atomvm · pguyot · May 2, 2026 · May 3, 2026 · May 2, 2026
diff --git a/.github/workflows/build-and-test-on-freebsd.yaml b/.github/workflows/build-and-test-on-freebsd.yaml
@@ -93,7 +93,7 @@ jobs:
       shell: freebsd {0}
       run: |
         cd $GITHUB_WORKSPACE;
-        sed -i '' 's/test_http_server/%test_http_server/g' tests/libs/eavmlib/tests.erl
+        sed -i '' 's/test_http_server, //g' tests/libs/eavmlib/tests.erl
 
     - name: "Build: create build dir"
       shell: freebsd {0}

diff --git a/.github/workflows/wasi-build.yaml b/.github/workflows/wasi-build.yaml
@@ -0,0 +1,183 @@
+#
+#  Copyright 2026 Paul Guyot <pguyot@kallisys.net>
+#
+#  SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+#
+
+name: WASI Build
+
+on:
+  push:
+    paths:
+      - '.github/workflows/wasi-build.yaml'
+      - 'CMakeLists.txt'
+      - 'CMakeModules/**'
+      - 'libs/**'
+      - 'src/platforms/wasi/**'
+      - 'src/libAtomVM/**'
+  pull_request:
+    paths:
+      - '.github/workflows/wasi-build.yaml'
+      - 'CMakeLists.txt'
+      - 'CMakeModules/**'
+      - 'libs/**'
+      - 'src/platforms/wasi/**'
+      - 'src/libAtomVM/**'
+
+permissions:
+  contents: write
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref != 'refs/heads/main' && github.ref || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+
+  compile_tests:
+
+    runs-on: ubuntu-24.04
+    container: erlang:28
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+
+    strategy:
+      fail-fast: false
+      matrix:
+        language: ["c-cpp"]
+
+    steps:
+    - name: Checkout repo
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+    - name: Install required packages
+      run: apt update && apt install -y gperf zlib1g-dev cmake ninja-build
+
+    - name: "Git config safe.directory for codeql"
+      run: git config --global --add safe.directory /__w/AtomVM/AtomVM
+
+    - name: "Initialize CodeQL"
+      uses: github/codeql-action/init@95e58e9a2cdfd71adc6e0353d5c52f41a045d225 # v4
+      with:
+        languages: ${{matrix.language}}
+        build-mode: manual
+        queries: +./code-queries/term-to-non-term-func.ql,./code-queries/non-term-to-term-func.ql,./code-queries/mismatched-atom-string-length.ql,./code-queries/mismatched-free-type.ql,./code-queries/term-use-after-gc.ql,./code-queries/allocations-exceeding-ensure-free.ql,./code-queries/allocations-without-ensure-free.ql
+
+    - name: Compile AtomVM and test modules
+      run: |
+        set -e
+        mkdir build
+        cd build
+        cmake .. -G Ninja -DAVM_WARNINGS_ARE_ERRORS=ON
+        ninja AtomVM atomvmlib erlang_test_modules test_etest test_alisp test_estdlib test_eavmlib
+
+    - name: "Perform CodeQL Analysis"
+      uses: github/codeql-action/analyze@95e58e9a2cdfd71adc6e0353d5c52f41a045d225 # v4
+
+    - name: Upload AtomVM and test modules
+      uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+      with:
+        name: atomvm-and-test-modules
+        path: |
+            build/**/*.avm
+            build/**/*.beam
+            build/src/AtomVM
+        retention-days: 1
+
+  wasi_build_and_test:
+    needs: compile_tests
+    runs-on: ubuntu-24.04
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          # No SMP, no networking - minimal stable target.
+          - target: wasm32-wasip1
+            disable_smp: ON
+            wasmtime_flags: ""
+          # SMP via wasi-threads, no networking. Needs shared-memory in wasmtime.
+          - target: wasm32-wasip1-threads
+            disable_smp: OFF
+            wasmtime_flags: "-W threads -W shared-memory -S threads"
+          # No SMP, networking via wasi:sockets@0.2.x - exercises BSD sockets and SSL.
+          - target: wasm32-wasip2
+            disable_smp: ON
