencies --- are installed. +-- 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 is preserved, so the line --- number gutter stays aligned. +-- assets/cgit.css styles. Every input byte up to the first NUL is preserved, so +-- the line number gutter stays aligned. --- Files larger than this are passed through without lexing. +-- +-- ===== 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 -local function scintillua_path() - local env = os.getenv("CGIT_SCINTILLUA_PATH") - if env then - return env - end - local candidates = { - "/usr/local/share/scintillua/lexers", - "/usr/share/scintillua/lexers", - "/opt/homebrew/share/scintillua/lexers", - } - local config = os.getenv("CGIT_CONFIG") - if config then - local dir = string.match(config, "^(.*)/[^/]+$") - if dir then - table.insert(candidates, 1, dir .. "/scintillua/lexers") - end - 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 +-- Environment variable that, when set, points straight at the Scintillua +-- lexers directory and is used alone. +local scintillua_env = "CGIT_SCINTILLUA_PATH" --- Scintillua tag name (first dotted component) to cgit css class. +-- 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", - constant = "hl-number", + 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) - s = string.gsub(s, "&", "&") - s = string.gsub(s, "<", "<") - s = string.gsub(s, ">", ">") - return 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() @@ -112,36 +170,43 @@ local function load_scintillua() 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. + -- 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 --- Resolve a lexer for the file, preferring Scintillua's own filename --- detection when this version provides it. +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 okl, lex = pcall(lexer_mod.load, lang) - if okl then + local lex = load_lexer_name(lang) + if lex then return lex end end - return nil end local ext = string.match(name, "%.([^.]+)$") if not ext then return nil end - local ok, lex = pcall(lexer_mod.load, string.lower(ext)) - if ok then - return lex - end - return nil + ext = string.lower(ext) + return load_lexer_name(ext_lexer[ext]) or load_lexer_name(ext) end local function highlight(text) @@ -197,6 +262,17 @@ function filter_close() end end end - html(escape(text)) + -- 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 |