chore: init, the basics

Implement core `ZipReader`, `ZipEntry` and basic API. Supports simple
zip format deserialization, without advanced features, or decompression.

.gitignore

@@ -0,0 +1,2 @@
+test.zip
+*_packages/

.luaurc

@@ -0,0 +1,6 @@
+{
+  "languageMode": "strict",
+  "aliases": {
+        "pkg": "./lune_packages"
+    }
+}

.vscode/settings.json

@@ -0,0 +1,6 @@
+{
+  "luau-lsp.require.mode": "relativeToFile",
+  "luau-lsp.require.directoryAliases": {
+    "@lune/": "~/.lune/.typedefs/0.8.9/"
+  }
+}

LICENSE.md

@@ -0,0 +1,7 @@
+Copyright © 2024 CompeyDev
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

lib/init.luau

@@ -0,0 +1,254 @@
+local SIGNATURES = table.freeze({
+	LOCAL_FILE = 0x04034b50,
+	CENTRAL_DIR = 0x02014b50,
+	END_OF_CENTRAL_DIR = 0x06054b50,
+})
+
+-- TODO: ERROR HANDLING !!
+
+local ZipEntry = {}
+export type ZipEntry = typeof(setmetatable({} :: ZipEntryInner, { __index = ZipEntry }))
+type ZipEntryInner = {
+	name: string,
+	size: number,
+	offset: number,
+	timestamp: number,
+	crc: number,
+	isDirectory: boolean,
+	parent: ZipEntry?,
+	children: { ZipEntry },
+	getPath: (ZipEntry) -> string,
+}
+
+function ZipEntry.new(name, size, offset, timestamp, crc): ZipEntry
+	return setmetatable(
+		{
+			name = name,
+			size = size,
+			offset = offset,
+			timestamp = timestamp,
+			crc = crc,
+			isDirectory = string.sub(name, -1) == "/",
+			parent = nil,
+			children = {},
+		} :: ZipEntryInner,
+		{ __index = ZipEntry }
+	)
+end
+
+function ZipEntry.getPath(self: ZipEntry): string
+	local path = self.name
+	local current = self.parent
+
+	while current and current.name ~= "/" do
+		path = current.name .. path
+		current = current.parent
+	end
+
+	return path
+end
+
+local ZipReader = {}
+export type ZipReader = typeof(setmetatable({} :: ZipReaderInner, { __index = ZipReader }))
+type ZipReaderInner = {
+	data: buffer,
+	entries: { ZipEntry },
+	directories: { [string]: ZipEntry },
+	root: ZipEntry,
+}
+
+function ZipReader.new(data): ZipReader
+	local root = ZipEntry.new("/", 0, 0, 0, 0)
+	root.isDirectory = true
+
+	local this = setmetatable(
+		{
+			data = data,
+			entries = {},
+			directories = {},
+			root = root,
+		} :: ZipReaderInner,
+		{ __index = ZipReader }
+	)
+
+	this:parseCentralDirectory()
+	this:buildDirectoryTree()
+	return this
+end
+
+function ZipReader.parseCentralDirectory(self: ZipReader): ()
+	local bufSize = buffer.len(self.data)
+	local pos = bufSize - 22
+
+	while pos > 0 do
+		if buffer.readu32(self.data, pos) == SIGNATURES.END_OF_CENTRAL_DIR then
+			break
+		end
+		pos = pos - 1
+	end
+
+	if pos < 0 then
+		error("Invalid ZIP file: End of Central Directory not found")
+	end
+
+	local cdOffset = buffer.readu32(self.data, pos + 16)
+	local cdEntries = buffer.readu16(self.data, pos + 10)
+
+	pos = cdOffset
+	for i = 1, cdEntries do
+		if buffer.readu32(self.data, pos) ~= SIGNATURES.CENTRAL_DIR then
+			error("Invalid central directory header")
+		end
+
+		local nameLength = buffer.readu16(self.data, pos + 28)
+		local extraLength = buffer.readu16(self.data, pos + 30)
+		local commentLength = buffer.readu16(self.data, pos + 32)
+		local timestamp = buffer.readu32(self.data, pos + 12)
+		local crc = buffer.readu32(self.data, pos + 16)
+		local size = buffer.readu32(self.data, pos + 24)
+		local offset = buffer.readu32(self.data, pos + 42)
+
+		local nameBuffer = buffer.create(nameLength)
+		buffer.copy(nameBuffer, 0, self.data, pos + 46, nameLength)