+            wasmtime_flags: "-S inherit-network -S allow-ip-name-lookup"
+
+    steps:
+    - name: Checkout repo
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+    - name: Install required packages
+      run: sudo apt-get update -y && sudo apt-get install -y cmake ninja-build gperf
+
+    - name: Install WASI SDK
+      run: |
+        set -euo pipefail
+        WASI_SDK_VERSION=33
+        wget -q "https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-${WASI_SDK_VERSION}/wasi-sdk-${WASI_SDK_VERSION}.0-x86_64-linux.tar.gz"
+        sudo mkdir -p /opt/wasi-sdk
+        sudo tar xzf "wasi-sdk-${WASI_SDK_VERSION}.0-x86_64-linux.tar.gz" --strip-components=1 -C /opt/wasi-sdk
+
+    - name: Install wasmtime
+      run: |
+        set -euo pipefail
+        WASMTIME_VERSION=44.0.1
+        WASMTIME_TARBALL="wasmtime-v${WASMTIME_VERSION}-x86_64-linux.tar.xz"
+        WASMTIME_SHA256="afd58715f105e3a7f454169daed22168c5736ec5f225fb04c4ac62c54c9508a3"
+        wget -q "https://github.com/bytecodealliance/wasmtime/releases/download/v${WASMTIME_VERSION}/${WASMTIME_TARBALL}"
+        echo "${WASMTIME_SHA256}  ${WASMTIME_TARBALL}" | sha256sum -c -
+        sudo mkdir -p /opt/wasmtime
+        sudo tar xf "${WASMTIME_TARBALL}" --strip-components=1 -C /opt/wasmtime
+        echo "/opt/wasmtime" >> $GITHUB_PATH
+
+    - name: Build (${{ matrix.target }})
+      working-directory: ./src/platforms/wasi/
+      run: |
+        set -euo pipefail
+        mkdir build
+        cd build
+        cmake -G Ninja \
+              -DCMAKE_TOOLCHAIN_FILE=../wasi-sdk.cmake \
+              -DAVM_DISABLE_JIT=ON \
+              -DAVM_DISABLE_SMP=${{ matrix.disable_smp }} \
+              -DWASI_TARGET=${{ matrix.target }} \
+              ..
+        ninja
+
+    - name: Download AtomVM and test modules
+      uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+      with:
+        name: atomvm-and-test-modules
+        path: build
+
+    - name: Test (${{ matrix.target }})
+      working-directory: ./build
+      run: |
+        set -euxo pipefail
+        WASM=../src/platforms/wasi/build/src/AtomVM.wasm
+        FLAGS="${{ matrix.wasmtime_flags }}"
+        wasmtime run ${FLAGS} --dir=. ${WASM} tests/libs/alisp/test_alisp.avm
+        wasmtime run ${FLAGS} --dir=. ${WASM} tests/libs/estdlib/test_estdlib.avm
+        wasmtime run ${FLAGS} --dir=. ${WASM} tests/libs/etest/test_etest.avm
+        wasmtime run ${FLAGS} --dir=. ${WASM} tests/libs/eavmlib/test_eavmlib.avm
+
+    - name: "Rename and write sha256sum"
+      if: startsWith(github.ref, 'refs/tags/')
+      working-directory: src/platforms/wasi/build/src
+      run: |
+        ATOMVM_WASM=AtomVM-${{ matrix.target }}-${{ github.ref_name }}.wasm
+        mv AtomVM.wasm "${ATOMVM_WASM}"
+        sha256sum "${ATOMVM_WASM}" > "${ATOMVM_WASM}.sha256"
+
+    - name: "Release"
+      uses: softprops/action-gh-release@b4309332981a82ec1c5618f44dd2e27cc8bfbfda # v3.0.0
+      if: startsWith(github.ref, 'refs/tags/')
+      with:
+        draft: true
+        fail_on_unmatched_files: true
+        files: |
+          src/platforms/wasi/build/src/AtomVM-${{ matrix.target }}-${{ github.ref_name }}.wasm
+          src/platforms/wasi/build/src/AtomVM-${{ matrix.target }}-${{ github.ref_name }}.wasm.sha256
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -19,6 +19,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added UART API to rp2 platform
 - Added `"USB_SERIAL_JTAG"` peripheral to the ESP32 `uart` module on chips with a built-in
   USB-Serial-JTAG controller (C3/C5/C6/C61/H2/H21/H4/P4/S3)
+- Added WASI platform, with `wasm32-wasip1` (no SMP, no networking),
+  `wasm32-wasip1-threads` (SMP, no networking) and `wasm32-wasip2` (no SMP,
+  networking via `wasi:sockets@0.2.x`) target triples
 
