no_std support

.github/workflows/pr.yml

@@ -18,6 +18,8 @@ jobs:
     - uses: actions/checkout@v3
     - name: Add musl target
       run: rustup target add x86_64-unknown-linux-musl
+    - name: Add no_std target
+      run: rustup target add thumbv7m-none-eabi
     - name: Install musl-gcc
       run: sudo apt update && sudo apt install -y musl-tools
     - name: Format Check
@@ -26,6 +28,12 @@ jobs:
       run: cargo build -r --all-features --verbose
     - name: Build
       run: cargo build -r --verbose
+    - name: Build no_std
+      run: cd tests/ensure_no_std && cargo build -r --target thumbv7m-none-eabi
+    - name: Test no_std
+      run: cargo test -r --no-default-features
+    - name: Build only std
+      run: cargo build -r --example regorus --no-default-features --features "std"
     - name: Doc Tests
       run: cargo test -r --doc
     - name: Run tests

Cargo.toml

@@ -6,6 +6,7 @@ members = [
     "bindings/wasm",
     "bindings/java",
     "bindings/ruby/ext/regorusrb",
+    "tests/ensure_no_std",
 ]
 
 [package]
@@ -15,7 +16,7 @@ version = "0.1.5"
 edition = "2021"
 license-file = "LICENSE"
 repository = "https://github.com/microsoft/regorus"
-keywords = ["interpreter", "opa", "policy-as-code", "rego"]
+keywords = ["interpreter", "no_std", "opa", "policy-as-code", "rego"]
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
@@ -33,14 +34,15 @@ crypto = ["dep:constant_time_eq", "dep:hmac", "dep:hex", "dep:md-5", "dep:sha1",
 deprecated = []
 hex = ["dep:data-encoding"]
 http = []
-jwt = ["dep:jsonwebtoken", "dep:data-encoding"]
 glob = ["dep:wax"]
 graph = []
 jsonschema = ["dep:jsonschema"]
+jwt = ["dep:jsonwebtoken", "dep:data-encoding", "dep:itertools"]
+no_std = ["lazy_static/spin_no_std"]
 opa-runtime = []
 regex = ["dep:regex"]
 semver = ["dep:semver"]
-std = ["serde_json/std"]
+std = ["rand/std", "rand/std_rng", "serde_json/std"]
 time = ["dep:chrono", "dep:chrono-tz"]
 uuid = ["dep:uuid"]
 urlquery = ["dep:url"]
@@ -67,41 +69,62 @@ full-opa = [
     "yaml"
 ]
 
+# Features that can be used in no_std environments.
+# Note that: the spin_no_std feature in lazy_static must be specified.
+opa-no-std = [
+  "arc",
+  "base64",
+  "base64url",
+  "coverage",
+  "crypto",
+  "deprecated",
+  "graph",
+  "hex",
+  "no_std",
+  "opa-runtime",
+  "regex",
+  "semver",
+  # Configure lazy_static to use spinlocks.
+  "lazy_static/spin_no_std"
+]
+
 # This feature enables some testing utils for OPA tests.
 opa-testutil = []
+rand = ["dep:rand"]
 
 [dependencies]
-anyhow = { version = "1.0.45", default-features=false }
+anyhow = { version = "1.0.45", default-features = false }
 serde = {version = "1.0.150", default-features = false, features = ["derive", "rc"] }
-serde_json = { version = "1.0.89", default-features=false, features = ["alloc"] }
-serde_yaml = {version = "0.9.16", optional = true }
-lazy_static = "1.4.0"
-rand = "0.8.5"
-num = "0.4.1"
+serde_json = { version = "1.0.89", default-features = false, features = ["alloc"] }
+lazy_static =  { version = "1.4.0", default-features = false }
 
