github.com/bananabytelabs/wazero@v0.0.0-20240105073314-54b22a776da8/site/content/specs.md (about)

     1  +++
     2  title = "Specifications"
     3  +++
     4  
     5  wazero understands that while no-one desired to create confusion, confusion
     6  exists both in what is a standard and what in practice is in fact a standard
     7  feature. To help with this, we created some guidance both on the status quo
     8  of WebAssembly portability and what we support.
     9  
    10  The WebAssembly Core Specification is the only specification relevant to
    11  wazero, governed by a standards body. Release [1.0][1] is a Web Standard (REC).
    12  Release [2.0][2] is a Working Draft (WD), so not yet a Web Standard.
    13  
    14  Many compilers implement system calls using the WebAssembly System Interface,
    15  [WASI][5]. WASI is a WebAssembly community [subgroup][3], but has not published
    16  any working drafts as a result of their work. WASI's last stable point was
    17  [wasi_snapshot_preview1][4], tagged at the end of 2020.
    18  
    19  While this seems scary, the confusion caused by pre-standard features is not as
    20  bad as it sounds. The WebAssembly ecosystem is generally responsive regardless
    21  of where things are written down and wazero provides tools, such as built-in
    22  support for WASI, to reduce pain.
    23  
    24  The goal of this section isn't to promote a W3C recommendation exclusive
    25  approach, rather to help you understand common language around portable
    26  features and which of those wazero supports at the moment. While we consider
    27  features formalized through W3C recommendation status mandatory, we actively
    28  pursue pre-standard features as well interop with commonly used infrastructure
    29  such as AssemblyScript.
    30  
    31  In summary, we hope this section can guide you in terms of what wazero supports
    32  as well as how to classify a request for a feature we don't yet support.
    33  
    34  ### WebAssembly Core {#core}
    35  wazero conforms with tests defined alongside WebAssembly Core
    36  Specification [1.0][1] and [2.0][14].
    37  
    38  By default, the runtime configuration enables features in WebAssembly Core
    39  Specification, despite it not yet being a Web Standard (REC). You can select
    40  version 1.0 like so:
    41  ```go
    42  rConfig = wazero.NewRuntimeConfig().WithCoreFeatures(api.CoreFeaturesV1)
    43  ```
    44  
    45  One current limitation of wazero is that it doesn't implement the Text
    46  Format, e.g. compiling `.wat` files. Users can work around this using tools such as `wat2wasm` to
    47  compile the text format into the binary format. In practice, the text format is
    48  too low level for most users, so delays here have limited impact.
    49  
    50  #### Post 2.0 Features
    51  Features regardless of W3C release are inventoried in the [Proposals][10].
    52  repository. wazero implements [Finished Proposals][11] based on user demand,
    53  using [wazero.RuntimeConfig][7] feature flags. As of late 2022, all finished
    54  proposals are included in [2.0][14] Working Draft.
    55  
    56  Features not yet assigned to a W3C release are not reliable. Encourage the
    57  [WebAssembly community][12] to formalize features you rely on, so that they
    58  become assigned to a release, and reach the W3C recommendation (REC) phase.
    59  
    60  ### WebAssembly System Interface (WASI) {#wasi}
    61  
    62  Many compilers implement system calls using the WebAssembly System Interface,
    63  [WASI][5]. WASI is a WebAssembly community [subgroup][3], but has not published
    64  any working drafts as a result of their work. WASI's last stable point was
    65  [wasi_snapshot_preview1][4], tagged at the end of 2020.
    66  
    67  Some functions in this tag are used in practice while some others are not known
    68  to be used at all. Further confusion exists because some compilers, like
    69  GrainLang, import functions not used. Finally, some functions were added and
    70  removed after the git tag. For example, [`proc_raise`][13] was removed and
    71  [`sock_accept`][15] added.
    72  
    73  For all of these reasons, wazero will not implement all WASI features, just to
    74  complete the below chart. If you desire something not yet implemented, please
    75  [raise an issue](https://github.com/bananabytelabs/wazero/issues/new) and include
    76  your use case (ex which language you are using to compile, a.k.a. target Wasm).
    77  
    78  Notes:
    79   * AssemblyScript has its own ABI which can optionally use [wasi-shim][17]
    80   * C (via clang) supports the maximum WASI functions due to [wasi-libc][16]
    81   * Rust supports WASI via its [wasm32-wasi][18] target.