 ### Changed
 - Updated network type db() to dbm() to reflect the actual representation of the type
@@ -38,6 +41,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   longer lines return `{error, {parser, {line_too_long, Prefix}}}` with the first 128 bytes of
   the offending line. Callers whose upstream servers emit unusually large headers must account
   for this limit
+- `socket:setopt(Socket, {socket, reuseaddr}, _Value)` and
+  `socket:setopt(Socket, {socket, linger}, _Value)` are accepted on platforms
+  that do not implement the options
 
 ### Removed
 - Removed `ahttp_client` support for obsolete line folding (RFC 9112 §5.2); folded header and
@@ -55,6 +61,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed a bug in `supervisor` handling of failing child
 - Fixed two bugs related to closing fds in `atomvm:subprocess/4`
 - Fixed `erlang:localtime/1` memory leak, use-after-free, and TZ restore bugs on newlib/picolibc
+- `socket:recv/3` and `socket:recvfrom/3` now tolerate spurious select wakeups
+- `gen_tcp_socket` and `gen_udp_socket` no longer leak `pending_selects` entries
+- `socket:send/2` and `socket:sendto/3` now wait via select
+- `socket:bind`, `socket:listen`, `socket:accept`, `socket:connect`,
+  `socket:shutdown`, `socket:sockname`, `socket:peername`, `socket:recv`,
+  `socket:recvfrom`, `socket:send` and `socket:sendto` operating on a fd
+  that was already closed by another process now return `{error, closed}`
+  rather than `{error, ebadf}`
+- `gen_tcp_socket` and `gen_udp_socket` now return proper result (`ok` or
+  `{error, closed}`) when the underlying process exited.
 
 ## [0.7.0-alpha.1] - 2026-04-06
 

diff --git a/README.Md b/README.Md
@@ -20,6 +20,7 @@ Supported Platforms
 * STM32 MCUs (with official ST HAL/LL SDK, see [stm32](https://doc.atomvm.org/main/getting-started-guide.html#getting-started-on-the-stm32-platform))
 * Raspberry Pi Pico and Pico 2 (see [rp2](https://doc.atomvm.org/main/getting-started-guide.html#getting-started-on-the-raspberry-pi-pico-platform))
 * Browsers and NodeJS with WebAssembly (see [emscripten](https://doc.atomvm.org/main/getting-started-guide.html#getting-started-with-atomvm-webassembly))
+* Standalone WebAssembly runtimes such as wasmtime (see [wasi](https://doc.atomvm.org/main/build-instructions.html#building-for-wasi))
 
 AtomVM aims to be easily portable to new platforms with a minimum effort, so additional platforms
 might be supported in a near future.
@@ -72,8 +73,9 @@ available in the documentation for
 [ESP32](https://doc.atomvm.org/main/build-instructions.html#building-for-esp32),
 [STM32](https://doc.atomvm.org/main/build-instructions.html#building-for-stm32),
 [Raspberry Pi Pico and Pico 2](https://doc.atomvm.org/main/build-instructions.html#building-for-raspberry-pi-pico)
-(rp2), and
-[WASM](https://doc.atomvm.org/main/build-instructions.html#building-for-nodejs-web) (NodeJS/Web).
+(rp2),
+[WASM](https://doc.atomvm.org/main/build-instructions.html#building-for-nodejs-web) (NodeJS/Web), and
+[WASI](https://doc.atomvm.org/main/build-instructions.html#building-for-wasi) (standalone WebAssembly).
 
 Project Status
 ==============

diff --git a/doc/src/build-instructions.md b/doc/src/build-instructions.md
@@ -20,7 +20,7 @@ The native C parts of AtomVM compile to machine code on MacOS, Linux, and FreeBS
 
 The Erlang and Elixir parts are compiled to BEAM byte-code using the Erlang (`erlc`) and Elixir compilers.  For information about specific versions of required software, see the [Release Notes](./release-notes.md).
 