 # Crypto
-constant_time_eq = {version = "0.3.0", optional = true}
-hmac = {version = "0.12.1", optional = true}
-sha2 = {version= "0.10.8", optional = true}
-hex = {version = "0.4.3", optional = true}
-sha1 = {version = "0.10.6", optional = true}
-md-5 = {version = "0.10.6", optional = true}
-
-data-encoding = { version = "2.4.0", optional = true }
+constant_time_eq = {version = "0.3.0", optional = true, default-features = false }
+hmac = {version = "0.12.1", optional = true, default-features = false}
+sha2 = {version= "0.10.8", optional = true, default-features = false }
+hex = {version = "0.4.3", optional = true, default-features = false, features = ["alloc"] }
+sha1 = {version = "0.10.6", optional = true, default-features = false }
+md-5 = {version = "0.10.6", optional = true, default-features = false }
+
+data-encoding = { version = "2.4.0", optional = true, default-features=false, features = ["alloc"] }
 scientific = { version = "0.5.2" }
 
-regex = {version = "1.10.2", optional = true}
-semver = {version = "1.0.20", optional = true}
+regex = {version = "1.10.2", optional = true, default-features = false }
+semver = {version = "1.0.20", optional = true, default-features = false }
 wax = { version = "0.6.0", features = [], default-features = false, optional = true }
 url = { version = "2.5.0", optional = true }
-uuid = { version = "1.6.1", features = ["v4", "fast-rng"], optional = true }
+uuid = { version = "1.6.1", default-features = false, features = ["v4", "fast-rng"], optional = true }
 jsonschema = { version = "0.17.1", default-features = false, optional = true }
 chrono = { version = "0.4.31", optional = true }
 chrono-tz = { version = "0.8.5", optional = true }
 jsonwebtoken = { version = "9.2.0", optional = true }
-itertools = "0.12.1"
+itertools = { version = "0.12.1", default-features = false, optional = true }
+
+serde_yaml = {version = "0.9.16", default-features = false, optional = true }
+rand = { version = "0.8.5", default-features = false, optional = true } 
 
 [dev-dependencies]
+anyhow = "1.0.45"
 cfg-if = "1.0.0"
 clap = { version = "4.4.7", features = ["derive"] }
 prettydiff = { version = "0.6.4", default-features = false }
@@ -131,6 +154,12 @@ name="kata"
 harness=false
 test=false
 
+[[example]]
+name="regorus"
+harness=false
+test=false
+doctest=false
+
 [package.metadata.docs.rs]
 # To build locally:
 # RUSTDOCFLAGS="--cfg docsrs" cargo +nightly doc --all-features --no-deps

README.md

@@ -88,14 +88,14 @@ features. By default all features are enabled.
 The default build of regorus example program is 6.4M:
 ```bash
 $ cargo build -r --example regorus; strip target/release/examples/regorus; ls -lh target/release/examples/regorus
--rwxr-xr-x  1 anand  staff   6.4M Jan 19 11:23 target/release/examples/regorus*
+-rwxr-xr-x  1 anand  staff   6.3M May 11 22:03 target/release/examples/regorus*
 ```
 
 
-When all features except for `yaml` are disabled, the binary size drops down to 2.9M.
+When all default features are disabled, the binary size drops down to 1.9M.
 ```bash
-$ cargo build -r --example regorus --features "yaml" --no-default-features; strip target/release/examples/regorus; ls -lh target/release/examples/regorus
--rwxr-xr-x  1 anand  staff   2.9M Jan 19 11:26 target/release/examples/regorus*
+$ cargo build -r --example regorus --no-default-features; strip target/release/examples/regorus; ls -lh target/release/examples/regorus
+-rwxr-xr-x  1 anand  staff   1.9M May 11 22:04 target/release/examples/regorus*
 ```
 
 Regorus passes the [OPA v0.64.0 test-suite](https://www.openpolicyagent.org/docs/latest/ir/#test-suite) barring a few

