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| | | /** |
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| | | * **The `node:wasi` module does not currently provide the** |
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| | | * **comprehensive file system security properties provided by some WASI runtimes.** |
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| | | * **Full support for secure file system sandboxing may or may not be implemented in** |
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| | | * **future. In the mean time, do not rely on it to run untrusted code.** |
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| | | * |
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| | | * The WASI API provides an implementation of the [WebAssembly System Interface](https://wasi.dev/) specification. WASI gives WebAssembly applications access to the underlying |
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| | | * operating system via a collection of POSIX-like functions. |
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| | | * |
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| | | * ```js |
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| | | * import { readFile } from 'node:fs/promises'; |
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| | | * import { WASI } from 'node:wasi'; |
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| | | * import { argv, env } from 'node:process'; |
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| | | * |
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| | | * const wasi = new WASI({ |
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| | | * version: 'preview1', |
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| | | * args: argv, |
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| | | * env, |
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| | | * preopens: { |
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| | | * '/local': '/some/real/path/that/wasm/can/access', |
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| | | * }, |
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| | | * }); |
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| | | * |
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| | | * const wasm = await WebAssembly.compile( |
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| | | * await readFile(new URL('./demo.wasm', import.meta.url)), |
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| | | * ); |
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| | | * const instance = await WebAssembly.instantiate(wasm, wasi.getImportObject()); |
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| | | * |
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| | | * wasi.start(instance); |
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| | | * ``` |
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| | | * |
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| | | * To run the above example, create a new WebAssembly text format file named `demo.wat`: |
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| | | * |
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| | | * ```text |
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| | | * (module |
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| | | * ;; Import the required fd_write WASI function which will write the given io vectors to stdout |
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| | | * ;; The function signature for fd_write is: |
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| | | * ;; (File Descriptor, *iovs, iovs_len, nwritten) -> Returns number of bytes written |
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| | | * (import "wasi_snapshot_preview1" "fd_write" (func $fd_write (param i32 i32 i32 i32) (result i32))) |
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| | | * |
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| | | * (memory 1) |
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| | | * (export "memory" (memory 0)) |
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| | | * |
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| | | * ;; Write 'hello world\n' to memory at an offset of 8 bytes |
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| | | * ;; Note the trailing newline which is required for the text to appear |
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| | | * (data (i32.const 8) "hello world\n") |
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| | | * |
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| | | * (func $main (export "_start") |
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| | | * ;; Creating a new io vector within linear memory |
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| | | * (i32.store (i32.const 0) (i32.const 8)) ;; iov.iov_base - This is a pointer to the start of the 'hello world\n' string |
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| | | * (i32.store (i32.const 4) (i32.const 12)) ;; iov.iov_len - The length of the 'hello world\n' string |
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| | | * |
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| | | * (call $fd_write |
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| | | * (i32.const 1) ;; file_descriptor - 1 for stdout |
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| | | * (i32.const 0) ;; *iovs - The pointer to the iov array, which is stored at memory location 0 |
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| | | * (i32.const 1) ;; iovs_len - We're printing 1 string stored in an iov - so one. |
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| | | * (i32.const 20) ;; nwritten - A place in memory to store the number of bytes written |
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| | | * ) |
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| | | * drop ;; Discard the number of bytes written from the top of the stack |
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| | | * ) |
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| | | * ) |
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| | | * ``` |
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| | | * |
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| | | * Use [wabt](https://github.com/WebAssembly/wabt) to compile `.wat` to `.wasm` |
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| | | * |
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| | | * ```bash |
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| | | * wat2wasm demo.wat |
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| | | * ``` |
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| | | * @experimental |
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| | | * @see [source](https://github.com/nodejs/node/blob/v25.x/lib/wasi.js) |
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| | | */ |
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| | | declare module "node:wasi" { |
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| | | interface WASIOptions { |
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| | | /** |
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