-This guide provides information about how to build AtomVM for the various supported platforms (Generic UNIX, ESP32, and STM32).
+This guide provides information about how to build AtomVM for the various supported platforms (Generic UNIX, ESP32, STM32, RP2, Emscripten WASM, and WASI).
 
 ```{attention}
 In order to build AtomVM AVM files for ESP32 and STM32 platforms, you will also need to build
@@ -92,6 +92,7 @@ It is possible to use a local copy of `uf2tool` source code by setting `UF2TOOL_
 * [STM32](#building-for-stm32)
 * [RP2](#building-for-rp2) (including Pico boards)
 * [WASM](#building-for-emscripten) (NodeJS or web)
+* [WASI](#building-for-wasi) (WebAssembly System Interface, wasmtime/wasmer)
 
 ## Building for Generic UNIX
 
@@ -1218,3 +1219,103 @@ $ cd src/platforms/emscripten/tests/
 $ npm install cypress
 $ npx cypress open
 ```
+
+## Building for WASI
+
+WASI (WebAssembly System Interface) allows AtomVM to run as a pure WebAssembly module without JavaScript dependencies.  Unlike the Emscripten build, WASI targets standalone runtimes such as wasmtime, WasmEdge, and wasmer.
+
+### WASI Prerequisites
+
+* [WASI SDK](https://github.com/WebAssembly/wasi-sdk/releases) at version 33 or
+  newer recommended
+* A WASI runtime, such as [wasmtime](https://wasmtime.dev) (recommended)
+* `cmake` 3.13 or later
+* Erlang/OTP
+
+### WASI Target Modes
+
+The build supports three target triples, picked automatically from `AVM_DISABLE_SMP`. SMP and networking sit on different targets and are currently mutually exclusive:
+
+| Target triple             | SMP | Networking                         | Selection                                              |
+| ------------------------- | --- | ---------------------------------- | ------------------------------------------------------ |
+| `wasm32-wasip1-threads`   | yes | no                                 | default (`-DAVM_DISABLE_SMP=OFF`)                      |
+| `wasm32-wasip2`           | no  | yes (`wasi:sockets@0.2.x`)         | `-DAVM_DISABLE_SMP=ON`                                 |
+| `wasm32-wasip1`           | no  | no                                 | `-DAVM_DISABLE_SMP=ON -DWASI_TARGET=wasm32-wasip1`     |
+
+`erlang:system_info(system_architecture)` reports the active triple (e.g. `wasm32-wasip2`).
+
+### WASI Build Instructions
+
+Default (SMP, no networking):
+
+```shell
+$ cd src/platforms/wasi/
+$ mkdir build
+$ cd build
+$ cmake -G Ninja \
+        -DCMAKE_TOOLCHAIN_FILE=../wasi-sdk.cmake \
+        -DAVM_DISABLE_JIT=ON \
+        ..
+$ ninja
+```
+
+For networking (single-threaded `wasm32-wasip2`):
+
+```shell
+$ cmake -G Ninja \
+        -DCMAKE_TOOLCHAIN_FILE=../wasi-sdk.cmake \
+        -DAVM_DISABLE_JIT=ON \
+        -DAVM_DISABLE_SMP=ON \
+        ..
+```
+
+The WASI SDK location is detected automatically from the `WASI_SDK_PATH` environment variable, `/opt/local/libexec/wasi-sdk` (MacPorts), or `/opt/wasi-sdk`.
+
+### Running AtomVM on WASI
+
+WASI uses capability-based security.  Grant directory access with `--dir` when running:
+
+```shell
+$ wasmtime run --dir=. build/src/AtomVM.wasm myapp.avm
+```
+
+For SMP (`wasm32-wasip1-threads`) wasmtime needs the threads proposal:
+
+```shell
+$ wasmtime run -W threads -W shared-memory --dir=. build/src/AtomVM.wasm myapp.avm
+```
+
+For networking (`wasm32-wasip2`) grant socket and DNS capabilities:
+
+```shell
+$ wasmtime run -S inherit-network -S allow-ip-name-lookup --dir=. \
+    build/src/AtomVM.wasm myapp.avm
+```
+
+You can load multiple AVM or BEAM files by listing them as additional arguments:
+
+```shell
+$ wasmtime run --dir=. build/src/AtomVM.wasm myapp.avm libs/atomvmlib.avm
+```
+
+### Running tests with WASI
+
+Build the test modules first using the Generic UNIX build (see above).  Then run:
+
+```shell
+$ cd build
+$ wasmtime run --dir=. ../src/platforms/wasi/build/src/AtomVM.wasm \
+    tests/libs/alisp/test_alisp.avm
+$ wasmtime run --dir=. ../src/platforms/wasi/build/src/AtomVM.wasm \
+    tests/libs/estdlib/test_estdlib.avm
+$ wasmtime run --dir=. ../src/platforms/wasi/build/src/AtomVM.wasm \
+    tests/libs/etest/test_etest.avm
+```
+
+### WASI Platform Limitations
+
+* JIT compilation is not supported; the WebAssembly sandbox prohibits executable memory.
+* Networking requires the `wasm32-wasip2` target; the WASI Preview 1 targets (`wasm32-wasip1` and `wasm32-wasip1-threads`) have no sockets.
+* SMP requires the `wasm32-wasip1-threads` target; `wasm32-wasip2` does not provide threads.
+* Process creation (fork/exec) is not supported on any WASI target.
+* Directory access requires explicit capability grants via `--dir`.
diff --git a/doc/src/welcome-to-atomvm.md b/doc/src/welcome-to-atomvm.md
@@ -55,7 +55,7 @@ AtomVM is licensed under the terms of the [Apache2](https://www.apache.org/licen
 
 ## Source Code
 
-The [AtomVM Github Repository](https://github.com/atomvm/AtomVM) contains the AtomVM source code, including the AtomVM virtual machine and core libraries.  The AtomVM [Build Instructions](./build-instructions.md) contains instructions for building AtomVM for Generic UNIX, ESP32, and STM32 platforms.
+The [AtomVM Github Repository](https://github.com/atomvm/AtomVM) contains the AtomVM source code, including the AtomVM virtual machine and core libraries.  The AtomVM [Build Instructions](./build-instructions.md) contains instructions for building AtomVM for Generic UNIX, ESP32, STM32, RP2, Emscripten, and WASI platforms.
 
 ## Contributing