examples/regorus.rs

@@ -1,7 +1,37 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-use anyhow::{bail, Result};
+use anyhow::{anyhow, bail, Result};
+
+#[allow(dead_code)]
+fn read_file(path: &String) -> Result<String> {
+    std::fs::read_to_string(path).map_err(|_| anyhow!("could not read {path}"))
+}
+
+#[allow(unused_variables)]
+fn read_value_from_yaml_file(path: &String) -> Result<regorus::Value> {
+    #[cfg(feature = "yaml")]
+    return regorus::Value::from_yaml_file(path);
+
+    #[cfg(not(feature = "yaml"))]
+    bail!("regorus has not been built with yaml support");
+}
+
+fn read_value_from_json_file(path: &String) -> Result<regorus::Value> {
+    #[cfg(feature = "std")]
+    return regorus::Value::from_json_file(path);
+
+    #[cfg(not(feature = "std"))]
+    regorus::Value::from_json_str(&read_file(path)?)
+}
+
+fn add_policy_from_file(engine: &mut regorus::Engine, path: String) -> Result<()> {
+    #[cfg(feature = "std")]
+    return engine.add_policy_from_file(path);
+
+    #[cfg(not(feature = "std"))]
+    engine.add_policy(path.clone(), read_file(&path)?)
+}
 
 fn rego_eval(
     bundles: &[String],
@@ -35,23 +65,23 @@ fn rego_eval(
                 _ => continue,
             }
 
-            engine.add_policy_from_file(entry.path())?;
+            add_policy_from_file(&mut engine, entry.path().display().to_string())?;
         }
     }
 
     // Load given files.
     for file in files.iter() {
         if file.ends_with(".rego") {
             // Read policy file.
-            engine.add_policy_from_file(file)?;
+            add_policy_from_file(&mut engine, file.clone())?;
         } else {
             // Read data file.
             let data = if file.ends_with(".json") {
-                regorus::Value::from_json_file(file)?
+                read_value_from_json_file(file)?
             } else if file.ends_with(".yaml") {
-                regorus::Value::from_yaml_file(file)?
+                read_value_from_yaml_file(file)?
             } else {
-                bail!("Unsupported data file `{file}`. Must be rego, json or yaml.")
+                bail!("Unsupported data file `{file}`. Must be rego, json or yaml.");
             };
 
             // Merge given data.
@@ -61,9 +91,9 @@ fn rego_eval(
 
     if let Some(file) = input {
         let input = if file.ends_with(".json") {
-            regorus::Value::from_json_file(&file)?
+            read_value_from_json_file(&file)?
         } else if file.ends_with(".yaml") {
-            regorus::Value::from_yaml_file(&file)?
+            read_value_from_yaml_file(&file)?
         } else {
             bail!("Unsupported input file `{file}`. Must be json or yaml.")
         };
@@ -95,8 +125,12 @@ fn rego_lex(file: String, verbose: bool) -> Result<()> {
     use regorus::unstable::*;
 
     // Create source.
+    #[cfg(feature = "std")]
     let source = Source::from_file(file)?;
 
+    #[cfg(not(feature = "std"))]
+    let source = Source::from_contents(file.clone(), read_file(&file)?)?;
+
     // Create lexer.
     let mut lexer = Lexer::new(&source);
 
@@ -122,8 +156,12 @@ fn rego_parse(file: String) -> Result<()> {
     use regorus::unstable::*;
 
     // Create source.
+    #[cfg(feature = "std")]
     let source = Source::from_file(file)?;
 
+    #[cfg(not(feature = "std"))]
+    let source = Source::from_contents(file.clone(), read_file(&file)?)?;
+
     // Create a parser and parse the source.
     let mut parser = Parser::new(&source)?;
     let ast = parser.parse()?;

scripts/pre-push

@@ -5,17 +5,27 @@
 set -eo pipefail
 
 if [ -f Cargo.toml ]; then
-   # Run precommit checks
+   # Run precommit checks.
    dir=$(dirname "${BASH_SOURCE[0]}")
    "$dir/pre-commit"
 
-   # Ensure that the public API works
+   # Ensure that the public API works.
    cargo test -r --doc
 
-   # Ensure that we can build with all features
+   # Ensure that no_std build succeeds.
+   # Build for a target that has no std available.
+   if command -v rustup > /dev/null; then
+       rustup target add thumbv7m-none-eabi
+       (cd tests/ensure_no_std; cargo build -r --target thumbv7m-none-eabi)
+   fi
+
+   # Ensure that we can build with only std.
+   cargo build -r --example regorus --no-default-features --features std
+
+   # Ensure that we can build with all features.
    cargo build -r --all-features
 
-   # Ensure that all tests pass
+   # Ensure that all tests pass.
    cargo test -r
    cargo test -r --test aci
    cargo test -r --test kata