+		local name = buffer.tostring(nameBuffer)
+
+		local entry = ZipEntry.new(name, size, offset, timestamp, crc)
+		table.insert(self.entries, entry)
+
+		pos = pos + 46 + nameLength + extraLength + commentLength
+	end
+end
+
+function ZipReader.buildDirectoryTree(self: ZipReader): ()
+	for _, entry in self.entries do
+		local parts = {}
+		for part in string.gmatch(entry.name, "([^/]+)/?") do
+			table.insert(parts, part)
+		end
+
+		local current = self.root
+		local path = ""
+
+		for i, part in parts do
+			path ..= part
+			if i < #parts then
+				if not self.directories[path] then
+					local dir = ZipEntry.new(path, 0, 0, entry.timestamp, 0)
+					dir.isDirectory = true
+					dir.parent = current
+
+					self.directories[path] = dir
+					table.insert(current.children, dir)
+				end
+
+				current = self.directories[path]
+				continue
+			end
+
+			entry.parent = current
+			table.insert(current.children, entry)
+		end
+	end
+end
+
+function ZipReader.findEntry(self: ZipReader, path: string): ZipEntry
+	if path == "/" then
+		return self.root
+	end
+
+	path = string.gsub(path, "^/", ""):gsub("/$", "")
+	for _, entry in self.entries do
+		if string.gsub(entry.name, "/$", "") == path then
+			return entry
+		end
+	end
+
+	return self.directories[path]
+end
+
+function ZipReader.extract(self: ZipReader, entry: ZipEntry): buffer
+	if entry.isDirectory then
+		error("Cannot extract directory")
+	end
+
+	local pos = entry.offset
+	if buffer.readu32(self.data, pos) ~= SIGNATURES.LOCAL_FILE then
+		error("Invalid local file header")
+	end
+
+	local nameLength = buffer.readu16(self.data, pos + 26)
+	local extraLength = buffer.readu16(self.data, pos + 28)
+
+	pos = pos + 30 + nameLength + extraLength
+
+	local content = buffer.create(entry.size)
+	buffer.copy(content, 0, self.data, pos, entry.size)
+
+	-- TODO: decompress data! `buffer.readu16(self.data, entry.offset + 8)`
+	-- will give the compression method, where method id 8 corresponds to
+	-- deflate
+
+	return content
+end
+
+function ZipReader.extractDirectory(self: ZipReader, path: string): { [string]: buffer }
+	local files = {}
+	path = string.gsub(path, "^/", "")
+
+	for _, entry in self.entries do
+		if not entry.isDirectory and string.sub(entry.name, 1, #path) == path then
+			files[entry.name] = self:extract(entry)
+		end
+	end
+
+	return files
+end
+
+function ZipReader.listDirectory(self: ZipReader, path: string): { ZipEntry }
+	local entry = self:findEntry(path)
+	if not entry or not entry.isDirectory then
+		error("Not a directory")
+	end
+
+	return entry.children
+end
+
+function ZipReader.walk(self: ZipReader, callback: (entry: ZipEntry, depth: number) -> ()): ()
+	local function walkEntry(entry: ZipEntry, depth: number)
+		callback(entry, depth)
+
+		for _, child in entry.children do
+			-- ooo spooky recursion... blame this if shit go wrong
+			walkEntry(child, depth + 1)
+		end
+	end
+
+	walkEntry(self.root, 0)
+end
+
+export type ZipStatistics = { fileCount: number, dirCount: number, totalSize: number }
+function ZipReader.getStats(self: ZipReader): ZipStatistics
+	local stats: ZipStatistics = {
+		fileCount = 0,
+		dirCount = 0,
+		totalSize = 0,
+	}
+
+	for _, entry in self.entries do
+		if entry.isDirectory then
+			stats.dirCount = stats.dirCount + 1
+			continue
+		end
+
+		stats.fileCount = stats.fileCount + 1
+		stats.totalSize = stats.totalSize + entry.size
+	end
+
+	return stats
+end
+
+return {
+	load = function(data)
+		return ZipReader.new(data)
+	end,
+}

