feat: first pass at gs/os implementation

Signed-off-by: Christian Stewart <christian@aperture.us>

Author: paralin

gs/os/dir.gs.ts

@@ -1,42 +1,54 @@
 import * as $ from "@goscript/builtin/index.js";
 import { ErrUnimplemented } from "./error.gs.js";
+import { createFileInfo, getDeno, getNodeFS, newHostError } from "./types_js.gs.js";
+import { FileInfoToDirEntry } from "@goscript/io/fs/readdir.js";
 
 import * as fs from "@goscript/io/fs/index.js"
 
 type DirEntry = fs.DirEntry;
 
-// ReadDir reads the named directory,
-// returning all its directory entries sorted by filename.
-// If an error occurs reading the directory,
-// ReadDir returns the entries it was able to read before the error,
-// along with the error.
 export function ReadDir(name: string): [$.Slice<DirEntry>, $.GoError] {
-	// Directory reading not supported in JavaScript environment
+	const denoObj = getDeno()
+	if (denoObj?.readDirSync) {
+		try {
+			const entries: DirEntry[] = []
+			for (const entry of denoObj.readDirSync(name)) {
+				const dirEntry = FileInfoToDirEntry(createFileInfo(entry.name, {
+					isDirectory: () => entry.isDirectory,
+					isSymbolicLink: () => entry.isSymlink,
+					mode: 0,
+					size: 0,
+				}))
+				if (dirEntry !== null) {
+					entries.push(dirEntry)
+				}
+			}
+			entries.sort((a, b) => (a?.Name() ?? "").localeCompare(b?.Name() ?? ""))
+			return [$.arrayToSlice(entries), null]
+		} catch (err) {
+			return [null, newHostError(err)]
+		}
+	}
+	const nodeFS = getNodeFS()
+	if (nodeFS?.readdirSync) {
+		try {
+			const entries = nodeFS.readdirSync(name, { withFileTypes: true }).map((entry: any) =>
+				FileInfoToDirEntry(createFileInfo(entry.name, {
+					isDirectory: () => typeof entry.isDirectory === "function" ? entry.isDirectory() : false,
+					isSymbolicLink: () => typeof entry.isSymbolicLink === "function" ? entry.isSymbolicLink() : false,
+					mode: 0,
+					size: 0,
+				}))
+			).filter((entry: DirEntry | null): entry is DirEntry => entry !== null)
+			entries.sort((a, b) => (a?.Name() ?? "").localeCompare(b?.Name() ?? ""))
+			return [$.arrayToSlice(entries), null]
+		} catch (err) {
+			return [null, newHostError(err)]
+		}
+	}
 	return [null, ErrUnimplemented]
 }
 
-// CopyFS copies the file system fsys into the directory dir,
-// creating dir if necessary.
-//
-// Files are created with mode 0o666 plus any execute permissions
-// from the source, and directories are created with mode 0o777
-// (before umask).
-//
-// CopyFS will not overwrite existing files. If a file name in fsys
-// already exists in the destination, CopyFS will return an error
-// such that errors.Is(err, fs.ErrExist) will be true.
-//
-// Symbolic links in fsys are not supported. A *PathError with Err set
-// to ErrInvalid is returned when copying from a symbolic link.
-//
-// Symbolic links in dir are followed.
-//
-// New files added to fsys (including if dir is a subdirectory of fsys)
-// while CopyFS is running are not guaranteed to be copied.
-//
-// Copying stops at and returns the first error encountered.
 export function CopyFS(dir: string, fsys: fs.FS): $.GoError {
-	// File system copying not supported in JavaScript environment
 	return ErrUnimplemented
 }
-

gs/os/exec.gs.ts

@@ -137,7 +137,7 @@ export class ProcAttr {
 	);
 }
 
-// Stub ProcessState for JavaScript environment
+// ProcessState mirrors the minimal JavaScript process surface.
 export class ProcessState {
 	public _fields: {}
 
@@ -159,14 +159,13 @@ export class ProcessState {
 	);
 }
 
-// Signal interface stub
+// Signal matches the Go signal interface shape when available.
 export type Signal = null | {
 	Signal(): void
 	String(): string
 }
 export const Signal = null as any;
 