    82  
    83  <details><summary>Click to see the full list of supported WASI functions</summary>
    84  <p>
    85  
    86  | Function                | Status |     Known Usage |
    87  |:------------------------|:------:|----------------:|
    88  | args_get                |   ✅    |          TinyGo |
    89  | args_sizes_get          |   ✅    |          TinyGo |
    90  | environ_get             |   ✅    |          TinyGo |
    91  | environ_sizes_get       |   ✅    |          TinyGo |
    92  | clock_res_get           |   ✅    |                 |
    93  | clock_time_get          |   ✅    |          TinyGo |
    94  | fd_advise               |   👷   |                 |
    95  | fd_allocate             |   ✅    |            Rust |
    96  | fd_close                |   ✅    |          TinyGo |
    97  | fd_datasync             |   ✅    |            Rust |
    98  | fd_fdstat_get           |   ✅    |          TinyGo |
    99  | fd_fdstat_set_flags     |   ✅    |            Rust |
   100  | fd_fdstat_set_rights    |   💀   |                 |
   101  | fd_filestat_get         |   ✅    |             Zig |
   102  | fd_filestat_set_size    |   ✅    |        Rust,Zig |
   103  | fd_filestat_set_times   |   ✅    |        Rust,Zig |
   104  | fd_pread                |   ✅    |             Zig |
   105  | fd_prestat_get          |   ✅    | Rust,TinyGo,Zig |
   106  | fd_prestat_dir_name     |   ✅    | Rust,TinyGo,Zig |
   107  | fd_pwrite               |   ✅    |        Rust,Zig |
   108  | fd_read                 |   ✅    | Rust,TinyGo,Zig |
   109  | fd_readdir              |   ✅    |        Rust,Zig |
   110  | fd_renumber             |   ✅    |            libc |
   111  | fd_seek                 |   ✅    |          TinyGo |
   112  | fd_sync                 |   ✅    |              Go |
   113  | fd_tell                 |   ✅    |            Rust |
   114  | fd_write                |   ✅    | Rust,TinyGo,Zig |
   115  | path_create_directory   |   ✅    | Rust,TinyGo,Zig |
   116  | path_filestat_get       |   ✅    | Rust,TinyGo,Zig |
   117  | path_filestat_set_times |   ✅    |       Rust,libc |
   118  | path_link               |   ✅    |        Rust,Zig |
   119  | path_open               |   ✅    | Rust,TinyGo,Zig |
   120  | path_readlink           |   ✅    |        Rust,Zig |
   121  | path_remove_directory   |   ✅    | Rust,TinyGo,Zig |
   122  | path_rename             |   ✅    | Rust,TinyGo,Zig |
   123  | path_symlink            |   ✅    |        Rust,Zig |
   124  | path_unlink_file        |   ✅    | Rust,TinyGo,Zig |
   125  | poll_oneoff             |   ✅    | Rust,TinyGo,Zig |
   126  | proc_exit               |   ✅    | Rust,TinyGo,Zig |
   127  | proc_raise              |   💀   |                 |
   128  | sched_yield             |   ✅    |            Rust |
   129  | random_get              |   ✅    | Rust,TinyGo,Zig |
   130  | sock_accept             |   ✅    |        Rust,Zig |
   131  | sock_recv               |   ✅    |        Rust,Zig |
   132  | sock_send               |   ✅    |        Rust,Zig |
   133  | sock_shutdown           |   ✅    |        Rust,Zig |
   134  
   135  Note: 💀 means the function was later removed from WASI.
   136  
   137  </p>
   138  </details>
   139  
   140  [1]: https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/
   141  [2]: https://www.w3.org/TR/2022/WD-wasm-core-2-20220419/
   142  [3]: https://github.com/WebAssembly/meetings/blob/main/process/subgroups.md
   143  [4]: https://github.com/WebAssembly/WASI/blob/snapshot-01/phases/snapshot/docs.md
   144  [5]: https://github.com/WebAssembly/WASI
   145  [6]: https://github.com/WebAssembly/spec/tree/wg-1.0/test/core
   146  [7]: https://pkg.go.dev/github.com/bananabytelabs/wazero#RuntimeConfig
   147  [9]: https://github.com/bananabytelabs/wazero/issues/59
   148  [10]: https://github.com/WebAssembly/proposals
   149  [11]: https://github.com/WebAssembly/proposals/blob/main/finished-proposals.md
   150  [12]: https://www.w3.org/community/webassembly/
   151  [13]: https://github.com/WebAssembly/WASI/pull/136
   152  [14]: https://github.com/WebAssembly/spec/tree/d39195773112a22b245ffbe864bab6d1182ccb06/test/core
   153  [15]: https://github.com/WebAssembly/WASI/pull/458
   154  [16]: https://github.com/WebAssembly/wasi-libc
   155  [17]: https://github.com/AssemblyScript/wasi-shim
   156  [18]: https://github.com/rust-lang/rust/tree/1.68.0/library/std/src/sys/wasi