pesde.lock

@@ -0,0 +1,39 @@
+name = "0x5eal/unzip"
+version = "0.1.0"
+target = "luau"
+
+[graph."jiwonz/pathfs"."0.1.0 lune"]
+direct = ["pathfs", { name = "jiwonz/pathfs", version = "^0.1.0", target = "lune" }, "standard"]
+resolved_ty = "standard"
+
+[graph."jiwonz/pathfs"."0.1.0 lune".target]
+environment = "lune"
+lib = "init.luau"
+
+[graph."jiwonz/pathfs"."0.1.0 lune".pkg_ref]
+ref_ty = "pesde"
+name = "jiwonz/pathfs"
+version = "0.1.0"
+index_url = "https://github.com/pesde-pkg/index"
+
+[graph."jiwonz/pathfs"."0.1.0 lune".pkg_ref.target]
+environment = "lune"
+lib = "init.luau"
+
+[graph."lukadev_0/result"."1.2.0 luau"]
+direct = ["result", { name = "lukadev_0/result", version = "^1.2.0" }, "standard"]
+resolved_ty = "standard"
+
+[graph."lukadev_0/result"."1.2.0 luau".target]
+environment = "luau"
+lib = "lib/init.luau"
+
+[graph."lukadev_0/result"."1.2.0 luau".pkg_ref]
+ref_ty = "pesde"
+name = "lukadev_0/result"
+version = "1.2.0"
+index_url = "https://github.com/pesde-pkg/index"
+
+[graph."lukadev_0/result"."1.2.0 luau".pkg_ref.target]
+environment = "luau"
+lib = "lib/init.luau"

pesde.toml

@@ -0,0 +1,16 @@
+name = "0x5eal/unzip"
+version = "0.1.0"
+description = "unzip implementation in pure Luau"
+authors = ["Erica Marigold <hi@devcomp.xyz>"]
+repository = "https://github.com/0x5eal/luau-unzip"
+license = "MIT"
+
+[target]
+environment = "luau"
+
+[indices]
+default = "https://github.com/pesde-pkg/index"
+
+[dependencies]
+result = { name = "lukadev_0/result", version = "^1.2.0" }
+pathfs = { name = "jiwonz/pathfs", version = "^0.1.0", target = "lune" }

test.luau

@@ -0,0 +1,37 @@
+local fs = require("@lune/fs")
+local zip = require("./lib")
+
+local file = fs.readFile("test.zip")
+local reader = zip.load(buffer.fromstring(file))
+
+print("Directory structure:")
+reader:walk(function(entry, depth)
+    local prefix = string.rep("  ", depth)
+    local suffix = if not entry.isDirectory then string.format(" (%d bytes)", entry.size) else ""
+    print(prefix .. entry.name .. suffix)
+end)
+
+print("\nContents of /lib/:")
+local assets = reader:listDirectory("/lib/")
+for _, entry in ipairs(assets) do
+    print(entry.name, entry.isDirectory and "DIR" or entry.size)
+end
+
+local configEntry = reader:findEntry("config.json")
+if configEntry then
+    local content = reader:extract(configEntry)
+    print("\nConfig file size:", buffer.len(content))
+end
+
+-- Get archive statistics
+local stats = reader:getStats()
+print(string.format([[
+
+Archive stats:
+Files: %d
+Directories: %d
+Total size: %d bytes]],
+    stats.fileCount,
+    stats.dirCount,
+    stats.totalSize
+))