GitLab

Cheng Shao pushed to branch wip/wasm-dyld-pie at Glasgow Haskell Compiler / GHC

Commits:

33278bf7

by Cheng Shao at 2025-10-24T23:30:48+02:00

wasm: support running dyld fully client side in browser

1 changed file:

utils/jsffi/dyld.mjs

Changes:

utils/jsffi/dyld.mjs

@@ -285,7 +285,10 @@ function originFromServerAddress({ address, family, port }) {
+ }
  // Browser/node portable code stays above this watermark.
 -const isNode = Boolean(globalThis?.process?.versions?.node);
 +let isNode = Boolean(globalThis?.process?.versions?.node);
 +if (globalThis.Deno) {
 +  isNode = false;
 +}
  // Too cumbersome to only import at use sites. Too troublesome to
  // factor out browser-only/node-only logic into different modules. For
@@ -307,18 +310,22 @@ if (isNode) {
      ws = require("ws");
    } catch {}
  } else {
 -  wasi = await import(
 -    "https://cdn.jsdelivr.net/npm/@bjorn3/browser_wasi_shim@0.4.2/dist/index.js"
 -  );
 +  wasi = await import("https://esm.sh/gh/haskell-wasm/browser_wasi_shim");
+ }
  // A subset of dyld logic that can only be run in the host node
  // process and has full access to local filesystem
 -class DyLDHost {
 +export class DyLDHost {
    // Deduped absolute paths of directories where we lookup .so files
    #rpaths = new Set();
    constructor({ out_fd, in_fd }) {
 +    // When running a non-iserv shared library with node, the DyLDHost
 +    // instance is created without a pair of fds, so skip creation of
 +    // readStream/writeStream, they won't be used anyway
 +    if (!(typeof out_fd === "number" && typeof in_fd === "number")) {
 +      return;
 +    }
      this.readStream = stream.Readable.toWeb(
        fs.createReadStream(undefined, { fd: in_fd })
      );
@@ -373,6 +380,77 @@ class DyLDHost {
+   }
+ }
 +// Runs in the browser and uses the in-memory vfs, doesn't do any RPC
 +// calls
 +export class DyLDBrowserHost {
 +  // Deduped absolute paths of directories where we lookup .so files
 +  #rpaths = new Set();
 +  // The PreopenDirectory object of the root filesystem
 +  rootfs;
++
 +  // Given canonicalized absolute file path, return Uint8Array of file
 +  // content, or null if absent
 +  #readFile(p) {
 +    const { ret, entry } = this.rootfs.dir.get_entry_for_path({
 +      parts: p.split("/").filter((tok) => tok !== ""),
 +      is_dir: false,
 +    });
 +    return ret === 0 ? entry.data : null;
 +  }
++
 +  constructor({ rootfs }) {
 +    this.rootfs = rootfs;
 +  }
++
 +  close() {}
++
 +  installSignalHandlers(_cb) {}
++
 +  // p must be canonicalized absolute path
 +  async addLibrarySearchPath(p) {
 +    this.#rpaths.add(p);
 +    return null;
 +  }
++
 +  async findSystemLibrary(f) {
 +    if (f.startsWith("/")) {
 +      if (this.#readFile(f)) {
 +        return f;
 +      }
 +      throw new Error(`findSystemLibrary(${f}): not found in /`);
 +    }
++
 +    for (const rpath of this.#rpaths) {
 +      const r = `${rpath}/${f}`;
 +      if (this.#readFile(r)) {
 +        return r;
 +      }
 +    }
++
 +    throw new Error(
 +      `findSystemLibrary(${f}): not found in ${[...this.#rpaths]}`
 +    );
 +  }
++
 +  async fetchWasm(p) {
 +    let buf = this.#readFile(p);
 +    if (buf.buffer.resizable) {
 +      buf = new Uint8Array(buf);
 +    }
 +    return new Response(buf, {
 +      headers: { "Content-Type": "application/wasm" },
 +    });
 +  }
++
 +  stdout(msg) {
 +    console.info(msg);
 +  }
++
 +  stderr(msg) {
 +    console.warn(msg);
 +  }
 +}
++
  // Fulfill the same functionality as DyLDHost by doing fetch() calls
  // to respective RPC endpoints of a host http server. Also manages
  // WebSocket connections back to host.