-// Stub functions that return ErrUnimplemented
 export function Getpid(): number {
 	return -1 // Not available in JavaScript
 }
@@ -195,4 +194,3 @@ export function newHandleProcess(pid: number, handle: number): Process {
 export function newPIDProcess(pid: number): Process {
 	return new Process({Pid: pid})
 }
-

gs/os/exec_posix.gs.ts

@@ -36,7 +36,7 @@ export class ProcessState {
 		return cloned
 	}
 
-	// All methods return stub values for JavaScript environment
+	// JavaScript does not expose process timing and wait status details.
 	public UserTime(): any {
 		return 0 // Duration not available
 	}
@@ -92,4 +92,3 @@ export class ProcessState {
 		{ "pid": { kind: $.TypeKind.Basic, name: "number" } }
 	);
 }
-

gs/os/file_constants_js.gs.ts

@@ -1,8 +1,16 @@
 import * as $ from "@goscript/builtin/index.js";
 import { ErrUnimplemented } from "./error.gs.js";
+import { getDeno, getEnv, getNodeFS, getPlatform, newHostError } from "./types_js.gs.js";
 
-// JavaScript-specific stubs for file constants and operations
-// These provide the required constants and stub implementations
+function pickFirstEnv(keys: string[]): string {
+	for (const key of keys) {
+		const value = getEnv(key)
+		if (value !== "") {
+			return value
+		}
+	}
+	return ""
+}
 
 // File open flags - using values compatible with typical Unix systems
 export const O_RDONLY = 0
@@ -19,7 +27,7 @@ export const SEEK_SET = 0
 export const SEEK_CUR = 1
 export const SEEK_END = 2
 
-// LinkError stub for compatibility
+// LinkError carries details for link-related path errors.
 export class LinkError {
 	public get Op(): string {
 		return this._fields.Op.value
@@ -76,23 +84,77 @@ export class LinkError {
 	}
 }
 
-// Directory and file operation stubs
 export function Readlink(name: string): [string, $.GoError] {
+	const denoObj = getDeno()
+	if (denoObj?.readLinkSync) {
+		try {
+			return [denoObj.readLinkSync(name), null]
+		} catch (err) {
+			return ["", newHostError(err)]
+		}
+	}
+	const nodeFS = getNodeFS()
+	if (nodeFS?.readlinkSync) {
+		try {
+			return [nodeFS.readlinkSync(name), null]
+		} catch (err) {
+			return ["", newHostError(err)]
+		}
+	}
 	return ["", ErrUnimplemented]
 }
 
 export function TempDir(): string {
-	return "/tmp"
+	const value = pickFirstEnv(["TMPDIR", "TEMP", "TMP"])
+	if (value !== "") {
+		return value
+	}
+	return getPlatform() === "win32" ? "." : "/tmp"
 }
 
 export function UserCacheDir(): [string, $.GoError] {
-	return ["", ErrUnimplemented]
+	if (getPlatform() === "win32") {
+		const value = pickFirstEnv(["LOCALAPPDATA", "APPDATA", "USERPROFILE"])
+		if (value !== "") {
+			return [value, null]
+		}
+		return ["", ErrUnimplemented]
+	}
+	const value = pickFirstEnv(["XDG_CACHE_HOME"])
+	if (value !== "") {
+		return [value, null]
+	}
+	const [home, err] = UserHomeDir()
+	if (err !== null || home === "") {
+		return ["", err ?? ErrUnimplemented]
+	}
+	return [home.replace(/\/+$/, "") + "/.cache", null]
 }
 
 export function UserConfigDir(): [string, $.GoError] {
-	return ["", ErrUnimplemented]
+	if (getPlatform() === "win32") {
+		const value = pickFirstEnv(["APPDATA", "USERPROFILE"])
+		if (value !== "") {
+			return [value, null]
+		}
+		return ["", ErrUnimplemented]
+	}
+	const value = pickFirstEnv(["XDG_CONFIG_HOME"])
+	if (value !== "") {
+		return [value, null]
+	}
+	const [home, err] = UserHomeDir()
+	if (err !== null || home === "") {
+		return ["", err ?? ErrUnimplemented]
+	}
+	return [home.replace(/\/+$/, "") + "/.config", null]
 }
 
 export function UserHomeDir(): [string, $.GoError] {
+	const keys = getPlatform() === "win32" ? ["USERPROFILE", "HOMEDRIVE", "HOME"] : ["HOME"]
+	const value = pickFirstEnv(keys)
+	if (value !== "") {
+		return [value, null]
+	}
 	return ["", ErrUnimplemented]
-} 
+}