@@ -540,7 +618,7 @@ class DyLDRPCServer {
          res.end(
+           `
  import { DyLDRPC, main } from "./fs${dyldPath}";
 -const args = ${JSON.stringify({ libdir, ghciSoPath, args })};
 +const args = ${JSON.stringify({ libdirs: [libdir], ghciSoPath, args })};
  args.rpc = new DyLDRPC({origin: "${origin}", redirectWasiConsole: ${redirectWasiConsole}});
  args.rpc.opened.then(() => main(args));
+ `
@@ -832,6 +910,10 @@ class DyLD {
          ],
          { debug: false }
        );
++
 +      if (this.#rpc instanceof DyLDBrowserHost) {
 +        this.#wasi.fds[3] = this.#rpc.rootfs;
 +      }
+     }
      // Both wasi implementations we use provide
@@ -1218,15 +1300,39 @@ class DyLD {
+   }
+ }
 -export async function main({ rpc, libdir, ghciSoPath, args }) {
 +// The main entry point of dyld that may be run on node/browser, and
 +// may run either iserv defaultMain from the ghci library or an
 +// alternative entry point from another shared library
 +export async function main({
 +  rpc, // Handle the side effects of DyLD
 +  libdirs, // Initial library search directories
 +  ghciSoPath, // Could also be another shared library that's actually not ghci
 +  args, // WASI argv without the executable name. +RTS etc will be respected
 +  altEntry, // Optional alternative entry point function name
 +  altArgs, // Argument array to pass to the alternative entry point function
 +}) {
    try {
      const dyld = new DyLD({
        args: ["dyld.so", ...args],
        rpc,
      });
 -    await dyld.addLibrarySearchPath(libdir);
 +    for (const libdir of libdirs) {
 +      await dyld.addLibrarySearchPath(libdir);
 +    }
      await dyld.loadDLLs(ghciSoPath);
 +    // At this point, rts/ghc-internal are loaded, perform wasm shared
 +    // library specific RTS startup logic, see Note [JSFFI
 +    // initialization]
 +    dyld.exportFuncs.__ghc_wasm_jsffi_init();
++
 +    // We're not running iserv, just invoke user-specified alternative
 +    // entry point and pass the arguments
 +    if (altEntry) {
 +      return await dyld.exportFuncs[altEntry](...altArgs);
 +    }
++
 +    // iserv-specific logic follows
      const reader = rpc.readStream.getReader();
      const writer = rpc.writeStream.getWriter();
@@ -1245,19 +1351,19 @@ export async function main({ rpc, libdir, ghciSoPath, args }) {
        writer.write(new Uint8Array(buf));
      };
 -    dyld.exportFuncs.__ghc_wasm_jsffi_init();
 -    await dyld.exportFuncs.defaultServer(cb_sig, cb_recv, cb_send);
 +    return await dyld.exportFuncs.defaultServer(cb_sig, cb_recv, cb_send);
    } finally {
      rpc.close();
+   }
+ }
 -export async function nodeMain({ libdir, ghciSoPath, out_fd, in_fd, args }) {
 +// node-specific iserv-specific logic
 +async function nodeMain({ libdir, ghciSoPath, out_fd, in_fd, args }) {
    if (!process.env.GHCI_BROWSER) {
      const rpc = new DyLDHost({ out_fd, in_fd });
      await main({
        rpc,
 -      libdir,
 +      libdirs: [libdir],
        ghciSoPath,
        args,
      });
@@ -1370,6 +1476,8 @@ export async function nodeMain({ libdir, ghciSoPath, out_fd, in_fd, args }) {
    );
+ }
 +// Can't be reused with isMain in post-link.mjs, import.meta.filename
 +// evaluates to filename of source location
  function isNodeMain() {
    if (!globalThis?.process?.versions?.node) {
      return false;
@@ -1378,6 +1486,8 @@ function isNodeMain() {
    return import.meta.filename === process.argv[1];
+ }
 +// node iserv as invoked by
 +// GHC.Runtime.Interpreter.Wasm.spawnWasmInterp
  if (isNodeMain()) {
    const libdir = process.argv[2];
    const ghciSoPath = process.argv[3];